Tag Archives: Flooding

Southward shift faces US climate by 2100

Climate change means a big shift for city dwellers worldwide. Americans can look ahead to very different cities as the US climate heads south.

LONDON, 21 February, 2019 − If the world continues to burn ever-increasing levels of fossil fuels, then life will change predictably for millions of American city dwellers as the US climate heats up. They will find conditions that will make it seem as if they have shifted south by as much as 850 kilometres.

New Yorkers will find themselves experiencing temperature and rainfall conditions appropriate to a small town in Arkansas. People from Los Angeles will discover what it is like to live, right now, on the southernmost tip of the Baja peninsula, Mexico. People in Abilene, Texas will find that it is as if they had crossed their own frontier, deep into Salinas, Mexico.

The lawmakers in Washington will have consigned themselves to conditions appropriate to Greenwood, Mississippi. Columbus, Ohio, will enjoy the climate of Jonesboro, Arkansas. Folk of Anchorage, Alaska, will find out what it feels like to live on Vancouver Sound. People of Vancouver, meanwhile, will feel as if they had crossed the border into Seattle, Washington.

This exercise in precision forecasting, published in the journal Nature Communications, has been tested in computer simulations for approximately 250 million US and Canadian citizens in 540 cities.

That is, around three quarters of all the population of the United States, and half of all Canadians, can now check the rainfall and temperature changes they can expect in one human lifetime, somewhere between 2070 and 2099.

“It is my hope that people have that ‘wow’ moment, and it sinks in for the first time the scale of the changes we’re expecting in a single generation”

There are a number of possible climate shifts, depending on whether or not 195 nations fulfil the vow made in Paris in 2015 to work to keep the average rise in global temperatures to “well below” 2°C by 2100.

In fact, President Trump has announced a US withdrawal from the Paris Agreement, and many of the nations that stand by the promise have yet to commit to convincing action.

So researchers continue to incorporate the notorious “business-as-usual” scenario in their simulations. So far, these have already predicted a sweltering future for many US cities, with devastating consequences for electrical power supplies and ever more destructive superstorms, megadroughts and floods, with huge economic costs for American government, business and taxpayers.

And, other researchers have found, climate change may already be at work: there is evidence that the division between the more arid American West and the more fertile eastern states has begun to shift significantly.

Long trip south

So the latest research could prove another way of bringing home to US citizens some of the challenges ahead.

“Under current high emissions, the average urban dweller is going to have to drive more than 500 miles (850 kms) to the south to find a climate like that expected in their home city by 2080. Not only is climate changing, but climates that don’t presently exist in North America will be prevalent in a lot of urban areas,” said Matt Fitzpatrick, of the University of Maryland, who led the study.

“Within the lifetime of children living today, the climate of many regions is projected to change from the familiar to conditions unlike those experienced in the same place by their parents, grandparents or perhaps any generation in millennia,” he said.

“It is my hope that people have that ‘wow’ moment, and it sinks in for the first time the scale of the changes we’re expecting in a single generation.” − Climate News Network

Climate change means a big shift for city dwellers worldwide. Americans can look ahead to very different cities as the US climate heads south.

LONDON, 21 February, 2019 − If the world continues to burn ever-increasing levels of fossil fuels, then life will change predictably for millions of American city dwellers as the US climate heats up. They will find conditions that will make it seem as if they have shifted south by as much as 850 kilometres.

New Yorkers will find themselves experiencing temperature and rainfall conditions appropriate to a small town in Arkansas. People from Los Angeles will discover what it is like to live, right now, on the southernmost tip of the Baja peninsula, Mexico. People in Abilene, Texas will find that it is as if they had crossed their own frontier, deep into Salinas, Mexico.

The lawmakers in Washington will have consigned themselves to conditions appropriate to Greenwood, Mississippi. Columbus, Ohio, will enjoy the climate of Jonesboro, Arkansas. Folk of Anchorage, Alaska, will find out what it feels like to live on Vancouver Sound. People of Vancouver, meanwhile, will feel as if they had crossed the border into Seattle, Washington.

This exercise in precision forecasting, published in the journal Nature Communications, has been tested in computer simulations for approximately 250 million US and Canadian citizens in 540 cities.

That is, around three quarters of all the population of the United States, and half of all Canadians, can now check the rainfall and temperature changes they can expect in one human lifetime, somewhere between 2070 and 2099.

“It is my hope that people have that ‘wow’ moment, and it sinks in for the first time the scale of the changes we’re expecting in a single generation”

There are a number of possible climate shifts, depending on whether or not 195 nations fulfil the vow made in Paris in 2015 to work to keep the average rise in global temperatures to “well below” 2°C by 2100.

In fact, President Trump has announced a US withdrawal from the Paris Agreement, and many of the nations that stand by the promise have yet to commit to convincing action.

So researchers continue to incorporate the notorious “business-as-usual” scenario in their simulations. So far, these have already predicted a sweltering future for many US cities, with devastating consequences for electrical power supplies and ever more destructive superstorms, megadroughts and floods, with huge economic costs for American government, business and taxpayers.

And, other researchers have found, climate change may already be at work: there is evidence that the division between the more arid American West and the more fertile eastern states has begun to shift significantly.

Long trip south

So the latest research could prove another way of bringing home to US citizens some of the challenges ahead.

“Under current high emissions, the average urban dweller is going to have to drive more than 500 miles (850 kms) to the south to find a climate like that expected in their home city by 2080. Not only is climate changing, but climates that don’t presently exist in North America will be prevalent in a lot of urban areas,” said Matt Fitzpatrick, of the University of Maryland, who led the study.

“Within the lifetime of children living today, the climate of many regions is projected to change from the familiar to conditions unlike those experienced in the same place by their parents, grandparents or perhaps any generation in millennia,” he said.

“It is my hope that people have that ‘wow’ moment, and it sinks in for the first time the scale of the changes we’re expecting in a single generation.” − Climate News Network

Global water supply shrinks in rainier world

The global water supply is dwindling, even though rainfall is heavier. Once again, climate change is to blame.

LONDON, 20 December, 2018 – Even in a world with more intense rain, communities could begin to run short of water. New research has confirmed that, in a warming world, extremes of drought have begun to diminish the world’s groundwater – and ever more intense rainstorms will do little to make up the loss in the global water supply.

And a second, separate study delivers support for this seeming paradox: worldwide, there is evidence that rainfall patterns are, increasingly, being disturbed. The number of record-dry months has increased overall. And so has the number of record-breaking rainy months.

Both studies match predictions in a world of climate change driven by ever-higher ratios of greenhouse gases in the atmosphere, from ever-increasing combustion of fossil fuels. But, unlike many climate studies, neither of these is based on computer simulation of predicted change.

Each is instead based on the meticulous analysis of huge quantities of on-the-ground data. Together they provide substance to a 40-year-old prediction of climate change research: that in a warming world, those regions already wet will get ever more rain, while the drylands will tend to become increasingly more arid.

As global temperatures creep up – and they have already risen by 1°C in the past century, and could be set to reach 3°C by 2100 – so does the capacity of the atmosphere to absorb more moisture. It follows that more rain must fall. But at the same time more groundwater evaporates, and the risk of damaging drought increases.

“What we did not expect, despite all the extra rain everywhere in the world, is that the large rivers are drying out”

Australian scientists report in the journal Water Resources Research that they studied readings from 43,000 rainfall stations and 5,300 river monitoring sites in 160 countries. And they confirm that even in a world of more intense rain, drought could become the new normal in those regions already at risk.

“This is something that has been missed. We expected rainfall to increase, since warmer air stores more moisture – and that is what climate models predicted too,” said Ashish Sharma, an environmental engineer at the University of New South Wales.

“What we did not expect, despite all the extra rain everywhere in the world, is that the large rivers are drying out. We believe the cause is the drying of soils in our catchments. Where once these were moist before a storm event – allowing excess rainfall to run off into rivers – they are now drier and soak up more rain, so less water makes it as flow.”

The study matches predictions. Just in the last few months, climate scientists have warned that catastrophic climate change could be on the way, and that the double hazard of heat waves and sustained drought could devastate harvests in more than one climatic zone in the same season; and that those landlocked rainfall catchment areas that are already dry are becoming increasingly more parched.

But over the same few months, researchers have established repeatedly that tomorrow’s storms will be worse and that more devastating flash floods can be expected even in one of the world’s driest continents, Australia itself.

Less water available

Of all rainfall, only 36% gets into aquifers, streams and lakes. The remaining two thirds seeps into the soils, grasslands and woodlands. But more soil evaporation means less water is available from river supplies for cities and farms.

US researchers have already confirmed that if soils are moist before a storm, 62% of rainfall leads to floods that fill catchments. If soils are dry, only 13% of the rain leads to flooding.

“It’s a double whammy. Less water is ending up where we can’t store it for later use. At the same time, more rain is overwhelming drainage infrastructure in towns and cities, leading to more urban flooding,” said Professor Sharma.

“Small floods are very important for water supply, because they refill dams and form the basis of our water supply. But they’re happening less often, because the soils are sucking up extra rain. Even when a major storm dumps a lot of rain, the soils are so dry they absorb more water than before, and less reaches the rivers and reservoirs”, he said. “We need to adapt to this emerging reality.”

