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Saturday, February 28, 2009

NSIDC Arctic Sea Ice Extent Graph February 26, 2009

NSIDC: February 26, 2009

Near-real-time data now available

Arctic sea ice reflects sunlight, keeping the polar regions cool and moderating global climate. According to scientific measurements, Arctic sea ice has declined dramatically over at least the past thirty years, with the most extreme decline seen in the summer melt season.

Read timely scientific analysis year-round below. We provide an update during the first week of each month, or more frequently as conditions warrant.

Sign up for the Arctic Sea Ice News RSS feed for automatic notification of analysis updates. Updates are also available via Twitter.

Click on graph to enlarge the details. Sea ice data updated daily, with one-day lag. Gray line shows 1979-2000 average extent for the day shown. Click for high-resolution image. Learn about update delays, which occasionally occur in near-real-time data. Read about the data. —Credit: National Snow and Ice Data Center

Note: The daily image update now uses data from the SSM/I sensor on the Defense Meteorological Satellite Program F13 satellite. For more information on the data, see the February 26 post to Arctic Sea Ice News & Analysis.

Near-real-time sea ice data updates are again available from Arctic Sea Ice News & Analysis. We have switched to the Special Sensor Microwave/Imager (SSM/I) sensor on the Defense Meteorological Satellite Program (DMSP) F13 satellite following the sensor drift problem described in our February 18 post.

The temporary error in the near-real-time data does not change the conclusion that Arctic sea ice extent has been declining for the past three decades. This conclusion is based on peer reviewed analysis of quality-controlled data products, not near-real-time data.

time series graph showing F13 and F15 sea ice extent Figure 1. SSM/I Arctic sea ice extent data from F13 (dashed green line) and F15 (solid blue line) were consistent until late January, when the F15 SSM/I sensor began to degrade. —Credit: National Snow and Ice Data Center
High-resolution image

Impact of the F15 sensor drift

On February 18, we reported that the F15 sensor malfunction started out having a negligible impact on computed ice extent, which gradually increased as the sensor degraded further. At the end of January, the F15 sensor underestimated ice extent by 50,000 square kilometers (19,300 square miles) compared to F13. That is still within the margin of error for daily data. By mid-February, the difference had grown to 500,000 square kilometers (193,000 square miles), which is outside of expected error. However, that amount represents less than 4% of Arctic sea ice extent at this time of year. When the computed daily extent dropped sharply on February 16, the sensor failure became obvious.

NSIDC stopped displaying the problematic data, and recalculated sea ice extent using data from the DMSP F13 satellite, an older sensor in the same series of satellites. The recalculation changed the January monthly average ice extent by less than the margin of error for the sensor. As we reported in our February 3 post, growth of Arctic sea ice did indeed slow in January because of unusual atmospheric conditions. Using F13 data instead of F15, the September daily minimum that we reported on September 16, 2008, changed from 4.52 million square kilometers (1.74 million square miles) to 4.54 million square kilometers (1.75 million square miles), within the margin of error for daily data.

The F15 sensor drift does not change any of our conclusions regarding the long-term decline in Arctic sea ice extent. Such scientific conclusions, published in peer-reviewed journals, are based on quality-controlled monthly to annually averaged data. We have quality-controlled the final data through 2007; a thorough audit of the more recent data from 2008 shows that any discrepancies fall within the margin of error.

artist's rendering of a DMSP satellite Figure 2. NSIDC acquires sea ice data from a series of Defense Meteorological Satellite Program (DMSP) satellites. Overlap between satellite sensors allows us to build a consistent long-term data record. —Credit: Image courtesy Air Force Space Command Defense Meteorological Satellite Program
High-resolution image

Building long time series from satellite data

Like cars, airplanes, and other machines, satellites do not last forever. Scientists monitor satellites for problems, and new satellites must be launched to replace them. One advantage of the DMSP series of satellites is the continual overlap between one satellite and the next. This overlap allows scientists to compare and calibrate data from each satellite to ensure consistency over time. By using a series of intercalibrated sensors, we can build a consistent long-term record of sea ice extent.

Before acquiring data from F15, NSIDC obtained sea ice data from the SSM/I sensors on the DMSP F8, F11, and F13 satellites. In March 2008, we switched from the F13 satellite to the F15 satellite because the F13 SSM/I sensor had started to have regular areas of missing data. The missing data were caused by malfunctioning data recorders on the satellite, not because of any problem with the sensor itself. At the time, we were concerned that the recorder problem would become more serious. However, the F13 data recorders have not degraded further.

In comparison, the F15 sensor drift makes those data unreliable for our purposes, so we have switched back to F13. As a long-term solution, we are working on a transition to the newest sensor, which is on the F17 satellite.

map of sea ice from space, animated to show missing data and corrected imageFigure 3. This animated map shows how NSIDC scientists now correct for missing data in the daily time series. The daily sea ice extent map labeled "raw data" shows areas of missing data as gray wedges and speckles. The map labeled "interpolated" shows the daily image used to calculate the daily time series. Sea Ice Index data. About the data. —Credit: National Snow and Ice Data Center
High-resolution image

Correcting the daily time series

The daily extent map now shows any areas of missing data as dark gray regions, speckles, or spider web patterns. However, in the time series chart we account for the missing data by averaging the extent for that region from the day before and the day after the gap, a mathematical technique called interpolation. Interpolation is an appropriate approach because ice cover changes slowly. The animation in Figure 3 shows an Arctic sea ice extent map with regions of missing data (Raw Data: 2009.02.08), and the same map, showing the filled-in data (Interpolated: 2009.02.08).

Isolated areas of missing data occasionally occur in near-real-time sea ice data. We adjust for such gaps during the quality control for the final data products, which are usually released about a year after the near-real-time data. The final data products form the basis for peer-reviewed scientific analysis; this is typical for all fields that use satellite data, not just sea ice science. For more information about quality control for NSIDC sea ice data, see Do your data undergo quality control? on the Frequently Asked Questions about Arctic sea ice Web page.

Graph with months on x axis and extent on y axisFigure 4. This time series of F13 SSM/I (blue line) versus AMSR-E (red line) Arctic sea ice extent from 2006 to February, 2009 shows how SSM/I and AMSR-E data match up over the last three years. The gray line shows the 1979-2000 average. —Credit: National Snow and Ice Data Center
High-resolution image

Cross-checking data

A number of other satellites can detect sea ice, and provide an independent check for consistency of the SSM/I data. The NASA Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) sensor generally serves as a good comparison for SSM/I data from the DMSP F-series satellites. Recent comparison shows that ice extent from F-13 tracks close to that from AMSR-E. AMSR-E and several other types of satellite and ground-based measurements have confirmed the long-term decline in Arctic sea ice extent over the past thirty years.

