Climate Feedback

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)

Russia has been a rather puzzling actor in the complicated diplomatic game which resulted in the Kyoto protocol, and which will be played out again in Copenhagen in December. Climate warming doesn’t make headlines, and has so far not been a big concern, between Moscow and Vladivostok. What prompted Russian leaders to ratify Kyoto was the prospect of making good money from emissions trading, rather than conviction that man-made climate change is a real phenomenon and a threat to society.

Now they have changed their minds. In April, Vladimir Putin and his ministers approved a new climate ‘doctrine’ – well, that’s how they call these things in Moscow – which for the first time officially recognizes severe risks of global warming and calls for immediate action. My story over at Nature News explains the nature and significance of the baffling doctrine, details of which are beginning to leak.

Critics point out that Russia plans to focus on adaptation to climate change, while putting less emphasis on actually reducing its emissions. Others say Russia’s new climate policy has been quietly constructed behind closed doors, without any involvement from industry, NGOs and the public. That’s all true; but Russia’s recognition of the scientific basis of climate change, and its apparent willingness to pro-actively partake in international climate protection efforts, outweighs these flaws. Let’s see what Moscow will put on the table in Copenhagen.

Sure, all eyes in December will be on China, and Russia’s taciturn climate diplomacy has in the past been a fickle and half-hearted affair. Even so, one must not under-estimate Moscow’s influence at international negotiation tables.

The climatic importance of Russia’s natural landscape, in particular its boreal forests and its permafrost soils, is beyond doubt anyway. For example, huge amounts of old carbon that accumulated over thousands of years are stored in permafrost soils which occupy more than 60% of Russia’s 17 million square-kilometre land area. How much of it will be released as the southern permafrost boundary shifts northwards as a result of climate warming, possibly by up to 100 kilometres in the next 20-25 years?

A paper in Nature this week suggests that, globally, permafrost thawing may lead to the release of an extra billion tonnes of carbon per year into the atmosphere. The team measured carbon flows at a tundra site in Alaska where permafrost has been thawing for 20 years, and then calculated from the data the likely trajectory of global carbon release from thawing permafrost. Here's an editor's summary.

Russian scientists were not involved in the study, led by Edward Schuur of the University of Florida in Gainesville. That’s a pity. If Moscow’s new interest in climate led to more frequent east-west collaborations in science, such as on permafrost, it would be a boon.

Quirin Schiermeier

Posted by Quirin Schiermeier on May 28, 2009
Categories: Adaptation, Climate Policy, Climate Science, GHG emissions, Mitigation, Quirin Schiermeier, Topics, UN Conference on Climate Change, Copenhagen | Permalink | Comments (0) | TrackBacks (0)

This week’s Nature has an extended climate special made of original research papers, features, commentaries, editorials, essays and book reviews. Here’s the content at a glance.

An uplifting read the package is not, but this will hardly surprise devoted readers of these pages. What’s it all about then? Well, Gavin Schmidt and David Archer, in their news and views piece, get to the heart of it: “Dangerous climate change, even loosely defined, is going to be hard to avoid.”

Some highlights:
Malte Meinshausen and colleagues find that cumulative emissions from 2000 to 2050 of about 1,400 billion tonnes of CO2 yield a 50% probability of exceeding 2 °C warming – the somewhat randomly defined threshold of dangerous climate change - by the end of the twenty-first century Here's an editor's summary of the paper. Just to be clear: Known 2000-2006 emissions were almost 250 billion tonnes.

Myles Allen and colleagues take a slightly different approach to calculating the climate response to anthropogenic emissions. They show that cumulative emissions of one trillion tonnes of carbon (3,670 billion tonnes CO2) over the entire 1750-2050 period yield a 90% probability of warming between 1.3 and 3.9 °C above pre-industrial temperatures, with 2 °C of warming being the best estimate. About half a trillion tonne has been emitted since the onset of industrialization. Here's an editor's summary.

