Climate Feedback

Olive Heffernan

“Imagine farmers being able to determine what to plant and where based on drought forecasts three to five years out”, said Jane Lubchenco, head of NOAA, in Geneva last month.

Speaking to delegates at the World Climate Conference, Lubchenco was lending her voice to the vision of climate services, which would deliver climate predictions as reliable and useable as weather forecasts, and tailored to meet the needs of specific end-users. Underlying the vision of climate services is the assumption that further research will result in reliable climate predictions indispensable to adaptation planners.

In July, Germany opened a centre in Hamburg to provide the nation with such services. The Waxman-Markey Bill, passed by the US House of Representatives in June, would launch a similar service within the US, and headed by NOAA, to develop and distribute climate information and predictions to decision-makers.

But in a new Commentary on Nature Reports Climate Change, Mike Hulme and co-authors urge caution in relying on climate predictions to aid adaptation. They write:

Scientists and decision-makers should treat climate models not as truth machines, but instead as one of a range of tools to explore future possibilities.

They highlight that unlike weather forecasts - whose value in informing decision-making can routinely be tested over time by comparison with observed weather patterns - the skill of climate predictions is unknown, especially at the decade-to-century timescale.

Hulme and co-authors illustrate the perils of relying on the predict-then-adapt mode of planning with an example from the Australian state of Victoria. In this case, predictions from a 2005 study of the water supply to Melbourne assured decision-makers that existing plans provided a sufficient buffer against projected climate change up to 2020. But by 2006, water supply levels had dropped far below that predicted even for the most severe climate change scenario (see figure below).

Continue reading "Climate Prediction: keeping it in perspective " »

Posted by Olive Heffernan on October 29, 2009
Categories: Climate prediction, Communicating Climate Change, Olive Heffernan, Opinion, WCC-3 | Permalink | Comments (0) | TrackBacks (0)

Unless major breakthroughs in policy, industry and individual behavior turn around our emissions trajectory pronto, this century could well see average global temperatures 4 degrees Celsius or more above their pre-industrial baseline. That's the starting point for the 4 Degrees and Beyond conference in Oxford this week. Here, 130 scientists and policy experts are taking a detailed look at a world warmed by twice the amount that's usually considered dangerous.

Putting weight behind the 4-degree premise was new modelling research presented this morning by Richard Betts of the UK Hadley Centre (press release, Guardian). Betts's team used a complex, coupled ocean-atmosphere model to simulate the IPCC's extreme-emissions A1FI scenario (the FI stands for fossil fuel intensive) - an emissions trajectory that's previously been run only on simpler models. It's time to take this scenario seriously, argues Betts, given that our emissions are running at the upper end of what the IPCC projected a decade ago.

They also tried out weakening climate sinks on land and sea - feedbacks that are increasingly apparent in recent research, Betts says. Depending on the strength of the feedbacks, 4 degrees of average warming could be reached well before 2100 - as early as 2060 in a worst case scenario, and in the 2070s according to the team's best guess. Regional warming would be far greater, they found - 7 degrees in many areas, up to 10 in western and southern Africa, and 10 or more in the Arctic.

Sessions afterwards started sketching out consequences in detail. Philip Thornton of the University of Edinburgh looked at agriculture in Africa, where projected impacts are predictably devastating, with yields falling over 50% for certain crops and crop failure years growing more frequent in many regions. Adaptations for this amount of change are a big question mark. Intensive agriculture in highlands - among the few spots that will benefit - may be one possibility for preserving the food supply.

Meanwhile in Finland - where you might expect balmier weather to be a boon - intense climate change may also prove a curse to farmers, reports Reimund Rotter of MTT Agrifood Research Finland. The picture there is complicated - the possible responses depend on many variables. A new type of barley that might compensate for losses to rising temperature or drought would only work in certain soil types, for example. But it's clear that the North as well as the South will have its problems with the radically different 4-degree world.

Anna Barnett

Posted by Anna Barnett on September 28, 2009
Categories: 4 Degrees and Beyond, Adaptation, Anna Barnett, Climate Science, Climate prediction, Society | Permalink | Comments (0) | TrackBacks (0)

Heads of state agreed yesterday in Geneva to establish a global framework to deliver climate services to society. “We agreed on the need for climate services across all nations”, says Martin Visbeck, chair of the committee of scientific experts to the World Climate Conference.

The global framework will oversee the supply of demand-driven climate data to end-users such as farmers to water-resource managers, with the ultimate aim of aiding adaptation to climate change. Climate services would particularly help developing nations, for example, many of which lack access to the weather and climate observations needed to plan their global-warming adaptation strategies.

But the implementation of such services will face several political and scientific hurdles. Over the next four months, an independent task force set up by World Meteorological Organization, which convened the conference, will work out how to make this vision a reality. An arduous 12-month consultation process with signatory nations will then follow.

I’ve reported this for Nature News in full here. The news story covers the scientific challenges ahead in moving from climate ‘projections’ to decadal scale ‘predictions’, and also looks at the issue of data sharing, which will be require some careful negotiating over the coming months.

Ultimately, delegates expressed optimism about the vision agreed in Geneva this week, but there are concerns about how tough its implementation will be. According to Visbeck, the deal was much stronger on Tuesday, but “an unfortunate negotiation” meant that a couple of keys aspects were changed late in the day. One crucial change is that WMO is now ‘convening’ the implementation strategy rather than leading on it. Lacking one organization at the helm, the process of decision making could become that much harder. Secondly, a clause was added that says to all UN member states can weigh on each stage of the implementation plan before the final report is delivered to WMO in January 2011. “We didn’t achieve the maximum achievable”, says Visbeck.

In the meantime, however nations are charging ahead with implementing serivice-oriented climate science on their own steam. In July, Germany opened a national climate services centre in Hamburg, and the US is currently discussing plans for a national climate service in Congress and among relevant agencies.

