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Northern peatlands, typical for subarctic Scandinavia and Russia, contain one third of the world’s soil organic carbon. How much extra carbon these soils will release to the atmosphere, through accelerated respiration in a warmer climate, has been pretty much guesswork. Data from an eight-year in situ experiment carried out in Sweden now suggest that even modest warming will release enough extra carbon to effectively equalize the European Union’s emissions reductions achieved under the Kyoto Protocol.

Ellen Dorrepaal and her colleagues studied ecosystem response to climate warming at a test site near the Swedish Abisko scientific research station, some 200 kilometres inside the Arctic Circle. In a paper in Nature today (subscription required) they report that warming accelerated the respiration of carbon in peat overlaying the permafrost by almost 70 % - much more than previously thought. Here's an editor's summary.

Extrapolated to the total northern peatland area, the results suggest that climate warming of 1 degree Celsius over the next decade might lead to a global increase in respiration of 38-100 million tonnes of carbon per year. For comparison: The EU’s Kyoto target is to reduce emissions by 92 million tonnes of carbon per year.

The researchers stress that the effect is likely to last: “In contrast to long-term studies in forest, meadow and tundra ecosystems, the warming effect did not decline towards the eighth year of the study,” they write.

The net effect of warming on northern carbon reservoirs includes possible gains from increased plant growth. But in Arctic ecosystems dominated by peat and moss, there are too few productive woody shrubs growing to offset the warming effect on soils.

Quirin Schiermeier

Image: Subarctic peatland in Abisko, North Sweden where the consequences for CO2-respiration rates were investigated. Credit: Ellen Dorrepaal

Posted by Quirin Schiermeier on July 30, 2009
Categories: Categories, Biosphere feedbacks, Climate Science, GHG emissions, Quirin Schiermeier, Topics, Uncertainty | Permalink | Comments (3) | TrackBacks (0)

The G8 meeting last week – the last get-together of the leaders of the world’s major industrialized nations before the United Nations climate summit in December - was loaded with expectations as to what Obama & Co might give climate negotiators to take with them to Copenhagen.

The answer, in a nutshell, is two degrees.

Is that enough? The Nature news story here has the context and offers two opposite expert views.

“The G8 announcement is depressing,” says economist Gwyn Prins, a co-author of the pointed anti-Kyoto polemic ‘How to get climate policy back on course’ (pdf file), whom I interviewed last week for the article.

“Politicians are mistaking making statements for actually doing something. We really need to try something different,” he says. He believes the prospect is “vanishingly small” for developed and developing nations to agree on a meaningful deal in Copenhagen.

Others are not so pessimistic. Hans Joachim Schellnhuber, director of the German PIK and something of an elder statesman of science-led global change diplomacy, is actually quite enthusiastic about the G8’s two degrees target, which he believes will breathe new life into international climate politics.

“Now we can calculate precisely how much greenhouse gas we can still afford to emit if we don’t want to exceed a given probability of getting into dangerous territory,” he says.

Continue reading "What the G8 target means" »

Posted by Quirin Schiermeier on July 15, 2009
Categories: Categories, Climate Policy, GHG emissions, Major Economies Meeting, Politics, Quirin Schiermeier, Topics, UN Conference on Climate Change, Copenhagen | Permalink | Comments (0) | TrackBacks (0)

Why carbon dioxide concentrations over the past 24 million years or so have never dropped below 200 parts per million, despite environmental conditions that have been favourable for CO2 drawdown by rock weathering and sedimentation, has always been a bit of a mystery.

Now scientists suggest an almost provocatively simple mechanism that might have kept the planet from cooling more severely than it actually did during past glacial climates: Changes in terrestrial vegetation stopped the weathering-driven decline in atmospheric CO2 concentrations which else would have turned Earth into a lifeless freezer.

Weathering is known to be largely controlled by vegetation. So the team, led by Mark Pagani of Yale University, describes in a paper in Nature today a negative feedback whereby limited plant growth during cold conditions slows down the rate of weathering and sedimentation, thus preventing carbon dioxide levels from dropping even further. An editor's summary of the paper is here.

This “bold and provocative” hypothesis provides an “elegant twist” on existing ideas about climate-vegetation interactions, Yves Goddéris and Yannick Donnadieu write in an accompanying News and Views article (subscription required).

But the proposed feedback mechanism raises contentious issues as well. For example, Goddéris and Donnadieu argue that in the tropics the role of vegetation cover in the climate system might not be as significant as proposed.

Quirin Schiermeier

Posted by Quirin Schiermeier on July 02, 2009
Categories: Categories, Biosphere feedbacks, Climate Science, GHG emissions, Palaeoclimate, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

Cross-posted from The Great Beyond

A gargantuan plan of supplying European consumers with electricity generated in the Saharan desert could see the light of day earlier than even the most optimistic solar energy aficionados had expected.