In clear, if we want a reasonably good chance of staying beyond 2°C warming, we cannot afford burning all the oil, gas and coal buried in the ground. We can’t actually afford burning more than half the proven reserves. If we continue burning fossil fuels at current rates we will leave the ‘safety zone’ in less than 20 years. Let’s face it: We have a bad hand – and we can’t bluff the planet.

Continue reading "The wheel of climate fortune" »

Posted by Quirin Schiermeier on April 30, 2009
Categories: Adaptation, Climate Science, Climate prediction, GHG emissions, Quirin Schiermeier, Topics, Uncertainty | Permalink | Comments (0) | TrackBacks (0)

Cross-posted from The Great Beyond

Following the collapse on April 4 of a narrow ice bridge that had connected the Wilkins ice shelf with a small island off the Antarctic Peninsula, the northern ice front of the ice sheet is beginning to disintegrate.

A high-resolution radar image taken on April 20 by the German TerraSAR-X satellite shows large icebergs being released from a rift zone near Latady Island. Scientists expect up to 3,400 square kilometretres of the Wilkins Ice Sheet to break into icebergs before a new stable ice front will form.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 29, 2009
Categories: Cryosphere, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

Cross-posted from In the Field

It’s a warm and sunny spring day today in Vienna - can you guess then whether the coming summer will be colder or warmer than usual? Well, if you think that you hardly have more – though certainly not less - than a 50% chance of getting it right you’re, uhm, right. But guess what: Supercomputer-powered seasonal climate forecasts don’t do much better.

Seasonal climate predictions work relatively well only in the tropics. In Europe and North America their predictive skills are still pretty poor, meaning that forecast and observed climatology are often two very different things. And in some regions seasonal forecasts are actually worse than plain guessing.

This means that seasonal climate forecasts don’t yet provide reliable, if any, guidance for farmers, tourism managers, forest fire fighters, or for me and you. The idea that slowly varying boundary conditions, such as sea surface temperature distribution, snow cover and soil moisture, push the climate in a certain direction is well-established. But statistical climatology is one thing, daily wheather is another.

Andreas Weigel of the Swiss Weather Service, a rising star in the seasonal forecast community, made a few suggestions here at the EGU as to how predictive skills could be improved. Using more than one climate model is one promising possibility, statistical post-processing an re-calibrating forecasts is another, he explained in his well-received medal award lecture today

In the same session, Marie Boisserie of Florida Stae University in Tallahassee reported that when she included realistic initial soil moisture conditions to a climate model it greatly improved its predictive skills. Two-month forecasts of summer temperatures and precipitation in the US were more than twice as accurate than without the precipitation-derived soil moisture data.

Problem is that as yet there exists no reliable global observational database of soil moisture.
All eyes are now on the European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) mission, designed to observe soil moisture over the Earth's landmasses and salinity over the oceans, to be launched in June.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 21, 2009
Categories: Climate Science, Conferences and Meetings, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

In a Mexican eco park, of all places, scientists have found compelling evidence that sea-levels can rise – nah, jump – at scary rates during warm climates such as ours.

That the global sea-level can rise by almost half a metre per decade when huge glaciers melt towards the end of an ice age has already been known. But a paper in Nature today (Editor’s summary) suggests that a similar jump has occurred at the close of the sea-level ‘highstand’ during the warm period, the Eemian Interglacial.

The team, led by Paul Blanchon of the National Autonomous University of Mexico in Cancun, analyzed the age structure of exceptionally well-exposed coral reefs at Xcaret, a popular theme park on the northeast Yucatán peninsula. Because no earthquakes have occurred in the more recent geological history of the region, the peninsula is an ideal location to study sea-level behaviour.

The team found that at the end of the last interglacial many reefs were flooded and replaced by new reefs on higher ground. Age and layering of the corals indicate that a rapid 2-3 metres jump in sea-level occurred around 121,000 years ago, possibly within less than one century.