Olive Heffernan

Posted by Olive Heffernan on September 04, 2009
Categories: 3a66c47d615e63162dcac400812ffa53, Climate prediction, Data, Olive Heffernan, WCC-3 | Permalink | Comments (0) | TrackBacks (0)

Tipping points - those critical thresholds in a complex system where a small nudge can cause a catastrophic response - are perhaps the most fearsome threats to the Earth’s climate, but they also haunt ecosystems, financial markets, and even sufferers of medical conditions such as epilepsy and asthma. A fascinating review in Nature today (subscription) sketches out the mathematical patterns on which many of these instances seem to be based, and describes giveaway signs that might warn us to change course before the system tips.

One common warning sign, for example, is flickering between the pre-tipping point state and the post-tipping point state. In climatology, abrupt changes traced in records of the Earth’s past suggest the planet has regularly gone through tipping points, such as the sudden warm-ups that change glacial periods into deglaciations. Earlier this year researchers reported in Nature Geoscience that rapid flickering signaled the end of Earth’s most recent cold spell, the so-called Younger Dryas period. The authors of the new review, led by Marten Scheffer of Wageningen University in The Netherlands, say that in a similar way, debilitating epileptic seizures can be preceded by frequent small symptomless seizures - the ‘flickers’ of the epileptic brain.

Continue reading "Why a climate crisis is like an epileptic seizure" »

Posted by Anna Barnett on September 03, 2009
Categories: Anna Barnett, Climate prediction, Earth science, Extreme Events | Permalink | Comments (1) | TrackBacks (0)

Climate scientists, weather forecasters and policy makers are gathered in Geneva this week to discuss the need for reliable climate predictions to help society adapt to climate change.

The third World Climate Conference of the World Meteorological Organization, which runs from 31 August to 4 September 2009, aims to produce a new global framework for delivering climate information to end users.

Scientists at the conference are hopeful that with sustained support for climate research and improved computing capabilities they could reliably predict climate impacts at much higher resolution – perhaps down to several tens of kilometres over the coming decades. The ultimate goal , and one that was voiced at last year’s World Climate Modelling Summit in Reading (which we covered here) is to produce climate predictions that are as reliable and useable as weather forecasts.

That would be a vast improvement on the projections available from today’s global climate models. Most of these enable estimates of how temperature, and other climate variables such as rainfall, will change over areas of several hundred kilometres up until the end of the century and beyond.

While a large focus of the conference is on improving climate modelling in order to make reliable predictions, delegates in Geneva are also discussing the need to tailor information to the needs of specific end-users.

“A forecast in not enough; our challenge is to communicate what we know that the future in a manner that can allow people to make decisions”, said Gro Harlem Brundtland, special envoy of the UN secretary-general on climate change, at the opening session on Monday. At the end of the 5-day conference, delegates will issue a declaration of their intent to establish a new global framework to meet this challenge.

But major advances will be needed in the science of prediction before climate information is of real service to society. “In 10-15 years we may have climate forecasts like we now have weather forecasts”, said Guy Brasseur of the National Centre for Atmospheric Research (NCAR) in Boulder, Colorado to delegates here on Monday. “We have the international vision, expertise and scientific commitment to deliver climate services”, said Brasseur, but he also warned of the difficulties in developing climate models of sufficiently high spatial resolution and reliability.

One hurdle is the massive investment needed to fund one or more supercomputers; others include accessing data and sustaining long-term observations. Despite these, several attempts to improve predictive capability are underway worldwide. One of these, being championed by Tim Palmer of the European Centre for Medium-Range Weather Forecasts is the concept of ‘seamless prediction’, in which one modelling system is used to predict atmospheric conditions on time scales varying from hours to decades. Other efforts, being headed by scientists from the UK Met Office and elsewhere, are focused on how climate change will pan out in the coming decades, and combines aspects of seasonal forecasting with centennial prediction (which I won’t go into now, but hope to come back to). Still another approach is Earth System Modelling, which attempts to model the whole earth system – including feedbacks - more comprehensively than climate models, at spatial scales of 150km across.

Scientists at the conference are excited at the possibility that such efforts will lead to greater predictability, but are also concerned that end-users could have unrealistic expectations of what that means. “We’ll never be able to produce absolute predictions of what will happen in the future”, says Vicky Pope of the UK Met office. She says that scientists must work within a risk management framework so that people don’t misuse the data. “We are nervous about the uncertainties and errors associated with the models we are using”, says Jerry Meehl of NCAR, adding “That needs to be part of the message that gets out with climate services”.

Olive Heffernan

Posted by Olive Heffernan on September 01, 2009
Categories: Climate prediction, Communicating Climate Change, Olive Heffernan, Regional climate, WCC-3 | Permalink | Comments (0) | TrackBacks (0)

In the latest salvo of the scientific debate over future sea level rise, a new report counters claims that rapidly swelling seas will soak estimates published by the UN climate planel in 2007.

A major “it’s worse than we thought” story out of March’s Copenhagen Climate Congress, for example, was that sea level could climb more than a metre by 2100 - seemingly far worse than the rise of up to 59 centimetres indicated in the 2007 report from the Intergivernmental Panel on Climate Change (IPCC). This was in fact something of a straw-man comparison, since the IPCC total explicitly excluded the impacts of accelerated glacier melt, and the new studies were attempting to add these impacts in.

But the latest study suggests that even considering glacier effects, the 2100 rise is likely to be well under a metre. A trio of researchers - Mark Siddall of Columbia University in New York, Thomas Stocker of the University of Bern (current co-chair of IPCC Working Group I) and Peter Clark of Oregon State University - used a new method that looks to the past to inform this future projection.

Continue reading "Sea level rise: not so fast" »

Posted by Anna Barnett on July 28, 2009
Categories: Climate prediction, In the News, Ocean science, Palaeoclimate | Permalink | Comments (2) | TrackBacks (0)

A reconstruction of the Earth’s climatic history during a key hot period 55 million years ago has highlighted a yawning gap in our understanding: this period’s rise in carbon dioxide accounts for just half of its warming. Some as-yet-unidentified climate feedbacks could be at work, the scientists behind the research conclude.

