Climate Science Is Not Settled

We are very far from the knowledge needed to make good climate policy, writes leading scientist Steven E. Koonin

Steven E. Koonin

Sept. 19, 2014 12:19 p.m. ET

The idea that "Climate science is settled" runs through today's popular and policy discussions. Unfortunately, that claim is misguided. It has not only distorted our public and policy debates on issues related to energy, greenhouse-gas emissions and the environment. But it also has inhibited the scientific and policy discussions that we need to have about our climate future.

My training as a computational physicist—together with a 40-year career of scientific research, advising and management in academia, government and the private sector—has afforded me an extended, up-close perspective on climate science. Detailed technical discussions during the past year with leading climate scientists have given me an even better sense of what we know, and don't know, about climate. I have come to appreciate the daunting scientific challenge of answering the questions that policy makers and the public are asking.

The crucial scientific question for policy isn't whether the climate is changing. That is a settled matter: The climate has always changed and always will. Geological and historical records show the occurrence of major climate shifts, sometimes over only a few decades. We know, for instance, that during the 20th century the Earth's global average surface temperature rose 1.4 degrees Fahrenheit.

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Tens of thousands of people marched in New York City Sunday to raise awareness and demand action on climate change ahead of Tuesday's United Nations Climate Summit. Photo: AP

Nor is the crucial question whether humans are influencing the climate. That is no hoax: There is little doubt in the scientific community that continually growing amounts of greenhouse gases in the atmosphere, due largely to carbon-dioxide emissions from the conventional use of fossil fuels, are influencing the climate. There is also little doubt that the carbon dioxide will persist in the atmosphere for several centuries. The impact today of human activity appears to be comparable to the intrinsic, natural variability of the climate system itself.

Rather, the crucial, unsettled scientific question for policy is, "How will the climate change over the next century under both natural and human influences?" Answers to that question at the global and regional levels, as well as to equally complex questions of how ecosystems and human activities will be affected, should inform our choices about energy and infrastructure.

But—here's the catch—those questions are the hardest ones to answer. They challenge, in a fundamental way, what science can tell us about future climates.

Even though human influences could have serious consequences for the climate, they are physically small in relation to the climate system as a whole. For example, human additions to carbon dioxide in the atmosphere by the middle of the 21st century are expected to directly shift the atmosphere's natural greenhouse effect by only 1% to 2%. Since the climate system is highly variable on its own, that smallness sets a very high bar for confidently projecting the consequences of human influences.

A second challenge to "knowing" future climate is today's poor understanding of the oceans. The oceans, which change over decades and centuries, hold most of the climate's heat and strongly influence the atmosphere. Unfortunately, precise, comprehensive observations of the oceans are available only for the past few decades; the reliable record is still far too short to adequately understand how -->

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Scientists measure the sea level of the Ross Sea in Antarctica. National Geographic/Getty Images

But feedbacks are uncertain. They depend on the details of processes such as evaporation and the flow of radiation through clouds. They cannot be determined confidently from the basic laws of physics and chemistry, so they must be verified by precise, detailed observations that are, in many cases, not yet available.

Beyond these observational challenges are those posed by the complex computer models used to project future climate. These massive programs attempt to describe the dynamics and interactions of the various components of the Earth system—the atmosphere, the oceans, the land, the ice and the biosphere of living things. While some parts of the models rely on well-tested physical laws, other parts involve technically informed estimation. Computer modeling of complex systems is as much an art as a science.

For instance, global climate models describe the Earth on a grid that is currently limited by computer capabilities to a resolution of no finer than 60 miles. (The distance from New York City to Washington, D.C., is thus covered by only four grid cells.) But processes such as cloud formation, turbulence and rain all happen on much smaller scales. These critical processes then appear in the model only through adjustable assumptions that specify, for example, how the average cloud cover depends on a grid box's average temperature and humidity. In a given model, dozens of such assumptions must be adjusted ("tuned," in the jargon of modelers) to reproduce both current observations and imperfectly known historical records.

We often hear that there is a "scientific consensus" about climate change. But as far as the computer models go, there isn't a useful consensus at the level of detail relevant to assessing human influences. Since 1990, the United Nations Intergovernmental Panel on Climate Change, or IPCC, has periodically surveyed the state of climate science. Each successive report from that endeavor, with contributions from thousands of scientists aro und the world, has come to be seen as the definitive assessment of climate science at the time of its issue.