Graph with months on x axis and extent on y axisFigure 5. This time series shows the difference between F13 SSM/I (solid green line) and AMSR-E (dashed pink line) Arctic sea ice extent from December 1, 2008 to February 12, 2009. AMSR-E starts out lower than SSM/I, but ends up higher, with differences of up to 100,000 square kilometers (38,600 square miles). Credit: National Snow and Ice Data Center
High-resolution image


While the AMSR-E satellite can provide a good check on SSM/I data, scientists prefer not to use it to extend the long-term sea ice record. Although AMSR-E has a lower absolute error, continuing to use SSM/I provides a lower relative error, which is more important for tracking long-term changes in conditions.

Figure 5 illustrates the difference between AMSR-E and SSM/I sea ice extent. AMSR-E starts out lower than SSM/I, but ends up higher, with differences of up to 100,000 square kilometers (38,600 square miles). Experts expect this to be the case because of differences in the way the sensors detect sea ice. Thus, by comparing sea ice extent data from the same satellite sensor, we can build a more reliable picture of how extent has changed over the last three decades.

NASA logoNSIDC scientists provide Arctic Sea Ice News & Analysis, with partial support from NASA.

For previous analysis, please see the drop-down menu under Archives in the right navigation at the top of this page. Link to this page:

Chris Field of IPCC, interviewed by Democracy Now, and testifies before U.S. Senate Committee on Environment & Public Works, repeats remarks of AAAS

From Democracy Now!, February 26, 2009

Member of UN Environment Panel Warns Greenhouse Emissions Rising at Alarming, Unexpected Rate

Fieldweb We speak to Chris Field, a leading member of the Nobel Prize-winning Intergovernmental Panel on Climate Change, about his warning that the amount of greenhouse gases in the atmosphere is rising more rapidly than expected in recent years. Field says the current trajectory of climate change is now much worse than the IPCC had originally projected. On Wednesday, Field told a Senate panel droughts caused by global warming could make parts of the American Southwest dangerous to live in.

Christopher Field, founding director of the Carnegie Institution’s Department of Global Ecology and professor of biology and environmental earth system science at Stanford University.

JUAN GONZALEZ: A leading member of the Nobel Prize-winning Intergovernmental Panel on Climate Change is warning the amount of greenhouse gases in the atmosphere is rising more rapidly than expected in recent years. The scientist, Chris Field, says the current trajectory of climate change is now much worse than the IPCC had originally projected in part due to China and India’s increasing reliance on coal power.

The research shows carbon emissions have grown sharply since 2000, despite growing concerns about global warming. During the 1990s, carbon emissions grew by less than one percent per year. Since 2000, emissions have grown at a rate of 3.5% per year. No part of the world had a decline in emissions from 2000 to 2008.

Earlier this month, Field told the American Association for the Advancement of Science, “We are basically looking now at a future climate beyond anything we’ve considered seriously in climate model situations.”

AMY GOODMAN: On Wednesday, Chris Field testified before a Senate panel and warned droughts caused by global warming could make parts of the American Southwest dangerous to live in.

Professor Field joins us now from Stanford University, the founding director of the Carnegie Institution’s Department of Global Ecology and a professor of biology and environmental earth system science at Stanford University. He’s also co-chair, just been named, of Working Group 2 of the Nobel Prize-winning Intergovernmental Panel on Climate Change.

We welcome you to Democracy Now!, Dr. Field.

CHRISTOPHER FIELD: Thank you very much.

AMY GOODMAN: Why don’t you review what you told the Senate yesterday? It was a pretty heated hearing.

CHRISTOPHER FIELD: It was. And I think it’s important for people to know that the IPCC, the Intergovernmental Panel on Climate Change, provides a definitive assessment of where we are with climate, but that science continues to evolve. And in particular, we’ve seen rapid increase in knowledge in two important areas: areas that I call forcing, how hard we’re pushing on the climate system, and feedbacks, what we expect the earth system to do in response to this harder forcing. In particular, we’ve seen CO2 emissions grow very rapidly, as you’ve already described.

The idea is that we’ve used climate models to explore possible futures. We characterize economic growth rates, population, kinds of ways that energy is generated, and use those to say, well, what might CO2 emissions be going into the future? And that’s what the climate models run.

If we look since 2000, we’ve seen a rapid acceleration in CO2 emissions, so that the actual trajectory of emissions has grown more rapidly than in any of the scenarios that were characterized in detail. The reason I say we’re on a trajectory of climate change that we haven’t explored is that we have only looked at scenarios where the growth of CO2 was limited to in the range of 2.0-2.5% per year. We genuinely don’t know what a climate will look like with the more rapid rate of increase that we’re actually seeing.

JUAN GONZALEZ: And as we mentioned in the lead-in, you see that the increasing emissions from China and India have been part of the reason why the modeling so far has not been as accurate as expected?

CHRISTOPHER FIELD: Well, it’s not exactly right to say “the modeling so far.” You know, we characterized possible futures based on expectations of the way the world might unfold, and these weren’t intended as predictions; they were just supposed to characterize possibilities.

But what we have seen is that the time since 2000 was a period of rapid economic growth, and it was also a period of time where a large fraction of the economic growth was fueled by electricity based on coal, and coal is the energy source that releases the most CO2 per unit of useful energy that’s released. The consequence of that is that we have seen a very rapid increase in CO2 emissions.

AMY GOODMAN: Christopher Field, can you lay out the scenario that you laid out before the Senate? What exactly do you see happening at the end of the century, if we go on the trajectory we’re on now?

CHRISTOPHER FIELD: Well, the important thing to remember is that we’re not committed to any particular trajectory and that there are a range of different possibilities. The possibility that is increasingly stark and that we really want to be increasingly certain to avoid is one where we end up with climate forcing at the high end of the possible scenarios. The IPCC projected that with the scenarios it explored, we could see 2100 temperatures that were anywhere from as little as 2 °F to as much as 11-12 °F warmer than possible.

And what we increasingly see is that with temperatures at the upper end of this warming range, we begin to get a large series of very dangerous feedbacks from the earth’s system. In particular, we see tropical forest transitioning from taking up large amounts of carbon to taking up very little or even releasing carbon. And it looks like there’s an increasing risk that high latitude ecosystems that are characterized by these frozen soils called permafrost may release some of the organic matter that’s stored in this permafrost to the atmosphere. So you end up in a situation where, instead of having ecosystems storing large amounts of carbon, they're storing very little or releasing large amounts.

The calculations to date are that tropical forests—and this is something that is explored in the IPCC—could, at the higher ranges of temperature forcing, release anywhere from a hundred billion to 500 billion extra tons of carbon to the atmosphere by 2100. And that should be put in the context of understanding that during the entire period from the beginning of the Industrial Revolution until now, all of the world societies have only released a little over 300 billion tons of carbon to the atmosphere.

AMY GOODMAN: What could happen in the Southwest?

CHRISTOPHER FIELD: Well, if you look at the projections from the IPCC, North America is characterized by a variety of different patterns of precipitation, with increasing precipitation at high latitudes and a sharp decrease in precipitation across the American Southwest. We basically see a big tongue of area that extends from California to about Oklahoma, where the combination of decreased precipitation and increased temperature, increased evaporation, leads to decreased river runoff. And that decrease is quite large, in the range of 25 to even 35 percent. It really projects a period of extreme stress on water resources, limited availability of water for all of the kinds of water users that are out there, from agriculture to industry to cities to instream ecological uses.

