RealClimate, a blog maintained by real climate scientists, is busy doing damage control. This story will no doubt rage for weeks, so I'm just going to pick one example of the back and forth before trying to take some time to go deeper, if merited.

Here's an e-mail that has gotten particular attention, with the supposedly damning language bolded:

Dear Ray, Mike and Malcolm,

Once Tim's got a diagram here we'll send that either later today or first thing tomorrow.

I've just completed Mike's Nature trick of adding in the real temps to each series for the last 20 years (ie from 1981 onwards) amd from 1961 for Keith's to hide the decline. Mike's series got the annual land and marine values while the other two got April-Sept for NH land N of 20N. The latter two are real for 1999, while the estimate for 1999 for NH combined is +0.44C wrt 61-90. The Global estimate for 1999 with data through Oct is +0.35C cf. 0.57 for 1998.

Thanks for the comments, Ray.

Cheers, Phil

Here's RealClimate's explanation:

The paper in question is the Mann, Bradley and Hughes (1998) Nature paper on the original multiproxy temperature reconstruction, and the "trick" is just to plot the instrumental records along with reconstruction so that the context of the recent warming is clear. Scientists often use the term "trick" to refer to a "a good way to deal with a problem", rather than something that is "secret", and so there is nothing problematic in this at all. As for the "decline," it is well known that Keith Briffa's maximum latewood tree ring density proxy diverges from the temperature records after 1960 (this is more commonly known as the "divergence problem" -- see e.g. the recent discussion in this paper) and has been discussed in the literature since Briffa et al in Nature in 1998 (Nature, 391, 678-682). Those authors have always recommend not using the post 1960 part of their reconstruction, and so while "hiding" is probably a poor choice of words (since it is "hidden" in plain sight), not using the data in the plot is completely appropriate, as is further research to understand why this happens.

So what's going on here? Put aside the question of whether the words "trick" or "hide" have nefarious or innocuous meanings. The scientific problem is that in attempting to reconstruct temperatures in the past, climate scientists are often faced with the problem that there were no humans standing around holding thermometers and writing down temperatures. So scientists use "proxies" -- tree rings, or ice cores, or fossilized clams, or lake pollen trapped in sediment. The "divergence problem" referred to above references a case where in one particular instance, tree ring variations in density did not match actual recorded temperatures after 1960.

That poses a conundrum, although not one that throws the entire science of multiproxy paleoclimate reconstruction into doubt.  More importantly, t the divergence problem, as RealClimate notes, is not a secret. It's exactly the kind of thing that climate scientists feast on. Such problems are discussed and debated every day by climate scientists (and every other kind of scientist.) The great thing about science is that the process of gathering  more data, improving models and theories is infinitely ongoing, and working out how to handle puzzlers like this, both in private e-mails and in the peer-reviewed literature, is what scientists live for.

Overall, the more data we have, the more clear it has become to the vast majority of scientists working in this field that the earth has gotten significantly hotter at an alarming rate in the last century, most likely due to increased concentrations of greenhouse gases in the atmosphere. And if there really is a smoking gun in the hacked e-mails that convicts scientists of fraudulent behavior or faking data, well, let's hear it. I'm not convinced by the above example. But if enough scientists are, that's a different matter.

I think Ollie's got his history a little mixed up. If I recall, Republicans, following the advice of consultant Frank Luntz, as formulated in his famous 2002 memo, started using the words "climate change" instead of "global warming" because global warming was "too frightening."

From an account in the UK Guardian:

The phrase "global warming" should be abandoned in favor of "climate change", Mr Luntz says, and the party should describe its policies as "conservationist" instead of "environmentalist", because "most people" think environmentalists are "extremists" who indulge in "some pretty bizarre behavior... that turns off many voters".

I guess one example of that bizarre behavior was a little semiotic jujitsu, in which environmentalists embraced the climate change name switch, but tacked on catastrophic to get the original point across.

Ironically, climate change appears to have stalled in the run-up to the upcoming world summit in the Danish capital, where thousands of politicians, bureaucrats, scientists, business leaders and environmental activists plan to negotiate a reduction in greenhouse gas emissions. Billions of euros are at stake in the negotiations.