Only swift and substantial melting of Greenland and Antarctic ice sheets can explain the extreme rate at which the seal level rose to its highstand some 4-6 metres above today’s sea-level.

The implications for our warming planet are clear. As modern temperatures approach those at the height of the Eemian Interglacial, the rate of seal-level rise could soon – perhaps very soon - shift gear, from modest to catastrophic.

The spectacular break-up of the Wilkins Ice shelf off the Antarctic Peninsula is a reminder that we are getting closer to the point where things could get really nasty.

“Given the dramatic disintegration of ice shelves and discovery of rapid ice loss from both the Antarctic and Greenland ice sheets, the potential for sustained rapid ice loss and catastrophic sea-level rise in the near future is confirmed by our discovery of sea-level instability at the close of the last interglacial,” the authors conclude.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 16, 2009
Categories: Ocean science, Palaeoclimate, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

The narrow strip of ice which connected the Wilkins ice shelf with a small island off the southwestern Antarctic Peninsula has finally collapsed, threatening to speed up the disintegration of the 11,000 square kilometres-large shelf.

Scientists had expected the break up. A partial collapse of the ice sheet last year had already thinned and twisted the natural ice bridge which connected the Wilkins ice shelf with Charcot Island, providing stability. On 1 April scientists monitoring satellite images of the region first noticed that rifts had occurred in the Manhattan-sized strip of ice. On 4 April it broke into pieces.

Satellite image: Terra SAR-X ScanSAR, 5 April 2009 © DLR, 2009
(Charcot Island is to the left. The island at the bottom right is Latady Island. Behind the broken ice bridge are icebergs from the June/July 2008 break up)

The collapse could accelerate erosion of the Wilkins ice sheet, which is located in one of the most rapidly warming regions of Antarctica. Its demise threatens to speed up the flow of continental glaciers to the coast, with implications for global sea level rise.

Quirin Schiermeier

Posted by Quirin Schiermeier on April 07, 2009
Categories: Cryosphere, Quirin Schiermeier, Topics | Permalink | Comments (2) | TrackBacks (0)

Two papers in Nature today shed light on the possible future behaviour of the West Antarctic ice sheet (WAIS), complete loss of which would produce a worldwide rise in sea level of around 5 metres.

The two teams - one using a high-resolution ice sheet model, the other looking at glacial records contained in seafloor sediment – independently arrive at similar conclusions: The WAIS has intermittently melted during the past five million years or so, and its oscillations follow a 40,000 year cycle in the Earth’s axial tilt. Small variations in tilt – called the obliquity of the ecliptic – result in reduced or increased amounts of sunlight reaching the poles, thus pacing the succession of ice ages and warm periods.

During the warmest interglacial phases the WAIS has in the past episodically collapsed entirely, the studies suggest (Editor's Summary) Global temperatures around 3 degrees Celsius warmer than today seem to have sufficed to initiate the transition from grounded ice to open waters in the Ross Bay, reports the team led by Tim Naish of Victoria University in Wellington, New Zealand, who analysed a sediment core recovered from beneath the Ross ice shelf by the ANDRILL programme. Model simulations suggest the transition from full glacial to intermediate state (such as today’s) to nearly ice-free conditions can proceed rapidly. In the warmest ‘super-interglacials’, such as one around 1.07 million years ago, it took only around thousand years for the WAIS to collapse, report David Pollard and Robert DeConto of Pennsylvania State University in the second study.

Image: Punchstock

Continue reading "Antarctica: Memento melting " »

Posted by Quirin Schiermeier on March 19, 2009
Categories: Cryosphere, Palaeoclimate, Quirin Schiermeier, Topics | Permalink | Comments (1) | 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)

The Earth’s large forests take up substantially more atmospheric carbon dioxide through photosynthesis than they release back to the atmosphere through respiration. Thus acting as a carbon ‘sink’, they (and the oceans) are our closest natural allies in the fight against climate change.

But many forests are at threat - not only from logging and clearing, but from climate change itself.