JUAN GONZALEZ: Well, one of the centerpieces of the Obama administration’s efforts to respond to climate change is, obviously, the whole development now of carbon emission permits and capping and trading of these permits. As a scientist, what would be your concerns about a solution that centers so much around this kind of a market approach, in terms of how effective it might be in dealing with the future?

CHRISTOPHER FIELD: Well, if I look at the problem, the thing that really strikes me is that we don’t have very long to get an effective climate regime in place. The risk with these ecosystem feedbacks is that once we get past a certain point in warming, the problem gets more difficult every year, because we’re ending up with, you know, essentially less and less help from the oceans and the land. And from my perspective, the really critical thing is that we get a handle on the emissions growth so that we can slow it rapidly and turn the corner, so that we’re looking at a period of decreased emissions moving into the future.

AMY GOODMAN: I wanted to ask not only about what’s happening in the Southwest, but a vicious cycle you talked about that could do everything from ignite tropical forests to melt the Arctic tundra.

CHRISTOPHER FIELD: The idea of these vicious cycle feedbacks is that once warming reaches a certain point, the amount of assistance that we’re getting in terms of carbon storage from the land and oceans tends to go down. And this is quite clear from the IPCC models, and it’s clear from a number of other more recent lines of work. In the IPCC, the models characterize a future in which tropical forests at the high range of warming have a potential to release large amounts of carbon to the atmosphere.

One of the new numbers that’s a great concern to me is that we’ve been doing studies of how much organic matter is stored in these frozen soils in northern latitudes, permafrost soils, and the new numbers are that approximately a billion tons of carbon is stored in the organic matter in these high latitude soils. Climate model projections indicate that at high amounts of warming large fractions of the permafrost could melt, and some of the projections have that at from 60 to 90 percent of the permafrost melting.

And the surprising thing about these permafrost soils is that the organic matter that’s contained within them is not this incredibly stabilized, difficult-to-decompose stuff; it’s basically frozen plants that have been sitting there for, in some cases, tens of thousands of years. And when the permafrost is thawed, these plants decompose quite quickly, releasing their carbon as CO2 to the atmosphere or as methane to the atmosphere, which is a greenhouse gas that, on a molecule per molecule basis, is about 25 times as powerful as CO2.

The basic risk is that if we reach a certain point in the warming, what we’ll end up with is a vicious cycle, where the warming causes additional permafrost melt, which causes additional CO2 to be released to the atmosphere, which causes additional warming, which creates this vicious cycle.

We don’t have evidence that it’s a clear tipping point, or we don’t know where there might be a tipping point out there. And one of the things that I’m advocating is that we both advance the science quickly enough to figure out if indeed there is a threshold beyond which this can’t be stopped, but also to take action as a society to ensure that we’re very conservative with respect to how far along this pathway we go.

AMY GOODMAN: Christopher Field, we want to ask you to stay with us. We’re going to break. When we come back, want to play for you the comment of one of the climate change deniers. A professor from Princeton University was invited also to testify. Then we’re going to be looking at the power of the lobbyists around climate change, and a massive conference is taking place this weekend of grassroots youth activists in Washington called Power Shift. We’ll speak with them and find out about what’s considered to be one of the largest civil disobedience in US history is going to take place on Monday outside a coal plant outside Washington, D.C. Stay with us.


AMY GOODMAN: On Wednesday, our guest, Chris Field, testified before the Senate Committee on Environment and Public Works. The Republican minority invited Princeton University physicist William Happer to testify at the same hearing. He’s a former Energy Department official and chair of the board of directors of the George Marshall Institute, an organization that’s reportedly received $715,000 from ExxonMobil since 1998. This is a part of what Professor Happer had to say.

    WILLIAM HAPPER: The increasing concentrations of CO2 in the atmosphere will cause some warming of the earth’s surface. The key question is, will the net effect of the warming and any other effects of CO2 be good or bad for humanity? I believe the increase of CO2 will be good.

    I predict that future historians will look back on this period much as we now look back on the period just before we passed the 18th Amendment to the US Constitution to prohibit the manufacturing, sale or transportation of intoxicating liquors. At the time, the 18th Amendment seemed to be exactly the right thing to do. It was a 1917 version of saving the planet from the ravages of climate change. More than half the states enacted prohibition laws before the 18th Amendment was finally ratified. Only one state, Rhode Island, voted against it, and my hat’s off to the senator from Rhode Island. I’m sorry he’s not here.

    Well, there were many people who thought that Prohibition might do more harm than good, but they were completely outmatched by the temperance movement, whose motives and methods had much in common with the movement to stop climate change. Deeply sincere people thought they were saving humanity from the evils of alcohol, just as many people now sincerely think they’re saving humanity from the evils of CO2. Prohibition was a mistake, and our country’s probably still not fully recovered from the damage it did. For example, institutions like organized crime got their start in that era. Drastic limitations on CO2 are likely to damage our country in an analogous way. There’s tremendous opportunity for corruption there.

AMY GOODMAN: Professor Happer of Princeton University. Professor Field, your response?

CHRISTOPHER FIELD: Well, there’s been a tremendous amount of science to assess the likely impacts of rising CO2 on climate, and the IPCC overwhelmingly concludes that the overall impact is likely to be sharply negative. I think that as we look at new science, we see increasing validation of the conclusions of the IPCC, in terms of the mechanisms of climate change and in terms of the impacts of climate change.

You know, the assessment of whether the issue of Prohibition is relevant to climate, I think, is really a red herring. There’s essentially never been an activity that’s—where the scientific community has been as coordinated and as careful in its assessment as it’s been with climate change. And to say that, well, sometimes the science is wrong just really doesn’t reflect the amount, not only of careful thinking and coordination, but also the amount of testing of all the ideas that’s gone into the modern scientific assessment of climate change. You know, essentially every component of our understanding has been scrutinized and tested and evaluated from different directions. And although there’s still a lot we don’t understand completely, some of which I have already talked about this morning, the overall analysis of where we’re headed and what the mechanisms are is just deeply well established.

JUAN GONZALEZ: Well, we want to thank you for being with us, Chris Field, a professor of biology and environmental earth science at Stanford University.

AMY GOODMAN: And we also wanted to ask if you might stay with us as we’re joined by a guest in Washington, because we want to get your comment on the politics of and the money behind those who are lobbying against the whole issue of climate change.

Link to U.S. Senate Committee hearing page:

Link to above text:

James Hansen talks with Charlie Rose about Coal, Sea Level Rise, 4th Generation Nuclear Power -- Must See Video

James Hansen talks with Charlie Rose about Coal, Sea Level Rise, and 4th Generation Nuclear Power Plants -- Must See Video!