The era under scrutiny is the Palaeocene-Eocene Thermal Maximum (PETM). Paleoclimatologists believe that the PETM could mimic our own future climate, because it’s thought to have kicked off with a pulse of carbon dioxide roughly equivalent to what humans are currently pumping out by burning fossil fuels. In a study published in Nature Geoscience (subscription), Richard Zeeb of the Universtiy of Hawaii and colleagues make a new, more precise estimate of the PETM’s carbon dioxide release based on ocean sediment records.

The increasing carbon levels caused ocean acidification that dissolved deep-sea carbonate compounds. By using measurements of this process along with a carbon-cycle model, the team inferred that during the period’s initial CO2 spike, no more than 3 billion tonnes of the gas was released over 5,000 years. Even before then, the planet looked like a greenhouse – it had a much warmer climate than today and about 1,000 parts per million CO2 in the atmosphere. Over the main phase of the PETM, the group estimates the CO2 level rose to 1,700 parts per million.

But according to the IPCC’s best guess at climate sensitivity, that 70% rise should have pushed up global temperatures 3.5 degrees Celsius at most. Other proxy records indicate, though, that temperatures soared by 5 to 9 degrees. In other words, the consensus climate sensitivity - the value, devilishly hard to pin down, for how much warming will result from a given greenhouse gas increase - doesn’t seem to be holding.

Continue reading "Unknown climate culprit for Palaeocene-Eocene warming" »

Posted by Anna Barnett on July 14, 2009
Categories: Anna Barnett, Climate prediction, Palaeoclimate | Permalink | Comments (0) | TrackBacks (0)

Nature Geoscience’s latest issue highlights the challenges of understanding fluctuating sea level – from 70 million years ago to the future (sea level content free to registered users). A collection of commentaries and research papers look at how sea level has changed in the past and try to project its future evolution. In addition, the issue provides insights into some of the societal impacts of sea level change, and how some countries are planning for the future.

Continue reading "Focussing on sea level" »

Posted by Alicia Newton on June 30, 2009
Categories: Adaptation, Alicia Newton, Climate prediction | Permalink | Comments (0) | TrackBacks (0)

Long-awaited projections of how climate change will impact the UK have been met with caution by scientists.

The projections, released yesterday in London, offer the most detailed picture yet of how the UK - piece by piece, in sections just 25 km sq - will be affected by various climate impacts.

Their main message is that without substantial efforts to cut global greenhouse gas emissions, Britons could be in for a hard time by the 2080s. While the risk of flooding will worsen in the North West, the South East will face an anticipated 22% decline in summer rainfall. If emissions continue to rise, London will likely experience a 2-6°C degree rise in temperature and sea-level rise of 36cm.

The UK government hopes the information will enable citizens and local authorities adapt to the changes that lie ahead, but some fear the projections provide misleading information.

That’s because the method used to produce these highly detailed projections of the future is new – and hasn’t yet been through peer-review. Bob Watson, chief scientist with the UK Department of the Environment Food and Rural Affairs (DEFRA) is confident it’s just a matter of time before the methodology is used on a broader scale. He expects it “will be taken up by other regions and highlighted by the IPCC in their next report”.

But while the projections were originally slated for release last November, an independent committee was convened at the eleventh hour to check out the methodology.

Oxford climatologist Myles Allen was on the committee, and he’s concerned that the results stretch the science beyond its current capabilities. His main worry is that as recently as 2007, the Intergovernmental Panel on Climate Change didn’t think that climate variables could be reliably resolved at spatial scales beyond a couple of 1000kms. And no research published since has challenged that view.

He spoke to me about this for Nature News, where I’ve covered the story in detail. He also spoke of his concerns on yesterday’s Newsnight, which is definitely worth a look.

Continue reading "Cautious response to UK climate projections " »

Posted by Olive Heffernan on June 19, 2009
Categories: Climate prediction, In the News, Olive Heffernan, Regional climate | Permalink | Comments (2) | TrackBacks (0)

Today's theme at the AGU Chapman Conference on Abrupt Climate Change is that big baddie of climatic tipping points, the shutdown (and rebooting) of the Atlantic Meridional Overturning Circulation, or AMOC. Could this massive system go down again? Tom Delworth of NOAA took on that question and offered up some interesting new modelling evidence.

When running strong, AMOC carries heat from the Southern Hemisphere northward. It's thought that some of the past coolings under scrutiny here stem from slowing or stopping of this conveyor belt. AMOC's future change in response to greenhouse gas increases was recently considered in an assessment report on abrupt change by the US Climate Change Science Program, which Delworth helped author.

While some state-of-the-art models suggest the circulation could slow this century - a 25-30% decrease is the report's best estimate - not a single one forecasts another shutdown in that time. That led the US panel to evaluate AMOC shutdown as "very unlikely", in the parlance of the IPCC - meaning a less than 10% probability. The lack of support from models meant they couldn't set the likelihood any higher, says Delworth - but on the other hand, the possibility of flawed simulations kept them from setting it lower, at "extremely unlikely". But Delworth's new work validates the model results.

Continue reading "AGU Chapman: Meridional madness" »

Posted by Anna Barnett on June 16, 2009
Categories: AGU Chapman conference on Abrupt Climate Change, Anna Barnett, Climate prediction, Extreme Events, Palaeoclimate | Permalink | Comments (0) | TrackBacks (0)

A scant 21,000 years ago, Columbus, Ohio, was blanketed by the Laurentide ice sheet. Today it is home to the Byrd Polar Research Centre at Ohio State University, where this morning I sat in a glacially air-conditioned lecture hall watching an animation of that sheet flickering rapidly back and forth across Columbus and the rest of the northern parts of the continent. Such strobe-light climate change from the Earth's past is the focus of the AGU Chapman Conference on Abrupt Climate Change, being held here this week.