Take drought. How will mature tropical rain forests respond to dryer conditions, which some climate models suggest might be ahead in the not-so-distant future?

The 2005 drought in the Amazon basin gave scientists an opportunity to find out. What they saw is not particularly heartening: Prolonged dryness has apparently turned some affected areas of the Amazon from a carbon sink to a carbon source, a team led by Oliver Phillips of Leeds University in Britain reports in Science today (Abstract here).

Patches subjected to a 100-milimetre decrease in rainfall released on average 5.3 tonnes of carbon per hectare – around 9 times the amount undisturbed tropical forests take up, on average, per year. Basin-wide, between 1.2-1.6 billion tonnes of carbon were released during the 2005 drought, the team estimates.

Over at Nature News, I’ve put together a little briefing on what we know and what we don’t know about the tropical carbon sink.

Quirin Schiermeier

Image: Punchstock

Posted by Quirin Schiermeier on March 06, 2009
Categories: Biodiversity and Ecology, Biosphere feedbacks, Climate Science, Deforestation, Mitigation, Quirin Schiermeier, Topics | Permalink | Comments (1) | 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)

A couple of news items from the ocean fertilization front:

The Indo-German LOHAFEX experiment in the Southern Ocean, suspended two weeks ago, can be conducted as planned. Independent reviews sought by the German science ministry concluded that the experiment is in agreement with environmental standards and international law. On Tuesday, the team on board the German Polarstern started dumping its cargo of 20 tonnes of iron sulphate. The ship will stay around the area for around six weeks, giving the scientists’ enough time to observe the growth and decay of an ‘artificial’ algal bloom.

Picture: RV Polarstern (Alfred Wegener Institute)

It’ll be interesting how their observations, in particular concerning the rate and efficiency of carbon export to the deep ocean, will relate with data reported in a Nature paper this week on natural iron fertilization.

The CROZEX study was conducted in 2004 and 2005 near the Crozet archipelago at the northern boundary of the Southern Ocean. Raymond Pollard of the National Oceanography Centre Southampton and his team found that natural iron fertilization, by dust supplied from the Crozet Islands, increases biological production and the amount of organic carbon taken down into the deep ocean.

That’s not particularly surprising. But what’s amazing is this: The amount of carbon sequestered to 200 metres depth, while 18 times greater than that during an artificially induced bloom (like LOHAFEX), was a stunning 77 times smaller than the amount that had previously been determined during a natural bloom in the nearby Kerguelen region. What’s more, carbon flux at 3,000 metres, where carbon dioxide sucked up at the surface would be safely locked away for centuries, was just 3% of that at 100 metres. Check out this week's Nature podcast and the paper here (subscription)

“CROZEX carbon sequestration for a given iron supply (…) falls 15-20 times short of some geo-engineering estimates,” the authors conclude. This, you’ve guessed it, has “significant implications for proposals to mitigate the effects of climate change through purposeful addition of iron the ocean.”

It has indeed. The Nature news story here makes the point that the findings, if they hold up, could actually be the final blow to such proposals. The notion that putting a little iron into the oceans here and there will suck up most of the surplus atmospheric carbon dioxide is pretty much dead, so it seems. Alas, it was just too good to be true.

Quirin Schiermeier

Posted by Quirin Schiermeier on January 29, 2009
Categories: Climate Science, GHG emissions, Mitigation, Ocean science, Quirin Schiermeier, Topics | Permalink | Comments (2) | TrackBacks (0)

After eleven months of legislative work, the European Parliament gave its backing today to the European Union’s (EU) climate change package which aims to ensure that the EU will achieve its self-set climate targets by 2020: a 20% reduction in greenhouse gas emissions relative to 1990 levels, a 20% improvement in energy efficiency, and a 20% share for renewables in the EU energy mix.

EU heads of states, who had hammered out the agreement last week, called the legislation "historic". But critics say the reduction targets are less ambitious than they appear, basically a bluff. What bothers environmentalist most are the many far-reaching concessions to power plants and other emission-intensive industries participating in the EU’s mandatory emissions trading system.

