Might the climate be far more sensitive to increasing CO2 than we currently think?

Question

Global warming 'skeptics' made a pretty big deal of the Schwartz study which concluded that the climate may be less sensitive to increases in CO2 than most scientists believe (he concludes a 1.1 +/- 0.5°C increase from a doubling of CO2). However, this was a rather oversimplified and flawed model.

http://www.realclimate.org/index.php/archives/2007/09/climate-insensitivity/

Most studies put the sensitivity around a 3°C increase for a doubling of CO2.

http://members.aol.com/bpl1960/ClimateSensitivity.html

However, a new study led by James Hansen has concluded that the climate may be more sensitive than we think - around a 6°C warming for CO2 doubling.

http://www.realclimate.org/index.php/archives/2008/04/target-co2/

"The standard definition...assumes the land surface, ice sheets and atmospheric composition...stay the same. Hansen's long term sensitivity...allows all of these to vary and feed back on the temperature response."

Read the link and give your thoughts.

Answer 1

yah...global climate change is getting dangerous...will get scary

Answer 2

global warming is a fade....it was global cooling in the 70's!  FYI water vapor is twice as strong as CO2 as a greenhouse gas AND it is present at concentrations ~200 x's that CO2. I have access to all the real scientific papers and none of them provide convincing evidence that a 30% increase in CO2 is causing global warming. Also, it is fun to find out how some researchers calculate global temperature....by thermometers in CITIES. Read up on the heat-island effect and you will see the conection:

http://www.epa.gov/hiri/

This is a natural cycle. Don't get me wrong, burning fossil fuels is bad because of the pollution.

Answer 3

My opinion is that we (meaning the general population) don't know enough about the complexities of global warming/climate change to be debating it as fiercely as we are.  Some of the views expressed here are so simplistic as to border on absurdity; others are more reality based but too often scientifically unqualified people reach conclusions that omit relevant facts.  I am speaking primarily of the people who deny global warming rather than those who do not, but there is a lot of misinformation, shallow understanding, and misinterpetation of the studies and data related to the phenomenon on both sides.  I would certainly put myself in the category of having only a moderate knowledge at best of what is going on with our climate and the causes.

One thing that is striking to me though, is the comparisons with past climactic changes here on earth and events on other planets in the solar system.  And you know, there are those who compare mankind's activities with a single vocanic eruption-or even flatulent bovines.  This disturbs me because it seems to indicate a fundamental inability to grasp the situation, that being that mankind's contribution to natural events could easily be the 'tipping point' that pushes us over the edge of catastrophic alterations in the weather.

I recently watched a National Geographic program called 'Global Warning' and found it very interesting.  Granted, a National Geographic television show is no means what we would describe as 'peer reviewed,' haw.  But your point about temperature sensitivity to CO2 in the atmosphere is very relevant to the point of the program.  For one example, beneath the ocean floor are very large deposits of frozen methane, kept comatose by cold sea temperatures and pressure.  The atmosphere, according to this program, is 29 times more sensitive to methane than CO2.  Research has indicated that an average global increase of 9 degrees would tip the balance and release this stored methane into the atmosphere, resulting in a rapid and large increase in temperatures.

So the point is that if mankind's activities do indeed affect global warming, we don't have to outdo a volcano or all the farting cows on the planet, all we have to do is contribute enough to tip the balance-in this example and based on your information about sensitivity, even if natural causes are responsible for increasing temperatures-and would cause an increase in global temperature of, say six degrees...and humans are responsible to an additional three degrees by virtue of doubling CO2 levels in the atmosphere,  all that methane could be released and there ya go.

Now obviously, this is only a small part of the equation and is vastly simplified in order to illustrate the principles in play that I don't think the general population is contemplating...but we should really think about it.  I mean, what if the sensitivity to CO2 doubling is indeed twice the 3 degrees of most studies?  How much have global temperatures already increased in the last century...and how close could we really be to that nine degree threshold that would release tons and tons of a very powerful greenhouse gas into the atmosphere if we are responsible for doubling the amount of CO2 into the atmosphere and the six degree increase as a result is really accurate?  I'd be interested in studying and learning more about the various factors in play and how humans might be affecting the outcome.

Answer 4

First off, I notice you post a propagandize piece on the theory.  I for one am not interested in reading someone else of a leftist political persuasion trying to debunk someone's theory.  It would be more informative to let Schwartz tell it. Second, I don't think you are qualified to judge his theory as flawed.  I suspect you are a lawyer and not a scientist.  Third, Hansen has been shown to be a polical opportunist who is about the most biased source you could find.  I think it is Hansen who conveniently manipulates the other variables to come up with the conclusions he was looking for.  It is more of a demonstration of the falibility of climate models than anything definitive one way or the other.

I read JS post later.  He pretends that Hansen is a conservative.  The link he provided sure doesn't add up to that.  Why is it that liberals (it used to be a good word but no more) will never admit to be liberal.   I am as liberal as is prudent.  Perhaps they consider themselves as conservative as possible.  The problem is compared to me, they are flaming leftists.

Answer 5

It's definitely possible.

Answer 6

Absolutely, a lot more healthy than we could have ever imagined.

More CO2, even more plant life, more oxygen, cooler temps, healthier planet, healthier animal life, more CO2, even more plant life, more oxygen, healthier planet, healthier animal life , more CO2, even more plant life, More oxygen, healthy planet, healthy animals, CO2, healthy plants, healthy animals, healthy planet, CO2, plants, O2, animals, CO2, plants, O2, animals, living planetary system.

Need I go on or do you think you are bright enough to do some linking to finally see the natural cycle of our planet.

Can you visualise this simple feedback loop we have plenty of evidence this has been happening since life began. So far you have no proof, only inaccurate models that haven't been able to predict precise data about the earths climate.

Give up and rethink your position when you have reliable models that actually predict events and then can be proven to be right until then all you really have are guesses that don't match reality yet.

Answer 7

If his theory is correct, it is not enough that every decade should warm.  Every decade should warm at a faster rate than the previous.  We are not seeing that.

I will not even comment that the empirical evidence coming out from the satellite data shows water vapour is not as sensitive to co2 as the models show.

Answer 8

Be careful to accurately represent Schwartz's work.  It was primarily about the possible mitigating, cooling effect of aerosol pollutants, not at all a direct criticism of CO2's heating potential.  Schwartz's theory explains possible mitigation of C02's effects in the past, but carrying that into the future assumes and requires exponential growth of anthropogenic aerosol pollution, which is a gross and dangerous oversimplification.

For example, if transportation and coal power plant emissions are cut while other CO2 impacts continue (deforestation for example, plus reduced natural sequestering or even outgassing from a warming ocean), aerosol influence could go down quickly while the relative strength of CO2 forcing would go up.  Aerosols also remain in the air for a short time, so continued mitigation of the CO2 in the air already, continued aerosol pollution, must continue for centuries (without adding more CO2 that must also be offset).  Schwartz's scenario is a house of cards that surely can't continue without intentional aerosol pollution, which will lead to other serious harmful side effects (acid rain and ocean acidification, etc).

So in effect both scientists could be right, Schwartz about past or current observations, Hansen about future trends in the relative strength of CO2's share of the forcing.  We need a scenario-based approach such as Hansen's to best understand the potential outcomes and be able to choose the ones with the least long term damage and costs.

It's also important to note that as two of the worlds leading experts on climate, Schwartz and Hansen are in violent agreement that extremely urgent action is needed:

http://www.ecd.bnl.gov/news/NationalPost...

Stephen Schwartz knows as much about the effects of aerosols on climate change as anyone in the world, and he's worried. He believes climate change is so massive an economic issue that we face costs "in the trillions if not quadrillions of dollars." He thinks a Herculean effort and great sacrifice is required to get the world down to zero net increase in carbon dioxide concentrations, an effort he compares to that which the Allies undertook in their all-out war against n**i Germany and Japan.

"Recall World War II, where everyone was making a sacrifice: gas rationing, tire rationing, no new car production, food rationing," he explains. "I don't think the people of the world are ready or prepared to make such a level of personal sacrifice. Perhaps when the consequences of climate change become more apparent that will change. But by that time, there will be irreversible changes in climate."

http://www.ecd.bnl.gov/news/NorthShoreSu...

"I'm very concerned about the world my grandchildren will live in," said Mr. Schwartz, who is currently studying climate change. "There could be an increase of four to eight degrees in the next century, and that's huge. The last time there was a five-degree Celsius decrease was the last ice age. An increase of eight degrees Fahrenheit would bring change unprecedented in the last half-million years."

Edits:   ----------------------------------------...

Mt. Zion:  You're absolutely wrong.  The current warming is not similar to past natural warming (such as 1000 years ago), it's 42X faster than the average for the last 5000-10,000 years.

http://www.alertnet.org/thenews/newsdesk...

The Medieval Warm Period, for example, was extremely harmful to many cultures globally:

http://answers.yahoo.com/question/index;...

Jim Z.:  James Hansen is a conservative (as am I).  You cheapen the discussion and lose your credibility when you misrepresent facts and make the wild leap to the entirely unsupported claim that this is a politial issue.

http://www.columbia.edu/~jeh1/polinclin....

cookie:  A better world due to increased CO2 is wishful thinking, but not supported by the evidence:

http://www.killerinourmidst.com/methane%...

"Contrary to previous projections," the authors note, "[climate warming] (which they attribute to human activity) is likely to be the greatest threat in many if not most regions." The study did not examine the "historically unprecedented" carbon dioxide levels with which organisms will have to contend, or interactions between climate change and other ecological threats, which the authors indicate are likely to be even more severe than climate change in isolation (Thomas, 2004). The message of this study is simple: climate change kills -- and kills extraordinary numbers of living things -- even when it is minor.

During some past warmings, the majority of all life on the planet died:

http://en.wikipedia.org/wiki/Permian-Tri...

Climate simulation of the latest Permian: Implications for

mass extinction

http://www.cgd.ucar.edu/ccr/aboutus/staf...

indianaflywheels: You mean the attack on Mann's "hockey stick" graph by Exxon-funded Frasier Institute senior fellow Ross McKitrick and oil industry consultant Stephen McIntyre?  Look up McIntyre and "CGX Energy".  

The oil industry attacks on climate expert Mann notwithstanding, the dramatic uptick in warming is still clearly shown in other records:

http://www.realclimate.org/index.php?p=1...

"Indeed, the reconstruction of temperature from glacier data is notable for having a rather distinctive "hockey stick" shape, the aspect of the original Mann, Bradley & Hughes reconstruction that seems to attract the most attention and criticism. This poses a substantial challenge to those who have dismissed the “hockey stick” as due to biases or errors."

Note also the recent determination of current glacier melt rates at 42X historical levels (link above).

It gets downright boring seeing the same misrepresentations and character assasinations trotted out daily as if they counteract hard science.

Answer 9

No it most definitely is not, because if you attribute any of the temperature increase over the last 150 years to CO2, you only get a 1.0 C increase for a little over 100 PPM. And there are many papers than can attribute at least 50% of that temperature increase to changes in a long term increase in TSI. So that only leaves you 0.5 C at the most assocaiated with CO2. The next 100 PPM will have a lesser effect on a logarithmic scale, unless you choose to believe the IPCC and their inflated water vapor feedback mechanism.

Answer 10

Good points Dana, but I am much more concerned with the rate of increase in CO2 production than whether the effect is 1, 3, or 6 degrees per doubling  .  I fear the experts and not the deniers will prove correct, but the lower it is, the more time we have, and that's the main thing that matters to me. This is one case where you have root for the bad guys to be right.

Answer 11

Maybe, but then again, maybe not.  This just shows how little we really know, and I have a problem with making major decisions based on ignorance.

Answer 12

Very plausible.  I certainly think it's more LIKELY that CO2 sensitivity is higher than what the IPCC says, than it's lower.

"If the IPCC says it you better believe it and then leave room to think it is actually a lot worse than they have said."   Tim Flannery

Answer 13

Don't you think it would be a good idea to figure out where you going to get all the energy needed to make the planet warm up? You say magic will make the planet warm but in actual facts warming anything as large as a planet requires a lot of energy. It is energy that ain't there now so where is it going to come from? You know-it does not matter what any of your experts say; it still takes energy. Where are you going to get it?

Answer 14

I thought it was interesting that someone would actually try to standardize the biosphere. Good for him, he achieved a plateau no man has ever been before.

Answer 15

We can dam the rivers; oops, no more salmon or fertile soil.  We can use fertilizers and pesticides to increase yields, oops; now the soil is dead.  We can use the rivers to carry our waste;  oops, now we have ocean dead zones all over the world.  We can use antibiotics indiscriminately; oops, now we have super bugs.  We can fish the oceans with factory trawlers; oops, no more fish.  We can pump the aquifers indiscriminately and recharge them with sewage; oops, no more clean water anywhere.  

We can convert terrestrial carbon into atmospheric carbon on a planetary scale; oops,

now we live on Venus.

We can genetically or nano engineer our way out of this;  oops,

God only knows what we have done.

Answer 16

when i try to visualise all the multiple feebacks and possible discontinuities, my head spins. the bio-geo-chemical earth system is so incredibly complicated, and so finely balanced, i am not at all surprised that as models include more of the slow feedbacks the picture gets worse.

Answer 17

Mt_zion - Tamino has a lot of good stuff on his site (ya gotta read beyond the first article). Try these articles:

http://tamino.wordpress.com/2008/03/26/r...

http://tamino.wordpress.com/2008/04/04/f...

and

http://www.wunderground.com/blog/RickyRo...

Jim M - The energy to warm us that much is already here.  It's called the sun. The reason we aren't that warm now, is simply because most of that energy bounces back out into space. As greenhouse gas levels rise and prevent more and more of the energy from going back out into space, we warm up.

I skimmed the actual study and read realclimates article on it yesterday. It is quite concerting, but given it's predictions are at the higher end of the range estimates, I think it's prudent to wait for the actual publication date and give some time for additional commentary on it.

Jim Z - your ad hominen attack on Hansen is simply bogus. Despite the character assassination attempts by the denier camp he's still among the top-25 most cited (thus his work is clearly highly esteemed) climate scientists in the world.  And this paper has 8 co-authors. Do you merely discount them all as political hacks  or liars with the wave of your wand? That's beneath anyone interested in actual scientific debate.

Answer 18

I think it is ridiculous that computer models are considered an acceptable forecasting tool 100 years down the road when they can't even tell us whether or not my plans on Sunday will be ruined by rain.

They cannot predict hurricane seasons, winters, summers, droughts, nothing.  We DO NOT have a good enough grip on climate and natural phenomenon such as geothermal events and solar fluctuations and ocean currents to do anything more than make a guess.

Answer 19

Who's making a "pretty big deal"??

We are experiencing the same warming pattern that we experienced a thousand years ago.  Why is that a big deal?  In terms of the heat content of the planet as a whole, or even the oceans, a few tenths of degree rise in air temp is not significant, nor is it even discernible that this temp rise isn't just noise anyway.