Though it's a fairly small gathering of 150 experts, it doesn't have the annual reunion feeling of some meetings; many of the people here seem never to have met before. We've got palaeoscientists of various persuasions: they reconstruct climatic history via models, ice, sediment, or - as geochemist Henry Pollack described his work on borehole temperature records to me over hors d'oerves - by "taking the Earth's temperature through its rectum". (Jokes about giant thermometers ensued.)

The common thread is figuring out what caused abrupt changes in the past - and what that implies about the prospects for their return. Says Richard Alley, a Penn State glaciologist and IPCC author, "The IPCC reports are the most optimistic thing we can put forward, because the projections are smooth. If you look at any palaeo record, there are bumps. This meeting is all about the bumps."

One innovative study on show today applied the models behind those smooth future projections to the bumpy past record. Bette Otto-Bliesner of NCAR says her group's research is the first to feed palaeo data into an IPCC-style coupled global climate model and run it continuously for several thousand years during the last deglaciation - rather than just taking snapshots in time, as was done previously. Having given the model instructions about what the greenhouse gas levels, sea ice extent, and meltwater flows should be, they found that it beautifully reproduced the bumpy North Atlantic temperature record.

Continue reading "AGU Chapman: It's all about the bumps" »

Posted by Anna Barnett on June 15, 2009
Categories: AGU Chapman conference on Abrupt Climate Change, Anna Barnett, Climate prediction, Palaeoclimate | Permalink | Comments (0) | TrackBacks (0)

Level 7 of the Metro Toronto Convention Centre is situated above Level 8, and Level 6 is higher still. Once you find your way around, it’s seems the perfect place to study atmospheric inversions and other climatological phenomena. That’s what is happening at the centre this week during the Joint Assembly of the American and Canadian Geophysical Unions, along with a half-dozen other Earth and space science societies.

This annual event, once known as AGU Spring Meeting, has attracted some 2,500 presentations, ranging from Atmospheric Science to Volcanology, and the ones touching on climate change turn up under a variety of headings. Climate change may occur globally, but it impacts locally, and regional impacts were the topic of numerous presentations Monday at Joint Assembly.

The issue facing researchers and policy makers alike is scaling down the results of global climate models to make useful predictions for specific locales, like cities, counties, or watersheds, predicting how climate change may affect local populations, industries, and wildlife.

In the US state of New Hampshire, for example, the multimillion dollar ski industry depends upon a large and consistent snowpack. Cameron Wake of the University of New Hampshire said that to be economically viable, ski operators must count on a season of at least 100 days, ideally including Christmas week. But, a group of regional scientists estimates that by 2100, New Hampshire will warm between 1.9o and 6.9o Celsius, the extremes of several models tested. The greatest warming will be in winter. Also, there will be more rain and less snow in winter, and anticipated droughts will further reduce the number of days with snow on the ground. By the 100-day standard, Wake said, and even with snowmaking equipment, almost all New England ski areas will be vulnerable by 2100.

New York City has always prided itself on its water supply. New Yorkers turn the tap and enjoy mountain spring water piped from protected watersheds far upstate. But will climate change affect the quality of that water—currently four million liters for nine million customers daily—in years to come? The city is actively addressing that question, said Mark Zion of New York’s Environmental Protection Agency.

Continue reading "AGU 2009 Joint Assembly: Global change, local impacts" »

Posted by Olive Heffernan on May 25, 2009
Categories: AGU 2009 Joint Assembly, Climate prediction, Harvey Leifert, Regional climate | 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)

Last year, I reported on efforts to merge climate modelling with weather forecasting to create probabilistic climate predictions, with the ultimate aim of providing information that could aid adaptation.

Given enough money to build a world climate research facility with hundreds of petaflops of computing power, scientists could study simulations at the kilometre scale, and answer some of the big questions in climate science, such as how and when regions will be affected, concluded the World Modelling Summit for Climate Prediction last May.

Now, a group of scientists led by Suraje Dessai of the University of Exeter and the Tyndall Centre, UK argue that better climate predictions will not necessarily aid adaptation, and that waiting for better predictability in order to act on climate change would be a ‘significantly flawed’ approach.

Writing in the latest issue of EOS, a newsletter of the American Geophysical Union, Dessai and co-authors say that, in any case, the ability to predict future climate is limited by inherent uncertainty that will always leave ‘some level of irreducible ignorance in our understanding’. Furthermore, our ability to predict other factors that are likely to influence the outcome of adaptation efforts, such as population growth or changes in technology, is even more limited than our ability to predict the climate.

But this lack of predictability should not be seen as an excuse to postpone strategies for adaptation, they argue. After all, many organizations such as water authorities only need to know the range of possible representations of future climate to better understand their vulnerabilities. The authors call on decision makers to examine their adaptation strategies over a wide range of potential future scenarios of climate and other economic, political and cultural factors. Society will benefit more, they say, from knowing the vulnerability of climate-influenced decisions in the face of large uncertainty than from any foreseeable increase in the accuracy and precision of climate predictions.

Olive Heffernan

Posted by Olive Heffernan on April 08, 2009
Categories: Adaptation, Climate Science, Climate prediction, Olive Heffernan | Permalink | Comments (0) | TrackBacks (0)

The Arctic has been losing summer sea ice fast. At the end of the melt season in September 2008 the ice extent was barely above its record low of 2007, even after a much cooler summer. Most climate models did not anticipate the pace of this ice disappearance and still can’t replicate it. And as shown in the figure above, the futures projected by models are all over the map.

But researchers are reporting this week that there may be a way around the problems with modelling sea ice. With a new method for using observations to constrain climate projections, they find that the summertime ice is going, going, and set to be gone well before 2100.

The study was published in Nature Geoscience (subscription) by Julien Boé and his colleagues at UCLA. They calculate that the models showing the fastest future ice loss are also the most realistic about the recent past - something you could guess at by looking at the graph above, where the actual ice trend is shown as a black line. So rather than simply averaging across models, their technique teases out the most likely future sea ice evolution using the differences between the models that show the 1979-2007 ice extent most accurately and those that perform less well at reproducing past trends (if you’ve a yen for statistics it’s worth checking out the paper itself - the method is explained in a neat graphic). They project, based on a moderate emissions scenario, that September sea ice will most likely disappear between 2066 and 2085. That is sooner than even the most pessimistic models suggest on their own (see graph again).