More about this is in my story over on Nature News.

Quirin Schiermeier

Posted by Quirin Schiermeier on December 17, 2008
Categories: Carbon markets, Climate Policy, GHG emissions, Politics, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

A paper this week in Nature (subscription) sheds new light on the causes of pronounced greenhouse-gas and climate fluctuations during glacial times.

The last ice-age, which covered the period from around 110,000 to 10,000 years before now, is famed for a series of climate swings known as Dansgaard-Oeschger events.

Scientists have found evidence in Greenland ice cores for abrupt warming episodes of up to 15 degrees Celsius within few decades, followed by a more gradual cooling. These glacial warm and cold periods swung back and forth between the poles in a kind of thermal seesaw effect, whereby Antarctic temperatures rose when Greenland temperatures dropped, and vice versa.

It has long been assumed that Dansgaard-Oeschger events were triggered by changes in Atlantic ocean-circulation. The new modelling study by Andreas Schmittner and Eric Galbraith now adds new evidence to the idea. Weakening Atlantic meridional overturning circulation, the heat conveyor which carries warm water surface water northwards and cold deep-water back south, is indeed the primary physical mechanism driving glacial climate fluctuations, they conclude. Here’s an editor’s summary.

Schmittner and Galbraith carried out simulations with a coupled model of glacial climate and (simplified) biogeochemical cycles. When they manipulated the Atlantic circulation – artificially ‘switching’ it off and on in their model, that is - the model nicely reproduced the temperature changes typical for Dansgaard-Oeschger events. Remarkably, the model also reproduced reasonably well the ice-core-derived changes in atmospheric concentrations of the greenhouse-gases carbon dioxide and nitrous oxide which accompany such events.

Continue reading "Glacial climate swings: It’s in the ocean" »

Posted by Quirin Schiermeier on November 20, 2008
Categories: Climate Science, Ocean science, Palaeoclimate, Quirin Schiermeier, Topics | Permalink | Comments (0) | TrackBacks (0)

Is the global financial crisis good or bad for green issues? The ongoing controversy over the European Union’s ambitious climate and energy package suggests the latter might be the case. But political and economical analysts seem to be increasingly confident that the current crisis might give rise to environmentally healthier policies and investment decisions.

The EU heads of state are still determined to finalise the package before the end of the year, but they expect tough negotiations with a group of reluctant countries led by Poland.

An editorial in this week’s Nature lays out the options and prospects for EU climate policies in light of the financial crisis:

“Striking the required bargains may require more time than the remaining two months under French presidency. But a well-weighed set of rules is far and away preferable to a rushed political compromise that would substantially water down the EU’s ambitious climate plan. (…) Meanwhile, the current economic turbulence cannot be allowed to serve as a pretext for lessening climate protection efforts.”

Meanwhile, United Nations (UN) Secretary-General Ban Ki-moon has said in a statement that the EU plan “could also be a boon for the economy, generating millions of new jobs at a time when the world is suffering from the financial crisis.”

Any agreement will come too late for the international climate talks next month in Poznan, Poland (of all places). But a strong European commitment to cutting greenhouse gas emissions by at least 20 % would be a much-needed signal to the UN climate meeting in Copenhagen 2009, where nations hope to conclude on a successor treaty to the Kyoto Protocol.

Continue reading "From greed to green?" »

Posted by Quirin Schiermeier on October 23, 2008
Categories: Business, Carbon markets, Climate Policy, GHG emissions, Opinion, Politics, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

The European Parliament’s environment committee yesterday voted largely in favour of the ambitious European climate action plan (subscription) proposed in January.

The decision, although preliminary, allows the European Union (EU) to go into the upcoming next round of international climate negotiations with a common goal of reducing greenhouse gas emissions across Europe by at least 20 % by 2020. The European commission, Council and Parliament must yet formally agree on details of the plan, but substantial changes are now considered unlikely.

