Tag Archives: Freshwater

Rare water data drives heating debate underground

Global warming’s effects are being felt even below the Earth’s surface, as researchers find that temperatures are rising not only in oceans, but also in subterranean freshwater sources. LONDON, 25 November, 2014 − Two great bodies of water have begun to feel the heat. European scientists report that they have evidence that the planet’s groundwater – the subterranean ocean of freshwater that bubbles into wells, freshens desert springs, scours great underground limestone caverns and makes possible the irrigation of crops in the world’s farmlands – may be responding to climate change. And out on the open sea, average global surface temperatures in the northern summer of 2014 were the highest ever recorded. Both claims will require verification from other sources: in science, one set of measurements is never enough.

Precious resource

In the case of the groundwater temperature rises, this will not be easy. Although water authorities everywhere are concerned about the depletion of this precious resource, and there are routine chemical and microbiological checks, sustained records of groundwater temperatures are rare. But a team from ETH Zurich in Switzerland and Karlsruhe Institute of Technology in Germany had an advantage: they had data from four wells near the German cities of Cologne and Karlsruhe, where temperature records have been maintained systematically for nearly 40 years. They report in the journal Hydrology and Earth System Sciences that, after a detailed study of evidence from the four sources, they were able to identify a pattern of very small but significant rises in the groundwater temperatures that mirrored – but came later than – changes in average temperatures above ground. That is, even far below the surface, global warming is making its presence felt. Research like this is not easy, and there will be plenty of questions and some argument about how they reached these conclusions.

Warming stages

Groundwater is ancient rainfall that seeped down into the bedrock and filled the pores in the soil. As it is drawn from one source, it moves to fill the gap, so there will be questions about how “old” the water is, how swiftly it is being replenished, how well insulated it is from the surface, and how close it might be to seepage from surface rivers. However, the data reveals not just a rise in temperatures over the four decades, but also a series of warming stages that echo patterns of warming in the atmosphere far above. “Global warming is reflected directly in the groundwater, albeit damped and with a certain time lag,” says Peter Bayer, senior scientist in engineering geology at ETH Zurich. Meanwhile, Axel Timmermann, professor of oceanography at the University of Hawaii’s International Pacific Research Centre, says that global mean sea surface temperatures in 2014 were the highest ever recorded. They were higher even than those of 1988, a year marked by a powerful El Niño event that warmed the Pacific and reversed climate patterns, with sometimes catastrophic consequences in the form of floods, droughts, windstorms, forest fires and harvest failures.

Unexpected slowdown

The 2014 ocean warming may have brought to an end the so-called global warming hiatus, in which average surface air temperatures rose only very slowly between 2000 and 2013. While there have been a number of possible explanations for this unexpected slowdown – unexpected because greenhouse emissions have increased in that time – there has been no clinching argument. But Timmerman says that the long pause may have come to an end. He says: “The 2014 global ocean warming is mostly due to the North Pacific, which has warmed far beyond any recorded value and has shifted hurricane tracks, weakened trade winds and produced coral bleaching in the Hawaiian islands. “Record-breaking greenhouse gas concentrations and anomalously weak North Pacific summer trade winds, which usually cool the ocean surface, have contributed further to the rise in sea surface temperatures. The warm temperatures now extend in a wide swath from just north of Papua New Guinea to the Gulf of Alaska.” – Climate News Network

Global warming’s effects are being felt even below the Earth’s surface, as researchers find that temperatures are rising not only in oceans, but also in subterranean freshwater sources. LONDON, 25 November, 2014 − Two great bodies of water have begun to feel the heat. European scientists report that they have evidence that the planet’s groundwater – the subterranean ocean of freshwater that bubbles into wells, freshens desert springs, scours great underground limestone caverns and makes possible the irrigation of crops in the world’s farmlands – may be responding to climate change. And out on the open sea, average global surface temperatures in the northern summer of 2014 were the highest ever recorded. Both claims will require verification from other sources: in science, one set of measurements is never enough.

Precious resource

In the case of the groundwater temperature rises, this will not be easy. Although water authorities everywhere are concerned about the depletion of this precious resource, and there are routine chemical and microbiological checks, sustained records of groundwater temperatures are rare. But a team from ETH Zurich in Switzerland and Karlsruhe Institute of Technology in Germany had an advantage: they had data from four wells near the German cities of Cologne and Karlsruhe, where temperature records have been maintained systematically for nearly 40 years. They report in the journal Hydrology and Earth System Sciences that, after a detailed study of evidence from the four sources, they were able to identify a pattern of very small but significant rises in the groundwater temperatures that mirrored – but came later than – changes in average temperatures above ground. That is, even far below the surface, global warming is making its presence felt. Research like this is not easy, and there will be plenty of questions and some argument about how they reached these conclusions.

Warming stages

Groundwater is ancient rainfall that seeped down into the bedrock and filled the pores in the soil. As it is drawn from one source, it moves to fill the gap, so there will be questions about how “old” the water is, how swiftly it is being replenished, how well insulated it is from the surface, and how close it might be to seepage from surface rivers. However, the data reveals not just a rise in temperatures over the four decades, but also a series of warming stages that echo patterns of warming in the atmosphere far above. “Global warming is reflected directly in the groundwater, albeit damped and with a certain time lag,” says Peter Bayer, senior scientist in engineering geology at ETH Zurich. Meanwhile, Axel Timmermann, professor of oceanography at the University of Hawaii’s International Pacific Research Centre, says that global mean sea surface temperatures in 2014 were the highest ever recorded. They were higher even than those of 1988, a year marked by a powerful El Niño event that warmed the Pacific and reversed climate patterns, with sometimes catastrophic consequences in the form of floods, droughts, windstorms, forest fires and harvest failures.