This video is 22 minutes long, but it loads very nicely, large format. Dr. Hansen talks about his trip around the world to talk to leaders about what they are doing to reduce emissions.

Friday, February 27, 2009

Capitol Hill coal power plant targeted by environmentalists

Capitol Hill coal power plant targeted by environmentalists

Campaigners are converging on Washington to press for the closure of 'Congress's own coal fired power plant,' marking a political turning point for the future of the fossil fuel

Capitol Power Plant

The stacks of the Capitol Hill power plant loom in front of the dome of the United States Capitol. Photograph: Jocelyn Augustino

It might, in other circumstances, seem a quaint and harmless relic from another era: a coal plant built 99 years ago to assure Congress an independent source of power.

But the Capitol Hill Power Plant, a compact red brick building now encircled by modern concrete, is seen by some as evidence of how a powerful industry has been able to bend Congress to its will.

Coal is the dirtiest of fossil fuels, and yet provides half of America's electricity – a lethal connection that environmentalists say is epitomised in the continued existence of a plant that should have been retired decades ago.

"In terms of carbon emissions, this plant is small potatoes, but it really is a very powerful iconic symbol. It is Congress's own coal fired power plant," said Matt Leonard of Greenpeace. "It can burn gas or oil or coal and people have fought very hard over the years to make sure it burns coal."

That may be about to change. On Thursday, Democratic leaders in Congress called for an overhaul of the plant so it could run entirely on natural gas by the end of 2009.

The order came down as more than 10,000 young people began converging on Washington – campus activists, union organisers, and even members of college sororities – to lobby members of Congress to reduce America's reliance on coal.

Organisers say this could be the tipping point in the fight against coal, after years of steady activism on college campuses and in rural coal-mining communities.

Since mid-2006, plans for more than 83 coal plants have been halted. This week alone, Michigan's governor announced a moratorium on all new coal plants, and a Georgia court put a stop on a coal plan for failing to put in place pollution controls.

The campaign got an extra push late last year when Al Gore championed a drive to make Americans aware of the connection between coal and electricity.

The Reality Coalition has plastered public transport with its ads, which seek to
counter the industry's argument that coal is abundant and cheap, and that technology enabling the production of "clean" or carbon-free coal is on the horizon.

The latest television ad, produced by the Oscar-winning Coen brothers, shows a salesman spraying black smog from an aerosol can to debunk the notion of clean coal.

With Barack Obama in the White House and the Democrats in Congress poised to act on climate change, this could be the beginning of the end of America's coal age.

Obama called on Congress this week to pass legislation to cut carbon - leading some to hope that the battle over coal is in its final phase.

Organisers of the Power Shift lobbying effort aim to give it the final push. They say they have set up meetings with 80 Senators and 287 members of the house of representatives, Republican and Democrat, to convince them to vote for action on climate change.

"We are not mincing words. When we walk into those offices in Congress we will be calling for bold carbon reduction," said Jessy Tolkan, 27, the director of the Energy Action Coalition, which represents 50 youth organisations. "We want an immediate moratorium on coal. We don't believe in clean coal."

Meanwhile, some 2,000 others, led by the NASA climate scientist, Jim Hansen, and the actor, Darryl Hannah, will gather for a protest at the Capitol's coal plant.

The survival of the plant – the only coal burning station within Washington's boundaries – is a testament to the power of coal. It also offers a cautionary tale to the environment activists who think they are within early reach of victory.

The Capitol Hill facility is no longer needed for electricity. Congress got hooked up to the city's main electrical grid in 1952, and the plant is used only for heat and air conditioning for Congress and nearby official buildings.

Last year, the Democratic speaker, Nancy Pelosi, demanded the plant switch from coal to natural for supplying the house of representatives. But until Thursday Pelosi's counterpart in the Senate, the majority leader, Harry Reid, balked at turning off the last two burners.

The reluctance is in part deference to the oldest Senator, Robert Byrd, a Democrat from the coal mining state of West Virginia, who has had years of experience of protecting his interests.

But it also comes down to cash and influence. The coal industry has waged a ferocious struggle for its survival – as have lobbyists for other polluting industries who have invested millions in trying to block action on climate change.

Opposing energy reform provided employment to 2,340 lobbyists last year – a 300% increase since 2003, according to a report from the Centre for Public Integrity. The report estimated that about 15% of all Washington's lobbyists were now working to try to stop Congress from passing a law putting a cap on carbon.

At the front of the pack is the American Coalition for Clean Coal Electricity, an industry-funded organisation, spent nearly $40m last year on television ads and a lobbying effort for coal.

If Joe Lucas, vice-president of the ACCE, thinks coal could be on its way out, he was betraying no sign of it. "There have always been people who have not recognised the necessity of using coal to generate electricity," he said.

"America not using coal would be like Saudi Arabia not using oil. We have more energy in the form of coal than Opec has oil so the thought that the United States is not going to use coal is somewhat without foundation."

Link to article:

Chris Field: Decisive Action Needed as Warming Predictions Worsen, Says Carnegie Scientist

UPDATE: For readers searching for Dr. Field's very important remarks, see this post for an interview that took place on the 26th and also a link to a video of his testimony before the Senate Committee on the Environment & Public Works from Feb. 25th (the link below goes to the transcript of the interview):

Decisive Action Needed as Warming Predictions Worsen, Says Carnegie Scientist

Image courtesy NASA

Stanford, CA— Greenhouse gases in the atmosphere are rising more rapidly than expected, increasing the danger that without aggressive action to reduce emissions the climate system could cross a critical threshold by the end of the century, warns a leading member of the Nobel Prize-winning Intergovernmental Panel on Climate Change. Studies indicate that greenhouse warming could trigger a vicious cycle of feedback, in which carbon dioxide released from thawing tundra and increasingly fire-prone forests drives global temperatures even higher.

Chris Field, director of the Carnegie Institution’s Department of Global Ecology and co-chair of the IPCC Working Group 2, addressed these issues at a symposium titled “What Is New and Surprising since the IPCC Fourth Assessment?” at the annual meeting of the American Association for the Advancement of Science (AAAS) in Chicago. The IPCC Fourth Assessment, for which Field was a coordinating author, was published in 2007. As co-chair, Field will oversee the Working Group 2 Report on the predicted impacts of climate change for the IPCC Fifth assessment, scheduled to be published in 2014. The Fifth Assessment will incorporate the results of new studies that predict more severe changes than did previous assessments.

“The data now show that greenhouse gas emissions are accelerating much faster than we thought,” says Field. “Over the last decade developing countries such as China and India have increased their electric power generation by burning more coal. Economies in the developing world are becoming more, not less carbon-intensive. We are definitely in unexplored terrain with the trajectory of climate change, in the region with forcing, and very likely impacts, much worse than predicted in the fourth assessment.”