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There is little doubt in the scientific community that continually growing amounts of greenhouse gases in the atmosphere, due largely to carbon-dioxide emissions from the conventional use of fossil fuels, are influencing the climate. Pictured, an estuary in Patgonia. Gallery Stock

For the latest IPCC report (September 2013), its Working Group I, which focuses on physical science, uses an ensemble of some 55 different models. Although most of these models are tuned to reproduce the gross features of the Earth's climate, the marked differences in their details and projections reflect all of the limitations that I have described. For example:

• The models differ in their descriptions of the past century's global average surface temperature by more than three times the entire warming recorded during that time. Such mismatches are also present in many other basic climate factors, including rainfall, which is fundamental to the atmosphere's energy balance. As a result, the models give widely varying descriptions of the climate's inner workings. Since they disagree so markedly, no more than one of them can be right.

• Although the Earth's average surface temperature rose sharply by 0.9 degree Fahrenheit during the last quarter of the 20th century, it has increased much more slowly for the past 16 years, even as the human contribution to atmospheric carbon dioxide has risen by some 25%. This surprising fact demonstrates directly that natural influences and variability are powerful enough to counteract the present warming influence exerted by human activity.

Yet the models famously fail to capture this slowing in the temperature rise. Several dozen different explanations for this failure have been offered, with ocean variability most likely playing a major role. But the whole episode continues to highlight the limits of our modeling.

• The models roughly describe the shrinking extent of Arctic sea ice observed over the past two decades, but they fail to describe the comparable growth of Antarctic sea ice, which is now at a record high.

• The models predict that the lower atmosphere in the tropics will absorb much of the heat of the warming atmosphere. But that "hot spot" has not been confidently observed, casting doubt on our understanding of the crucial feedback of water vapor on temperature.

• Even though the human influence on climate was much smaller in the past, the models do not account for the fact that the rate of global sea-level rise 70 years ago was as large as what we observe today—about one foot per century.

• A crucial measure of our knowledge of feedbacks is climate sensitivity—that is, the warming induced by a hypothetical doubling of carbon-dioxide concentration. Today's best estimate of the sensitivity (between 2.7 degrees Fahrenheit and 8.1 degrees Fahrenheit) is no different, and no more certain, than it was 30 years ago. And this is despite an heroic research effort costing billions of dollars.

These and many other open questions are in fact described in the IPCC research reports, although a detailed and knowledgeable reading is sometimes required to discern them. They are not "minor" issues to be "cleaned up" by further research. Rather, they are deficiencies that erode confidence in the computer projections. Work to resolve these shortcomings in climate models should be among the top priorities for climate research.

Yet a public official reading only the IPCC's "Summary for Policy Makers" would gain little sense of the extent or implications of these deficiencies. These are fundamental challenges to our understanding of human impacts on the climate, and they should not be dismissed with the mantra that "climate science is settled."

While the past two decades have seen progress in climate science, the field is not yet mature enough to usefully answer the difficult and important questions being asked of it. This decidedly unsettled state highlights what should be obvious: Understanding climate, at the level of detail relevant to human influences, is a very, very difficult problem.

We can and should take steps to make climate projections more useful over time. An international commitment to a sustained global climate observatio ges over decades, it will take many years to get the data needed to confidently isolate and quantify the effects of human influences.

Policy makers and the public may wish for the comfort of certainty in their climate science. But I fear that rigidly promulgating the idea that climate science is "settled" (or is a "hoax") demeans and chills the scientific enterprise, retarding its progress in these important matters. Uncertainty is a prime mover and motivator of science and must be faced head-on. It should not be confined to hushed sidebar conversations at academic conferences.

Society's choices in the years ahead will necessarily be based on uncertain knowledge of future climates. That uncertainty need not be an excuse for inaction. There is well-justified prudence in accelerating the development of low-emissions technologies and in cost-effective energy-efficiency measures.

But climate strategies beyond such "no regrets" efforts carry costs, risks and questions of effectiveness, so nonscientific factors inevitably enter the decision. These include our tolerance for risk and the priorities that we assign to economic development, poverty reduction, environmental quality, and intergenerational and geographical equity.