In the second close look at change so far, researchers based in Germany report in the journal Geophysical Research Letters  that they analysed data from 50,000 weather stations worldwide to measure rainfall on a monthly basis.

Climate drives aridity

The US has seen a more than 25% increase of record wet months in the eastern and central regions between 1980 and 2013. Argentina has seen a 32% increase. In central and northern Europe the increase is between 19% and 37%; in Asian Russia, it has been about 20%.

But in Africa south of the Sahara the incidence of very dry months has increased by 50%. “This implies that approximately one out of three record dry months in this region would not have occurred without long-term climate change,” said Dim Coumou, of the Potsdam Institute for Climate Impact Research.

“Generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid- to high-latitudes more wet records. This largely fits the patterns that scientists expect from human-caused climate change.”

His colleague and lead author Jascha Lehmann said: “Normally, record weather events occur by chance and we know how many would happen in a climate without warning. It’s like throwing a dice: on average one out of six times you get a six.

“But by injecting huge amounts of greenhouse gases into the atmosphere, humankind has loaded the dice. In many regions, we throw sixes much more often, with severe impacts for society and the environment.

“It is worrying that we see significant increases of such extremes with just one degree of global warming.” – Climate News Network

The global water supply is dwindling, even though rainfall is heavier. Once again, climate change is to blame.

LONDON, 20 December, 2018 – Even in a world with more intense rain, communities could begin to run short of water. New research has confirmed that, in a warming world, extremes of drought have begun to diminish the world’s groundwater – and ever more intense rainstorms will do little to make up the loss in the global water supply.

And a second, separate study delivers support for this seeming paradox: worldwide, there is evidence that rainfall patterns are, increasingly, being disturbed. The number of record-dry months has increased overall. And so has the number of record-breaking rainy months.

Both studies match predictions in a world of climate change driven by ever-higher ratios of greenhouse gases in the atmosphere, from ever-increasing combustion of fossil fuels. But, unlike many climate studies, neither of these is based on computer simulation of predicted change.

Each is instead based on the meticulous analysis of huge quantities of on-the-ground data. Together they provide substance to a 40-year-old prediction of climate change research: that in a warming world, those regions already wet will get ever more rain, while the drylands will tend to become increasingly more arid.

As global temperatures creep up – and they have already risen by 1°C in the past century, and could be set to reach 3°C by 2100 – so does the capacity of the atmosphere to absorb more moisture. It follows that more rain must fall. But at the same time more groundwater evaporates, and the risk of damaging drought increases.

“What we did not expect, despite all the extra rain everywhere in the world, is that the large rivers are drying out”

Australian scientists report in the journal Water Resources Research that they studied readings from 43,000 rainfall stations and 5,300 river monitoring sites in 160 countries. And they confirm that even in a world of more intense rain, drought could become the new normal in those regions already at risk.

“This is something that has been missed. We expected rainfall to increase, since warmer air stores more moisture – and that is what climate models predicted too,” said Ashish Sharma, an environmental engineer at the University of New South Wales.

“What we did not expect, despite all the extra rain everywhere in the world, is that the large rivers are drying out. We believe the cause is the drying of soils in our catchments. Where once these were moist before a storm event – allowing excess rainfall to run off into rivers – they are now drier and soak up more rain, so less water makes it as flow.”

The study matches predictions. Just in the last few months, climate scientists have warned that catastrophic climate change could be on the way, and that the double hazard of heat waves and sustained drought could devastate harvests in more than one climatic zone in the same season; and that those landlocked rainfall catchment areas that are already dry are becoming increasingly more parched.

But over the same few months, researchers have established repeatedly that tomorrow’s storms will be worse and that more devastating flash floods can be expected even in one of the world’s driest continents, Australia itself.

Less water available

Of all rainfall, only 36% gets into aquifers, streams and lakes. The remaining two thirds seeps into the soils, grasslands and woodlands. But more soil evaporation means less water is available from river supplies for cities and farms.

US researchers have already confirmed that if soils are moist before a storm, 62% of rainfall leads to floods that fill catchments. If soils are dry, only 13% of the rain leads to flooding.

“It’s a double whammy. Less water is ending up where we can’t store it for later use. At the same time, more rain is overwhelming drainage infrastructure in towns and cities, leading to more urban flooding,” said Professor Sharma.

“Small floods are very important for water supply, because they refill dams and form the basis of our water supply. But they’re happening less often, because the soils are sucking up extra rain. Even when a major storm dumps a lot of rain, the soils are so dry they absorb more water than before, and less reaches the rivers and reservoirs”, he said. “We need to adapt to this emerging reality.”

In the second close look at change so far, researchers based in Germany report in the journal Geophysical Research Letters  that they analysed data from 50,000 weather stations worldwide to measure rainfall on a monthly basis.

Climate drives aridity

The US has seen a more than 25% increase of record wet months in the eastern and central regions between 1980 and 2013. Argentina has seen a 32% increase. In central and northern Europe the increase is between 19% and 37%; in Asian Russia, it has been about 20%.

But in Africa south of the Sahara the incidence of very dry months has increased by 50%. “This implies that approximately one out of three record dry months in this region would not have occurred without long-term climate change,” said Dim Coumou, of the Potsdam Institute for Climate Impact Research.

“Generally, land regions in the tropics and sub-tropics have seen more dry records, and the northern mid- to high-latitudes more wet records. This largely fits the patterns that scientists expect from human-caused climate change.”

His colleague and lead author Jascha Lehmann said: “Normally, record weather events occur by chance and we know how many would happen in a climate without warning. It’s like throwing a dice: on average one out of six times you get a six.

“But by injecting huge amounts of greenhouse gases into the atmosphere, humankind has loaded the dice. In many regions, we throw sixes much more often, with severe impacts for society and the environment.

“It is worrying that we see significant increases of such extremes with just one degree of global warming.” – Climate News Network

Hotter climate will cost Europe dear

Unrestrained global warming and a hotter climate will cost Europe dear in lives lost and economies squeezed. Even if it’s limited, there’ll be a price to pay.

LONDON, 23 November, 2018 – The continent must brace itself for the big heat: a hotter climate will cost Europe dear if average global temperatures soar by 3°C near the end of the century, when heat extremes could claim an additional 132,000 deaths a year.

Labour productivity in some southern European countries could fall by 10 to 15%. As sea levels rise, there could be a five-fold increase in coastal flood damage, to affect more than 2 million people and wreak economic tolls of €60 billion (US$68 bn) a year.

As extremes of rainfall increase, swollen rivers could expose three times as many people to inland flooding, and the damage from river floods could rise from €5.3m a year to €17.5m.

If, on the other hand, the world keeps the promise it made to itself in Paris in 2015, and contains global warming to 2°C or less by the century’s end, coastal flooding – which already affects 100,000 people and costs €1.25 bn a year – will affect only an estimated 436,000 and total €6 bn a year in annual damage.

Grim appraisal

But right now the world is on course to tip 3°C by the century’s end, and a new study by the European Commission’s joint research centre has made a sombre assessment of the likely costs.

There will be significant shifts in the times at which seeds sprout, flowers bloom and crops ripen, with big changes in soil water: this is going to affect agricultural productivity. Europe’s arid climate zone is expected to double in area.

Demand for energy to heat homes and offices is likely to fall, but any gains will be wiped out by a rapid rise in energy demand to cool cities and towns. Northern Europe can expect to get wetter, but some parts of southern Europe will, increasingly, face drought and water shortages.

Some of the forecasts are not new: researchers have repeatedly examined the impact of climate change on European harvests, and of sea level rise, for instance, on European coastal cities.

Terse summary

The latest report, labelled with the acronym Peseta III, presents a wider picture of change. It has been four years in the making, and is the product of consultation with experts in economics, biology, physics and engineering: its opening abstract says it all in three pithy sentences.

“The study assesses how climate change could affect Europe in eleven impact areas. Under a high warming scenario, several climate impacts show a clear geographical north-south divide. Most of the welfare losses, assessed for six impact areas, would be greatly reduced under a 2°C scenario.”

It attempts to put a crude measurement on the consumer cost to Europe’s economic welfare of various levels of possible climate change, and the headline figure is that 3°C warming could impose losses on the European Union nations of 1.9% of gross domestic product, or €240bn a year.

But this is an understatement “because key climate impacts cannot be quantified,” the researchers say. And once again, losses would be considerably lower if warming was contained to within 2°C.

Some winners

Under a lower warming regime, there could even be some benefits: Eastern Europe in particular could expect to see measurably higher agricultural yields, especially of wheat and maize.

In southern Europe, which will be both drier and warmer, yields are expected to decline. Irrigation may not be the answer: the harvest from irrigated fields is likely to start showing a decline by the mid-2030s.

By 2050, crop prices are likely to be depressed by the impacts of climate change. In effect, farmers could expect lower output, and on top of that, lower incomes per unit of output.

And these calculations do not include the direct impact of weather extremes – the heatwaves that shrivel seedlings, the hailstorms and high winds that damage blossom and so on – that are likely to be amplified by overall global warming.

“Under a high warming scenario, several climate impacts show a clear geographical north-south divide. Most of the welfare losses … would be greatly reduced under a 2°C scenario”

Transport, too, will be at the mercy of ever more intense and more frequent extremes of weather. By the century’s end, 200 airports and 850 seaports – large and small – could be affected by flooding from either rising sea levels or heavier downpours.