New studies are also revealing potentially dangerous feedbacks in the climate system that could convert current carbon sinks into carbon sources. Field points to tropical forests as a prime example. Vast amounts of carbon are stored in the vegetation of moist tropical forests, which are resistant to wildfires because of their wetness. But warming temperatures and shifting rainfall patterns threaten to dry the forests, making them less fireproof. Researchers estimate that loss of forests through wildfires and other causes during the next century could boost atmospheric concentration of CO2 by up to 100 parts per million over the current 386 ppm, with possibly devastating consequences for global climate.

Warming in the Arctic is expected to speed up the decay of plant matter that has been in cold storage in permafrost for thousands of years. “There is about 1,000 billion tons of carbon in these soils,” says Field. “When you consider that the total amount of carbon released from fossil fuels since the beginning of the Industrial Revolution is around 350 billion tons, the implications for global climate are staggering.”

“The IPCC fourth assessment didn’t consider either the tundra-thawing or tropical forest feedbacks in detail because they weren’t yet well understood,” he says. “But new studies are now available, so we should be able to assess a wider range of factors and possible climate outcomes. One thing that seems to be certain, however, is that as a society we are facing a climate crisis that is larger and harder to deal with than any of us thought. The sooner we take decisive action, the better our chances are of leaving a sustainable world to future generations.”
Audio Press Release

Link to article:

Mark Serreze (NSIDC) weighs in on George F. Will 's distortion of facts on Arctic sea ice extent 1979 and 2009

From Andrew Revkin's Dot Earth blog post on the George F. Will response:

P.S.: In his column defending his climate claims, Mr. Will says a flaw reported in sea-ice data at the National Snow and Ice Data Center in Boulder, Colo., justifies his statements about the Illinois group’s ice trends. Both Mr. Chapman in Illinois and Mark Serreze of the Boulder center reject this. Here’s Dr. Serreze’s view of the incident and that particular assertion:

Regarding the sensor problem, see our latest post where we discuss the issue in detail. The sensor problem on the F15 has no bearing on the Univ. IL numbers, which are based on the earlier F13 satellite (which we have temporarily gone back to). I got a call from George Will’s fact checker regarding his latest piece. I was a bit terse with the gentleman but of course gave him the info he was looking for. My response was something like “Well, I certainly would not want Mr. Will to be speaking from a viewpoint of ignorance.”

Regarding the “global ice at 1980 levels”, here is the canned response we wrote in rebuttal to the astonishingly twisted piece in Daily Tech: What the graph shows is that the global sea ice area for early January 2009 is on the long term average (zero anomaly). The author tries to read some relevance into the fact that the anomaly at the end of 1979 is also about zero. Given that there are many periods throughout the time series with a zero anomaly for the global total, it is puzzling why the end of 1979 was singled out.

Presumably the point is to somehow cast doubt on global warming. However, if so, the author could have instead made an equally silly case for global cooling by contrasting the near zero anomaly of early January 2009 with the strong negative anomalies characterizing the later part of 2008.

The key point is that looking at the global total area is not relevant. All climate models tell us that it is the Arctic sea ice cover that declines first, and that Antarctic ice extent falls only later, and may even (as observed) temporarily increase in response to changing patterns of atmospheric circulation. In other words, events are unfolding pretty much as expected. Finally, the statement that there was “substantial recovery” this year in the Arctic is simply rubbish. Ice extent at the end of the melt season in the Arctic was second lowest on record and ice extent is still (as of early January) well below normal.

Simply put, this article is a masterpiece of cherry picking, misinterpretation and misrepresentation.

Also, I worked very closely with a woman from Slate Magazine, who wrote a pretty decent piece on the issue:


BLOGGER'S NOTE: Also from the Cryosphere:

James Hansen: "Ways and Means" and peaceful protest at Capitol Power Plant, Washington, DC, March 2

The answer to the riddle became clear on the train on the way home. I had puzzled about the continued attraction of Cap&Trade. Empirical evidence shows that Cap&Trade does not have a prayer of phasing out fossil fuel emissions fast enough to save the planet, e.g., allowing us to phase-out coal-fired power plants. Clearly there must be people in the Obama administration who understand that. Yet Cap&Trade is still talked about as if it were something good. One wonders: do they really believe we have "a planet in peril"?

The testimony that I gave to the House Ways & Means Committee is available at

In my testimony I noted that a "Cap" raises the price of energy, just as does a simple honest carbon tax on oil, gas and coal at the first sale at the mine or port of entry. "Cap" is a pseudonym, disguising the fact that it is a tax, assuming that the public is a bunch of dummies, who will never catch on. With all its hooks and eyes, Cap&Trade will allow a lot of funny business. At least we would get a few Wall Street millionaires back in business, via speculation and gaming the Cap&Trade system (funded by John Q. Public, of course).

On the train I read on that the number of lobbyists in DC working to influence federal policy on climate change increased in the past few years by 300% to 2,340 lobbyists -- four climate lobbyists for every member of Congress. At least the alligator shoe business is doing well. Not too good for alligators, though.

A Carbon Tax & 100% Dividend would not let Congress enrich their favorites or divine winning technologies. Instead, the winners would be innovators who invent products with improved energy efficiency or develop carbon-free energies, which allow people to reduce their carbon tax. Of course, if you don't trust your innovation skills, it is easier to pay a lobbyist to get Congress to adopt a jury-rigged Cap&Trade system.

2340 lobbyists. They are outnumbered by the at least 2500 people, mostly young people (but everybody welcome), who plan to converge on Washington March 2 (despite inclement weather) to peacefully protest the Capitol Power Plant, which our Congress insists must be powered substantially by coal (our coal-black Senate seems to be the culprit). The Capitol Power Plant is just the symbolic target -- the real aim is to influence Congress to adopt legislation that will rapidly phase out coal use. See

The question is: who will Congress listen to? Protesters (bringing no gifts - it's hard enough to pay their own way) or lobbyists (with lobbying expenditures last year of about $90M).

Young folks, if you need an indication of what you are up against, let me give you one example. Peabody Coal (a.k.a. Peabody Energy) hires Dick Gephardt, paying him $120,000.00 per quarter in 2008. The amount of money going into lobbying is increasing rapidly. As Shakespeare would say, gird up your loins.

If democracy does not win this one, if the lobbyists win, perhaps the best we can do for our grandchildren is buy them a ticket to another planet. Of course, Congress would have to borrow the money from our grandchildren. But at least we would show that we are giving them some consideration.


Climate researchers Stephen Schneider & Ken Caldeira, panel discussion "The Challenges of Climate Change," Exploratorium, San Francisco, Mar 2, 7 p.m.

Scientists address climate change

by Louis Bergeron,

Stanford climate researchers Stephen Schneider and Ken Caldeira will be part of a panel discussion, "The Challenges of Climate Change," at the Exploratorium in San Francisco at 7 p.m. Monday, March 2.

In a paper published this week in the online edition of Proceedings of the National Academy of Sciences, Schneider and his co-authors present evidence that even modest increases in global mean temperature will likely have far more serious consequences than were projected in the 2007 report of the Intergovernmental Panel on Climate Change (IPCC).

