A scientific finding is not necessarily correct just because it appears in the peer-reviewed literature. There are a number of reasons. For one, not all journals are created equal. Some have less stringent review process. Some are more willing to accept papers from outside the editorial board's field of expertise or mandate. It's also important to remember that our scientific knowledge develops over time through trial and error via experiments done in the field, in the lab and on computers. Any one paper, no matter the author, no matter the journal, is not the law on a subject.
The trajectory of the publications and accumulated knowledge on a subject is going to be a better measure of scientific knowledge than the existence of one contrary publication, much like the multi-decadal temperature trends is a better indicator of what's happening to the climate than one year's weather.
A news story, I won't bother to link to the story, cited this list of "450 peer-reviewed papers supported skepticism of man-made global warming".
There are a few publications in well-respected scientific journals on the list. The large majority of those do not actually question the role of human activity in climate, rather point to complexity of climate change or the policy options(e.g. Zeebe et al. 2009 in Nature Geoscience). A large number are published editorials that do not actually contain any science. Many are from Energy and the Environment, a journal which advertises for papers skeptical of climate change, or Climate Research, where editors resigned because of a breakdown in the peer review process. And there are also papers from "Irrigation and Drainage", "Bulletin of Canadian Petroleum Geology", "Latvian Journal of Physics and Technical Sciences", "New Concepts in Plate Tectonics", "Journal of American Physicians and Surgeons", "Iron and Steel Technology" and "The Electricity Journal".
The list is being used to claim that there is widespread disagreement among scientists disagree about climate change. It is actually evidence for the exact opposite. Even if you included all 450 papers as relevant, critical analyses of the evidence for human influence on the climate, they would represent a minute fraction of the papers published on climate change in the past thirty years. In that way, it is evidence that the accumulated knowledge has led in another direction.
There's also a more common sense way to think about this list. If there really was so much disagreement about climate change in the scientific community, would the people who compiled this list needed to have included the articles from "Iron and Steel Technology" and "Topics in Catalysis"?
Wednesday, December 09, 2009
The path of climate science and the dissenting views
Monday, December 07, 2009
One reason the US climate bill will pass
Today the US EPA announced its intention to pursue regulations on carbon dioxide and other greenhouse gases. Don't overlook this development. The only thing that carbon-intensive industries and senators from carbon-intensive states hate more than the US climate bill would be the EPA regulating carbon dioxide.
Thursday, December 03, 2009
The Climategate positive feedback loop
I've avoided writing about "climategate" because of the artificial nature of the "scandal".
There is certainly a need to reduce tribalism in the scientific community (not just climate science!), improve peer review and improve the assessment process - I'll cheer those initiatives with enthusiasm.
That's not why the hackers released those emails were released online. The timing of the online publication of those e-mails were no fluke. The goal was to create a grand diversion from the important policy issues of the day. From the Times of London:
The computer was hacked repeatedly, the source close to the investigation said: “It was hacked into in October and possibly earlier. Then they gained access again in mid-November.” By not releasing the e-mails until two weeks before Copenhagen, the hacker ensured that the debate about them would rage during the summit. Very few of the e-mails are recent. One, in which Professor Jones mentions a “trick” which could “hide the decline” in temperatures, was sent in 1999.
Bob Ward, director of policy at the Grantham Research Institute on Climate Change, based at the London School of Economics, said: “From the timing of the release of the e-mails, it seems that the intention was not just to inform the public but to undermine mainstream climate researchers and influence the process in Copenhagen.”
Many scientists are now offering eloquent public explanations for the problems with some scientific practice and the assessment process. Terrific, but only in the abstract.
The problem is the impression given by a public blood letting. Climate scientists, people who trained in the physics and chemistry of the atmosphere, realize that regardless of issues with how some scientists conduct and publicize their work, all the basic concepts are still solid. That's not true for everyone else. So by constantly questioning scientific practice in public forums, it gives people the mistaken impressions there is dissension about the basic concepts, no matter how many caveats are then offered about strength of our understanding of the basic concepts (caveats just make it look like you're dodging the truth!). Good intentions aside, it is fueling public misconceptions about science and feeding the 24-7 scandal machine.
Perhaps the hackers understand climate dynamics better than we assume; they sure knew how to initiate a positive feedback.
Wednesday, December 02, 2009
Huge disparity in emissions targets within Canada
Basically, the hydro-based and manufacturing-based provinces (the east and BC) are willing to be aggressive in reducing emissions and the more resource-intensive provinces are either reticent (Saskatchewan) or downright hostile (Alberta).