Reached a plateau

The planet's temperature curve rose sharply for almost 30 years, as global temperatures increased by an average of 0.7 degrees Celsius (1.25 degrees Fahrenheit) from the 1970s to the late 1990s. "At present, however, the warming is taking a break," confirms meteorologist Mojib Latif of the Leibniz Institute of Marine Sciences in the northern German city of Kiel. Latif, one of Germany's best-known climatologists, says that the temperature curve has reached a plateau. "There can be no argument about that," he says. "We have to face that fact."

Even though the temperature standstill probably has no effect on the long-term warming trend, it does raise doubts about the predictive value of climate models, and it is also a political issue. For months, climate change skeptics have been gloating over the findings on their Internet forums. This has prompted many a climatologist to treat the temperature data in public with a sense of shame, thereby damaging their own credibility.

"It cannot be denied that this one of the hottest issues in the scientific community," says Jochem Marotzke, director of the Max Planck Institute for Meteorology in Hamburg. "We don't really know why this stagnation is taking place at this point."

Just a few weeks ago, Britain's Hadley Centre for Climate Prediction and Research added more fuel to the fire with its latest calculations of global average temperatures. According to the Hadley figures, the world grew warmer by 0.07 degrees Celsius from 1999 to 2008, and not by the 0.2 degrees Celsius assumed by the United Nations Intergovernmental Panel on Climate Change. And, say the British experts, when their figure is adjusted for two naturally occurring climate phenomena, El Niño and La Niña, the resulting temperature trend is reduced to 0.0 degrees Celsius -- in other words, a standstill.

The differences among individual regions of the world are considerable. In the Arctic, for example, temperatures rose by almost three degrees Celsius, which led to a dramatic melting of sea ice. At the same time, temperatures declined in large areas of North America, the western Pacific and the Arabian Peninsula. Europe, including Germany, remains slightly in positive warming territory.

Mixed messages

But a few scientists simply refuse to believe the British calculations. "Warming has continued in the last few years," says Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research (PIK). However, Rahmstorf is more or less alone in his view. Hamburg Max Planck Institute scientist Jochem Marotzke, on the other hand, says: "I hardly know any colleagues who would deny that it hasn't gotten warmer in recent years."

The controversy sends confusing and mixed messages to the lay public. Why is there such a vigorous debate over climate change, even though it isn't getting warmer at the moment? And how can it be that scientists cannot even arrive at a consensus on changes in temperatures, even though temperatures are constantly being measured?

The global temperature-monitoring network consists of 517 weather stations. But each reading is only a tiny dot on the big world map, and it has to be extrapolated to the entire region with the help of supercomputers. Besides, there are still many blind spots, the largest being the Arctic, where there are only about 20 measuring stations to cover a vast area. Climatologists refer to the problem as the "Arctic hole."

The scientists at the Hadley Center simply used the global average value for the hole, ignoring the fact that it has become significantly warmer in the Arctic, says Rahmstorf. But a NASA team from the Goddard Institute for Space Studies in New York, which does make the kinds of adjustments for the Arctic data that Rahmstorf believes are necessary, arrives at a flat temperature curve for the last five years that is similar to that of their British colleagues.

Marotzke and Leibniz Institute meteorologist Mojib Latif are even convinced that the fuzzy computing done by Rahmstorf is counterproductive. "We have to explain to the public that greenhouse gases will not cause temperatures to keep rising from one record temperature to the next, but that they are still subject to natural fluctuations," says Latif. For this reason, he adds, it is dangerous to cite individual weather-related occurrences, such as a drought in Mali or a hurricane, as proof positive that climate change is already fully underway.

"Perhaps we suggested too strongly in the past that the development will continue going up along a simple, straight line. In reality, phases of stagnation or even cooling are completely normal," says Latif.