And the Mediterranean climate zone – with its unique mix of habitat, ground cover, biodiversity and crops – would become increasingly vulnerable to droughts, fires, pests and invasive alien species.

Labour productivity will fall, especially in the south, and in some places employers might have to plan to shift some work to the cooler night, with the additional costs of chronic fatigue, anxiety and depression associated with night work.

At 3°C, heat extremes could lead to additional deaths per year up to 132,000. But even at 2°C this figure could soar to 58,000 extra deaths per year. – Climate News Network

Unrestrained global warming and a hotter climate will cost Europe dear in lives lost and economies squeezed. Even if it’s limited, there’ll be a price to pay.

LONDON, 23 November, 2018 – The continent must brace itself for the big heat: a hotter climate will cost Europe dear if average global temperatures soar by 3°C near the end of the century, when heat extremes could claim an additional 132,000 deaths a year.

Labour productivity in some southern European countries could fall by 10 to 15%. As sea levels rise, there could be a five-fold increase in coastal flood damage, to affect more than 2 million people and wreak economic tolls of €60 billion (US$68 bn) a year.

As extremes of rainfall increase, swollen rivers could expose three times as many people to inland flooding, and the damage from river floods could rise from €5.3m a year to €17.5m.

If, on the other hand, the world keeps the promise it made to itself in Paris in 2015, and contains global warming to 2°C or less by the century’s end, coastal flooding – which already affects 100,000 people and costs €1.25 bn a year – will affect only an estimated 436,000 and total €6 bn a year in annual damage.

Grim appraisal

But right now the world is on course to tip 3°C by the century’s end, and a new study by the European Commission’s joint research centre has made a sombre assessment of the likely costs.

There will be significant shifts in the times at which seeds sprout, flowers bloom and crops ripen, with big changes in soil water: this is going to affect agricultural productivity. Europe’s arid climate zone is expected to double in area.

Demand for energy to heat homes and offices is likely to fall, but any gains will be wiped out by a rapid rise in energy demand to cool cities and towns. Northern Europe can expect to get wetter, but some parts of southern Europe will, increasingly, face drought and water shortages.

Some of the forecasts are not new: researchers have repeatedly examined the impact of climate change on European harvests, and of sea level rise, for instance, on European coastal cities.

Terse summary

The latest report, labelled with the acronym Peseta III, presents a wider picture of change. It has been four years in the making, and is the product of consultation with experts in economics, biology, physics and engineering: its opening abstract says it all in three pithy sentences.

“The study assesses how climate change could affect Europe in eleven impact areas. Under a high warming scenario, several climate impacts show a clear geographical north-south divide. Most of the welfare losses, assessed for six impact areas, would be greatly reduced under a 2°C scenario.”

It attempts to put a crude measurement on the consumer cost to Europe’s economic welfare of various levels of possible climate change, and the headline figure is that 3°C warming could impose losses on the European Union nations of 1.9% of gross domestic product, or €240bn a year.

But this is an understatement “because key climate impacts cannot be quantified,” the researchers say. And once again, losses would be considerably lower if warming was contained to within 2°C.

Some winners

Under a lower warming regime, there could even be some benefits: Eastern Europe in particular could expect to see measurably higher agricultural yields, especially of wheat and maize.

In southern Europe, which will be both drier and warmer, yields are expected to decline. Irrigation may not be the answer: the harvest from irrigated fields is likely to start showing a decline by the mid-2030s.

By 2050, crop prices are likely to be depressed by the impacts of climate change. In effect, farmers could expect lower output, and on top of that, lower incomes per unit of output.

And these calculations do not include the direct impact of weather extremes – the heatwaves that shrivel seedlings, the hailstorms and high winds that damage blossom and so on – that are likely to be amplified by overall global warming.

“Under a high warming scenario, several climate impacts show a clear geographical north-south divide. Most of the welfare losses … would be greatly reduced under a 2°C scenario”

Transport, too, will be at the mercy of ever more intense and more frequent extremes of weather. By the century’s end, 200 airports and 850 seaports – large and small – could be affected by flooding from either rising sea levels or heavier downpours.

And the Mediterranean climate zone – with its unique mix of habitat, ground cover, biodiversity and crops – would become increasingly vulnerable to droughts, fires, pests and invasive alien species.

Labour productivity will fall, especially in the south, and in some places employers might have to plan to shift some work to the cooler night, with the additional costs of chronic fatigue, anxiety and depression associated with night work.

At 3°C, heat extremes could lead to additional deaths per year up to 132,000. But even at 2°C this figure could soar to 58,000 extra deaths per year. – Climate News Network

Climate impacts will seldom strike singly

Climate impacts aren’t just potentially catastrophic: they could be simultaneous multiple disasters. US scientists have compiled a catalogue of calamity and a map of mayhem.

LONDON, 20 November, 2019 − By 2100, climate impacts will be felt by everyone and most people will experience at least three simultaneous hazards, inexorably made more hazardous by the build-up of greenhouse gases in the atmosphere.

And they could be the lucky ones: some people could be menaced by six different kinds of warming-related hazard simultaneously.

Camilo Mora of the University of Hawaii at Manoa and 22 colleagues report in Nature Climate Change that they read systematically through 3,280 peer-reviewed papers on the subject of climate change, and compiled a matrix of 467 ways in which 10 major climate hazards – floods, droughts, heat waves, fires and so on – and six aspects of human dependency (health, food, water, etc.) could affect humanity.

They did, they say, identify some positive or neutral effects, but the overwhelming majority of climate impacts would create problems for human communities and their economies.

Medical prospects

Dr Mora has established a reputation for thinking on the scale of global catalogue. Recently, the geographer and his fellow researchers looked at medical records and heat extremes and listed 27 different ways in which heat waves could kill.

In recent years he has been involved in studies that have tried to measure the challenge to the global harvest because of carbon dioxide accretion in the atmosphere as a consequence of fossil fuel combustion; the first years in which particular locations around the world could feel the impact of irreversible climate change; and then the proportion of humans at risk from heat extremes by the end of the century.

The latest study concludes that even if greenhouse gas emissions are dramatically reduced, most of the world would still be confronted by one hazard at a time: the worldwide average temperature rise of 1°C has already started to change climates and heighten climatic extremes.

And if humans go on burning fossil fuels in what has become notorious as the business-as-usual scenario, then almost everybody could face three hazards at the same time. In some coastal regions some people could be hit by six.

“The evidence of climate change impacting humanity is abundant, loud and clear … How many wake-up calls will it take to wake up?”

Higher atmospheric temperatures accelerate the evaporation of soil water. Normally dry places will be at risk of drought, heatwave and wildfire. Normally rainy places will face catastrophic downpour, and flood. Warmer ocean waters will evaporate at greater rates, so windspeed and rainfall from hurricanes will also increase. Sea level rise driven by water temperatures, and by glacial melting, will raise the risk of coastal flooding and storm surges.

Some of these impacts have already affected human health, bringing death, disease and mental illness. They have affected the supply of food on land and at sea; they have damaged electrical supplies, transportation, water and sewage infrastructure; they have damaged property and reduced labour productivity; they have triggered migration and sparked violence, and Dr Mora and his colleagues have now compiled a database of more than 3,000 documented examples.

“Greenhouse gas emissions pose a broad threat to humanity by simultaneously intensifying many hazards that have proved harmful in the past,” said Dr Mora.

“Further, we predict that by 2100 the number of hazards occurring concurrently will increase, making it even more difficult for people to cope.”

List of impacts

The latest study simply looks at all the recent climate impacts recorded and assessed and categorises them in a range of ways.

These include the 33% loss of grain to drought and fire in Russia in 2010; the loss of three-fourths of all livestock during drought in Kenya in 2000; drinking water shortages for 33 million people in China in 2001; the rise in waterborne infectious diseases after the 2010 Indus floods overwhelmed sewage treatment plants in Pakistan; the cumulative damage by flood and storm to millions of homes in China, Pakistan, Bangladesh, Indonesia, the US and France; and – because of melting ice – the forced relocation of Inuit villages in Alaska.

Heatwaves caused blackouts for 670 million people in India in 2012, and 35 million in Saudi Arabia in 2010. After Hurricane Andrew in 1992 hammered the US east coast, a total of 12 insurance companies went bust.

The next step, having assembled the possible kinds of impact, was to model the way they would be amplified and intensified under various scenarios for global warming. Wealth and economic power offer no great protection. New York can expect at worst by 2100 to face at least four hazards; Sydney and Los Angeles three; Mexico City four, and the Atlantic coast of Brazil five.

Present danger

“The collision of cumulative climate hazards is not something on the horizon, it is already here,” Dr Mora said. “Co-occurring and colliding climate hazards are already making headlines worldwide.

“Last year, for instance, Florida recorded extreme drought, record high temperatures, over 100 wildfires, and the strongest-ever recorded hurricane in its Panhandle: the category 4 Hurricane Michael.

“Likewise, California is currently experiencing ferocious wild fires and one of the longest droughts, plus extreme heatwaves this past summer.”