Schneider, a professor of biology and senior fellow at the Woods Institute for the Environment at Stanford, was the coordinating lead author of a chapter of the IPCC report. Caldeira is an associate professor, by courtesy, of environmental Earth system science at Stanford and a staff scientist at the Carnegie Institution's Department of Global Ecology.

Corey S. Powell, editor-in-chief of Discover magazine, will moderate the panel. Discover is co-sponsoring the event with the National Science Foundation and the Exploratorium.

Anyone wanting to attend should RSVP at, where more details are available. The event is free and open to the public.

J.B. Smith, Stephen H. Schneider, M. Oppenheimer et al., Assessing dangerous climate change through an update of the IPCC "reasons for concern"

Proceedings of the National Academy of Sciences, Vol. , No. ; doi: 10.1073/pnas.0812355106

Assessing dangerous climate change through an update of the Intergovernmental Panel on Climate Change (IPCC) “reasons for concern”

  1. Joel B. Smitha,1,
  2. Stephen H. Schneiderb,c,1,
  3. Michael Oppenheimerd,
  4. Gary W. Yohee,
  5. William Haref,
  6. Michael D. Mastrandreac,
  7. Anand Patwardhang,
  8. Ian Burtonh,
  9. Jan Corfee-Morloti,
  10. Chris H. D. Magadzaj,
  11. Hans-Martin Füsself,
  12. A. Barrie Pittockk,
  13. Atiq Rahmanl,
  14. Avelino Suarezm and
  15. Jean-Pascal van Yperselen
  1. aStratus Consulting, Inc., Boulder, CO 80306-4059;
  2. bDepartment of Biology and
  3. cWoods Institute for the Environment, Stanford University, Stanford, CA 94305;
  4. dDepartment of Geosciences and the Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544;
  5. eDepartment of Economics, Wesleyan University, Middletown, CT 06459;
  6. fPotsdam Institute for Climate Impact Research, 14473 Potsdam, Germany;
  7. gShailesh J. Mehta School of Management, Indian Institute of Technology-Bombay Powai, Mumbai 400076, India;
  8. hUniversity of Toronto, Toronto, ON M6J 2C1 Canada;
  9. iOrganisation for Economic Cooperation and Development, 75776 Paris Cedex 16, France;
  10. jDepartment of Biological Sciences, University Lake Kariba Research Station, Harare, Zimbabwe;
  11. kCSIRO Marine and Atmospheric Research, Aspendale 3195, Australia;
  12. lBangladesh Centre for Advanced Studies, Dhaka, 1212 Bangladesh;
  13. mInstitute of Ecology and Systematic, Cuba Environmental Agency, 10800 Havana, Cuba; and
  14. nInstitut d'Astronomie et de Géophysique Georges Lemaître, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
  1. Contributed by Stephen H. Schneider, December 9, 2008 (sent for review March 18, 2008)


Article 2 of the United Nations Framework Convention on Climate Change [United Nations (1992) Accessed February 9, 2009] commits signatory nations to stabilizing greenhouse gas concentrations in the atmosphere at a level that “would prevent dangerous anthropogenic interference (DAI) with the climate system.” In an effort to provide some insight into impacts of climate change that might be considered DAI, authors of the Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC) identified 5 “reasons for concern” (RFCs). Relationships between various impacts reflected in each RFC and increases in global mean temperature (GMT) were portrayed in what has come to be called the “burning embers diagram.” In presenting the “embers” in the TAR, IPCC authors did not assess whether any single RFC was more important than any other; nor did they conclude what level of impacts or what atmospheric concentrations of greenhouse gases would constitute DAI, a value judgment that would be policy prescriptive. Here, we describe revisions of the sensitivities of the RFCs to increases in GMT and a more thorough understanding of the concept of vulnerability that has evolved over the past 8 years. This is based on our expert judgment about new findings in the growing literature since the publication of the TAR in 2001, including literature that was assessed in the IPCC Fourth Assessment Report (AR4), as well as additional research published since AR4. Compared with results reported in the TAR, smaller increases in GMT are now estimated to lead to significant or substantial consequences in the framework of the 5 “reasons for concern.”

  • 1To whom correspondence may be addressed. e-mail: or
  • Author contributions: J.B.S., S.H.S., M.O., G.W.Y., W.H., M.D.M., A.P., I.B., J.C.-M., C.H.D.M., H.-M.F., A.B.P., A.R., A.S., and J.-P.v.Y. performed research; and J.B.S., S.H.S., M.O., G.W.Y., W.H., M.D.M., A.P., I.B., J.C.-M., C.H.D.M., H.-M.F., A.B.P., A.R., A.S., and J.-P.v.Y. wrote the paper. Conflict of interest statement: The authors declare no conflict of interest. Freely available online through the PNAS open-access option.

Link to abstract:

Link to free, open-access article (pdf file):

Thursday, February 26, 2009

James Hansen, NASA's Chief Climate Scientist Stirs Controversy with Call for Civil Disobedience

NASA's Chief Climate Scientist Stirs Controversy With Call for Civil Disobedience

FoxNews, February 26, 2009

BLOGGER'S NOTE: My daughter is hopping into a car as I type this -- she's on her way from Carbondale, Illinois, to Washington, DC, to participate in the protest as a volunteer for Power Shift. The article below contains a lot of the usual bull that we have come to expect from Fox. I trust you, the reader, can differentiate between the parallel universe the denialists live in and the reality we actually do live in.

NASA's chief climate scientist is in hot water with colleagues and at least one lawmaker after calling on citizens to engage in civil disobedience at what is being billed as the largest public protest of global warming ever in the United States.

In a video on, Dr. James Hansen is seen urging Americans to "take a stand on global warming" during the March 2 protest at the Capitol Power Plant in Southeast Washington, D.C.

"We need to send a message to Congress and the president that we want them to take the actions that are needed to preserve climate for young people and future generations and all life on the planet," says Hansen, who has likened coal-fired power plants to "factories of death" and claims he was muzzled by the Bush administration when he warned of drastic climate changes.

"What has become clear from the science is that we cannot burn all of the fossil fuels without creating a very different planet. The only practical way to solve the problem is to phase out the biggest source of carbon — and that's coal."

But critics say Hansen's latest call to action blurs the line between astronomer and activist and may violate the Hatch Act, which prohibits federal employees from participating in partisan political activity.

"Oh my goodness," one of Hansen's former supervisors, Dr. John Theon, told when informed of the video. "I'm not surprised ... The fact that Jim Hansen has gone off the deep end here is sad because he's a good fellow."

Theon, a former senior NASA atmospheric scientist, rebuked Hansen last month in a letter to the Senate's Environment and Public Works Committee, saying Hansen had violated NASA's official position on climate forecasting without sufficient evidence and embarrassed the agency by airing his claims before Congress in 1988.

"Why he has not been fired I do not understand," Theon said. "As a civil servant, you can't participate in calling for a public demonstration. You may be able to participate as a private citizen, but when you go on the Internet and call for people to break the law, that's a problem."