Part 2: The difficulties of predicting the climate

Climatologists use their computer models to draw temperature curves which continue well into the future. They predict that the average global temperature will increase by about three degrees Celsius (5.4 degrees Fahrenheit) by the end of the century, unless humanity manages to drastically reduce greenhouse gas emissions. However, no one really knows what exactly the world climate will look like in the not-so-distant future, that is, in 2015, 2030 or 2050.

This is because it is not just human influence but natural factors that affect the Earth's climate. For instance, currents in the world's oceans are subject to certain cycles, as is solar activity. Major volcanic eruptions can also curb rising temperatures in the medium term. The eruption of Mount Pinatubo in June 1991, for example, caused world temperatures to drop by an average of 0.5 degrees Celsius, thereby prolonging a cooler climate phase that had begun in the late 1980s.

But the Mount Pinatubo eruption happened too long ago to be related to the current slowdown in global warming. So what is behind this more recent phenomenon?

Weaker solar activity

The fact is that the sun is weakening slightly. Its radiation activity is currently at a minimum, as evidenced by the small number of sunspots on its surface. According to calculations performed by a group of NASA scientists led by David Rind, which were recently published in the journal Geophysical Research Letters, this reduced solar activity is the most important cause of stagnating global warming.

Latif, on the other hand, attributes the stagnation to so-called Pacific decadal oscillation (PDO). This phenomenon in the Pacific Ocean allows a larger volume of cold deep-sea water to rise to the surface at the equator. According to Latif, this has a significant cooling effect on the Earth's atmosphere.

With his team at the Leibniz Institute of Marine Sciences, Latif has been one of the first to develop a model to create medium-term prognoses for the next five to 10 years. "We are slowly starting to attempt (such models)," says Marotzke, who is also launching a major project in this area, funded by the Federal Ministry for Research and Technology.

Despite their current findings, scientists agree that temperatures will continue to rise in the long term. The big question is: When will it start getting warmer again?

If the deep waters of the Pacific are in fact the most important factor holding up global warming, climate change will remain at a standstill until the middle of the next decade, says Latif. But if the cooling trend is the result of reduced solar activity, things could start getting warmer again much sooner. Based on past experience, solar activity will likely increase again in the next few years.

Betting on warmer temperatures

The Hadley Center group expects warming to resume in the coming years. "That resumption could come as a bit of a jolt," says Hadley climatologist Adam Scaife, explaining that natural cyclical warming would then be augmented by the warming effect caused by anthropogenic greenhouse gas emissions.

While climatologists at conferences engage in passionate debates over when temperatures will start rising again, global warming's next steps have also become the subject of betting activity.

Climatologist Stefan Rahmstorf is so convinced that his predictions will be correct in the end that he is willing to back up his conviction with a €2,500 ($3,700) bet. "I will win," says Rahmstorf.

His adversary Latif turned down the bet, saying that the matter was too serious for gambling. "We are scientists, not poker players."

Translated from the German by Christopher Sultan

The Berkeley SolarMap is even neater -- a very cool application that takes advantage of the capabilities of Google Maps, and allows you to quickly calculate the cost of a solar system for your home. In just a few minutes, I inputted a years worth of PG&E data on my gas and electricity expenses into Berkeley SolarMap's online calculator, plugged in my address so that system could estimate my available roof square footage from satellite photos, and ended up with an estimate for how much a system would cost and how much I would save on electricity (and how many pounds of carbon dioxide I would no longer be responsible for emitting).

That was the fun part. The not so fun part was that Berkeley SolarMap estimated the total cost of a system that would pay for 100 percent of my electricity needs at $27,000. Ouch. Sure, after after 25 years I would net out at zero, but that's still a little bit too long a time frame for me at the moment. I'm going to have to wait until Berkeley's solar power system financing plan expands.

Even though I have not yet been spurred to take advantage of the program, I'm still happy that stimulus money is helping to pay the wages of people creating these programs and doing the solar power consulting. Those are tax dollars spent that I do not regret one whit.

But America always took pride in being faster and more flexible than other nations. Does that no longer apply?