“The evidence of climate change impacting humanity is abundant, loud and clear”, said his co-author and colleague Daniele Spirandelli. “Clearly, the outstanding question is − how many wake-up calls will it take to wake up?” − Climate News Network

Climate impacts aren’t just potentially catastrophic: they could be simultaneous multiple disasters. US scientists have compiled a catalogue of calamity and a map of mayhem.

LONDON, 20 November, 2019 − By 2100, climate impacts will be felt by everyone and most people will experience at least three simultaneous hazards, inexorably made more hazardous by the build-up of greenhouse gases in the atmosphere.

And they could be the lucky ones: some people could be menaced by six different kinds of warming-related hazard simultaneously.

Camilo Mora of the University of Hawaii at Manoa and 22 colleagues report in Nature Climate Change that they read systematically through 3,280 peer-reviewed papers on the subject of climate change, and compiled a matrix of 467 ways in which 10 major climate hazards – floods, droughts, heat waves, fires and so on – and six aspects of human dependency (health, food, water, etc.) could affect humanity.

They did, they say, identify some positive or neutral effects, but the overwhelming majority of climate impacts would create problems for human communities and their economies.

Medical prospects

Dr Mora has established a reputation for thinking on the scale of global catalogue. Recently, the geographer and his fellow researchers looked at medical records and heat extremes and listed 27 different ways in which heat waves could kill.

In recent years he has been involved in studies that have tried to measure the challenge to the global harvest because of carbon dioxide accretion in the atmosphere as a consequence of fossil fuel combustion; the first years in which particular locations around the world could feel the impact of irreversible climate change; and then the proportion of humans at risk from heat extremes by the end of the century.

The latest study concludes that even if greenhouse gas emissions are dramatically reduced, most of the world would still be confronted by one hazard at a time: the worldwide average temperature rise of 1°C has already started to change climates and heighten climatic extremes.

And if humans go on burning fossil fuels in what has become notorious as the business-as-usual scenario, then almost everybody could face three hazards at the same time. In some coastal regions some people could be hit by six.

“The evidence of climate change impacting humanity is abundant, loud and clear … How many wake-up calls will it take to wake up?”

Higher atmospheric temperatures accelerate the evaporation of soil water. Normally dry places will be at risk of drought, heatwave and wildfire. Normally rainy places will face catastrophic downpour, and flood. Warmer ocean waters will evaporate at greater rates, so windspeed and rainfall from hurricanes will also increase. Sea level rise driven by water temperatures, and by glacial melting, will raise the risk of coastal flooding and storm surges.

Some of these impacts have already affected human health, bringing death, disease and mental illness. They have affected the supply of food on land and at sea; they have damaged electrical supplies, transportation, water and sewage infrastructure; they have damaged property and reduced labour productivity; they have triggered migration and sparked violence, and Dr Mora and his colleagues have now compiled a database of more than 3,000 documented examples.

“Greenhouse gas emissions pose a broad threat to humanity by simultaneously intensifying many hazards that have proved harmful in the past,” said Dr Mora.

“Further, we predict that by 2100 the number of hazards occurring concurrently will increase, making it even more difficult for people to cope.”

List of impacts

The latest study simply looks at all the recent climate impacts recorded and assessed and categorises them in a range of ways.

These include the 33% loss of grain to drought and fire in Russia in 2010; the loss of three-fourths of all livestock during drought in Kenya in 2000; drinking water shortages for 33 million people in China in 2001; the rise in waterborne infectious diseases after the 2010 Indus floods overwhelmed sewage treatment plants in Pakistan; the cumulative damage by flood and storm to millions of homes in China, Pakistan, Bangladesh, Indonesia, the US and France; and – because of melting ice – the forced relocation of Inuit villages in Alaska.

Heatwaves caused blackouts for 670 million people in India in 2012, and 35 million in Saudi Arabia in 2010. After Hurricane Andrew in 1992 hammered the US east coast, a total of 12 insurance companies went bust.

The next step, having assembled the possible kinds of impact, was to model the way they would be amplified and intensified under various scenarios for global warming. Wealth and economic power offer no great protection. New York can expect at worst by 2100 to face at least four hazards; Sydney and Los Angeles three; Mexico City four, and the Atlantic coast of Brazil five.

Present danger

“The collision of cumulative climate hazards is not something on the horizon, it is already here,” Dr Mora said. “Co-occurring and colliding climate hazards are already making headlines worldwide.

“Last year, for instance, Florida recorded extreme drought, record high temperatures, over 100 wildfires, and the strongest-ever recorded hurricane in its Panhandle: the category 4 Hurricane Michael.

“Likewise, California is currently experiencing ferocious wild fires and one of the longest droughts, plus extreme heatwaves this past summer.”

“The evidence of climate change impacting humanity is abundant, loud and clear”, said his co-author and colleague Daniele Spirandelli. “Clearly, the outstanding question is − how many wake-up calls will it take to wake up?” − Climate News Network

Worse storms in prospect as warmth rises

Once again, US government scientists warn that hurricane and flood hazard is amplified by a warming world. But worse storms are caused by big cities too.

LONDON, 19 November, 2018 – Worse storms are on the way, as many Americans know all too well. Hurricane Katrina was the costliest natural disaster ever to hit the US: it blew ashore over New Orleans in August 2005 to claim at least 1,833 lives and wreak economic damage worth, in today’s prices, $160bn.

And however bad it was, climate change made it worse. Because of global warming up to that point, up to 9% more rain fell over the city, some of it to sweep away the river defences and precipitate disastrous flooding.

A second study, also in Nature, warns: big cities make bad storms even worse. Urbanisation – all those roads, pavements, rooftops and so on – multiplies the risk of flooding on average 21-fold. The growth of Houston in Texas left a city at the mercy of Hurricane Harvey in 2017: the scale of flooding was without precedent.

The research is based on computer modelling of the impact of overall planetary warming – around 1°C in the past century – on local sea and coastal conditions.

Rising economic harm

Warmer atmospheres hold more water. With each 1°C rise, the capacity to absorb moisture increases by 7% , so in a warmer world storms will be wetter. With higher temperatures, storms are likely to be more ferocious. Researchers have repeatedly warned that because of these simple principles, as global temperatures rise, the US faces ever bigger economic losses each succeeding hurricane season.

Houston wasn’t prepared for what seemed like a once-in-a-thousand-years storm, but extreme rainstorms will become even more extreme and in Texas more Harvey-scale storms are on the way.

Water that falls on forest or wetland or coastal savannah is at least partly absorbed. Hard rain that hits tarmacadam and concrete could swiftly become a flash flood. So the latest study is a confirmation of much previous research.

“Efforts to build flood mitigation strategies must use an improved understanding of the multiple processes in place”

And although President Trump has condemned climate change science as a hoax devised by the Chinese, and announced a withdrawal from the Paris Agreement signed by 195 nations to limit global warming to if possible less than 2°C by 2100, the confirmation of greater climate change danger once again comes from a US government research base, the Lawrence Berkeley National Laboratory.

Christina Patricola, of the laboratory’s climate division, reports in Nature that she and a colleague chose 15 tropical cyclones that have occurred in the last decade in the Atlantic, the Pacific and the Indian Oceans, and then built computer simulations of those storms while changing factors such as air and ocean temperatures, humidity, and the greenhouse gas concentrations that dictate overall planetary temperatures.

The two scientists looked at the effects of climate change so far, and the shape of storms to come. They found that warming hitherto has made rainfall between 5% and 10% more intense, but may not have so far made much difference to overall hurricane windspeeds.

Strengthening winds

But if the climate continues to warm – and it could warm by 3°C or more this century, as ever greater combustion of fossil fuels puts ever more carbon dioxide into the atmosphere – peak wind speeds could increase by up to 25 knots or very nearly 50 kilometres per hour.

The scientists also found that future rainfall in such storms could increase by between 15% and 35%. And the same computer models that predict windier, wetter storms tomorrow accurately predicted the pattern of the storms that had already happened. “The fact that almost all of the 15 tropical cyclones responded in a similar way gives confidence to the results,” Dr Patricola said.

In a companion study, scientists from US universities looked at the other component of the Hurricane Harvey disaster in 2017: the changes in the city of Houston itself.

Between 25 and 30 August, Harvey dumped 1.3 metres of rain on the metropolis. Between 2000 and 2011, Houston had the largest urban growth and the fifth largest population growth in the entire US. That is, it became a bigger target, with a greater area of paving and sealed surfaces to channel the flowing water.

Slower and wetter

The changing contour of the city helped increase atmospheric drag, slowing the passage of the hurricane and delaying it for long enough to drop even more rain. And then the surface of asphalt and concrete made conditions worse.

So, the researchers concluded, the new building made the risk of catastrophic flooding somewhere between hardly at all and up to 90 times more likely, depending on which part of the city they were looking at. Altogether, the risk of more flooding on the scale of Harvey had increased 21-fold.

The message is that coastal cities must plan for the worst and keep planning. Hurricane winds and rainfall are going to intensify in the future. Cities will keep on growing as human numbers increase.

“Planning must take into account the compounded nature of these risks,” they conclude, “and efforts to build flood mitigation strategies must use an improved understanding of the multiple processes in place.” – Climate News Network

Once again, US government scientists warn that hurricane and flood hazard is amplified by a warming world. But worse storms are caused by big cities too.