Power plants in Europe will no longer receive free allowances for their greenhouse-gas emissions.TRAVELPIX/GETTY

Most hotly contested were the amendments to the EU’s emission trading system (ETS) which the European commission had proposed in January to strengthen the effectiveness of the scheme.

Introduced in 2005, the ETS is as yet the only mandatory emissions trading system in the world. Until now, power stations and other large European industries have benefitted from generous supply of free permits to release carbon dioxide. Much of the commission’s proposed reform was aimed to end the over-allocation of emission allowances.

The compromise now agreed upon in parliament doesn’t pull the teeth out of the original plan. As of 2013, power stations will not receive free emission allowances anymore. Instead, they will have to obtain 100% of allowances at auction.

Other energy-intensive industries, such as steel and cement facilities which, unlike the power sector, have to compete with suppliers outside the EU, will in a first phase merely have to obtain 15% (rather than 20 % as the commission had initially proposed) of emission allowances at auction. But the allocation of free allowances to manufacturing industries is to be gradually phased out by 2020.

The environment committee did make some concessions to industry, though. The threshold for facilities – currently around 10,000 - which participate in the ETS is to be raised from 10,000 to 25,000 tonnes of annual carbon dioxide emissions.

Continue reading "EU Parliament backs climate plan" »

Posted by Quirin Schiermeier on October 08, 2008
Categories: Business, Carbon markets, Climate Policy, Energy, GHG emissions, In the News, Politics, Quirin Schiermeier, Topics | Permalink | Comments (1) | TrackBacks (0)

One of the more irritating aspects, if you will, of global change is that air pollution has so far prevented the planet from warming more rapidly than it actually did. Clean air is of course a good thing. But reducing pollution might expose an as of yet ‘masked’ portion of global warming.

This could have a dramatic affect on the Amazon rainforest. A team led by Peter Cox of the University of Exeter, UK, reports in a paper in this week’s Nature that reductions in aerosol pollution will tremendously increase the risk of severe drought in the Amazon region. Here is an editor’s summary of the paper.

Although it accounts for nearly a quarter of the world's fresh water, drought is not unknown in Amazonia.

In the dry season, from July to October, rainfall in the region is linked to sea surface temperatures (SST) in the tropical Atlantic. In years with a pronounced temperature gradient - warming of the tropical Atlantic north of the equator relative to the south – the normal’ position of high and low atmospheric pressure systems can shift, delaying or suppressing the onset of the South American monsoon.

The effect has been observed in 2005, when large parts of the Amazon region were hit by the worst drought in decades. See a Nature news story by Mike Hopkin here (subscription required) and a New York Times story here about the devastating event.

Cox thinks that the 2005 drought was a harbinger of things to come. Their “simulations for the 21st century show a strong tendency for the SST conditions associated with the 2005 drought to become much more common, owing to continuing reductions in reflective aerosol pollution in the Northern Hemisphere.”

Droughts like in 2005 will happen every two years by 2025, and in nine out of ten years by 2060, the model suggests.

How robust is this dire prediction? The Amazonian climate, for reasons not quite understood, is notoriously difficult to simulate. But the Hadley Centre’s climate model which was used for this study has previously reproduced features of the regional climate with greater accuracy than other models.

In Mike Hopkin's words, “the ultimate fear is that the Amazon forest - often touted as an invaluable piece of armour against climate change - could become part of the problem rather than a key element of the solution. Droughts make it more likely that it will become a net source of greenhouse gases to the atmosphere, rather than mopping them up.”

Quirin Schiermeier

You can vote or comment on the importance of the new paper in the Journal Club of Nature Reports Climate Change.

Posted by Quirin Schiermeier on May 08, 2008
Categories: Biosphere feedbacks, Climate Science, Climate prediction, Extreme Events, Quirin Schiermeier, Topics | Permalink | Comments (5) | TrackBacks (0)