Individuals and countries can legitimately disagree about these matters, so the discussion should not be about "believing" or "denying" the science. Despite the statements of numerous scientific societies, the scientific community cannot claim any special expertise in addressing issues related to humanity's deepest goals and values. The political and diplomatic spheres are best suited to debating and resolving such questions, and misrepresenting the current state of climate science does nothing to advance that effort.

Any serious discussion of the changing climate must begin by acknowledging not only the scientific certainties but also the uncertainties, especially in projecting the future. Recognizing those limits, rather than ignoring them, will lead to a more sober and ultimately more productive discussion of climate change and climate policies. To do otherwise is a great disservice to climate science itself.

Dr. Koonin was undersecretary for science in the Energy Department during President Barack Obama's first term and is currently director of the Center for Urban Science and Progress at New York University. His previous positions include professor of theoretical physics and provost at Caltech, as well as chief scientist of BP, BP -1.16 % where his work focused on renewable and low-carbon energy technologies.

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Diana Bostain profilePrivateuser

http://scienceblogs.com/gregladen/2014/09/20/bpdoes-koonin-anthropogenic-global-warming-is-real-important-and-must-be-addressed/

Arno Arrak user

I can see that dr. Koonin admitted problems with climate science that his colleagues would rather hide. The fact that they were omitted from the Summary for Policy Makers makesthat summary a fraud. I will add to this another fraud, cheating on temperature records. I have proved that GISS, NCDC, and HadCRUT showed raising global temperatures in the eighties and nineties when actually there was no warming at all for 18 years. This gives that period of no-warming the same status as the 21st century hiatus that is now well known. Proof of the existence of fake warming is in Figures 15 and 24 of my book "What Warming? Satellite view of global temperature change (2010)." Proof that all three organizations collaborated in this lies in traces of common computer processing. It takes the form of sharp upward spikes near the beginnings of years, all exaxtly in the same places. This is how a so-called "late twentieth century warming" that played a role in climate discussions at the time was made

Peter Cacioppi subscriber

"• Even though the human influence on climate was much smaller in the past, the models do not account for the fact that the rate of global sea-level rise 70 years ago was as large as what we observe today—about one foot per century."

Is there some links to this?

I'm not doubting this is accurate. But the alarmists claim the sea level rise has rapidly accelerated.

Richard Willson subscriber

@Peter Cacioppi

The alarmists are wrong according to one of the foremost specialists in this subject:

http://scienceandpublicpolicy.org/blog_watch/sea_level_is_not_rising.html

Fred Bartlett subscriber

Note to self: when pondering climate science based on uncalibrated climate models, ignore all that Navier-Stokes nonsense and seek out the opinion of the first Magic Passer you can find who spent his salad days pondering 'Marxist Studies' at some Ivy League Disneyland of subsidy, especially if he gives good speech for the cameras and is a master of the art of Political Optics.

I haven't seen Obama's college transcripts, but he has confidently told the nation that scientific debate is over on this topic. When I wonder what is it that is on his college transcripts that would lead me to believe him, that is me ignoring science. True enough: political science.

Joshua Sherwin subscriber

http://www.slate.com/articles/health_and_science/science/2014/10/the_wall_street_journal_and_steve_koonin_the_new_face_of_climate_change.html

Slav Rohlev subscriber

@Joshua Sherwin

Thanks for the link to the Slate rebuttal Joshua - it's a real gem!

After the death of Christopher Hitchens I never had reason to read Slate, and the vapid rebuttal to Koonin's essay confirms my decision.

I mean if Slate was a real printed newspaper at least it would have some value - like in an emergency when you run out of toilet paper. But as it is, in electronic format, it is COMPLETELY useless.

@Joshua Sherwin Slav Rholev has got it right! Pierrehumbert's snarky opinion piece is without support from current research, devoid of traceable published technical information and based on the same failed climate model predictions the whole CAGW cult is based on. All characteristics of current Slate publications.

Paul Alessio user

From the article: "Society's choices in the years ahead will necessarily be based on uncertain knowledge of future climates. That uncertainty need not be an excuse for inaction. There is well-justified prudence in accelerating the development of low-emissions technologies and in cost-effective energy-efficiency measures." Note that greenhouse gas emissions declined by 10% in the US over the period 2005-13 while real GDP grew 11%. So much for the argument that limiting emissions will cost the US economy.

