What if the skeptics are right, and our greenhouse gas model is inadequate?

Question

Specifically, what if we're underestimating the speed and strength of positive feedbacks such as ice sheet melt (albedo change) driving initial warming and resulting ocean outgassing (driving more CO2 release and additional warming)?

What effects might occur if 11 degrees F by 2100 (within the IPCC forecast range for expected warming) is a reasonable expectation for future warming rate? That is an average change of one degree in just over 8 years, over 11X faster than what we've seen over the past 100 years.

If our understanding is as poor as the skeptics claim, wouldn't we be just as likely to be underestimating the change and effects as over estimating them? Surely true skeptics would have to consider that possible outcome. So what's the outlook for people, economies, water, food, damage, or even survival in that scenario?

Answer 1

The problem with you theory is that the ice core data does not support your view.

It is well established within the climate science community that co2 lags temperatures by 800 years.  That means for a period of 800 years temperatures and co2 were going in the opposite direction.  Strong AGW supporters  argue that while the sun, or the earth's orbit  may have caused the initial temperature spike and outgassing of CO2 from the oceans, further temperature increases were caused by the increases in CO2.

The problem with this theory is that after the 800 year lag when both temperatures and co2 started to rise, we should have seen an rapid acceleration in warming if your theory is correct.  But there is nothing in the ice core samples that shows such an acceleration.  As a matter of fact we do not even see a minor acceleration.  This is further proof that co2 plays a minor role in temperatures changes.

Answer 2

That's tricky because it depends on why the theory is wrong.  It's difficult to speculate about this, because the skeptics have not come up with a viable alternative theory for what has caused the rapid recent global warming.

Their best explanation is a change in the Earth's albedo as you mention, but due to changing cloud cover.  Unfortunately there isn't a lot of long-term data with regards to cloud cover trends.

This does raise an interesting point though, because as you mention, ice is another big factor in the Earth's albedo.  So if the albedo in the form of clouds is playing a bigger role than scientists believe in global warming, the same should be true for the decreased surface area covered by ice.

Skeptics might argue 'oh but when the solar magnetic field decreases again and allows galactic cosmic ray flux to increase, seed more clouds, and increase the Earth's albedo, it will offset global warming.'  The problem with this explanation is that the solar magnetic field is linked to sunspots, and the number of sunspots has decreased over the past 30 years.

http://en.wikipedia.org/wiki/Babcock_Mod...

http://solar-center.stanford.edu/sun-on-...

So this suggests that the solar magnetic field is not playing a role in the current warming.  That puts us on very shaky footing - if decreasing cloud cover is to blame for the recent warming, but it's not linked to changes in the Sun, then what's causing it?

But for now let's throw science out the window, because that's what deniers like to do.  So let's just assume a decreasing albedo due to decreased cloud cover is causing the planet to warm, and we have no idea how this will change in the future.  But we do know that the warming is causing ice to melt, which is also decreasing the Earth's albedo.  This suggests that not only will the warming continue, but if the theoretical trend in cloud cover also continues, the warming could accelerate rapidly.

We've already seen a few IPCC predictions become too conservative (for example arctic ice melting and atmospheric CO2 increasing faster than predicted), so it's perfectly plausible that the IPCC's temperature predictions are on the conservative side.

If the planet warms 11°F in the next century, you're talking about a runaway greenhouse effect due to various feedbacks kicking in which will take the situation beyond our control with catastrophic consequences.  Really bad stuff for virtually all life on the planet.  The climate will change faster than most species (including humans) can adapt.

At least if the AGW theory is right, we still have control over the situation and have time to remedy it.  If the skeptics are right, it's just as likely that we will soon face catastrophic consequences as the warming will reverse itself.  In fact, the former is probably more likely.

*edit* "but what would our lives under that (boundary case) expected scenario look like?"

Bad.  I haven't seen the 6 degrees show mentioned by Ken, and I've got a book about the subject ('6 Degrees: Our Future on a Hotter Planet' by Mark Lynas), but I haven't read it yet (still in the middle of another global warming book by Fred Pearce).  So I've only read a little on this particular subject and for that reason would prefer not to comment on it in-depth.

You should watch the show or read the book though!

http://www.amazon.com/Six-Degrees-Future...

P.S. Is anyone else noticing that Tomcat's answer to everything is tropical troposphere?  To base every argument on data which has such massive error bars (different troposphere analyses show anywhere from 0.05 to 0.2°C warming per decade) seems kind of absurd to me.  Especially since the tropical troposphere would show greater warming than the surface whether the forcing were anthropogenic, solar, or whatever.