Officials at the U.S. Office of Special Counsel, which investigates possible Hatch Act violations, disagreed, saying Hansen is in the clear since it's an "issue-oriented activity," according to Hatch Unit attorney Erica Stern Hamrick.

The majority of federal government employees are allowed to take an active part in political activities, while workers at other departments like the FBI, Secret Service and National Security Council are subject to more restrictions on their political activities.

NASA spokesman Mark Hess also defended Hansen.

"He's doing this as a private citizen on his own time and there's nothing wrong with that," Hess told "There's nothing partisan here. You don't give up your rights to free speech by becoming a government employee."

Matt Leonard, a project coordinator for Greenpeace, one of more than 90 organizations endorsing the protest, said several thousand people are expected to participate and "peacefully disrupt operations" at the plant just blocks from Capitol Hill.

Participants are willing to "put their bodies on the line to stop climate change," including risking arrest, Leonard said.

"Our intention is to completely surround the facility, basically sending a message that these types of power plants can't be a part of our future," Leonard said. "They're destroying our environment."

Hansen will be in attendance and is expected to speak at the "completely nonviolent, peaceful" protest, Leonard said.

Meanwhile, Rep. Dana Rohrabacher, R-Calif., urged Hansen to rethink his plans.

"If he wants to have a demonstration concerning global warming, coming to the Capitol is not a right choice," Rohrabacher told "The bottom line is if Hansen wants to protest global warming, he should go to the National Cathedral and take it up with God rather than going to Capitol Hill."

Rohrabacher, a member of the House's Committee on Science and Technology, called on Hansen to "step out" of his role.

"He obviously doesn't feel comfortable with the restraints that come with being a scientist rather than a political activist," Rohrabacher said. "Most of us have always thought he has been hiding behind a scientific facade, and really, he was a political activist all along."

Chris Horner, author of "Red Hot Lies: How Global Warming Alarmists Use Threats, Fraud, and Deception to Keep You Misinformed," also denounced Hansen's latest call to arms against climate change.

"He's providing ample cause to question his employment on the taxpayer dime," Horner told "He's clearly abused his platform provided to him by the taxpayer, principally by the way he's been exposed of manipulating and revising data with the strange coincidence of him always found on the side of exaggerating the warming."

Horner claimed that Hansen doctored temperature data on two occasions in 2001 and once in 2007 in attempts to show an impending climate catastrophe.

"He's creating an upward slope that really wasn't there," Horner said. "At some point you have to say these aren't mistakes."

Hansen, who did not respond to repeated requests for comment on this story, was most recently honored for his work last month with the 2009 Carl-Gustaf Rossby Research Medal, the highest honor bestowed by the American Meteorological Society.

"Jim Hansen is performing a tremendous job at communicating our science to the public and, more importantly, to policymakers and decision-makers," Franco Einaudi, director of the Earth Sciences Division at NASA's Goddard Space Flight Center, said in a press release.

"The debate about global change is often emotional and controversial, and Jim has had the courage to stand up and say what others did not want to hear. He has acquired a credibility that very few scientists have. His success is due in part to his personality, in part to his scientific achievements, and in part to his refusing to sit on the sidelines of the debate."

Former Vice President Al Gore, who toured with Hansen while promoting "An Inconvenient Truth," did not return repeated requests for comment for this article.

Link to "article":,2933,501064,00.html

Samuli Helama et al., Multicentennial megadrought in northern Europe coincided with a global ENSO drought pattern during the Medieval Climate Anomaly

Geology, February 2009, Vol. 37, No. 2, 175178; doi:10.1130/G25329A.1
© 2009 Geological Society of America

Multicentennial megadrought in northern Europe coincided with a global El Niño–Southern Oscillation drought pattern during the Medieval Climate Anomaly

Samuli Helama1, Jouko Meriläinen2 and Heikki Tuomenvirta3

1Department of Geology, P. O. Box 64, 00014 University of Helsinki, 00014 Helsinki, Finland
2SAIMA Unit of Savonlinna Department of Teacher Education, University of Joensuu, P. O. Box 86, 57101 Savonlinna, Finland
3Finnish Meteorological Institute, P. O. Box 503, 00101 Helsinki, Finland


The El Niño–Southern Oscillation (ENSO) is a pacemaker of global climate, and the accurate prediction of future climate change requires an understanding of the ENSO variability. Recently, much-debated aspects of the ENSO have included its long-term past and future changes and its associations with the North Atlantic and European sectors, potentially in interaction with the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation. Here we present the first European dendroclimatic precipitation reconstruction that extends through the alternating climate phases of the Medieval Climate Anomaly and the Little Ice Age. We show that northern Europe underwent a severe precipitation deficit during the Medieval Climate Anomaly, which was synchronous with droughts in various ENSO-sensitive regions worldwide, while the subsequent centuries during the Little Ice Age were markedly wetter. We attribute this drought primarily to an interaction between the ENSO and the North Atlantic Oscillation, and to a lesser (or negligible) degree to an interaction between the ENSO and the Atlantic Multidecadal Oscillation.

Link to abstract:

Ted Scambos: East Antarctica is warming slightly

Environment ministers and other representatives from a dozen nations, on a fact-finding visit to Norway's Troll Research Station in Antarctica on Monday, Feb. 23, 2009, are shown here during a tour of the ice sheet below the Judulsessen massif of rock towers. Scientists reported in Geneva on Wednesday that, in a warming world, Antarctic glaciers are accelerating their dumping of ice into the sea, raising ocean levels. (AP Photo/Charles J. Hanley)

Ice in east Antarctica a bigger threat long term

TROLL RESEARCH STATION, Antarctica (AP) — Antarctica's western ice sheet is pushing ever faster into the sea, but scientists know an even greater long-term threat lies here in the vast, little-explored whiteness of east Antarctica.

An "absolutely titanic" store of ice that sits atop the east Antarctic plateau should be more closely monitored by glaciologists, the world's thinly spread corps of ice specialists, says Ted Scambos, a leading U.S. expert whose team last weekend finished a two-month scientific expedition across the forbidding plateau.

Scambos and Tom Neumann, leader of that joint U.S.-Norwegian "traverse" from the South Pole to this Norwegian outpost, commented Wednesday after the release in Geneva of a report summarizing initial findings from the 2007–2009 International Polar Year (IPY), a program of intensified research in the polar regions.

That report said west Antarctica has been warming, ice shelves floating on the sea fringing the west coast are weakening, and the glaciers they hold back are pouring ice faster into the sea.

The report doesn't forecast immediate Antarctic disasters because of global warming. Scientists point out, however, that if the western ice sheet ever collapsed completely, it would add some 7 meters to sea levels worldwide.

East Antarctica's ice appears more stable than the west's — "I wouldn't say it's stable, but more stable," said Neumann — but it has the theoretical potential to add some 200 feet (60 meters) to sea levels in centuries to come, scientists say. Even a small, more immediate shift here could raise oceans significantly.