Continue reading "Reconciling sea ice models with reality" »

Posted by Anna Barnett on March 19, 2009
Categories: Anna Barnett, Climate prediction, Cryosphere | Permalink | Comments (1) | TrackBacks (0)

Cross-posted from In the Field

A leader of the the Intergovernmental Panel on Climate Change told the AAAS annual meeting in Chicago on Saturday that the world's climate is likely to change much faster than predicted, leaving the world with two choices: start cutting carbon emissions earlier, or make the cuts deeper.

The comments came the morning after former U.S. Vice President Al Gore called on scientists at the meeting to help convey a sense of urgency about climate change to policy makers and the public.

"We are basically looking now at a future climate that is beyond anything we've considered seriously in climate model simulations," said Chris Field, co-chair of the IPCC's second working group and a professor at Stanford University and the Carnegie Institution for Science.

This is because the rate at which carbon is entering the atmosphere is increasing much faster than the IPPC modeled in its last report, issued in 2007. That report estimated that world temperatures could increase by between 1.1 to 6.4 degrees Celsius by 2100. But the surge in the use of coal to generate power in developing countries, combined with climate impacts on natural carbon sinks, such as oceans, forests and tundra, mean that future climate impacts will likely be more severe than the IPPC realized, Field said.

"We have higher emissions, and we have a less friendly natural system to picking up these higher emissions, and they both mean that looking forward, the challenge of stabilizing atmospheric carbon dioxide is getting more complicated than we thought it was before," Field said.

Continue reading "AAAS: Climate issue getting "more complicated"" »

Posted by Anna Barnett on February 16, 2009
Categories: Climate Science, Climate prediction, Deforestation, Energy, Erika Check Hayden, GHG emissions | Permalink | Comments (2) | TrackBacks (0)

As speculation grows that agreeing a global deal on climate change may extend well beyond the 2009 deadline, the risk of overshooting the EU’s target to limit the increase in global temperature to 2°C over pre-industrial levels looks increasingly likely.

The target is based on scientific evidence that below a 2°C increase, some of the worst impacts of climate change would be avoided. In its fourth assessment report, the IPCC calculated that limiting warming to that extent would mean stabilizing atmospheric concentrations at roughly 450 ppm CO2-equivalents.

But it’s clear at this year’s AGU that much uncertainty, and disagreement, remains on whether 2°C is an appropriate target and on the atmospheric greenhouse gas concentrations that equate to a given amount of warming.

Speaking here yesterday, James Hansen, director of the NASA Goddard Institute of Space Studies, called for atmospheric greenhouse gas concentrations to be restricted to 350ppm. Hansen also recently advised the UK government’s Environmental Audit Committee that the 2°C target should be revised to a 1°C increase above pre-industrial levels. Meanwhile, many of the scientists presenting work here are wrangling with whether stabilizing at 450ppm – or higher – is economically and technologically feasible.

The debate on where to stabilize is largely due to what Stanford’s Stephen Schneider dubs ‘double-barrelled uncertainty’ a term that encompasses the unknown factor in how far we can reduce emissions and in how the climate system will respond to any reductions we make.

The latter uncertainty – that inherent in the system – is measured in terms of climate sensitivity i.e. how much warming would occur if atmospheric GHG concentrations were doubled. This is currently estimated at 2-4.5°C, but Schneider said here on Tuesday that it’s more important for society to know the uncertainty around this range i.e. the chance that we will see a much larger degree of warming than anticipated for various atmospheric concentrations.

Given the fact that a massive reduction in emissions in the coming decades it is very unlikely, he says, and the fact that we could overshoot our target anyway, we need to take a serious look at the consequences. Schneider suggests that the IPCC should take it on board to evaluate climate scenarios for overshooting to 600 ppm and then subsequently reducing atmospheric concentrations to say 500ppm or 450ppm.

Continue reading "AGU 2008: Uncertainty and overshooting 2°C" »

Posted by Olive Heffernan on December 18, 2008
Categories: AGU, Climate Science, Climate prediction, GHG emissions, Olive Heffernan | Permalink | Comments (4) | TrackBacks (0)

Whether peak oil is good news for the climate ultimately depends on what replaces oil as our staple fuel source. It will be unsurprising to most that replacing dwindling oil reserves with coal would do little to solve the climate problem, but how much coal remains is also highly uncertain, according to Prof. David Rutledge of Caltech, who spoke to the press at the AGU this morning.

Andy Dessler of Texas A&M touched on this in a guest commentary posted here last month. In short, Dessler called for a global IPCC-like assessment of our fossil fuel reserves, pointing to a new analysis by Rutledge that shows the world’s available coal reserves are far lower than traditional estimates would suggest. If Rutledge’s estimates are correct, combustion of all remaining conventional oil, gas, and coal reserves would produce an atmospheric concentration of carbon dioxide of approximately 470 ppmv in 2100, near the stabilization target that many climatologists argue we must achieve to avoid the worst impacts of climate change.

While Rutledge’s estimates suggest that the worst-case scenarios of the IPCC may be unachievable, Ken Caldeira of Washington’s Carnegie Institute had a more sobering message. Caldeira and colleagues used a climate and carbon cycle model to look at how running out of oil could affect future climate scenarios. Their analysis showed that if we replaced oil with liquefied coal fuel promptly, we would reach 2°C above pre-industrial temperatures in 2042 instead of 2045. Replacing oil with renewables, however, would delay reaching 2°C above pre-industrial temperatures by 11 years. This is simply because per coal emits more carbon dioxide per unit of energy than oil; add to that the energy costs associated with conversion of coal to liquid fuels, a likely option if we run out of oil.