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

http://tamino.wordpress.com/2007/12/31/m...

Answer 3

> Subject: Re: Climate Change - take the test

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>     http://www.geocraft.com/WVFossils/GlobWa...

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Answer 4

If the model has underestimated the amount of climate forcing that AGW is causing, it should be very obvious in the tropical mid troposphere. However it is not, which logic would suggest that the model has been  over estimated. A five year long cooling trend in the tropics hardly supports the AGW theory as a impending planetary emergency. The real question is what if the skeptics are right and we are heading into LIA conditions over the next two decades, then the AGW supporters are misleading the world which will have severe implications for many nations.

http://www.ssmi.com/rss_research/climate...

EDIT:

Enso does not cause 5 year cooling trends, and I did answer the question, the data clearly indicates that the AGW theory has not under estimated the warming, because the mid troposphere does not support the current theory. I am not fighting the question, you are fighting the data.

EDIT DANA:

And your answer to everything is the GISS, which is just flat out wrong, and has nothing to do with the greenhouse theory, nothing whatsoever.

.

Answer 5

You're correct.  A good argument can be made that the IPCC report was probably overly cautious (we know from reports there were complaints by scientists about many worst-case scenario's being edited out) rather than overly alarmist.

The National Geographic channel recently showed "Six Degrees Could Change the World" (I've recorded it, but not watched it yet) which I've read does a scientifically accurate presentation of the consequences of various levels of warming.  You can find out more about it here:

http://channel.nationalgeographic.com/ch...

Edit:

Tomcat - we don't have a 5 year cooling trend.  All we have is 1 single warm year (1998) at 1.5σ above the 20-year trend line (the statistical equivalent to 1992 on the low end) that confuses people without any numerical analysis experience.  The 20 year trend-line (1988 - 2007) still shows a 0.2 C/decade slope. Climate trends are not determined by cherry-picking years and trend duration to achieve a predetermined goal.  I could cherry-pick 1992 and demonstrate a 0.34 C/decade trend line, but that wouldn't be valid (just like choosing 1998 as a starting point isn't valid).

Answer 6

You are absolutely correct - the climate scientists are FAR more likely to be underestimating the results of man's production of greenhouse gases than overestimating them.

"Of course, (the IPCC report) being a consensus document, a lot of the material that I think is reasonably well-supported also gets weeded out through that process. 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, Ph.D.

Answer 7

11 degrees by 2100 is just a guess.  No one can tell you what the climate will be 5 years from now, let alone 92 years from now.

If climate models were right, we would know how much the climate would warm up in relationship to the amount of co2.  But no one knows this.

We believe co2 should increase temperatures, but we know so little about the climate.

Answer 8

The skeptics are correct that parts of climate are poorly modeled (and understood) at present.  However, those misunderstood bits also are the most nonlinear processes.  However, the core radiative transfer is pretty much known, as are the large scale features of the atmospheric and oceanic circulation.  So my hunch is that the average warming will follow pretty much the middle scenario predicted by the IPCC.  However, the variability, or nonlinearity, in the system has been greatly underestimated so that as we get more warming, we will see more extreme events.  The climate (or maybe long-term weather patterns), will be highly variable, making adaptation next to impossible.  Imagine a 5 year long drought in the American Midwest followed by torrential rains and flooding.  The devastation to agriculture through loss of topsoil will be enormous.  Similarly, there might be several years in a row with no Atlantic hurricanes due to large increases in shear, and then a couple of years with a half-dozen landfalling cat-5's, or a cyclone season that lasts from June through December.  

Remember, most scientists, if you get them good and liquored up, will admit it is climate change caused by global warming, not one or the other.

Answer 9

My puzzlement is longstanding  over the venom about how wrong the AWG crowd is.

So WHAT if they are wrong, I wonder.  Why would getting off the petrochemical pipeline be a bad thing?  How is saving money while I save fuel a bad thing?  How is making my home more efficient, recycling materials, and saving the effort and expense of building more landfills bad?

How is not spending a fortune on imported oil, and thus denying the funding to terrorists who get money from oil producing countries, a bad thing?  WHY would I want to continue funding both sides of the war on terror?

EVEN if the SKEPTICS are completely right, even if humans don't add to any warming at all, how is being a good steward of our environment and resources a bad thing?

And, oh my....what if the skeptics are completely wrong?  I'm not willing to bet my children's future.