LONDON, 19 November, 2018 – Worse storms are on the way, as many Americans know all too well. Hurricane Katrina was the costliest natural disaster ever to hit the US: it blew ashore over New Orleans in August 2005 to claim at least 1,833 lives and wreak economic damage worth, in today’s prices, $160bn.

And however bad it was, climate change made it worse. Because of global warming up to that point, up to 9% more rain fell over the city, some of it to sweep away the river defences and precipitate disastrous flooding.

A second study, also in Nature, warns: big cities make bad storms even worse. Urbanisation – all those roads, pavements, rooftops and so on – multiplies the risk of flooding on average 21-fold. The growth of Houston in Texas left a city at the mercy of Hurricane Harvey in 2017: the scale of flooding was without precedent.

The research is based on computer modelling of the impact of overall planetary warming – around 1°C in the past century – on local sea and coastal conditions.

Rising economic harm

Warmer atmospheres hold more water. With each 1°C rise, the capacity to absorb moisture increases by 7% , so in a warmer world storms will be wetter. With higher temperatures, storms are likely to be more ferocious. Researchers have repeatedly warned that because of these simple principles, as global temperatures rise, the US faces ever bigger economic losses each succeeding hurricane season.

Houston wasn’t prepared for what seemed like a once-in-a-thousand-years storm, but extreme rainstorms will become even more extreme and in Texas more Harvey-scale storms are on the way.

Water that falls on forest or wetland or coastal savannah is at least partly absorbed. Hard rain that hits tarmacadam and concrete could swiftly become a flash flood. So the latest study is a confirmation of much previous research.

“Efforts to build flood mitigation strategies must use an improved understanding of the multiple processes in place”

And although President Trump has condemned climate change science as a hoax devised by the Chinese, and announced a withdrawal from the Paris Agreement signed by 195 nations to limit global warming to if possible less than 2°C by 2100, the confirmation of greater climate change danger once again comes from a US government research base, the Lawrence Berkeley National Laboratory.

Christina Patricola, of the laboratory’s climate division, reports in Nature that she and a colleague chose 15 tropical cyclones that have occurred in the last decade in the Atlantic, the Pacific and the Indian Oceans, and then built computer simulations of those storms while changing factors such as air and ocean temperatures, humidity, and the greenhouse gas concentrations that dictate overall planetary temperatures.

The two scientists looked at the effects of climate change so far, and the shape of storms to come. They found that warming hitherto has made rainfall between 5% and 10% more intense, but may not have so far made much difference to overall hurricane windspeeds.

Strengthening winds

But if the climate continues to warm – and it could warm by 3°C or more this century, as ever greater combustion of fossil fuels puts ever more carbon dioxide into the atmosphere – peak wind speeds could increase by up to 25 knots or very nearly 50 kilometres per hour.

The scientists also found that future rainfall in such storms could increase by between 15% and 35%. And the same computer models that predict windier, wetter storms tomorrow accurately predicted the pattern of the storms that had already happened. “The fact that almost all of the 15 tropical cyclones responded in a similar way gives confidence to the results,” Dr Patricola said.

In a companion study, scientists from US universities looked at the other component of the Hurricane Harvey disaster in 2017: the changes in the city of Houston itself.

Between 25 and 30 August, Harvey dumped 1.3 metres of rain on the metropolis. Between 2000 and 2011, Houston had the largest urban growth and the fifth largest population growth in the entire US. That is, it became a bigger target, with a greater area of paving and sealed surfaces to channel the flowing water.

Slower and wetter

The changing contour of the city helped increase atmospheric drag, slowing the passage of the hurricane and delaying it for long enough to drop even more rain. And then the surface of asphalt and concrete made conditions worse.

So, the researchers concluded, the new building made the risk of catastrophic flooding somewhere between hardly at all and up to 90 times more likely, depending on which part of the city they were looking at. Altogether, the risk of more flooding on the scale of Harvey had increased 21-fold.

The message is that coastal cities must plan for the worst and keep planning. Hurricane winds and rainfall are going to intensify in the future. Cities will keep on growing as human numbers increase.

“Planning must take into account the compounded nature of these risks,” they conclude, “and efforts to build flood mitigation strategies must use an improved understanding of the multiple processes in place.” – Climate News Network

Flash floods increase as mercury climbs

Heavy rain must fall somewhere. The danger lies in where it falls and on what kind of terrain. As cities grow, the risk of flash floods rises.

LONDON, 9 November, 2018 – Scientists once again have confirmed that humankind’s actions have triggered ever-greater extremes of rainfall – and an ever-greater rise in disastrous flash floods.

The study comes close on the heels of a warning by UN scientists of a dramatic increase in economic losses from climate-related disasters. Between 1998 and 2017, natural disasters cost the world’s nations direct losses of $2.9 trillion, and although earthquake and tsunami accounted for most deaths, floods, storms and other climate-related catastrophes accounted for 77% of the economic damage.

Scientists and engineers from China and the US report in the journal Nature Communications that flash floods now cause more deaths as well as more property and agricultural losses than any other severe weather-related hazards. These losses have been increasing for the last 50 years and over the last decade worldwide have topped $30bn a year.

And, they find, extremes in run–off from increasing extremes of rainfall are driven by what humans have done, and continue to do, to their planet: in the race for economic growth, people have burned ever more coal, oil and gas to dump ever-increasing levels of carbon dioxide emissions into the atmosphere.

Heat hazard rises

They have driven up global average temperatures by around 1°C in the last century, and without drastic action this average could reach 3°C by the century’s end.

As average temperatures rise, so does the hazard of extremes of heat. With every rise of 1°C the capacity of the atmosphere to absorb moisture rises by about 7%: higher temperatures are linked to ever-harder falls of rain. And rain that falls must go somewhere.

Moisture once naturally absorbed by forests, extensive wetlands or rich natural grasslands now increasingly lands on tarmacadam, brick, cement, tile or glass, to race down city streets, threaten ever more lives and sweep away costly homes, offices and bridges.

“Those who are suffering the most from climate change are those who are contributing least to greenhouse gas emissions”

Altogether one billion people are now settled in floodplains: the lives at risk are on the increase. And, the researchers warn, the losses will go on rising.

Most researchers have been unwilling to link specific floods directly to global warming. That cautious attitude shifted in the last few years as separate teams of climate scientists made connections between global warming and disastrous flooding and destructive storms in Europe, in India and in the US.

Australia – more often linked with extended drought and wildfire hazards than floods – has identified ever greater dangers from extreme rainfall.

The Nature study was based on decades of rainfall, run-off and temperature data collected on a daily basis and forms part of a widening search for ways to adapt to a danger that, inevitably, looks set to increase, particularly in the US.

Growth in extremes

“We were trying to find the physical mechanisms behind why precipitation and run-off extremes are increasing all over the globe,” said Jiabo Yin, a Wuhan University student working at the Earth Institute in the University of Columbia, who led the research.

“We know that precipitation and run-off extremes will increase significantly in the future, and we need to modify our infrastructures accordingly. Our study establishes a framework for investigating the runoff response.”

Altogether, according to the UN Office for Disaster Risk Reduction’s latest survey, the world experienced more than 7,000 major disasters in the last two decades: floods and storms accounted for 43% and 28.2% of them and were the most frequent kinds of disaster.

Together, such disasters claimed 1.3 million lives – almost 750,000 of these to a total of 563 earthquakes and tsunamis. An estimated 4.4 billion people were hurt, or lost their homes, or were displaced or placed in need of emergency help.

Biggest losers

The greatest economic losers were the US, with almost $945 billion, and China with $492bn. Storms, floods and earthquakes put three European nations in the top ten, with France, Germany and Italy losing around $50bn each in those two decades.

Once again, the UN study highlights the gap between rich and poor. “Those who are suffering the most from climate change are those who are contributing least to greenhouse gas emissions,” said Deberati Guha-Sapir, head of the UN’s Centre for Research on the Epidemiology of Disasters at the Catholic University of Louvain in Belgium.

“Clearly there is great room for improvement in data collection on economic losses, but we know from our analysis … that people in low income countries are six times more likely to lose all their worldly possessions or suffer injury in a disaster than people in high income countries.” – Climate News Network

Heavy rain must fall somewhere. The danger lies in where it falls and on what kind of terrain. As cities grow, the risk of flash floods rises.

LONDON, 9 November, 2018 – Scientists once again have confirmed that humankind’s actions have triggered ever-greater extremes of rainfall – and an ever-greater rise in disastrous flash floods.

The study comes close on the heels of a warning by UN scientists of a dramatic increase in economic losses from climate-related disasters. Between 1998 and 2017, natural disasters cost the world’s nations direct losses of $2.9 trillion, and although earthquake and tsunami accounted for most deaths, floods, storms and other climate-related catastrophes accounted for 77% of the economic damage.

Scientists and engineers from China and the US report in the journal Nature Communications that flash floods now cause more deaths as well as more property and agricultural losses than any other severe weather-related hazards. These losses have been increasing for the last 50 years and over the last decade worldwide have topped $30bn a year.

And, they find, extremes in run–off from increasing extremes of rainfall are driven by what humans have done, and continue to do, to their planet: in the race for economic growth, people have burned ever more coal, oil and gas to dump ever-increasing levels of carbon dioxide emissions into the atmosphere.