Continue reading "AGU 2008: Peak fuel reserves " »

Posted by Olive Heffernan on December 17, 2008
Categories: AGU, Climate prediction, Energy, GHG emissions, Olive Heffernan | Permalink | Comments (2) | TrackBacks (0)

The year 2008 was likely the coolest year of the current decade, but it was still the tenth warmest year on record since instrumental climate records began in 1850.

The average global sea-surface and land-surface air temperature from December 2007 to November 2008 was 14.3 °C, the World Meteorological Organization (WMO) has announced. This is slightly lower than for all previous years of the ‘naughties’, but still some 0.3 °C above the 1961-1990 annual average. The warmest year on record is 1998, with an average global temperature just above 14.5 °C.

Left: Global map of surface temperature anomalies in degrees Celsius for the 2008 meteorological year. Right: Annual-mean global-mean anomalies, except 2008, which is the 11-month (Jan-Nov) mean anomaly. Credit: NASA Goddard Institute for Space Studies.

When calculating global average temperatures, climatologists prefer the meteorological year, from December through November, as it is easier to split it into actual seasons than is the calendar year.

The WMO temperature analysis is based on land-based weather stations in 188 countries, complemented by measurements from ships, buoys and satellites. NASA’s Goddard Institute for Space Studies and the UK Met Office, which both contributed their own datasets to the WMO analysis, independently arrive at very similar values.

Continue reading "2008 cooling, but the heat is on" »

Posted by Quirin Schiermeier on December 17, 2008
Categories: Climate prediction, Climate variability, Extreme Events, Quirin Schiermeier | Permalink | Comments (3) | TrackBacks (0)

I hadn’t anticipated quite so much rain during the AGU’s Fall conference in San Francisco, but apparently this exact week is, on average, the city’s wettest of the year. Or so I heard at today’s session on how the region is likely to be impacted by climate change.

California has been long recognized as a leader on climate policy, both on the home front and even internationally. It passed its first climate bill twenty years ago and just last week, the state adopted the nation's most sweeping climate action plan to date, pledging to cut its greenhouse gas emissions by 15% by 2020.

A close look at how the region is expected to fare under various warming scenarios makes its leadership in this arena look a lot like common sense. While temperatures in California are expected to increase in line with global averages, more worrying for the state is the projected water shortages, according to Dan Cayan of the Scripps Institution of Oceanography in La Jolla, San Diego, who spoke at AGU today. California faces the possibility of a 10% decrease in precipitation over the course of the century and could concurrently lose half of its late spring snowmelt. That's bad news for a region that is already heavily reliant on external water sources.

Sea-level rise will also be part of the equation, especially for the numerous coastal properties with little protection, said Peter Gleick, president of the Oakland, California –based Pacific Institute. Should those in the interior think they’re better off, though, climate models show that inland regions will warm more rapidly than the coast and will likely be more populated in the future owing to lack of available living space on the coast.

Continue reading "AGU 2008: On the home front" »

Posted by Olive Heffernan on December 17, 2008
Categories: AGU, Adaptation, Climate prediction, Extreme Events, Olive Heffernan | Permalink | Comments (0) | TrackBacks (1)

Over the past 24 hours, some 15,000 earth scientists descended on San Francisco for the annual Fall conference of the American Geophysical Union. Delegates were a dead give away at the airport and on the BART yesterday with their large poster tubes in tow. It’s my first AGU and it could be the jet lag, but I’m feeling slightly overwhelmed by the sheer size and number of parallel sessions; at any given time I could be at one of at least four climate-related talks and invariably find myself wondering why the session next door is receiving louder applause.

A number of talks today focused on the need for climate science to become less curiosity driven and more specific to the needs of stakeholders such as local authorities and natural resource managers.

This is a topic that’s been getting a lot of attention recently. Earlier this year, for example, scientists called for a billion dollar investment in climate computing facilities to enable regional scale climate predictions on decadal time scales. At a press conference this morning, scientists including Jonathan Overpeck from the University of Arizona and Jack Fellows of UCAR highlighted the importance of partnerships between universities and decision makers in enabling states and regions to plan for climate change.

Continue reading "AGU 2008: conference kicks off " »

Posted by Olive Heffernan on December 16, 2008
Categories: AGU, Climate prediction, Features, Olive Heffernan, Regional climate, Research | Permalink | Comments (3) | TrackBacks (0)

The world's most advanced simulation of extreme weather on a warming Earth completed its first run last Friday - though the data won't be fully digested into human-readable format until spring. Yesterday I talked to meteorologist Greg Holland, co-leader of the study, at the Willis insurance company's London office - whose cycle racks, I can report, are tucked away discreetly across the street from its intimidatingly curved and purple-lit lobby.

Willis's research arm funded the work, along with the offshore oil industry, the US Department of Energy and the US National Center for Atmospheric Research (NCAR), where Holland is based. They all want to know how climate change will alter hurricane patterns in the Atlantic. At the request of several US state governors, the project is also looking at rainfall over the Rockies and winds in the Great Plains. Says Holland:

I'm not going to forecast a squall line through New York in 2050. But what we want to do is be able to say: "What are the statistics of squall lines going through New York in 2050?" or "What are the statistics of hurricanes coming into Miami in 2050?"

Continue reading "Forecasting the future of hurricanes" »

Posted by Anna Barnett on December 11, 2008
Categories: Anna Barnett, Atmospheric Science, Climate prediction, Hurricanes, In the News | Permalink | Comments (1) | TrackBacks (0)

More elderly readers of these pages may remember having heard in their school days back (circa 1970s) that scientists then thought an ice age would be coming soon. I certainly do – even though the alleged ‘global cooling consensus’ in the scientific literature of the time has recently been disproved as a myth.

Now an interesting new paper in Nature [subscription] suggests that a rapid natural transition towards a stable glacial climate, with permanent ice sheets covering large parts of North America and Eurasia, could indeed be ahead.