America's political system has evolved over the last 50 years in ways that have enhanced the power of business lobbies. The power of television and of money has grown exponentially. Eighty percent of the campaign contributions that candidates and officials running for reelection raise and spend go to TV ads, so they are required to raise enormous amounts of money, mainly from business lobbies. In a way, that has "re-feudalized" the political power and it gave much more power to established interests. When Obama was elected, I said: "What an exciting moment in our history." But his election did not cure all of the problems in the American system.

Seventeen years ago you, a young senator from Tennessee, and Bill Clinton, a young governor from Arkansas, moved into the White House on the promise of change. Clinton played the saxophone and there was a feeling of spring in the air. Why has it been so much tougher for Barack Obama?

It was hard for us, too. Just remember the resistance to our healthcare reform bill. Obama's progress on healthcare has already surpassed what we were able to do on healthcare. He will get a climate change bill adopted. So I am optimistic. These are still the early days of the Obama presidency. He had a bad summer, but he is having a good fall.

Isn't it getting harder and harder to remain an optimist?

I think there is a realistic basis for optimism. The Internet empowers individuals to play a more active role in the political process, as Obama's campaign has manifested. They felt shut out of the conversation of democracy during the television age, but they are coming back. It is not an accident that virtually every progressive reform movement in the world is now based on the Internet. There are more than 1 million, perhaps as many as 2 million grass-roots organizations that have been established worldwide on the issue of the climate crisis, most of them on the Internet.

Obama's political opponents also rely on the Internet, though. Could the reason for the resistance to his government be his skin color? Former President Jimmy Carter said many Americans still have a problem with a black man in the White House.

There is no doubt that the issue of race is always present in American politics and in the politics of any multiracial society. There is also no doubt that for some people it is an element in the manifested hostility to Obama. But I don't think it is the major theme at all. Obama is right when he reminds people: By the way, I was black before the election.

Perhaps the aggressive reactions can be explained by the fact that he, you and large parts of the Democratic Party misinterpreted the will of voters. Perhaps the last election had less to do with a desire among voters to implement transformational change than just getting rid of Bush.

Isn't that all related? The Bush-Cheney administration had betrayed some basic American values. So there was hunger for change. The difficulties the new government has encountered are in the Congress, and they are connected to the growing influence of business lobbies and people who are simply afraid of government.

Is that a new phenomenon?

People in Congress listen less to each other. The Senate chamber, for example, is now commonly empty when speeches are made. That was different in the past and I know why it has changed. The chamber is empty now because the senators have to be at cocktail parties and fundraisers to raise money. They feel as if they have to spend virtually all their time raising money.

"It is realistic to expect a treaty"

Isn't Obama's plate too full? He conducts war in Iraq and Afghanistan, he wants to close Guantánamo, he is trying to reform the healthcare system, he is promising progress on climate change and wants to strengthen, almost in passing, the rights of trade unions and homosexuals. Isn't that too much change for a rather conservative country like the United States?

I disagree with that criticism. After eight years of retrogression, Obama would have been more bitterly criticized if he had chosen only one priority and had not tried to address the many challenges that need to be undertaken. So I do think there is a grain of truth to it, but I also know that his mandate was and is strongest at the beginning of his term.

But Obama hasn't achieved much so far -- most of the reforms he announced still haven't been implemented. Many people already call him a sweet talker -- all talk, but little action.

One of the tools that a president has is to command the attention of the American people. It has to be used judiciously. There is such a thing as overexposure when a president depreciates the welcome. I think it is too early to make that judgment. There have been times when I thought that President Obama maybe got close to that line -- for instance, with regard to his television interviews. But it is the most powerful tool he has to make his direct presentation to the people.

The financial crisis hasn't made the president's job any easier. Are times of material want fundamentally bad for reform politicians?

The climate, financial and national security crises are all connected. They share the same cause: Our absurd dependency on foreign oil. As long as we need to spend billions of dollars each year to buy foreign oil from state-run oil companies in the Persian Gulf, our problems of a trade deficit, a budget deficit and a climate crisis will persist. Therefore, more and more Americans begin to realize that the right response to the climate challenge will also help with the economy and a more balanced budget.

