This is a summary of the stories we have published in the week ending Saturday 13 April.
7 April – While world leaders dither on taking action about climate change, volcanologists have found that if we are unlucky enough a cloud of volcanic ash from Iceland might solve the problem for us by blotting out the Sun. The eruption in Iceland in 2010 of the volcano Eyjafjallajökull, which caused 100,000 flights to be cancelled and stranded millions of people, was small-scale compared with what could happen (see our story of 21 March, Volcano “did little to lower CO2″.) Not only could Iceland’s eruptions be up to 100 times more powerful, they could shower vast quantities of dust into the atmosphere, not just disrupting air flights but cutting out sunlight. Previous archaeological work on peat bogs and lake beds across Europe has found layers of volcanic ash. The dates of these layers coincide with population crashes in various places, including Scotland.
8 April – Fossil fuel subsidies provided by both rich and poor countries to keep their citizens happy are holding back the world economy, accelerating climate change and damaging the health of current and future generations, according to the International Monetary Fund. The worst offender of all is the United States, which allows annual subsidies of $502 billion on fossil fuels. China with $279 bn and Russia at $116 bn are the two next largest offenders. The IMF researched 176 countries to investigate fuel subsidies. These are both direct subsidies, where consumers are sold petrol, oil, gas and coal at below the price of production, and indirect subsidies, where the tax is so low it does not pay for the damage to the planet from climate change, the cost of pollution to health, road damage by lorries, and the cost of accidents.
9 April – The wind blows almost everywhere, but its power to turn turbines may have been overestimated, according to US scientists. Amanda Adams from the University of North Carolina and David Keith of Harvard suggest that large-scale wind farms may create conditions that would ultimately limit their capacity to fulfil demand. The problem, they warn in Environmental Research Letters, is not one of economics, or engineering: it is one of atmospheric physics. When a steady wind slams into a blade and keeps it turning, it transfers energy to the blade, and thence to the turbine. That slows down the wind. Because each turbine carries a “wind shadow” beyond it, wind farm entrepreneurs have to compromise: they need to space their turbines as far apart as possible, given that it makes sense to erect as many turbines as possible on the limited land available. That is, output is going to depend on calculations involving both capacity and density.
9 April – The glaciers of the tropical Andes have shrunk by between 30 and 50% in 30 years and many will soon disappear altogether, cutting off the summer water supply for millions of people, according to scientists studying the region’s climate. Their findings are particularly significant because glaciers in the tropics, 99% of which are in the Andes, are regarded as among the most sensitive indicators of climate change on the planet, according to the Intergovernmental Panel on Climate Change (IPCC). In the Andes glaciers contribute to irrigation, hydroelectricity generation and water supply. For example, 15% of the water consumed in La Paz, the capital of Bolivia, comes from glaciers, a figure that doubles in the summer. The region, with 3.5 million people, is heavily dependent on melt water for its survival (and see our story of 25 January, Andean glaciers show record melting).
9 April – Airline passengers – and airlines too – could be in for a rough ride as the decades pass and the world warms. Two British scientists have asked the question literally uppermost in the minds of transatlantic flight planners: what difference will global warming make to atmospheric turbulence? Clear air turbulence is an enduring problem for commercial aircraft: pilots cannot see it coming, it doesn’t reflect signals to onboard radar, and satellite monitors cannot detect it. Pilots however encounter moderate or uncomfortable clear air turbulence at least one per cent of cruise time. This adds up to tens of thousands of bumpy episodes each year, and hundreds of passengers who didn’t fasten their seatbelts in time may be injured. Clear air turbulence is calculated to cost airlines £100 million ($150 million) a year in delays and damage, and… the mechanisms of turbulence are still, in that famously enigmatic scientific phrase, “not fully understood.”
9 April – What will be the effect of global warming on the Amazon rainforest? Over the last 30 years, forest fires, most of them deliberately started to clear land by cattle ranchers and soy farmers, have destroyed thousands of square miles of forest. This has increased carbon emissions, reduced rainfall and made the forest more vulnerable to drought. In 2005 and 2010 unprecedented droughts occurred… The prolonged drought of 2005 caused widespread damage to the area and was seen as a possible indication that the rainforest is showing the first signs of large-scale degradation caused by climate change. A research team, led by NASA’s Jet Propulsion Laboratory, has since analysed nearly a decade of satellite data on the Amazon. The team looked at rainfall measurements and the moisture content of the forest canopy and found that the drought caused widespread, observable damage to the canopy. The drought conditions were so severe that the rainforest was unable to fully recover before the next drought struck in 2010. The study also found evidence that each year the amount of rainfall is reducing. Between 1970 and 1998 it fell nearly 3.2% per year, and this trend has continued.
11 April – Chinese scientists have just confirmed that greenhouse gas emissions have sent the thermometer soaring in one country – China. This is, they say, the first study to directly link warmer daily minimum and maximum temperatures with climate change in one single nation, rather than on a global or hemispheric scale. Xuebin Zhang from Environment Canada in Toronto and his co-author Qiuzi Han Wen of the Institute of Atmospheric Physics in Beijing, China, and others report in Geophysical Research Letters that they… had the maximum, minimum and mean daily temperatures from 2,416 weather stations in China between 1961 and 2007… They calculated that carbon dioxide and other greenhouse gas emissions had probably increased the warmest annual extreme temperatures – the daily maximum and daily minimum for the hottest day and night of the year – by 0.92°C and 1.7°C respectively. They found that human activity had increased the coolest annual extreme temperatures – the maximum and minimum for the coldest day and night of the year – by 2.83°C and 4.44°C respectively.
12 April – Here is the puzzle: humans continue to pump increasing quantities of greenhouse gases into the atmosphere, and the world has warmed accordingly. Eleven of the 12 warmest years ever recorded have fallen in this century – but the rate of warming seems to have slowed rather than increased. So what has been taking the heat? Climate scientists from Barcelona in Spain and Toulouse in France think they have the answer. They report in Nature Climate Change that instead of going into the near-surface atmosphere where meteorologists could easily measure it, much of the extra heat has been absorbed by the oceans. This may not be the only explanation. There have also been arguments that volcanic eruptions might have put enough aerosols into the upper atmosphere to dim the sunlight and counter global warming a little. Stratospheric water vapour might also have damped things down, and some say the solar minimum – the spell of least activity in the Sun’s 11-year cycle – has been prolonged.
13 April – Researchers in North America claim to have found two new ways to deliver power to the people – and reduce the global carbon footprint. One team hopes to produce a low-cost, efficient technique for storing the surplus energy from wind power, or the solar panels on the roof. The other team hopes to deliver biofuels from the carbon dioxide in the air without even troubling the photo-synthesising plants that have, for the last half a billion years, taken on the task. The first advance is from chemists at the University of Calgary in Canada, who report in the journal Science that they have found new catalysts that could convert electrical energy, which cannot be simply stored, into chemical energy, which can… An even bigger claim, and still a very long way from the marketplace, comes from the University of Georgia in Athens in the US, where Michael Adams and colleagues have developed a micro-organism that absorbs carbon dioxide and generates stored energy in the form of tissue.