Heat hazard rises

They have driven up global average temperatures by around 1°C in the last century, and without drastic action this average could reach 3°C by the century’s end.

As average temperatures rise, so does the hazard of extremes of heat. With every rise of 1°C the capacity of the atmosphere to absorb moisture rises by about 7%: higher temperatures are linked to ever-harder falls of rain. And rain that falls must go somewhere.

Moisture once naturally absorbed by forests, extensive wetlands or rich natural grasslands now increasingly lands on tarmacadam, brick, cement, tile or glass, to race down city streets, threaten ever more lives and sweep away costly homes, offices and bridges.

“Those who are suffering the most from climate change are those who are contributing least to greenhouse gas emissions”

Altogether one billion people are now settled in floodplains: the lives at risk are on the increase. And, the researchers warn, the losses will go on rising.

Most researchers have been unwilling to link specific floods directly to global warming. That cautious attitude shifted in the last few years as separate teams of climate scientists made connections between global warming and disastrous flooding and destructive storms in Europe, in India and in the US.

Australia – more often linked with extended drought and wildfire hazards than floods – has identified ever greater dangers from extreme rainfall.

The Nature study was based on decades of rainfall, run-off and temperature data collected on a daily basis and forms part of a widening search for ways to adapt to a danger that, inevitably, looks set to increase, particularly in the US.

Growth in extremes

“We were trying to find the physical mechanisms behind why precipitation and run-off extremes are increasing all over the globe,” said Jiabo Yin, a Wuhan University student working at the Earth Institute in the University of Columbia, who led the research.

“We know that precipitation and run-off extremes will increase significantly in the future, and we need to modify our infrastructures accordingly. Our study establishes a framework for investigating the runoff response.”

Altogether, according to the UN Office for Disaster Risk Reduction’s latest survey, the world experienced more than 7,000 major disasters in the last two decades: floods and storms accounted for 43% and 28.2% of them and were the most frequent kinds of disaster.

Together, such disasters claimed 1.3 million lives – almost 750,000 of these to a total of 563 earthquakes and tsunamis. An estimated 4.4 billion people were hurt, or lost their homes, or were displaced or placed in need of emergency help.

Biggest losers

The greatest economic losers were the US, with almost $945 billion, and China with $492bn. Storms, floods and earthquakes put three European nations in the top ten, with France, Germany and Italy losing around $50bn each in those two decades.

Once again, the UN study highlights the gap between rich and poor. “Those who are suffering the most from climate change are those who are contributing least to greenhouse gas emissions,” said Deberati Guha-Sapir, head of the UN’s Centre for Research on the Epidemiology of Disasters at the Catholic University of Louvain in Belgium.

“Clearly there is great room for improvement in data collection on economic losses, but we know from our analysis … that people in low income countries are six times more likely to lose all their worldly possessions or suffer injury in a disaster than people in high income countries.” – Climate News Network

Weakened hurricanes may be wind farm bonus

When high winds meet tall sails in the right place, something’s got to give. Offshore wind farms may lead to weakened hurricanes.

LONDON, 23 October, 2018 − US scientists have identified yet another wonder of that icon of renewable energy, the offshore wind farm: they may result in weakened hurricanes. Turbines in the right place could not just take the heat out of a hurricane, they could reduce the risk of catastrophic flooding as well.

The prediction is based entirely on computer simulation: the US so far has just one 30MW commercial wind farm in operation with just five turbines, off the coast of Rhode Island.

But the reasoning begins from the basic laws of physics, and the answer delivers yet another argument for investment in renewable sources of energy, if only because the ferocity and destructive power of US hurricanes is set to increase with ever-greater emissions of greenhouse gases from fossil fuel combustion, and consequent ever-greater global warming.

Cristina Archer, a scientist at the University of Delaware, has already studied the ideal placing of wind turbines to extract maximum energy from the world’s winds, and more recently confirmed, with other researchers, that any hurricane that blew over a big enough marine wind farm would shed energy and hit the land with less destructive power.

“If you have arrays of wind turbines in the areas where there are hurricanes, you will likely see a reduction in precipitation inland”

It is an axiom of physics that energy is always conserved: if a turbine’s sails generate electrical energy from wind, then some of the kinetic energy of the wind must be surrendered.

Professor Archer and her colleagues report in the journal Environmental Research Letters that they took, among others, the case of Hurricane Harvey, which in 2017 deposited almost two thirds of a metre of rainwater on Houston, Texas, to cause devastating floods. They tested the behaviour of the simulated hurricane as it blew across a hypothetical barrier of from zero to 74,619 turbines.

When strong winds hit the turbines, they slow down. Wind scientists call this convergence. Winds slow, and are more likely to dump the water they hold, and then rise. Then the winds speed up again, a phenomenon known as divergence.

“Divergence is the opposite effect. It causes a downward motion, attracting air coming down, which is drier, and suppresses precipitation. I was wondering what would also happen when there is an offshore farm”, she said.

Multiple simulations

The researchers modelled a range of simulations with hypothetical wind farms staggered along the coasts of Texas and Louisiana. Hypothetical hurricanes caught up in a pattern of convergence would drop their rain before they hit the coast, and then begin divergence, which would mean that even less rain would be carried to landfall.

“By the time the air reaches the land, it’s been squeezed out of a lot of moisture,” Professor Archer said. “We got a 30% reduction of the precipitation with Harvey simulations. That means, potentially, if you have arrays of wind turbines in the areas where there are hurricanes, you will likely see a reduction in precipitation inland if the farm is there.”

This doesn’t mean that wind farms can always take the heat out of a hurricane: important factors include the hurricane’s precise track and the distance offshore of the turbines. There are no wind farms anywhere in the world with the tens of thousands of turbines modelled in the simulation: one of the world’s biggest, off Anholt Island, Denmark, has only 111 turbines.

“The more windfarms you have, the more impact they will have on a hurricane,” Professor Archer said. “By the time a hurricane actually makes a landfall, these arrays of turbines have been operating for days and days, extracting energy and moisture out of the storm. As a result, the storm will be weaker. Literally.” − Climate News Network

When high winds meet tall sails in the right place, something’s got to give. Offshore wind farms may lead to weakened hurricanes.

LONDON, 23 October, 2018 − US scientists have identified yet another wonder of that icon of renewable energy, the offshore wind farm: they may result in weakened hurricanes. Turbines in the right place could not just take the heat out of a hurricane, they could reduce the risk of catastrophic flooding as well.

The prediction is based entirely on computer simulation: the US so far has just one 30MW commercial wind farm in operation with just five turbines, off the coast of Rhode Island.

But the reasoning begins from the basic laws of physics, and the answer delivers yet another argument for investment in renewable sources of energy, if only because the ferocity and destructive power of US hurricanes is set to increase with ever-greater emissions of greenhouse gases from fossil fuel combustion, and consequent ever-greater global warming.

Cristina Archer, a scientist at the University of Delaware, has already studied the ideal placing of wind turbines to extract maximum energy from the world’s winds, and more recently confirmed, with other researchers, that any hurricane that blew over a big enough marine wind farm would shed energy and hit the land with less destructive power.

“If you have arrays of wind turbines in the areas where there are hurricanes, you will likely see a reduction in precipitation inland”

It is an axiom of physics that energy is always conserved: if a turbine’s sails generate electrical energy from wind, then some of the kinetic energy of the wind must be surrendered.

Professor Archer and her colleagues report in the journal Environmental Research Letters that they took, among others, the case of Hurricane Harvey, which in 2017 deposited almost two thirds of a metre of rainwater on Houston, Texas, to cause devastating floods. They tested the behaviour of the simulated hurricane as it blew across a hypothetical barrier of from zero to 74,619 turbines.

When strong winds hit the turbines, they slow down. Wind scientists call this convergence. Winds slow, and are more likely to dump the water they hold, and then rise. Then the winds speed up again, a phenomenon known as divergence.

“Divergence is the opposite effect. It causes a downward motion, attracting air coming down, which is drier, and suppresses precipitation. I was wondering what would also happen when there is an offshore farm”, she said.

Multiple simulations

The researchers modelled a range of simulations with hypothetical wind farms staggered along the coasts of Texas and Louisiana. Hypothetical hurricanes caught up in a pattern of convergence would drop their rain before they hit the coast, and then begin divergence, which would mean that even less rain would be carried to landfall.

“By the time the air reaches the land, it’s been squeezed out of a lot of moisture,” Professor Archer said. “We got a 30% reduction of the precipitation with Harvey simulations. That means, potentially, if you have arrays of wind turbines in the areas where there are hurricanes, you will likely see a reduction in precipitation inland if the farm is there.”

This doesn’t mean that wind farms can always take the heat out of a hurricane: important factors include the hurricane’s precise track and the distance offshore of the turbines. There are no wind farms anywhere in the world with the tens of thousands of turbines modelled in the simulation: one of the world’s biggest, off Anholt Island, Denmark, has only 111 turbines.

“The more windfarms you have, the more impact they will have on a hurricane,” Professor Archer said. “By the time a hurricane actually makes a landfall, these arrays of turbines have been operating for days and days, extracting energy and moisture out of the storm. As a result, the storm will be weaker. Literally.” − Climate News Network

Warmer climate means US faces big losses

Greenhouse gas emissions impose a social cost – in ecosystem damage, in climate extremes, in human health and wealth. The US faces big losses.