Thomas Crowley and William Hyde ran a coupled energy-balance/ice-sheet model to test their hypothesis. When forced with long-term variations in daily solar radiation which result from small cyclical changes in the Earth’s orbit, the best-fit model run (that is the one which most accurately reproduced ice sheet variations during the last 3 million years) predicted a rapid transition towards a cold climate regime to occur merely some 10,000 to 100,000 years from now.

Models and theory do indeed suggest that at critical points (namely when climate variability is at a maximum) large ice sheets can rapidly develop from very small perturbations in solar forcing.

Continue reading "Glaciation ahead - on a geological time scale " »

Posted by Olive Heffernan on November 12, 2008
Categories: Climate prediction, Climate variability, Features, Journal Club, Quirin Schiermeier | Permalink | Comments (1) | TrackBacks (0)

“In the 1970s, all the scientists were saying an ice age was coming.” This seems to be a popular sentiment echoed in blogs and novels aimed at challenging the consensus views regarding future climate change. It was even a key theme in Michael Crichton’s State of Fear , when a character suggests that scientists only jumped on the global warming bandwagon in a bid to secure funding.

But a new article in the Bulletin of the American Meteorological Society challenges the idea of a 'global cooling ' consensus. Thomas Peterson of NOAA teamed with William Connolley of the British Antarctic survey and science reporter John Fleck to create a survey of peer-reviewed climate literature from the 1970s. Looking at every paper that dealt with climate change projections or an aspect of climate forcing from 1965 to 1979, they were able to assess the ‘trends’ in the literature. They found that only 7 of the 71 total papers surveyed predicted global cooling. The vast majority (44) actually predicted that rising atmospheric carbon dioxide could lead to global warming.

Continue reading "The great global cooling myth" »

Posted by Alicia Newton on October 07, 2008
Categories: Alicia Newton, Climate Science, Climate prediction, Communicating Climate Change, GHG emissions | Permalink | Comments (12) | TrackBacks (0)

For all tree huggers out there, this week’s Science is dedicated to ‘forests in flux’, paying tribute to the trees and their contribution to the greater good. A special collection of articles in print, with complementary and online material, examines the fate of the world’s forests, in the face of climate change and an escalating human population.

If it’s been a while since you’ve had the chance to appreciate the languid leafiness of forest foliage, check out the online video. Or for those of you hoping for a more ‘hands on’ experience, there’s a whole section of Science Careers dedicated to opportunities in forest ecology.

There’s lots of serious science, with six Perspectives and one Review by researchers from all over the globe who give their tuppence worth on what’s needed to better understand forests and manage them properly.

Of particular relevance to discussions on how forests can mitigate global warming, Lera Miles and Valerie Kapos have a Perspective highlighting the risks involved in proposed schemes such as REDD (reduced emissions from deforestation and forest degradation) and how to minimize them. Also on this topic, Josep Canadell and Michael Raupach write on what science currently tells us is the best way to manage forests for sequestering carbon.

Drew Purves and Stephen Pacala discuss how forest dynamics remain one of the largest uncertainties in predicting future climate change and detail some of the efforts underway to improve their representation in models. Or for a really solid review of how forests affect climate change, check out Gordan Bonan’s piece here.

Or if that seems like a lot of tree pulp to get through, here are some interesting stats from the issue:

Forests cover ~42 million km2 in tropical, temperate, and boreal lands, and cover ~30% of the land surface

They store ~45% of terrestrial carbon and account for ~50% of terrestrial net primary production.

Forests hold more than double the amount of carbon in the atmosphere.

Carbon uptake by forests in the 1990s contributed to ~33% of anthropogenic carbon emission from fossil fuel and landuse change.

Olive Heffernan

Image: Plantations of Pinus radiata and Eucalyptus nitens in Gippsland (Victoria, Australia); courtesy of Michael Ryan.

Posted by Olive Heffernan on June 13, 2008
Categories: Biodiversity and Ecology, Biosphere feedbacks, Carbon markets, Climate Policy, Climate Science, Climate prediction, Deforestation, GHG emissions, Mitigation, Olive Heffernan, Uncertainty | Permalink | Comments (1) | TrackBacks (0)

A new study, published online Sunday by Nature Geoscience, presents solid evidence that temperatures in the Earth's lower atmosphere are increasing in line with temperature changes on the ground.

This issue has been hotly disputed in the past, partly owing to the fact that temperatures measured in the troposhere - the portion of the atmopshere stretching from 12 to 16 kilometeres above the Earth's surface - by satellites and weather balloons in the early 1990s didn't mirror the changes on the ground.

This fact was used as evidence against climate change, despite the fact that it has been long known that there were problems with the original data collection and analysis.

In the search for more accurate measurements, two scientients Robert Allen and Steven Sherwood of Yale University, have now developed a novel approach using wind rather than temperature data. Their research shows that the lower atmosphere has indeed warmed since 1970, as projected by most climate models, and in sync with warming on the ground measured using temperature data.

In a related News and Views article, aslo on Nature Geoscience, Peter Thorn of the UK Met Office Hadley Centre, one of the world's premier climate modelling facilities, writes:

This is not simply an interesting academic aside — not knowing where observational problems begin and modelling limitations end undermines our ability to understand and predict global climate change.

For further reading on the topic, check out the post over on Real Climate last week discussing the same issue, and highlighting some upcoming papers in the Journal of Climate.

Olive Heffernan

Posted by Olive Heffernan on May 27, 2008
Categories: Atmospheric Science, Climate Science, Climate prediction, Features, Journal Club, Olive Heffernan | Permalink | Comments (1) | TrackBacks (0)

While most Londoners spent last week maximising their time spent basking in the glorious sunshine that so rarely comes our way, I spent it largely indoors - at a place that predicts these sorts of unusual occurrences, otherwise known as the European Centre for Medium Range Weather Forecasts (ECMWF) in Reading.

The World Modelling Summit for Climate Prediction held there last week was itself something of a rare event – a union of the weather and climate communities, who met to discuss whether – and how – they can eventually provide climate predictions that are as useful, and as useable, as weather forecasts.