Law Counsel user

Confident that it can, once again, breach the constitutional separation of powers and bypass Congress, this time, by recasting a complex multilateral environmental treaty as a simple executive agreement not requiring Senate approval, the Obama administration touted its climate change bona fides to the world this past week at the United Nations Climate Summit in New York.

The President crowed about how the U.S. has significantly reduced its carbon emissions since 2006, and alluded to Environmental Protection Agency (“EPA”) automobile and power plant greenhouse gas (“GHG”) emissions control regulations triggered by EPA’s controversial 2009 Clean Air Act GHG Endangerment Findings.

Apparently, the president had been misinformed about the legal soundness of those findings and the regulations they have spawned. Indeed, White House officials should have told him that many of the climate assessments cited as scientific support for such findings did not satisfy the strict scientific peer review standards imposed by the U.S. Information Quality Act (“IQA”)...

See: http://dailycaller.com/2014/09/26/climate-change-chicanery-and-the-federal-agency-academic-complex/

Kenneth llindsey subscriber

Today Russia agreed to sell Natural Gas to Ukraine for $10.90 per mcf ($385 per mcm); which is almost 3x the price in the US. As Natural Gas has less than 1/2 the carbon of coal, it is surprising that Obama has not signed the 22 pending Nat Gas export licenses so we could share our surplus Natural Gas with our friends and allies in Europe. Unless he really doesn't care about Global Warming or our Allies. Sometimes I wonder if he can be trusted.

Jon Hay user

(completing the last post) This isn't some casino game or stockmarket investment where we can afford to sit in an ivory tower and wait till we have worked out the odds precisely and calculate exactly how much to spend. Real life isn't like that. There is only one world and one climate. That in itself means we should err on the side of caution.

It's quite obvious that very steep, very sustained cuts in CO2 emissions are necessary as soon as possible and for decades to come. Then we might have a chance of still having the world we are used to in 50 years' time.

And what's the downside if it turns out global warming was a fantasy?

We will have a spanking new, clean energy system that isn't reliant on dirty old, pollution-ridden oil, gas and coal. We will have made strides in international cooperation that humanity has never made before.

Don't moan about the cost - it's only money - central banks can invent trillions just to save a few banks. Spending = GDP anyway.

@Jon Hay Jon, we simply can't abandon the rigors of science and commit economy wrecking sums until we understand the problem and tailor a solution. As we are now in year 18 of a mini - coolinging period, climate is not now changing at an exponential rate. Second, the US is leading the world in reducing carbon already by using a Mix of Renewables and Natural Gas Advanced Combined Cycle Turbines for Baseload Power needs. Significantly, the US only has 400 coal plants; but there are approximately 10,000 worldwide (most of which don't even have scrubbers), so to have any hope of reducing global carbon the fight will have to be fought in the developing world because that's where the smoke is.

MICHAEL GREENBERG subscriber

@Jon Hay "Don't moan about the cost - it's only money - central banks can invent trillions just to save a few banks. Spending = GDP anyway"

This is where your thesis fell apart.

David Bryant subscriber

@Jon Hay

"It's quite obvious that very steep, very sustained cuts in CO2 emissions are necessary as soon as possible ..."

OK, Jon. Go set fire to your car and start riding a bicycle. Disconnect your house from the electric company, and turn off your furnace. And under no circumstance whatever should you cook your food. Oh yeah -- no more plastic bags or polyester clothing for you.

There. Isn't saving the planet great fun?

@Jon Hay It's not obvious at all that 'cuts in CO2' need to be made asap. Quite the opposite, it's become quite obvious that anthropogenic GHG's are not a significant factor in climate change. The only thing a crash carbon control effort would do is wreck our economy. A corollary to that is we wouldn't be able to afford the massive cost of renewable energy development and the necessary infrastructure required to implement an all-green power system.

@MICHAEL GREENBERG @Jon Hay A big programme of investment in clean energy generation, improved power grids and energy saving technology would be a huge boost to the economy, not "economy-wrecking" as some claim. The private sector is desperate to get on with this - ask GE - if only governments would dig their heads out of the sand and set the policy framework. I.e. a hard and ever-decreasing cap on carbon emissions.

@Kenneth llindsey I'm sorry but the US is not leading the world. If the US had shown leadership, Kyoto would have been a real global deal and we would be at least 10 years ahead of where we are now. Switching from coal to gas is fine for now but gas is still a hydrocarbon. It will have to go. I agree that the difficult battle will be in the developing world but if rich countries like the US with high per capita emissions could show leadership by recognising that they need to cut per capita emissions now and fast, we might have some chance of convincing poor countries to change course.

@David Bryant @Jon Hay What you describe will be a great deal more fun than living with 6 degrees of global warming, predicted if we carry on as we are.

@Jon Hay @David Bryant

Surely you jest. In bygone geologic ages, average atmospheric temperatures ranged as high as 16 deg C (30 deg F) higher than they are today. And the concentration of atmospheric CO2 has been as high as 7000 ppm, or 1650% higher than it is today. Earth's climate today is exceptionally cool, and there's remarkably little carbon dioxide in the atmosphere. Here, look at the chart in this article.

http://www.geocraft.com/WVFossils/Carboniferous_climate.html

Even over much shorter time periods (since the last Ice Age) the concentration of atmospheric CO2 has apparently varied in a range between 200 ppm (12000 years ago) and 350 ppm (3000 years ago). Why did it vary so much when people were not burning vast quantities of fossil fuel? We just don't know.

You're asking people to accept some prophecy of gloom and doom that's based on questionable methods, deliberately doctored data, and woefully inadequate theoretical underpinnings. Why? What's in it for you?

Of course science needs to be rigorous, and models and predictions should constantly be tested and improved. That is what the world scientific community is already doing, and the best summary of their thinking is the IPCC reports. And what the scientists say, all caveats noted, is that we should be very worried.

You really don't need a PhD to tell what is going on. The earth is already warming fast. Yes the climate fluctuates naturally, but this is much faster.

And that's with CO2 at the level we have now. If we could keep CO2 in the atmosphere at the present concentration (400 parts per million), it would therefore still go on warming. And that means the effects already under way (ice melting, permafrost melting and releasing methane, itself a powerful greenhouse gas) would continue.

But it's much worse than that - we are pumping more CO2 into the atmosphere every year, so that concentration is constantly rising.

And emissions are actually accelerating.

@Jon Hay The climate hasn't warmed for a decade and a half while CO2 continues to accumulate. CAGW is at best a minor climate effect and the climate models that predict otherwise are simply wrong. Natural forces are and always have been the dominant forcing of climate variability.

Terry Chapman subscriber

@Jon Hay Mass Psychological Illness

The New Religion of the Left

Ed Barry subscriber

Read the Hockey Stick Illusion to see how it works.

What is settled is who are getting the billions...liberal group thinkers. What is settled the liberal group thinkers will lie till they are blue in the face to get as much money as possible. This is about money not science...pure and simple. I worked on a grassroots effort to prevent industrial wind turbines from a national park....this is about MONEY! Everything else is spin. I see it in "environmental group" after environmental group....they want the money and will use any means to get it. This is a shameful time for most environmental groups. What I have seen from the Audubon Society concerning wind energy...is a BLACK MARK of cover-ups and pay-offs to get wind turbines built! The sad thing for much less money they could lower CO2 in a much less impactful way. Just look at the billions in industrial equipment scarring the land from "renewables"...that kill millions of animals. The State Mass. has produced no study of how many animals killed by their wind turbines LIE & HIDE!

RIK MYSLEWSKI user

@Ed Barry My, what an astonishingly ill-informed post, sir. Those "billions" to which you refer are being sucked up by a fossil-fuel industry that's desperately trying to sow doubt and confusion among those who haven't read the science, who don't understand risk management, or know that we are in deep doo-doo. (Would WSJ's filters would reject my comment if I used the more earthier term? Dunno...)

Speaking of the fossil-fuel industry, did you notice at the end of Steven Koonin's op-ed that he's identified as BP's former chief scientist? No conflict there, eh? I'd love to see his portfolio...

However, Mr. Barry, I do find myself in complete agreement with one of your statements: "This is about money not science...pure and simple." Yes it is, sir, yes it is...

Isn't everything during these anti-regulation, "Hell with you Jack, I got mine" days? And that money is trickling weakly to science while gushing to the fossil fuel industry, not only in profits, but also in government subsidies.

michael grottola subscriber

The reasoning by Dr. Koonin is akin to a defense attorney attempting to raise the slightest doubt to discredit a testimony. His "maybe's" and "could be's" stand in stark contrast to the weight of measured results and scientific (not political) conclusions.

Tom O'Hare subscriber

Pollution is bad and should be minimized as much as possible in the coming years.

Climate change is a moot point and has simply given concern for the environment a bad rap.

WILLIAM CURTIS subscriber

The fact that each molecule of CO2 in the atmosphere will redirect roughly 50% of outbound radiation it absorbs back to the earth is simple well known physics. Since more IR leaves the earth than comes in from the sun, this is a net increase in IR energy, just like turning on an infrared lamp. What is complex is where this additional heat will go and what will it do when it gets there. The author has data paralysis. If there is a natural cause of global heating or cooling he needs do the science and quantify it for us; in the meantime we need to tame the dragon we know. I don't like it but I don't like death or taxes either!

@WILLIAM CURTIS

(Cont.) It's not just CO2, either. It's also water vapor, and oxygen, and nitrogen, and argon, and trace gases like ethane and methane. (Did you know that oxygen is a greenhouse gas?) There's also the fact that natural processes (like plant respiration) will remove some of the CO2 from the air. And the inbound flux of solar radiation isn't exactly a constant. And the Earth's albedo can vary quite a lot -- less sunlight gets to the ground on a cloudy day. Even on a clear day, if the ground is covered with snow it will reflect a lot of energy (at visible wavelengths, not in the infrared) back into space. And the infrared radiation from Earth doesn't quite follow a perfect black-body curve.

The author doesn't have "data paralysis". He's smart enough to understand that this is a very difficult problem -- probably too tough for humans ever to work out in detail on a theoretical basis.

Just because a physicist can write an equation doesn't mean that it can be solved.

"The fact that each molecule of CO2 in the atmosphere will redirect roughly 50% of outbound radiation it absorbs back to the earth is simple well known physics."

Well, it depends on how roughly we're talking. If the molecule is close to the ground, it's 50%. If it's 3 miles up in the air, it's (roughly) 48.8%. If it's 10 miles up, it's 47.8%. If it's away on up in the ionosphere, say 50 miles off the ground, it's about 45%. 50% is the most it can be, if the re-radiation is isotropic.

The point is, it's really not all that simple.

"... he needs do the science and quantify it for us ..."

He needs to do the science? Why not you? After all, it's simple, right?

I don't think you've wrapped your head around a lot of complicating factors, William. Yeah, CO2 absorbs some infrared radiation -- at a couple of wavelengths. Does it capture 0.05% of the radiation flux? 0.001%? What's the cross-section for the quantum interaction between the radiation and the molecule?

@David Bryant @WILLIAM CURTIS

Not much of anything 50 miles up, so "about 50%" is a pretty good figure, if you want to pick nits, call it 48%. The emissions are random (i.e. isotropic). You are making the same mistake as the author, raising question that neither you, nor he, nor I can answer. That is the job of the IPCC, and I am sure they have, & they conclude there is a major problem. The point is, there is a solid set of physics that CO2 causes global heating, There is no reasonable evidence for a mechanism that will counteract it. Therefore the sensible thing to do is take steps to protect ourselves from a KNOWN threat until or unless some of you naysayers provide proof of that counteracting mechanism. Burying oneself in minutiae as you and the author are doing is a waste of everyone's time, including mine. I am no liberal and am concerned about the cost, but I'm not willing to wait until every possible question is answered before taking actgion.

Bryant, after reading the last half of your post I find you are dumber than I had given you credit for. I thought you had somewhat of a science background, but apparently you have learned a few scientific words and use them randomly. Symmetric gases, such as O₂, N₂, and Ar neither absorb or emit infrared radiation and are not contributors. Water vapor is the worst offender, but we cannot do without water! That leaves CO₂, methane, ozone, and a few others that, fortunately, do not occur in any abundance.

The fact that water vapor also is a greenhouse gas means that as CO2 increases global temperatures, it will increase the amount of water vapor in the air. (if you don't understand this phenomenon, read about relative humidity, vapor pressure & the like) You need to stay out of these discussions until you learn something.

