The greenhouse hypothesis is just that: a yet to be validated hypothesis or postulation. GCMs (computer climate models) do not validate a hypothesis. It takes physically observed hard data to validate the greenhouse hypothesis, and this is lacking today.

The greenhouse hypothesis, in and of itself, is that gases in the atmosphere trap infrared radiation and thereby heat the planet. That planet could be Venus or Mercury. Wonder why Mercury is cooler than Venus? Check the hard data.

Wonder why Earth isn't an ice ball? Check the hard data.

What would convince you?

We only get to run this experiment once, and I believe the basic and advanced science is sound. Of course not every answer is known yet. Science never knows every answer, never claims to.

You doubt that temperatures have increased? You doubt that greenhouse gases trap heat? You doubt that we're pumping them out? You think it's OK to just be complacent?

You doubt that this is an issue of national security?

Heads buried deeply in the sand, you run us to ruin.

Seriously, what would convince you?

NONE of the global climate models idolized by the IPCC and Hansen correctly forecast the cooling trend of the last ten years:

http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/monthly.png

And of course, the NASA GISS (Hansen's group) is the only one to show the least amount of cooling.

The fact that the European met agencies are showing this cooling could account for the surprising recent poll from the UK:

http://www.guardian.co.uk/environment/2008/jun/22/climatechange.carbonemissions

I'm looking forward to the day when the alarmists run out of batteries on this issue.

See the review of Freeman Dyson in the New York Review of Books, Volume 55, Number 10 · June 12, 2008.

http://www.nybooks.com/articles/21494

Dyson reviews, "A Question of Balance: Weighing the Options on Global Warming Policies" by William Nordhaus, an economist who compares several climate change policies using a model called DICE (Dynamic Integrated Model of Climate and the Economy). The optimal policy "...judged by Nordhaus to be the most cost-effective, with a worldwide tax on carbon emissions adjusted each year to give the maximum aggregate economic gain [3 trillion USD by 2100]."

The optimal policy, according to the DICE model, is contrasted with doing nothing, with a cost in environmental damage of $23 trillion; following the Kyoto Protocol will net $1 trillion with US participation and $0 otherwise; the Gore policy has a cost of $21 trillion. See the article for the rest.

You don't have to be a climate change naysayer to take issue with some of the economic proposals being offered.

The author presents the position of the radical eco-left, which will require a complete restructuring of society and the magical development of new technologies to replace existing ones. One should not be surprised. Googl'ing the author one discovers his career has been that of a Global Warming advocate.

I'm one of silly voters in the vast middle. I'm waiting for the believers on both sides, left and right, to actually debate the science behind their positions. Today all I see are political declarations of being "right" or "correct". The science has been taken over by the politically correct on both sides.

I am an independent politically and I would like to understand something regarding climate change. How is it that if the U.S. unilaterally implements draconian legislation to cut CO2 emissions that we alone will end climate change world wide (and most likely in the process destroy our economy to the wonderment and joy of much of the rest of the world)?

I have heard about the U.S. using 25% of the world's energy and only having 3% of the world's population. But as I understand it we also produce 30% of the world's GNP. Sounds like a nice trade off (I can't help but wonder what other country is as efficient in their use of energy). Particularly impressive since we are one of the most generous countries in the world. And I would suggest that our citizens are by and large quite well taken care of by any standard that one wishes to measure.

All considered, shouldn't we be equally concerned about Brazil, China, Russia, India, etc., etc., et al., or do they get a free pass and if so how do we "change" the world climate on our own.

For the sake of brevity and without picking your entire piece apart I might suggest that you look further into the ice that isn't melting in Greenland and the fact that if you look it up the Antarctic ice shelves are at their greatest extent since humans have been recording that information.

I would recommend that your readers look up the NIPCC report and the Hirsch Report for a little more enlightenment and maybe see what Bjorn Lindborgh has to say about all of this.

Climate change is undoubtedly occurring. What is questionable is this mad dash to eliminate it when we know so little about the entirety of what is causing it and what the outcome may be. When someone tells me that the debate is over and the science is done, I can't help but wonder what lurks beneath all of it.

P.S. Almost without error none of the Kyoto signing countries are meeting their goals. Help me understand so I can jump on the climate chnge (formerly a few months ago "Global Warming")wagon.

Thank You.

There are far too many aspects of Mr. Romm's post that are nonsensical. A few:

1) "Must be stopped" --- so people who disagree with HIM should be shut up, transparently by threat of force? Join Nero, Stalin, et al. Guess the 1st Amendment only counts when it is speech you like?

Like Mr. Krauthammer, a very thoughtful and well informed man whom you casually disparage, I am an agnostic regarding anthropogenic global warming. Thoughtful, well-meaning people can disagree. You're welcome to your own opinions, but if you wish to impugn the morals of those who don't share them you might reconsider.

Though Liberals like to toss around the term "warming denier" to put something predicted (by models) to happen in the future in a bucket with documented events of the past, many prominent and respected scientists are in the agnostic category. Not too many that make their money predicting global warming, unsurprisingly. I trust Freeman Dyson's evaluation of the science better than theirs and yours, however.

2) How many primary sources on global warming have YOU read? I've read a lot and seen some that are cogent and others that are ridiculous. Many openly state that models were built to fit recent climate history. That is known as "curve fitting" and statistically trivial; if you want to invest money on that basis I have some good stocks for you. Don't invest trillions of dollars of other people's money by force, however.

3) When the IPCC and others claim "95%" or "75%" confidence in a particular assertion they are simply making numbers up. How can they even pretend to assert levels of confidence when the essence of the uncertainty is factors not considered in their models, or parameters that they are estimating. US GDP growth is regularly revised, retroactively, and they have the arrogance to assert that models predicting the influence of carbon dioxide on cloud formation, indirectly, with many feedback loops, using dozens of parameters, are unquestionable? They are using the language of statistical significance utterly inappropriately. The real world is messy.

4) Please don't pretend that putting the brakes on a complete reworking of our economic system just happens to be politically convenient for greedy conscience-less conservatives, while Noble Liberals are just calling it by the science, sacrificing themselves for The Children.

"Global Warming" just happens to exactly match the Liberal agenda to a tee: a massive tranfer of economic control to government, with trillion dollars in disguised taxes to give to "deserving causes". Conservatives pre-judged the science as well, but let's not pretend that Liberals are simply disinterested.

5) Let's also remember that we're talking about models built by glorified weathermen. They can't predict tomorrow's weather competently. Are you really so sure that they've got it right 50 years from now?

Recent IPCC reports casually report that they missed a significant aspect of ocean circulation in their models, so there might be cooling for the next 10-20 years...but the warming will catch up eventually. To my mind this puts the thesis in the category of "not even wrong". If an hypothesis can't be disproven, it isn't science. And remember that this is now big business for the glorified weathermen -- why do you trust them more than Exxon?

At the essence Mr. Romm is implying that he knows the truth, and anyone else should be forced to shut up. Is that really what liberalism stands for?