The objective of this post is not to dump on Alberta or the oil industry, rather to point out just how large the disagreement is within Canada. The huge disparity between the Alberta policy and that of all the other provinces does raise the question about what it is realistic for Canada. If, say, Alberta refuses to budge on its oil expansion and emissions plan, could neighbouring BC even come close to its reduction target? Keep in mind, a substantial quantity of the planned oil extraction may end up being piped across and refined in BC in order to be shipped to Asia.
Monday, November 30, 2009
China's emissions pledge depends entirely on economic growth
Last week, China announced that it will reduce carbon "intensity" by 40 to 45 per cent below 2005 levels by the year 2020. The emissions intensity (emissions/$GDP) approach taken by the Canada and the US in the past has been much maligned here as a dishonest dodge.
It is, however, a reasonably fair way to bring a reluctant developing nation like China into an international emissions control framework. The problem of course is that actual emissions target depends entirely on how much the Chinese economy grows by 2020. So 40-45% sounds impressive, but won't amount to an actual reduction in emissions.
The graph above shows a spectrum of possibilities. Unless the growth rate is less than ~4%/year - highly unlikely - Chinese carbon emissions will be higher in 2020 than 2005. If China keeps up the planned 8%/year growth, emissions in 2020 will be 74-90% higher than 2005 levels.
And, just like in the US and Canada cases, Chinese emissions intensity will naturally decrease over time without any policy intervention. It decreased 10% from 2000 to 2005, and well over 40% from 1990 to 2005.
Wednesday, November 25, 2009
Skeptics aren't necessarily in it for the money either
A number of us like to joke about the ridiculous contention that climate scientists are in it for the money. It is worth noting that the critics of climate science are not necessarily in it for the dough either.
There appears to be this mistaken assumption that the few scientists who are skeptical of climate change science are doing so because the coal or oil industry wrote them such a big cheque (Canuck sp.) that they chose to abandon their previous understanding of climate science. It's not that simple. In most cases, the scientists who are influential climate skeptics were so well before receiving money from the fossil fuel lobby. The funding came to them because they were already making the argument for other reasons, usually political ideology and/or a horribly shortsighted faith in simple models*.
A great example is Myanna Lahsen's 2008 article on the three physicists from the George Marshall Institute that more or less founded climate change skepticism (hat tip to Eli):
By contrast to common suggestions, these scientists’ motivation is not fundamentally rooted in desires for financial gain. Being past retirement age and no longer active scientists, their fight for basic science, for instance, does not benefit them individually. And it is hard to believe that, upon retirement, these physicists would jeopardize their cherished professional images for mere financial gain.
Climate change "activists" make a huge mistake assuming that their opposition are only in it for the cash. There is real ideology at work. As I've argued before and will again, it's worth thinking about what motivates people the "other side". That may be the only way we'll ever find workable solutions to this mess.
* e.g. like arguing that since CO2 "only" changed from 0.028% to 0.038% of the lower atmosphere, it couldn't possible alter the climate, and thus ignoring all of radiative science
US to pledge emissions cut in Copenhagen
It's a step. Not a great leap for mankind; there is no teeth behind a emissions promise without legislation and an action plan to back it up. But a step nonetheless.
Mr. Obama will tell the delegates to the climate conference that the United States intends to reduce its greenhouse gas emissions “in the range of” 17 percent below 2005 levels by 2020 and 83 percent by 2050, officials said. The administration has resisted until now delivering a firm pledge on emissions reductions because Congress has not yet acted on global warming legislation and because several large developing nations, including China and India, have not detailed their own plans. (NY Times)
Lots of people will undoubtedly now take credit for Obama's promise to attend the meeting.
Mr. Obama... had been under considerable pressure from other world leaders and environmental advocates to make the trip as a statement of American seriousness about the climate change negotiations.
Right, must have been all that pressure from environmental advocates. And the band had not planned on doing that encore either.
Monday, November 23, 2009
The "CRU hack" and the deplorable state of reporting and blogging
This episode is a sad sad sad comment on the state of blogging and news reporting. Three reasons.
First, for legal reasons, I'd like to think that no news organization should be allowed to report on the content of that mail. This is the equivalent of someone breaking into your mailbox in front of your house, opening your mail, then publishing it. Seriously, how would you feel if the NY Times wrote about a private letter you mailed to a colleague or friend being stolen and tacked to lampposts all over town? Would you sue? Do you think it should be admissible in court? Is the lesson here that we can never consider e-mail or any communication to be private so we should go back to using the postal service?