Concerned Norwegian researchers plan to investigate the state of the Fimbul Ice Shelf, a gigantic table of thick ice reaching 120 miles into the sea at the coast 100 miles north of this research station, which sits in a stony mountain valley hemmed in by glaciers rumbling in slow motion toward the far-off southern Atlantic.

Kim Holmen, research director for the Norwegian Polar Institute, which operates Troll, took note of the melting ice shelves of the west.

"This is something we think is happening to the ice shelves in Dronning Maud Land," he said, referring to this Norwegian-claimed sector of east Antarctica. "The water coming in under the shelves is 1 °C warmer" — almost 2 °F.

Scambos, lead scientist at the U.S. National Snow and Ice Data Center at the University of Colorado, pointed out that a recently published research paper in the journal Nature indicated that east Antarctica, contrary to earlier scientific belief, has been warming in recent decades.

"Our preliminary results support that," he said of the traverse expedition's research. "The temperature measurements we were able to make looks like there was a very slight warming."

The 12-member U.S.-Norwegian team drilled deep cores into the eastern ice sheet to assess recent and historical climate trends, checked ice thickness with radar, and made other measurements. They drove the 1,400 miles (2,300 km) in a caravan of snow tractors pulling research, kitchen and sleeping modules on giant skis.

The interior of east Antarctica is almost entirely unexplored. "The area we traveled through had not been visited by a scientific traverse since the 1960s," said NASA glaciologist Neumann.

"This part of Antarctica is approximately the same size as Greenland and we don't know very much about it," he said. "But I hope our data on the ground will allow us to make a much better assessment of how this area is changing."

That will take months of follow-up analysis. Meantime, Scambos said, Wednesday's IPY report "gives us an idea of what sort of trouble we are getting ourselves into if we don't begin to turn around the impact of greenhouse gases on climate."

Link to article:

S. H. Schneider & M. D. Mastrandrea: Probabilistic assessment of “dangerous” climate change and emissions pathways

UPDATE: Link to most recent paper of February 26, 2009, concerning "Reasons for Concern" (free, open-access pdf file), PNAS 2009:

Proceedings of the National Academy of Sciences, November 1, 2005, Vol. 102, No. 44, 15727–15735; doi:10.1073/pnas.0507327102

Probabilistic assessment of “dangerous” climate change and emissions pathways

  1. Stephen H. Schneider*,, and
  2. Michael D. Mastrandrea*
  1. *Center for Environmental Science and Policy, Stanford University, Encina Hall East, E415, Stanford, CA 94305-6055; and Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020
  1. Contributed by Stephen H. Schneider, July 26, 2005


Climate policy decisions driving future greenhouse gas mitigation efforts will strongly influence the success of compliance with Article 2 of the United Nations Framework Convention on Climate Change, the prevention of “dangerous anthropogenic interference (DAI) with the climate system.” However, success will be measured in very different ways by different stakeholders, suggesting a spectrum of possible definitions for DAI. The likelihood of avoiding a given threshold for DAI depends in part on uncertainty in the climate system, notably, the range of uncertainty in climate sensitivity. We combine a set of probabilistic global average temperature metrics for DAI with probability distributions of future climate change produced from a combination of several published climate sensitivity distributions and a range of proposed concentration stabilization profiles differing in both stabilization level and approach trajectory, including overshoot profiles. These analyses present a “likelihood framework” to differentiate future emissions pathways with regard to their potential for preventing DAI. Our analysis of overshoot profiles in comparison with non-overshoot profiles demonstrates that overshoot of a given stabilization target can significantly increase the likelihood of exceeding “dangerous” climate impact thresholds, even though equilibrium warming in our model is identical for non-overshoot concentration stabilization profiles having the same target.


  • To whom correspondence should be addressed. e-mail:

  • Author contributions: S.H.S. and M.D.M. designed research, performed research, contributed new reagents/analytic tools, analyzed data, and wrote the paper.

  • This contribution is part of the special series of Inaugural Articles by members of the National Academy of Sciences elected on April 30, 2002.

  • Abbreviations: DAI, dangerous anthropogenic interference; CDF, cumulative density function; CO2e, CO2 equivalent; SC, slow change; RC, rapid change; OS, overshoot scenario; IPCC, Intergovernmental Panel on Climate Change; TAR, Third Assessment Report; EU, European Union; PDF, probability density function; MEA, maximum exceedence amplitude; DY, degree years.

  • See accompanying Profile on page 15725.

  • § During the negotiations leading to the creation of the Kyoto Protocol, the Alliance of Small Island States submitted a draft protocol requiring 20% cuts in emissions by 2005 for industrialized nations. Clearly, the Kyoto targets are not as stringent as this target proposed by one stakeholder group.

  • Research published after the TAR has indicated that some abrupt nonlinear global changes, such as breakdown of the Greenland or Western Antarctic ice sheets, may be triggered by lower temperature thresholds than those currently indicated in Fig. 1, column V (e.g., ref. 16). Therefore, a stakeholder basing his evaluation of DAI on Fig. 1, column V would likely produce a distribution for DAI thresholds lower than the one reported here if this information were taken into account, as it is likely to be in the next IPCC assessment in 2007.

  • In this article, we make an effort, as in ref. 19, to differentiate between emissions scenarios, which represent descriptions of possible future states of the world and the characteristics relevant for emissions, emissions pathways, which represent time-evolving paths for global emissions of greenhouse gases and aerosols, and concentration profiles, which represent time-evolving trajectories for atmospheric concentrations of greenhouse gases and aerosols.

  • ** O'Neill and Oppenheimer (20) compare the future temperature profiles generated by their emissions pathways to thresholds for individual climate impacts that may be considered dangerous, and consider the sensitivity of their results to three values for climate sensitivity, but they do not produce PDFs for their results.

  • †† The two-box model is of the form: Formula where T(t) is the temperature in the upper box in year t, T LO(t) is the temperature in the lower box in year t, F(t) is the radiative forcing above preindustrial levels in year t, and λ, σ1, σ2, and σ3 are constants as defined in ref. 29. We adjust σ1 and σ3 to use a 1-year time step by dividing σ1 and σ3 by 10.

  • ‡‡ Our presentation of results is intended to demonstrate our probabilistic framework, and presenting separately the results using each climate sensitivity distribution requires, for each analysis step, either one very busy figure or three separate figures displaying essentially the same information. We believe such complexity would obscure the demonstration of our analysis methods while adding little intellectual value.

  • §§ The DAI-EU threshold is defined as 2 °C above preindustrial temperatures, while we present temperature distributions of temperature increase above 2000. Therefore, we express the DAI-EU threshold as 1.4 °C, based on the central estimate of 0.6 °C warming over the 20th century in the IPCC TAR (21).

  • ¶¶ This is strictly true when using a simple climate model with a single equilibrium warming level for a given radiative forcing. Some nonlinear processes not included in our simple model can create multiple equilibria and path dependence (e.g., ref. 35). In such models, OS could imply lower thresholds for DAI than those we report here with this linear model.

Link to above text: