Study: CO2 may not warm the planet as much as thought

New Scientist ^ | 11/25/2011 | by Michael Marshall

[SeekAndFind]

The climate may be less sensitive to carbon dioxide than we thought – and temperature rises this century could be smaller than expected. That's the surprise result of a new analysis of the last ice age. However, the finding comes from considering just one climate model, and unless it can be replicated using other models, researchers are dubious that it is genuine.

As more greenhouse gases enter the atmosphere, more heat is trapped and temperatures go up – but by how much? The best estimates say that if the amount of carbon dioxide in the atmosphere doubles, temperatures will rise by 3 °C. This is the "climate sensitivity".

But the 3 °C figure is only an estimate. In 2007, the Intergovernmental Panel on Climate Change (IPCC) said the climate sensitivity could be anywhere between 2 and 4.5 °C. That means the temperature rise from a given release of carbon dioxide is still uncertain.

There have been several attempts to pin down the sensitivity. The latest comes from Andreas Schmittner of Oregon State University, Corvallis, and colleagues, who took a closer look at the Last Glacial Maximum around 20,000 years ago, when the last ice age was at its height.

They used previously published data to put together a detailed global map of surface temperatures. This showed that the planet was, on average, 2.2 °C cooler than today. We already know from ice cores that greenhouse gas levels in the atmosphere at the time were much lower than they are now.

Schmittner plugged the atmospheric greenhouse gas concentrations that existed during the Last Glacial Maximum into a climate model and tried to recreate the global temperature patterns. He found that he had to assume a relatively small climate sensitivity of 2.4 °C if the model was to give the best fit.

[mc5cents]

All I can add to that headline is: No sh!t Sherlock.

[steelyourfaith]

 

Beam me to Planet Gore !

[LibWhacker]

Thought can warm the planet more than carbon dioxide?

(sorry, couldn't resist)

[Right Wing Assault]

The climate may be less sensitive to carbon dioxide than we thought

What is the "WE" stuff?

[SpaceBar]

Climategate II damage control.

[mike_9958]

“All I can add to that headline is: No sh!t Sherlock.”

Perfect.....

[dennisw]

Water vapor is a larger greenhouse factor than CO2

[CedarDave]

The “New Scientist” is a left-leaning eco-friendly publication. For them to admit even a bit that CO2 is not this generation’s chicken-little pollutant shows progress in having the truth reach a closed-mind audience. At some point they will have to conclude that they have bet on the wrong science and will have to admit that AGW skeptics were correct.

[USFRIENDINVICTORIA]

“However, the finding comes from considering just one climate model, and unless it can be replicated using other models, researchers are dubious that it is genuine.”

Right ... running a computer model is the same as doing an experiment in the real world. Models can't be tweaked. Models are infallible — provided that two or more models produce the same answer. < /delusional warmist ravings

[proxy_user]

“Thought can warm the planet more than carbon dioxide?”

Yes, but scientists still find there is very little warming. Hmmm....

[South40]

Are you telling me this was a lie?

[BobP]

I'm off to light the charcoal grill and open a chilled carbonated beer from my 1970's frig right now.

Choke on that Algore!

[ROCKLOBSTER]

You don’t need a stupid study.

There is virtually NO CO2 in the atmosphere.

[USFRIENDINVICTORIA]

Lone Ranger: The climate may be less sensitive to carbon dioxide than we thought.

Tonto: What you mean "we", delusional paranoid warmist?

[hinckley buzzard]

At some point they will have to conclude that they have bet on the wrong science and will have to admit that AGW skeptics were correct.

They will never admit that. When the time comes, and they can no longer hold the fort, they will simply stuff the whole issue down the memory hole and, like the mad hatter's teaparty, just move on to the next place where they can create a whole new mess out of nothing.

[E. Pluribus Unum]

However, the finding comes from considering just one climate model, and unless it can be replicated using other models, researchers are dubious that it is genuine.

Hell, their computer models can't even predict today's climate, but any model that disagrees with theirs has to be held to an infinitely higher standard.

[aruanan]

Oh, these poor boobs. There's a ~60 year cycle, believed to be astronomical in origin, that accounts for nearly all the warming between 1970 and 2000. The increase in CO2 since the beginning of the Industrial Revolution was triggered by the warming of the Medieval Climate Optimum.

[rlmorel]

Yep. Just as they did with global cooling back in the Seventies...

[marktwain]

The best estimates say that if the amount of carbon dioxide in the atmosphere doubles, temperatures will rise by 3 °C. This is the "climate sensitivity".

My understanding is that the "climate sensitivity" refers to how much of a positive feedback they are assuming in the system. That is, they assume that adding some CO2 increases the amount of moisture which increases the temperature.

A number of researchers believe that the effect is exactly the opposite, that increasing the CO2 increases moisture which increases clouds, thus decreasing warming, that is, a negative feedback effect. Those researchers say this is much more likely, because we do not see small increases in CO2 causing a rapid acceleration in heating, which is what would happen with a positive feedback system.

It is my understanding that all the models the "climate change" crowd depend on have this positive feedback mechanism built into them. It is the only way they can produce the warming effects that they desire.

I have simplified things a good bit for brevity, but the essence is correct, I believe.