According to the Süddeutsche Zeitung, a group of 20 large German companies, led by the reinsurance giant Munich Re, and also including Siemens, Deutsche Bank and RWE, is determined to go ahead with an €400 billion project known as Desertec. If fully realized, the envisaged network of huge solar thermal power plants across North Africa could provide up to 15 % of Europe’s overall electricity needs by mid-century.

Next month already, the group plans to create a consortium that is to look in more detail into the technical and financial feasibility of the envisaged project. Developing concrete plans could take two to three years, Torsten Jeworek, a Munich Re board member, told the Süddeutsche Zeitung.

Continue reading "Europe looks to draw power from the Sahara" »

Posted by Quirin Schiermeier on June 17, 2009
Categories: Categories, Business, Energy, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

The skies over most land areas are not, as previous studies have suggested, becoming cleaner.
Aerosol pollution has in fact increased most everywhere since 1973, a team reports in Science today (Abstract). Only over Europe have skies brightened, they found.

Kaicun Wang of the University of Maryland, and his colleagues, looked at a 35-year record of clear-sky transparency from 3,250 stations around the world. At many stations visibility had notably decreased - the skies have dimmed.

Air pollution is worst In India, China, Africa and South America, where hundreds of millions are breathing air thick with soot and smog. Clean-air technologies are lacking, or have not yet had much effect, in these regions.

Previous studies concluded that the skies are getting cleaner, and that as a result more sunlight is reaching the surface. Atmospheric scientists believe that aerosols and dust have been shielding us from the worst of global warming.

But the overall cooling effect of aerosols has lately been questioned. The connection between different types of aerosol particles, clouds and solar radiation is more complicated than previously thought. Now it appears as if darker skies don’t necessarily mean less warming, and vice versa. My story
over at Nature News has more about these disturbing uncertainties.

Meanwhile, China is trying hard to reduce air pollution in its most populated cities. Strict regulations aimed at curbing pollution from cars have been set up last year in Beijing and Shanghai.

Quirin Schiermeier

Image: Punchstock

Posted by Quirin Schiermeier on March 13, 2009
Categories: Categories, Atmospheric Science, Quirin Schiermeier, Topics, Uncertainty | Permalink | Comments (0) | TrackBacks (0)

Tropical forests which (still) cover around 10% of the global land area contain more carbon per hectare than any other form of vegetation. It’s obvious from that that their growth or decline has a huge impact on the global carbon budget.

Cutting down forests will add carbon to the atmosphere, no matter which kind of land cover replaces the jungle. But what’s happening in tropical forests that have long been undisturbed by logging, storms or fire? Theoretically, the carbon balance of such old-growth forest – if tree growth and death are in equilibrium, that is - should be next to zero.

But apparently it’s not. In a paper in Nature today (subscription), a team led by Simon Lewis of Leeds University in Britain reports that tree biomass in intact African forests increased between 1968 and 2007. Across 79 plots monitored in ten countries large living trees added an average 0.63 tonnes of carbon per hectare each year. Scaled up to the continent, and including roots, smaller trees and dead wood, African forests seem to have stored 340 million tonnes of carbon per year during recent decades. Previous studies suggested that Amazonian forests are accumulating biomass and carbon at a similar rate. Globally, intact tropical forests seem to take up 1.3 billion tonnes of carbon per year – equivalent to almost 20% of annual carbon dioxide emissions worldwide.

Continue reading "Jungle Fit!" »

Posted by Quirin Schiermeier on February 18, 2009
Categories: Categories, Biosphere feedbacks, Deforestation, GHG emissions, Mitigation, Quirin Schiermeier, Topics | Permalink | Comments (2) | TrackBacks (0)

With an uninterrupted 17-million year sediment record of Antarctic’s climatic past now available, scientists are hoping for unique new insights into the continent’s climatic past.

A few initial results of the Antarctic Geological Drilling programme (ANDRILL) were announced last week at the general assembly of the European Geosciences Union in Vienna. There is an online news story here.

Antarctica’s ice sheets, so it seems, respond more sensitively to climate fluctuations than has been assumed. During warmer periods, the West Antarctic Ice Sheet and its floating extension, the western Ross Ice Shelf, have shrunk substantially. Some 3.5 million years ago the ice seems to have disappeared completely for around 200,000 years. There were snow-capped mountains, alpine trees, gushing rivers, quiet lakes – the frozen continent was a place where you would love to go fishing or hiking, were it not for the midges.

The world was warmer then than it is today, but not substantially so. If temperatures continue to rise, glaciers in Antarctic’s warmer western part might begin to retreat again before long. A few million years ago, Antarctic melting probably raised sea levels globally by 10 metres or so. If history repeats itself, we’re headed for trouble.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 24, 2008
Categories: Recent contributors, Categories, Conferences and Meetings, EGU 2008, Palaeoclimate, Quirin Schiermeier | Permalink | Comments (5) | TrackBacks (0)