Second, even if you ignore the legality, there's ample reason to consider the contents of the mail with caution. It is private communication so people for whom that communication were not intended are not qualified to interpret that communication. I barely am able to follow some messages that I receive without looking over past correspondence for context. So, no, I will not defend anything that the scientists wrote. Nor will I condemn any of it either. For one reason: I have no idea what exactly those words meant. Neither do you. Every single thing in those messages could be misinterpreted because we are missing the context.
Finally, even if you ignore the legality, and ignore the lack of context, this episode is full of the same "post first, ask questions later" approach that usually destroys whatever good the blogosphere might accomplish. The vast majority of the bloggers, reporters and comment-ers are reacting to snippets pulled out private conversations, and done so by people whose objective is to question climate science. Stop it.
This episode is not a window into how climate science works. It's a window into how electronic communication has altered our standards and the way we work. Nobody looks good here. We should all be embarrassed.
This is the last you'll hear of it on Maribo.
Saturday, November 21, 2009
Public confusion about scientific consensus
The Globe and Mail reports that a new poll from Hoggan & Associates found Canadians are embarrassed over the lack of Canadian action on climate change. Now it is possible that readers will dismiss that finding because the pollsters are connected with a number of environmental organization (an observation, not a judgment), but I encourage people to think about the following:
There was also strong support for the view that “most scientists agree that human activity is the primary cause of climate change,” a position held by 62 per cent of the public, compared to the 38 per cent who felt there was “still much debate” among researchers.
The key "accomplishment" of the movement to question the science of climate change is seeding doubt among the public. There is widespread agreement that human activity is causing climate change among scientists who actually study the issue. But poll the public on whether scientists agree and you get a different answer.
The results at right, which I've used to spur discussion in class, are from work in the U.S. by Jon Krosnick at Stanford University, who has done some terrific research on public perceptions of climate change.
The irony is that many of the people being polled think climate change is happening and caused by humans, yet also think scientists are not sure. This clear contradiction - people learned of climate change from scientists, after all - shows just how effective the lobbying and disinformation campaigns have been.
Friday, November 20, 2009
Narnia plans to reduce emissions by 30% by the year 2020
As we head towards Copenhagen, there will be endless comparison of proposed emission targets. For example, from the NY Times:
This week, South Korea said it would cut emissions by 30 percent from “business as usual” by 2020. Russia’s president said his country would try to reduce emissions by 25 percent by then, instead of 15 percent as announced earlier. Last week, Brazil promised reductions of about 40 percent below current projections by 2020.
Ah, fractions.
The Narnians and reporters everywhere need to do a bit of math. 30% of what? The simple climate policy public relations trick is to emphasize the percent reduction and de-emphasize the year from which that percent is being calculated. Narnia's 30% could be a reduction from emissions during the Kyoto base year of 1990. It could use the present as the base year. Or it could be a reduction from the business-as-usual projection for the year 2020.
This excerpt about S Korea, Russia and Brazil tells us very little about the actual emissions policy. Russia's emissions are lower than they were in 1990, before the collapse of the Soviet Union [and its greenhouse gas emissions], so it still uses the 1990 baseline. The 25% is not as much a change from today as it sounds. For South Korea and Brazilian, we'd need to know what "current projections" and "business as usual" are to understand their targets. In both countries, the projections being used are higher than what the countries actually expect would happen. So the proposed decrease, while laudable, is not as big as it sounds.
Wednesday, November 18, 2009
Tuesday, November 17, 2009
US-China cooperation on climate and, er, coal
The US and China have released a joint statement on a number of issues, including "Climate Change, Energy and the Environment". After the standard political jargon about the need for full co-operation in global agreements, comes some specifics:
The two sides welcomed the launch of a U.S.-China Electric Vehicles Initiative designed to put millions of electric vehicles on the roads of both countries in the years ahead. Building on significant investments in electric vehicles in both the United States and China, the two governments announced a program of joint demonstration projects in more than a dozen cities, along with work to develop common technical standards to facilitate rapid scale-up of the industry. The two sides agreed that their countries share a strong common interest in the rapid deployment of clean vehicles.