@Vilhelm Bjerknes @WILLIAM CURTIS

I am not willing to bet the house on climate doves. Your statement that skeptics have verified better needs to be challenged-where is that verification? remember we are looking at a "heating" effect, not a "warming" effect. Heat can be absorbed in many places without having much effect on temperature - Ice to water and water to vapor are two big ones. Since ice is very reflective and water vapor is a strong greenhouse gas, loss of the former and increase of the latter will exacerbate the problem. Keep in mind also, that even if we stopped increasing GH gasses right now, the planet would continue to heat up until a new steady state condition (heat outbound=heat inbound)is achieved - this takes years. I am not ready to gamble on speculation. I am no liberal and I am concerned about the cost. Nuclear energy is the best short term answer, it is already the second largest source of reduced CO2 after hydroelectric. and 3 times as effective as renewables

Vilhelm Bjerknes subscriber

Lots of plots (link below) showing forecast vs observed. I don't know of any climate models that have EVER underforecast the warming. They have all busted too high. I think the models are valuable, but their track record is one of substantial directional bias. I'm not willing to bet our future on forecasts that have proven biased and with marginal skill and contradicted by solar models.

Also, with the logarithmic response of CO2 to temperature, cutting emissions will have almost no affect at phenomenal cost. This is difficult to dispute. With 1% of global energy coming from wind and solar, I'm not sure where the power will come from.

So, what to do? The forecast cannot be relied upon and cutting emissions enough to make a difference is implausible.

The good news is that the last 20 years have given us a remarkably stable climate. So "do nothing" seems like a really smart choice at this point.

www.flickr.com/photos/125630565@N05/sets/72157645113383959/

@Vilhelm Bjerknes @WILLIAM CURTIS Interesting points, thanks. If we could summarize the debate it seems that there are concerns about ACGW, but proving correlation to the complex global climate system has proved elusive even after 30 years. Assuming that runaway carbon may become a problem, and rejecting catastrophic measures, the best available solution for the next ten years is to promote a mix of 1) Renewables (which are still expensive but falling in price) and for Baseload: 2) Natural Gas (using the New Advanced Combined Cycle Natural Gas Turbines). This system is being adopted in many communities in the US and is both reducing pollution and lowering energy costs, since Advanced Combined Cycle Nat Gas Turbines are the cheapest energy source according to the EIA.

1. The IPCC is a UN wealth redistribution operation whose propaganda has little to do with science.

2. CO2 can cause global warming since it is a GHG but its effect is minor compared to natural climate change forcings.

3. It is much more prudent to require that the claims of significant CO2 warming are true before we implement economy-killing measures like banning or greatly reducing use of fossil fuels.

4. You're the one buried in minutiae and dazzled by the propaganda of the CAGW alarmists.

@WILLIAM CURTIS Lots of people are doing the science and getting many different results when they quantify it. Almost all scientists agree a doubling of CO2 will yield ~ 1.1 deg K rise in temp... but then the feedbacks kick in. Feedbacks are the primary area of dispute. Climate Hawks argue a 3x feedback will lead to likely catastrophes. Climate Doves argue a 0.5x dampening feedback will make CO2 induced climate change a minor event. Although I'm an atmospheric scientist, I'm not sure who is right or what will happen. What I do know is that so far, the skeptics have verified better in the real world and the science is clearly "not settled". The uncertainty does not warrant betting trillions of dollars on what may not be a problem.

Besides, lots of peer reviewed solar guys are making arguments that solar induced cooling is coming. Cooling scares me a lot more.

1. Heating and warming are different terms for the same thing.

2. The distinction you mistakenly make is when heating causes a change of state instead of a significant temperature change.

3. The planet might also cool down due to the dominant natural forces of climate change. The past decade and a half are good testament to that. In fact the recent cooling occurred with increasing CO2 which invalidates the CAGW hypothesis and models.

@WILLIAM CURTIS You've got that 'bass ackwards'. Increasing global temperatures cause increasing Water Vapor and CO2. This has been demonstrated conclusively in the Antarctic ice cores going back at least a half million years.

@Richard Willson @WILLIAM CURTIS

Richard, apparently you don't understand - as the temperature of the oceans increase due to CO2 emissions, it will increase the amount of water vapor in the air, which is itself a GHG, so you have a self reinforcing effect. I am not sure why you can't understand this, in fact your first sentence says that. ???