LONDON, 3 October, 2018 – Of the nations that stand to be most seriously affected by climate change, perhaps surprisingly, near the top of the list, the US faces big losses.

American and European scientists have taken a fresh look at what they call the social cost of carbon (SCC): that is, the damage that greenhouse gas emissions from fossil fuel combustion will do to world economies. And whichever way they make the country-by-country comparisons, one nation is among the world leaders in self-harm – the USA.

It is not alone: India, a rapidly-growing economy, and Saudi Arabia, one of the world’s wealthiest, join the US in the top three. China, which is now the world’s highest carbon dioxide emitter, is in the top five.

Calculations about the future economic costs of something that has yet to happen in a fast-changing world are of the kind that induce migraine, and always incorporate a wide range of possible outcomes.

The US Environmental Protection Agency has proposed that by 2020, the global costs of an additional tonne of carbon dioxide in the atmosphere could range from $12 to $62. But a new study in the journal Nature Climate Change suggests that these costs could be much higher, at approximately $180 to $800 per tonne.

“It’s surprising just how consistently the US is one of the biggest losers, even when compared to other large economies”

And the price to be paid by the US alone could be $50 per tonne. Since the US – which under President Trump has announced its intention to withdraw from a 2015 global agreement to limit greenhouse gas emissions – now emits almost five billion tonnes of CO2 a year, this could be costing the US economy about $250bn.

“We all know carbon dioxide released from burning fossil fuels affects people and ecosystems around the world, today and in the future; however, these impacts are not included in market prices, creating an environmental externality whereby consumers of fossil fuel energy do not pay for and are unaware of the true costs of their consumption,” said Katharine Ricke of the University of San Diego, who led the study.

President Trump once dismissed global warming and climate change driven by profligate fossil fuel use as a “hoax” devised by the Chinese. But US climate research – often from US government agencies such as NASA and the National Atmospheric and Oceanic Administration – has consistently warned of the potentially devastating future costs to the US.

Coastal flooding could create a new class of climate refugee within the US. Hurricanes will gain in ferocity and potential devastation. Forest fires are already on the increase.

The famously arid drylands of the US west have begun to march eastwards, and the extremes of heat and drought linked to a rise in global average warming are almost certain to cause harvest losses, all as a consequence of fossil fuel emissions. Clean energy policies, conversely, could cut air pollution and save American lives.

Assumptions reversed

The San Diego research reverses some long-standing assumptions, one of which is that while strong, rich economies benefit from fossil fuel use, the developing nations pay the highest price in the social costs of carbon, or SCCs.

The new calculations suggest much more uneven outcomes: the European Union, for instance, is likely to be less harmed by increased emissions, even though it is one of the world leaders in the attempt to combat climate change.

“Our analysis demonstrates that the argument that the primary beneficiaries of reductions in carbon dioxide emissions would be other countries is a total myth,” said Dr Ricke.

“We consistently find, through hundreds of uncertainty scenarios, that the US always has one of the highest country-level SCCs. It makes a lot of sense because the larger your economy is, the more you have to lose.

“Still, it’s surprising just how consistently the US is one of the biggest losers, even when compared to other large economies.” – Climate News Network

Greenhouse gas emissions impose a social cost – in ecosystem damage, in climate extremes, in human health and wealth. The US faces big losses.

LONDON, 3 October, 2018 – Of the nations that stand to be most seriously affected by climate change, perhaps surprisingly, near the top of the list, the US faces big losses.

American and European scientists have taken a fresh look at what they call the social cost of carbon (SCC): that is, the damage that greenhouse gas emissions from fossil fuel combustion will do to world economies. And whichever way they make the country-by-country comparisons, one nation is among the world leaders in self-harm – the USA.

It is not alone: India, a rapidly-growing economy, and Saudi Arabia, one of the world’s wealthiest, join the US in the top three. China, which is now the world’s highest carbon dioxide emitter, is in the top five.

Calculations about the future economic costs of something that has yet to happen in a fast-changing world are of the kind that induce migraine, and always incorporate a wide range of possible outcomes.

The US Environmental Protection Agency has proposed that by 2020, the global costs of an additional tonne of carbon dioxide in the atmosphere could range from $12 to $62. But a new study in the journal Nature Climate Change suggests that these costs could be much higher, at approximately $180 to $800 per tonne.

“It’s surprising just how consistently the US is one of the biggest losers, even when compared to other large economies”

And the price to be paid by the US alone could be $50 per tonne. Since the US – which under President Trump has announced its intention to withdraw from a 2015 global agreement to limit greenhouse gas emissions – now emits almost five billion tonnes of CO2 a year, this could be costing the US economy about $250bn.

“We all know carbon dioxide released from burning fossil fuels affects people and ecosystems around the world, today and in the future; however, these impacts are not included in market prices, creating an environmental externality whereby consumers of fossil fuel energy do not pay for and are unaware of the true costs of their consumption,” said Katharine Ricke of the University of San Diego, who led the study.

President Trump once dismissed global warming and climate change driven by profligate fossil fuel use as a “hoax” devised by the Chinese. But US climate research – often from US government agencies such as NASA and the National Atmospheric and Oceanic Administration – has consistently warned of the potentially devastating future costs to the US.

Coastal flooding could create a new class of climate refugee within the US. Hurricanes will gain in ferocity and potential devastation. Forest fires are already on the increase.

The famously arid drylands of the US west have begun to march eastwards, and the extremes of heat and drought linked to a rise in global average warming are almost certain to cause harvest losses, all as a consequence of fossil fuel emissions. Clean energy policies, conversely, could cut air pollution and save American lives.

Assumptions reversed

The San Diego research reverses some long-standing assumptions, one of which is that while strong, rich economies benefit from fossil fuel use, the developing nations pay the highest price in the social costs of carbon, or SCCs.

The new calculations suggest much more uneven outcomes: the European Union, for instance, is likely to be less harmed by increased emissions, even though it is one of the world leaders in the attempt to combat climate change.

“Our analysis demonstrates that the argument that the primary beneficiaries of reductions in carbon dioxide emissions would be other countries is a total myth,” said Dr Ricke.

“We consistently find, through hundreds of uncertainty scenarios, that the US always has one of the highest country-level SCCs. It makes a lot of sense because the larger your economy is, the more you have to lose.

“Still, it’s surprising just how consistently the US is one of the biggest losers, even when compared to other large economies.” – Climate News Network

Landslides are growing risk to poorest

Waterlogged hillsides are dangerous. For those who live on them, or further downhill, they can be deadly. The global risk from landslides is rising.

LONDON, 3 September, 2018 – Lethal landslides are on the increase. Between 2004 and 2016, sudden cascades of rock, rubble and mud have claimed at least 50,000 lives. And fatal slips down unstable hillside slopes have steadily increased this century, according to new research.

British geographers report in the journal Natural Hazards and Earth System Sciences that they had amassed a database of 4,800 fatal landslides since 2004 and found that at least 700 of them had what they call a direct human fingerprint: they happened because people built on unstable soils, they mined, legally and illegally, they cut into hillsides, and they allowed pipes to leak.

In addition, heavy rainfall, earthquakes, explosions, dam collapses and freezing and thawing also set the earth moving at ever greater speeds, with deadly consequences.

The researchers also report that they found that other catalogues of natural disaster consistently under-estimated the toll exacted by landslides.

“It was surprising to find clear trends within the database that fatal landslides … were increasing globally during the period of 2004 to 2016”

One study found that the International Disaster Database, maintained by the international disaster community, under-estimated the number of fatal landslides by between 1400% and 2000%, often because the death tolls from such events were lumped in with other forms of disaster that might precipitate landslip: among them volcanic eruption, earthquake and flooding.

“We were aware that humans are placing increasing pressure on their local environment, but it was surprising to find clear trends within the database that fatal landslides triggered by construction, illegal hill-cutting and illegal mining were increasing globally during the period of 2004 to 2016,” said Melanie Froude, of the University of Sheffield, who led the study.

All the countries in the premier league for fatal landslides were in Asia: one in five of these happened in India, but Pakistan, Myanmar and the Philippines also suffered increasing losses.

Poorest in the shadows

Such findings are no surprise. First, there are more people on the planet, looking for new places to live and new ways of making a living, and the poorest are always more likely to be forced to the margins, to live on or in the shadow of dangerous, unstable slopes.

Second, the world is warming: for every extra degree Celsius the moisture-holding capacity of the atmosphere increases by about 7%, so more rain is likely to fall with ever greater intensity to saturate more soil and dislodge more rock. The researchers found that 79% of all landslides could be linked to rainfall.

And, with greater warming, there is a greater hazard of devastating superstorms, along with hurricanes and tropical cyclones that deliver the conditions for catastrophic floods not just in Asia but in Europe and the US.

Paradoxically, extremes of heat and drought can also create dangerous slopes: dangerous wild fires can remove the tree cover that stops hillsides from slipping, and drive people from their homes to places that could later be just as hazardous.

Applying knowledge

Research like this is never just academic: the point of such studies is to draw attention to natural disasters that need never have happened, and identify the communities most at risk.

And these, the scientists say, are more frequently in poor countries, with the poorest of all disproportionately at risk. The point the scientists make is that there is nothing inevitable about a “natural” disaster. Human error, heedlessness and ignorance all contribute to loss, suffering and death.