German Chancellor Angela Merkel was less optimistic after the G-20 summit in Pittsburgh. She did not believe there would be a majority for a U.S. climate change law in Congress before the world climate summit in Copenhagen in December.

I am more optimistic. I do not think that we will have the final enactment of the Conference Committee Report in Congress before Copenhagen. But if President Obama is able to go to Copenhagen having passed legislation in the House and having passed it in the Senate, it will be inevitable that the legislation comes out even if the Conference Committee is still pending.

What are your expectations for Copenhagen ?

I think it is realistic to expect a treaty. It will not be as strong as I would like it to be. But it will put a price on carbon and change the forward planning of businesses and cities and states, provinces and nations. In 1986, when the first crisis of the global atmosphere emerged with the discovery of the ozone hole above Antarctica, one year later the nations of the world passed the Montreal Protocol. It was bitterly criticized by environmentalists as being too weak and insufficient. But then it was toughened and toughened, and it is working quite well, and we are on our way to solving that crisis. I am expecting a similar process for Copenhagen. We will produce a treaty that launches the beginning of a huge transformation process.

The U.S. is expecting more commitment from China. Should Obama use his upcoming Asia trip to increase pressure on Beijing?

They have to accept binding provisions. Many developing nations are still thinking that the wealthier countries will take binding obligations, and the developing countries will have non-binding provisions. That is not a formula for success. In an I.T.-empowered outsourcing world it is very easy to replicate the technological basis for production in low-wage countries. Workers in Germany and the United States and other wealthy nations fear for their jobs. We can't tell them: "We are going to have these binding obligations, but the places that have already gotten some of your jobs are going to have no obligations at all." That wouldn't work.

Isn't that even more of an incentive for developing nations not to accept any binding emission caps?

They are starting to feel the consequences of such a policy. India now faces the prospect of black carbon emissions greatly accelerating the melting of ice that forms the source of the majority of the water in the Indus, the Ganges and the Brahmaputra rivers. They must cut back on black carbon for their own survival.

Do you see indications of a shift in awareness in China, which is the second greatest polluter in the world after the U.S.?

China has been changing fairly dramatically on this issue. While they are still opening a new coal-fired generating plant every eight or nine days, they will soon be the No. 1 power in wind and the No. 1 power in solar. In each of the last several years, they have planted two and a half times as many trees as the rest of the world put together. They are building an 800-kilovolt supergrid that, by 2020, will be the most advanced in the world. They have revised their new five-year plan, beginning a little over a year from now, to adapt the formula by which all bureaucrats and officials are evaluated for advancement or not. They have placed their success in reducing CO2 as one of the principal factors by which they pursue their career successfully or not. These are significant changes.

Will Obama travel to Copenhagen ?

He hasn't told me that he will, and no one representing him has told me that he will. But I see the calendar, I see unfolding of events and I feel certain he will go.

The White House is currently dampening expectations, because if the American president travels to Copenhagen for the summit, the rest of the world will expect a binding agreement from the United States on emissions caps.

Yes, of course. President Obama has already enacted a binding set of regulations that require a cut in emissions. But the big difference will be whether or not the Senate legislation on climate change passes or not. I believe that the draft bill introduced by Sen. John Kerry and Sen. Barbara Boxer really does open up very new prospects. They are likely to add a title to the draft that expands support for nuclear energy. I also think they will add some provisions accelerating the substitution of gas for coal. Gas has only half the CO2 emissions of coal and two-thirds of that from oil. I think that will also generate more support and split the energy lobbies somehow. Therefore, I think there is a very real prospect that the legislation will pass, and that as a result, Obama will have the ability to go to Copenhagen with a more substantive position.

How do you see your own role in this process?

Sometimes the language of Yiddish is the most expressive. I want to be a "nudge" in Copenhagen. Someone who is pushing for action.

The most effective way to "nudge" people into action is to be president of the United States of America. Will you ever run for this office again?

Well, I am trying to recover from politics. But of course there is always a danger of a relapse when you are in recovery.

Mr. Vice President, we thank you for this interview.