The four-day summit culminated in a call for a massive investment, around a billion dollars, to fund a new global research facility or facilities with computer and research resources that would ‘revolutionize’ climate modelling capabilities, bringing into view the holy grail of ‘seamless’ weather-to-climate prediction.

We’ve covered the summit in some detail in this week’s Nature [subscription], in my news story and an editorial by Oliver Morton.

In short, the idea is that an injection of cash on this scale could bring about a quantum leap in climate simulations by funding climate computers far beyond those in use today. Currently, computers used for modelling the climate are in the 10-teraflop range, which means that they operate at inconceivably high speeds and run models that divide the globe into 100 kilometre cells to roughly project how global climate is likely to change in the long-term.

Though these models have had a key role in warning us of the gradual warming of our planet, they’ve fared pretty poorly when it comes to gauging the likelihood of extreme localised events, such as flooding or more frequent hurricanes. But scientists at the conference said that if they had access to supercomputers – with speeds in the range of hundreds of petaflops (basically 10,000 times more processing power) - they could resolve climate globally on the scale of kilometres, potentially creating models good enough to inform nations of the specific regional challenges they can expect in adapting to climate change.

Continue reading "A revolution - for climate model evolution " »

Posted by Olive Heffernan on May 14, 2008
Categories: Climate Science, Climate prediction, Features, In the News, Journal Club, Olive Heffernan, Technology | Permalink | Comments (0) | TrackBacks (0)

Money talks, and so do bloggers. Unable to resist the correlation, a number of climate scientists and analysts have adapted their online podiums into betting tables. The RealClimate team are the latest to roll up to the climate casino, staking €5,000 against the predictions of a recent Nature paper (subscription required) that in the next decade, falling temperatures in some regions will cause a slight slowdown in global warming.

The paper's authors, Keenlyside et al., have yet to accept or reject the bet, and it's not available to any other cooling proponent who may be feeling lucky. But if your opinion on global warming is burning a hole in your pocket, you have some options. Brian Schmidt's Backseat Driving, for example, lists several standing offers to all takers.

Those like Schmidt who back the scientific consensus that the Earth is warming, however, have had a hard time convincing anyone to gamble large sums on cooling. A few bookmaker's highlights:

Continue reading "RealClimate roll up to the climate casino" »

Posted by Anna Barnett on May 09, 2008
Categories: Anna Barnett, Climate prediction | Permalink | Comments (9) | 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)

A paper in this week’s Nature predicts that, rather than warming, North Atlantic sea surface temperatures may actually decrease slightly in the next decade. What’s more, the paper suggests global surface temperatures may not actually increase either.

Has global warming stopped? Is this a nail in Al Gore’s coffin?

Well, no.

Despite headlines such as ‘Doubt is cast over global warming’ and ‘Global warming could stop NATURALLY for ten years, say scientists’ that is not what this paper is about.

What this new paper by Noel Keenlyside, of the Leibniz Institute of Marine Sciences in Germany, sets out to do is incorporate data on short term variations in climate into our models of climate change. By doing this they push us into the arena of creating shorter term predictions, in this case of the next decade.

In a “News and Views” commentary on the piece in the same issue of Nature Richard Wood explains:

Keenlyside and colleagues’ model uses a very simple ocean initialization method in which they add heat to or remove it from the ocean surface until sea surface temperatures across the globe are close to observed values. They use their model to produce a set of retrospective ‘forecasts’ starting from earlier states, which they test against what actually happened. Their system produces refined temperature predictions a decade ahead for large parts of Europe and North America.

Whether their prediction of a plateau for warming for a decade in North America and Europe is correct or not, their research may signal a shift that many climate researchers have been calling for for awhile now — toward service-oriented climate science ...

I am sure that this is an excellent paper by world class scientists. But when I look at the broader significance of the paper what I see is that there is in fact nothing that can be observed in the climate system that would be inconsistent with climate model predictions. If global cooling over the next few decades is consistent with model predictions, then so too is pretty much anything and everything under the sun.

Cross posted by Daniel Cressey on The Great Beyond

Posted by Olive Heffernan on May 01, 2008
Categories: Climate Science, Climate prediction, Climate variability, Daniel Cressey, In the News | Permalink | Comments (8) | TrackBacks (0)

In a Science paper last year (subscription required), Rahmstorf et al. pointed to 2001-2006 measurements of global temperature at the top end of the IPCC's 2001 projections - and global sea level rise well beyond the range predicted in 2001 - as evidence that "the climate system, in particular sea level, may be responding more quickly to climate change than our current generation of models indicates." Today in a letter to Nature Geoscience (subscription required), Roger Pielke, Jr, questions whether models from that 2001 generation improve on the predictive power of their forbears.

Pielke checks predictions from all four IPCC reports, dating back to 1990, against reality. Each report made a series of 'if-then' statements about the likely results of various emissions scenarios; in hindsight, Pielke can pick out which of these possible greenhouse experiments has actually been running on Earth since 1990 and compare the results to the IPCC's shifting hypotheses.

Whereas the 2001 projections undershot the observed temperatures and sea levels, the 1990 projections overshot them, he concludes. Projections of temperature and sea level fell substantially between the 1990 and 1995 IPCC reports, when aerosols were added to models and carbon-cycle simulations were tweaked. But because they dropped too far, the adjusted post-1995 projections "are not obviously superior in capturing climate evolution", says Pielke.

That's not to say that 2001 models were no better than those a decade older. Including more information has made recent simulations more sophisticated - but so far it hasn't much improved their ability to sketch out future climates, probably because important factors are still missing. Predictions from the two most recent reports do, however, seem to have crept toward the actual climate evolution, and additional rounds of of refinements may help the models to home in further.

Anna Barnett

Posted by Anna Barnett on March 31, 2008
Categories: Anna Barnett, Climate Science, Climate prediction | Permalink | Comments (7) | TrackBacks (0)