“With appropriate regulation to guide engineering design, education and enforcement by regulation by specialist inspectors, landslides triggered by construction, mining and hill-cutting are entirely preventable,” Dr Froude said. – Climate News Network

Waterlogged hillsides are dangerous. For those who live on them, or further downhill, they can be deadly. The global risk from landslides is rising.

LONDON, 3 September, 2018 – Lethal landslides are on the increase. Between 2004 and 2016, sudden cascades of rock, rubble and mud have claimed at least 50,000 lives. And fatal slips down unstable hillside slopes have steadily increased this century, according to new research.

British geographers report in the journal Natural Hazards and Earth System Sciences that they had amassed a database of 4,800 fatal landslides since 2004 and found that at least 700 of them had what they call a direct human fingerprint: they happened because people built on unstable soils, they mined, legally and illegally, they cut into hillsides, and they allowed pipes to leak.

In addition, heavy rainfall, earthquakes, explosions, dam collapses and freezing and thawing also set the earth moving at ever greater speeds, with deadly consequences.

The researchers also report that they found that other catalogues of natural disaster consistently under-estimated the toll exacted by landslides.

“It was surprising to find clear trends within the database that fatal landslides … were increasing globally during the period of 2004 to 2016”

One study found that the International Disaster Database, maintained by the international disaster community, under-estimated the number of fatal landslides by between 1400% and 2000%, often because the death tolls from such events were lumped in with other forms of disaster that might precipitate landslip: among them volcanic eruption, earthquake and flooding.

“We were aware that humans are placing increasing pressure on their local environment, but it was surprising to find clear trends within the database that fatal landslides triggered by construction, illegal hill-cutting and illegal mining were increasing globally during the period of 2004 to 2016,” said Melanie Froude, of the University of Sheffield, who led the study.

All the countries in the premier league for fatal landslides were in Asia: one in five of these happened in India, but Pakistan, Myanmar and the Philippines also suffered increasing losses.

Poorest in the shadows

Such findings are no surprise. First, there are more people on the planet, looking for new places to live and new ways of making a living, and the poorest are always more likely to be forced to the margins, to live on or in the shadow of dangerous, unstable slopes.

Second, the world is warming: for every extra degree Celsius the moisture-holding capacity of the atmosphere increases by about 7%, so more rain is likely to fall with ever greater intensity to saturate more soil and dislodge more rock. The researchers found that 79% of all landslides could be linked to rainfall.

And, with greater warming, there is a greater hazard of devastating superstorms, along with hurricanes and tropical cyclones that deliver the conditions for catastrophic floods not just in Asia but in Europe and the US.

Paradoxically, extremes of heat and drought can also create dangerous slopes: dangerous wild fires can remove the tree cover that stops hillsides from slipping, and drive people from their homes to places that could later be just as hazardous.

Applying knowledge

Research like this is never just academic: the point of such studies is to draw attention to natural disasters that need never have happened, and identify the communities most at risk.

And these, the scientists say, are more frequently in poor countries, with the poorest of all disproportionately at risk. The point the scientists make is that there is nothing inevitable about a “natural” disaster. Human error, heedlessness and ignorance all contribute to loss, suffering and death.

“With appropriate regulation to guide engineering design, education and enforcement by regulation by specialist inspectors, landslides triggered by construction, mining and hill-cutting are entirely preventable,” Dr Froude said. – Climate News Network

Australian rain proves fiercer than expected

As the world warms, the storm clouds gather. And Australian rain is now often of a ferocity and intensity without precedent.

LONDON, 8 August, 2018 – Australian rain across much of the country is reaching an unexpected ferocity, and scientists who predicted a greater number of ever more intense rainstorms as the planet warms may have to think again – and think big.

A new study says the rate of rainfall in Australia during thunderstorms is in fact increasing twice or even three times beyond expectation, and much faster than would be expected with global warming. The largest downpours arrive with the most extreme events.

And although climate change predictions long ago foresaw the danger of ever more intense storms, researchers have looked back over the last 50 years to show that this is already happening.

What they did not expect to find was that such rainstorms are much more intense than anything they had expected under a regime of global warming and climate change, driven by profligate human use of fossil fuels.

“The important thing now is to understand why rainfall is becoming so much more intense in Australia and to look at changes in other places around the world”

“It was thought there was a limit on how much more rain could fall during these extreme events as a result of rising temperatures,” said Selma Guerreiro, an engineer at the University of Newcastle in the UK, who led the study.

“Now that upper limit has been broken, and instead we are seeing increases in rainfall, two to three times higher than expected during these short, intense rainstorms. This does not mean that we will see this rate of increase everywhere. But the important thing now is to understand why rainfall is becoming so much more intense in Australia and to look at changes in other places around the world.

“How these rainfall events will change in the future will vary from place to place and depend on local conditions besides temperature increases.”

She and her colleagues report in Nature Climate Change that they looked at what could be expected, under predictable conditions. One expectation is that as the air warms by 1°C, its capacity to absorb moisture increases by almost 7%, which means with more warmth there will be more evaporation, and more rainfall.

They looked over the records for the years 1966-1989 and 1990-2013 at data for daily and hourly rainfall – which should record the most intense downpours – from more than 100 weather stations. Between the two periods, global average temperatures increased by 0.48°C. They observed hourly extremes that were double, and even three times, the expected scale for any particular temperature rise.

Consistent predictions

That Australia is a continent of extremes, and a landscape that continues to deliver the unexpected, is no surprise. All climate models predict more extreme rainfall.  Climate change has already been implicated in Australia’s catastrophic 2010 floods. Researchers have consistently predicted a stormier future for Australia, with ever greater temperatures.

One of the researchers, Seth Westra of the University of Adelaide, explicitly predicted rising rainfall five years ago. In the same year researchers confirmed that so much rain had fallen on Australia in 2010 that global sea level actually dropped.

But the latest study does more than confirm recent certainties: it highlights the peculiar hazard that can be linked to storm intensity. The heavier and more focused the downpour, the greater the risk of urban flooding, landslips and potentially lethal flash floods. And although engineers and city planners expected to have to deal with more stormwater, what could happen is far worse than anything they are now prepared for.

“If we keep seeing this rate of change,” Professor Westra said, “we risk committing future generations to levels of flood risk that are unacceptable by today’s standards.” – Climate News Network

As the world warms, the storm clouds gather. And Australian rain is now often of a ferocity and intensity without precedent.

LONDON, 8 August, 2018 – Australian rain across much of the country is reaching an unexpected ferocity, and scientists who predicted a greater number of ever more intense rainstorms as the planet warms may have to think again – and think big.

A new study says the rate of rainfall in Australia during thunderstorms is in fact increasing twice or even three times beyond expectation, and much faster than would be expected with global warming. The largest downpours arrive with the most extreme events.

And although climate change predictions long ago foresaw the danger of ever more intense storms, researchers have looked back over the last 50 years to show that this is already happening.

What they did not expect to find was that such rainstorms are much more intense than anything they had expected under a regime of global warming and climate change, driven by profligate human use of fossil fuels.

“The important thing now is to understand why rainfall is becoming so much more intense in Australia and to look at changes in other places around the world”

“It was thought there was a limit on how much more rain could fall during these extreme events as a result of rising temperatures,” said Selma Guerreiro, an engineer at the University of Newcastle in the UK, who led the study.

“Now that upper limit has been broken, and instead we are seeing increases in rainfall, two to three times higher than expected during these short, intense rainstorms. This does not mean that we will see this rate of increase everywhere. But the important thing now is to understand why rainfall is becoming so much more intense in Australia and to look at changes in other places around the world.

“How these rainfall events will change in the future will vary from place to place and depend on local conditions besides temperature increases.”

She and her colleagues report in Nature Climate Change that they looked at what could be expected, under predictable conditions. One expectation is that as the air warms by 1°C, its capacity to absorb moisture increases by almost 7%, which means with more warmth there will be more evaporation, and more rainfall.

They looked over the records for the years 1966-1989 and 1990-2013 at data for daily and hourly rainfall – which should record the most intense downpours – from more than 100 weather stations. Between the two periods, global average temperatures increased by 0.48°C. They observed hourly extremes that were double, and even three times, the expected scale for any particular temperature rise.

Consistent predictions

That Australia is a continent of extremes, and a landscape that continues to deliver the unexpected, is no surprise. All climate models predict more extreme rainfall.  Climate change has already been implicated in Australia’s catastrophic 2010 floods. Researchers have consistently predicted a stormier future for Australia, with ever greater temperatures.

One of the researchers, Seth Westra of the University of Adelaide, explicitly predicted rising rainfall five years ago. In the same year researchers confirmed that so much rain had fallen on Australia in 2010 that global sea level actually dropped.

But the latest study does more than confirm recent certainties: it highlights the peculiar hazard that can be linked to storm intensity. The heavier and more focused the downpour, the greater the risk of urban flooding, landslips and potentially lethal flash floods. And although engineers and city planners expected to have to deal with more stormwater, what could happen is far worse than anything they are now prepared for.

“If we keep seeing this rate of change,” Professor Westra said, “we risk committing future generations to levels of flood risk that are unacceptable by today’s standards.” – Climate News Network