Unexpected slowdown

The 2014 ocean warming may have brought to an end the so-called global warming hiatus, in which average surface air temperatures rose only very slowly between 2000 and 2013. While there have been a number of possible explanations for this unexpected slowdown – unexpected because greenhouse emissions have increased in that time – there has been no clinching argument. But Timmerman says that the long pause may have come to an end. He says: “The 2014 global ocean warming is mostly due to the North Pacific, which has warmed far beyond any recorded value and has shifted hurricane tracks, weakened trade winds and produced coral bleaching in the Hawaiian islands. “Record-breaking greenhouse gas concentrations and anomalously weak North Pacific summer trade winds, which usually cool the ocean surface, have contributed further to the rise in sea surface temperatures. The warm temperatures now extend in a wide swath from just north of Papua New Guinea to the Gulf of Alaska.” – Climate News Network

Warmer freshwater emits more methane

FOR IMMEDIATE RELEASE Scientists think the amount of methane emitted to the atmosphere from freshwater ecosystems will increase as the climate warms, triggering further warming. LONDON, 20 March – British scientists have identified yet another twist to the threat of global warming. Any further rises in temperature are likely to accelerate the release of methane from rivers, lakes, deltas, bogs, swamps, marshlands and rice paddy fields. Methane or natural gas is a greenhouse gas. Weight for weight, it is more than 20 times more potent than carbon dioxide over a century, and researchers have repeatedly examined the contribution of natural gas emitted by ruminant cattle to global warming. But Gabriel Yvon-Durocher of the University of Exeter and colleagues considered something wider: the pattern of response to temperature in those natural ecosystems that are home to microbes that release methane. They report in Nature that they looked at data from hundreds of field surveys and laboratory experiments to explore the speed at which the flow of methane increased with temperature. Microbes, algae, freshwater plants and animals are all part of an active ecosystem and take their nourishment from and return waste to the atmosphere. Healthy plants take carbon dioxide from the atmosphere with photosynthesis. Most of the methane in freshwater systems is produced by an important group of microbes called Archaea that live in waterlogged, oxygen-free sediments and play an important role in decay. Plant uptake of carbon dioxide is affected by temperature, and so is microbial methane production. Respiration also releases carbon dioxide. The questions the researchers set out to answer were: which gas is more likely to be released in greater quantities as temperatures rise? And is the outcome the same whether they examine the Archaea only, or all the microbes in an ecosystem, or the entire package of submerged freshwater life?

More heat, more methane

The answer is, the scientists say, that methane emissions go up with the mercury, and that the ratio of methane to carbon dioxide also goes up in step with temperature. And the result is the same whether you consider the microbes or the whole ecosystem. “The discovery that methane fluxes are much more responsive to temperature than the processes that produce and consume carbon dioxide highlights another mechanism by which the global carbon cycle may serve to accelerate rather than mitigate future climate change,” says Dr Yvon-Durocher. This is not the end of the story. All such studies raise as many questions as they answer, and more research is necessary. The next puzzle is how to fit such findings into models of climate change. However, the researchers feel they have cleared up one point. Dr Yvon-Durocher says: “Our research provides scientists with an important clue about the mechanisms that may control the response of methane emissions from ecosystems to global warming.” – Climate News Network

FOR IMMEDIATE RELEASE Scientists think the amount of methane emitted to the atmosphere from freshwater ecosystems will increase as the climate warms, triggering further warming. LONDON, 20 March – British scientists have identified yet another twist to the threat of global warming. Any further rises in temperature are likely to accelerate the release of methane from rivers, lakes, deltas, bogs, swamps, marshlands and rice paddy fields. Methane or natural gas is a greenhouse gas. Weight for weight, it is more than 20 times more potent than carbon dioxide over a century, and researchers have repeatedly examined the contribution of natural gas emitted by ruminant cattle to global warming. But Gabriel Yvon-Durocher of the University of Exeter and colleagues considered something wider: the pattern of response to temperature in those natural ecosystems that are home to microbes that release methane. They report in Nature that they looked at data from hundreds of field surveys and laboratory experiments to explore the speed at which the flow of methane increased with temperature. Microbes, algae, freshwater plants and animals are all part of an active ecosystem and take their nourishment from and return waste to the atmosphere. Healthy plants take carbon dioxide from the atmosphere with photosynthesis. Most of the methane in freshwater systems is produced by an important group of microbes called Archaea that live in waterlogged, oxygen-free sediments and play an important role in decay. Plant uptake of carbon dioxide is affected by temperature, and so is microbial methane production. Respiration also releases carbon dioxide. The questions the researchers set out to answer were: which gas is more likely to be released in greater quantities as temperatures rise? And is the outcome the same whether they examine the Archaea only, or all the microbes in an ecosystem, or the entire package of submerged freshwater life?

More heat, more methane

The answer is, the scientists say, that methane emissions go up with the mercury, and that the ratio of methane to carbon dioxide also goes up in step with temperature. And the result is the same whether you consider the microbes or the whole ecosystem. “The discovery that methane fluxes are much more responsive to temperature than the processes that produce and consume carbon dioxide highlights another mechanism by which the global carbon cycle may serve to accelerate rather than mitigate future climate change,” says Dr Yvon-Durocher. This is not the end of the story. All such studies raise as many questions as they answer, and more research is necessary. The next puzzle is how to fit such findings into models of climate change. However, the researchers feel they have cleared up one point. Dr Yvon-Durocher says: “Our research provides scientists with an important clue about the mechanisms that may control the response of methane emissions from ecosystems to global warming.” – Climate News Network