This is terrific climate change initiative if the source of electricity is substantially less carbon-intensive than oil. It is a tad worrisome coming from the two countries with the largest coal reserves on the planet. Which leads into the next item in the statement:
The two sides strongly welcomed work in both countries to promote 21st century coal technologies. They agreed to promote cooperation on large-scale carbon capture and sequestration (CCS) demonstration projects and to begin work immediately on the development, deployment, diffusion, and transfer of CCS technology. The two sides welcomed recent agreements between Chinese and U.S. companies, universities, and research institutions to cooperate on CCS and more efficient coal technologies.
This is followed by a paragraph about partnership on renewable energy ("wind, solar, advanced bio-fuels, and a modern electric power grid"). The order is not a fluke. Read through the statement, and it is appears that both countries expect coal to remain king, and that emissions reductions will depend on the development and widespread implementation of CCS technology at coal-fired power plants. No surprise, I suppose.
Saturday, November 14, 2009
World Leaders Agree to Delay Climate Change Deal
This news comes from the APEC summit in Singapore. NY Times:
SINGAPORE — President Obama and other world leaders have decided to put off the difficult task of reaching climate change agreement at a global climate conference scheduled for next month, agreeing instead to make it the mission of the Copenhagen conference to reach a less specific “politically binding” agreement that would punt the most difficult issues into the future.
The announcement is a simple dose of reality: there simply was not enough time left to reach a deal at Copenhagen. It'll be universally reported as "bad" news for the climate. Maybe yes. The flip side is that perhaps now that the artificial December deadline is removed, the key countries can engage in intelligent policy conversations. The "Copenhagen" or bust mentality was not helping anyone.
Tuesday, November 10, 2009
Himalayan glaciers and the virtue of reading beyond the headline
My number one pet peeve with the blogosphere is that too many bloggers post on a new report or paper without actually looking at the new report or paper. Bloggers regularly bash mainstream media for lazy reporting then often go ahead and base entire posts solely on newspaper stories. Hypocrisy aside, it is a real shame. Blogs should be an opportunity to examine and debate science and policy issues in more depth than is available in the mainstream media
Case in point, the excitement in the blogosphere (see Roger Pielke Jr) over a new report from the Indian government claiming there is "no evidence" for climate change shrinking Himalayan glaciers. It's worth looking at the actual report.
First, the report is part of a series that "is meant to serve as a basis for informed debate and discussion on critical issues related to the environment." In other words, it is not a scientific assessment conducted by the Indian Government. The report even has a disclaimer that the views contained in the report "are not necessarily endorsed" by the government.
Second, the report is about glaciology. It contains no analysis that could determine, one way or another, if human-induced climate change is contributing to glacier decline. In order to detect a climate change signal, you'd need to combine the glaciology data with climate data and most likely models capable of simulating the evolution of the climate with and without human influence.
Third, despite all this, the report does in fact state that glaciers in the Himalayas have been retreating over the past century.
Glaciers in the Himalayas (India) have been exhibiting a continuous secular retreat since the earliest recording began around the middle of the nineteenth century. Kumdan glaciers, of the Upper Shyok valley, have been the only exception for their periodic fluctuations.
There are plenty of charts and graphs to support the fact that glaciers have been retreating. The author's quibble appears to be over the "alarmist" portrayals of glacier decline in other forums. The first line of the conclusion:
Data that has been generated from the glacier studies, in the Himalayas, over the last 100 years or so, indicates that the glaciers, in the Himalayas, have been, by and large, shrinking and retreating continuously, barring a flip here and there, but the rate of retreat can not be considered as alarming / abnormal, especially in the last decade or so.
The report presents no definition of "alarming / abnormal" (say, in terms of % change) nor does it present data or any analysis to test the notion that the retreat is or is not alarming / abnormal. All we're really left with is that glaciers are retreating and the retreat may or may not be caused by climate change.
Wednesday, November 04, 2009
Science lesson on the Late Show
Al Gore's long interview with David Letterman last night could serve as an object lesson for scientists on how to relate a complex subject like climate change to a popular audience. Though it is a sad comment on the media that a late night comedian asks better questions about science and the planet than a network news anchor [and that a retired politician is the best spokesmen on those same issues].
Alas, the highlighted video on the Late Show website is not the section where Gore and Letterman discussed Copenhagen, or ocean acidification, or the plight of the world's coral. It is the final minute of the interview, in which Letterman asked about the "carbon billionaire" accusation in that dreadful New York Times train wreck I mentioned yesterday.
Controversy, even artificial and debunked controversy, wins over content, which is why the editors at the NY Times should be hanging their heads over the decision to publish that article.