@Kenneth llindsey @Vilhelm Bjerknes @WILLIAM CURTIS

Ken, I agree with you, and with so much riding on the outcome, prudence is better than waiting to see if the train wreck really occurs. I am afraid that some countries i.e. China and India, will have to suffer some real problems before they take significant measures. We need to do what we can without bankrupting the world. I think that nuclear energy should be part of this, so far it reduces CO2 by three times as much world wide as all installed renewables. (Economist magazine sep 20 2014 - pg 21-23,a good read.) Fracking for natural gas is also good. I have my doubts about coal carbon capture, If we pump all that stuff underground for 50 years then it starts leaking out, we will be screwed.

Well, oxygen and nitrogen do not absorb very strongly in the infrared. But they do in fact help keep Earth warm, because of their abundance. If there were no nitrogen in the atmosphere, for instance, and atmospheric pressure were only say 3 psi at sea level, our "weather" would be much more like the moon's -- 200 degrees F or hotter in the daytime, and 100 below or so in the middle of the night.

Think of it this way -- the bulk of the atmosphere does not absorb strongly in the infrared. But the thermal energy absorbed by say a methane molecule is much more likely to be transferred to a nitrogen molecule (by a collision) than it is to be re-radiated. Even though only a few trace gases (mainly water vapor) absorb the infrared radiation from the ground, that heat energy is mostly transferred to the abundant diatomic gases, which do not tend to lose their thermal energy by radiation. In other words, nitrogen is the thermal blanket that keeps us warm at night.

That's good, William. When confronted with facts, you respond by calling people names. How mature you are.

I'm not a physics troll. I'm a mathematician, and a statistician. I did study physics and chemistry as an undergraduate at Caltech; I made straight As. Forty years ago I lived just a few rooms away from Steve Koonin, who wrote this article. Steve is a brilliant guy. He was studying the theory of black holes under Kip Thorne when he was just 19 years old (1971).

Yeah, I understand that water vapor absorbs (and emits) infrared radiation. You are overlooking the fact that there are three different modes of heat transfer: radiation, conduction, and convection. The heat energy absorbed by say a molecule of H2O (a vibrational quantum) can leave that molecule in different ways. It may emit a photon (re-radiation). Or it may bump into another molecule (say N2) and transfer energy to it (conduction). If it warms molecules nearby, it may cause heat transfer by convection.

David Taylor subscriber

Dr. Koonan didn't mention the most important fact regarding climate change. The earth fell into a brutal ice age regime approximately 100,000 years ago.That regime persisted for approximately 90,000 when the earth quickly (in geological terms) warmed. This cycle of 100,000 year ice age followed by 10,000 year inter glacial has persisted for many cycles. To my knowledge, not a single model has hind casted the ice age or the inter glacial. I would say a mile deep ice sheet over Detroit is a gross change and I would expect any model to comprehend it. Until we understand why we experience these glacial epochs and know at least approximately when we should expect the next one, we should put these models on ice and stop worrying about global warming. Mankind will survive global warming with minor stress. The same cannot be said of severe global cooling.

@David Taylor The glacial periods on time scale of 10,000 years can be forecast fairly easily with Milankoich variables. The CO2 threat is on a much shorter time frame... more like 50-100 years.

@David Taylor David - check out 'Milankovitch' cycles to get the skinny on the ice ages and interglacial periods. A good start:

http://www.sciencemag.org/content/194/4270/1121

RICHARD PRATT subscriber

"Climate Science Is Not Settled". Quite true and also quite irrelevant because the climate change religious dogma is totally settled, and, like most religious fanatics, not one of its adherents is willing to be bothered by facts to the contrary.

David Jones user

What a pleasure to read a thorough, fact based exposition on this politically charged issue for a change.

@David Jones facts....you mean guesses that change as each is exposed. This is about money...how many leftists scientists have seen their coffers fill regardless of their merit. Group Thinker gets money...actual scientists...not needed. The games they play to say the warmed 2.5 degrees in the last 100 years....are unseemly. They know the answer and work back from that. Please tell us how a hundreds years from now they will know that the Antarctica is 8% bigger than 30 years ago? They manipulate even the satellite data...to get what they want. Heck they just recalculated the formula for cooling degree days to make it look worse.

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