New York Times drops the ball reporting on Gore
The New York Times printed this absolute train wreck about Al Gore. Apparently some commentators are claiming Gore is arguing for action on climate change in order to make himself rich. So the NY Times printed a pointless story about those claims. It is ridiculous on a number of levels.
Level one: This is news because some people say it is news.
Critics, mostly on the political right and among global warming skeptics, say Mr. Gore is poised to become the world’s first “carbon billionaire,” profiteering from government policies he supports that would direct billions of dollars to the business ventures he has invested in. Representative Marsha Blackburn, Republican of Tennessee, asserted at a hearing this year that Mr. Gore stood to benefit personally from the energy and climate policies he was urging Congress to adopt.
The claimants are politically motivated. They are also quite likely to be wrong. The story even goes on to suggest that possibility. If they are wrong, and the argument is politically motivated, why give the story any attention at all? It simply provides a mouthpiece.
Level two: Complete lack of context
Mr. Gore is not a lobbyist, and he has never asked Congress or the administration for an earmark or policy decision that would directly benefit one of his investments. But he has been a tireless advocate for policies that would move the country away from the use of coal and oil, and he has begun a $300 million campaign to end the use of fossil fuels in electricity production in 10 years.
Interesting, you say. Unless, of course, you contrasted the single investment data point in this article (Gore) with data on other investors in the energy sector. The article does not make one mention of the fact that the CEOs and investors in the fossil fuel industry do actively lobby in Washington, do ask Congress for earmarks and policy, and do financially benefit from those activities.
Level three: Politics anyone?
But Marc Morano, a climate change skeptic who until recently was a top aide to Senator James M. Inhofe, Republican of Oklahoma, said that what he saw as Mr. Gore’s alarmism and occasional exaggerations distorted the debate and also served his personal financial interests.
Shouldn't the second clause in that sentence make the editors think that Morano might not be worth quoting on this subject? This is a classic case of the knee-jerk reaction of quoting "the other side", even though the other side is not the least bit objective. In this case, it adds nothing, other than a chance to further polarize the readers.
Listen, I'm not defending Gore. I'm criticizing the Times for an abominable editorial decision.
It's perfectly legitimate to report on Gore's growing wealth from his investing activities. That's not this story. This is reporting on a made-up controversy. And even though the story debunks many of the claims about Gore being "in it for the gold" as MT would say, the harm is done by shining a light on it.
There's no reason to run articles like this. Just because someone makes a stupid claim does not mean you have to report about it.
Wednesday, October 28, 2009
The climate science filibuster
Over the past couple months, there have been another online kerfuffle about the famous "hockey stick" millennial temperature reconstruction. Namely, Steve McIntrye attempted to show that one the tree ring reconstructions may have been biased, such that selecting a different set of trees from a nearby site would imply no 20th century warming Tim Lambert had a fine summary of the dust-up. And James Hrynyshyn is one of a few who made the obvious but overlooked point that you don't need dendrochronology to tell us temperatures warmed in the 20th century - we have actual measurements.
Out of the dust came many complaints in the blogosphere about climate scientists not being responsive to online criticism like that of McIntrye. The implication is that scientists are obliged to respond quickly to any and all criticisms of my research as well as to any requests for data.
Now, it is quite unrealistic given the pressures on our time. But leaving that aside, is it even wise? Is responding to every online criticism and data request the best use of scientists' time? Think of it this way: wouldn't you rather that doctors spend their time actually developing treatments for autism, rather than refuting the crazy theory that MMR vaccinations cause autism?
There are only 24 hours in a day. It's a zero sum game. There may be some value in individual aspects of McIntrye's statistical criticisms of the hockey stick work over the year. A lot of it has been off the mark too. Either way, dealing with the constant hockey stick criticisms slows important research by paleo-climatologists work.
Add it all up and you have a filibuster. Keep talking and it will stop the rest of the participants from getting anything done.
That's why I sense peer review is even more important in the age of blogs. Research gets some vetting, the poor quality work is filtered out, and the community knows what to take seriously. The system may not be perfect, but I think even its greatest critics would agree that peer review works better than the US Senate.
Saturday, October 24, 2009
Reactions to the International Day of Climate Action
I'd love to get people's reactions to the International Day of Climate Action. Whether you participated or not, take a minute to write a quick first reaction in the comments. A paragraph, a sentence, a word. Anonymity is fine.
Friday, October 23, 2009
Carbon consequences of the biofuels land use cascade
I've written here before about the land use cascade, the sequence of land transformations and land use changes that follow a change in one region.
A new Policy Forum in Science argues that ignoring the cascading carbon consequences of converting lands for biofuels will undercut global efforts to reduce greenhouse gas emissions.
The logic is not new. If croplands and pasture lands are converted to biofuel production, then some other forest or grassland must be cleared to produce the crops or providing the grazing area taken away by the biofuel production. It might happen in the neighbouring county. It might happen on another part of the planet. Either way, it will release soil carbon and plant carbon to the atmosphere (more immediately via burning or later via respiration and decomposition).
The authors argue that we need a new accounting system:
The accounting now used for assessing compliance with carbon limits in the Kyoto Protocol and in climate legislation contains a far-reaching but fixable flaw that will severely undermine greenhouse gas reduction goals (1). It does not count CO2 emitted from tailpipes and smokestacks when bioenergy is being used, but it also does not count changes in emissions from land use when biomass for energy is harvested or grown. This accounting erroneously treats all bioenergy as carbon neutral regardless of the source of the biomass, which may cause large differences in net emissions. For example, the clearing of long-established forests to burn wood or to grow energy crops is counted as a 100% reduction in energy emissions despite causing large releases of carbon.
If it is not fixed, this "accounting problem" has and will continue to cause poor national and international policy decisions.
The Kyoto Protocol caps the energy emissions of developed countries. But the protocol applies no limits to land use or any other emissions from developing countries, and special crediting rules for "forest management" allow developed countries to cancel out their own land-use emissions as well. Thus, maintaining the exemption for CO2 wrongly treats bioenergy from all biomass sources as carbon neutral, even if the source involves clearing forests for electricity in Europe or converting them to biodiesel crops in Asia.
This accounting error has carried over into the European Union's cap-and-trade law and the climate bill passed by the U.S. House of Representatives. Both regulate emissions from energy but not land use and then erroneously exempt CO2 emitted from bioenergy use.
How could it be fixed? The authors argue for a more full and fair accounting of emissions caused by biofuels or bioenergy.
The straightforward solution is to fix the accounting of bioenergy. That means tracing the actual flows of carbon and counting emissions from tailpipes and smokestacks whether from fossil energy or bioenergy. Instead of an assumption that all biomass offsets energy emissions, biomass should receive credit to the extent that its use results in additional carbon from enhanced plant growth or from the use of residues or biowastes. Under any crediting system, credits must reflect net changes in carbon stocks, emissions of non-CO2 greenhouse gases, and leakage emissions resulting from changes in land-use activities to replace crops or timber diverted to bioenergy.
This full accounting is necessary but will be difficult to implement given the uncertainty in soil carbon budgets and the complexity of the land use cascade.
Wednesday, October 21, 2009
Letter from 18 US scientific organizations supporting the US climate bill
Released today (hat tip). It's signed by the leaders of American Association for the
I suppose Canadian scientific societies may want to consider a similar letter of support for the US bill, given that there's no Canadian legislation to support!
Dear Senator:
As you consider climate change legislation, we, as leaders of scientific organizations, write to state the consensus scientific view. Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver.
These conclusions are based on multiple independent lines of evidence, and contrary assertions are inconsistent with an objective assessment of the vast body of peer-reviewed science. Moreover, there is strong evidence that ongoing climate change will have broad impacts on society, including the global economy and on the environment. For the United States, climate change impacts include sea level rise for coastal states, greater threats of extreme weather events, and increased risk of regional water scarcity, urban heat waves, western wildfires, and the disturbance of biological systems throughout the country. The severity of climate change impacts is expected to increase substantially in the coming decades.(1) If we are to avoid the most severe impacts of climate change, emissions of greenhouse gases must be dramatically reduced. In addition, adaptation will be necessary to address those impacts that are already unavoidable. Adaptation efforts include improved infrastructure design, more sustainable management of water and other natural resources, modified agricultural practices, and improved emergency responses to storms, floods, fires and heat waves. We in the scientific community offer our assistance to inform your deliberations as you seek to address the impacts of climate change.
1. The conclusions in this paragraph reflect the scientific consensus represented by, for example, the Intergovernmental Panel on Climate Change and U.S. Global Change Research Program. Many scientific societies have endorsed these findings in their own statements, including the American Association for the Advancement of Science, American Chemical Society, American Geophysical, American Meteorological Society, and American Statistical Association.
