Is the science of climate change settled?

No, but we still know enough to start taking action

Posted by Andrew Dessler (Guest Contributor) at 10:47 AM on 09 May 2007

Read more about: climate | climate science | climate change skepticism | Al Gore

A few weeks ago, I was perusing Grist when I ran across an ad for A Convenient Fiction, a slideshow rebuttal of Al Gore's An Inconvenient Truth. The author was none other than Steve Hayward, who you might remember from the AEI-$10,000-payola scandal.

I had actually seen this slideshow discussed in the New York Times, and was interested to see it. In my previous communications with Hayward, he was at great pains to describe himself as someone who believed the science as described by the IPCC. I wanted to see if the slideshow bore that out.

Both Hayward's slideshow and Gore's are pieces of advocacy, so neither gives a truly balanced view. Nor would one expect balance in this type of presentation. From a scientific viewpoint, the movies are actually comparable: both have much correct science in them, but both also make statements beyond what the scientific consensus can support.

Overall, however, I think Hayward distorts the science to a greater degree than Gore. A good example is his a statement that the latest IPCC report has reduced its estimate of the magnitude of human influence on warming. This is clearly a misrepresentation of science. I don't think there's anything in Gore's movie as misleading.

One of the main points in Hayward's presentation is that the "science of climate change is not settled." The implication is that because of this scientific uncertainty action to head off climate change is premature. However, this statement, as appealing as it might sound, shows a gross misunderstanding of uncertainty in science and policy.

In science, important and novel claims are repeatedly tested by independent scientific groups. A claim is only accepted if it passes all of these independent tests -- if it meets an exacting and rigorous standard. Because of this, it can take decades for the scientific community to accept revolutionary claims, like the slow movement of plate tectonics.

The reason for this is that accepting an incorrect claim can be quite costly, since it will confuse and misdirect subsequent research and casts doubt on the accumulated body of related prior knowledge.

In policy, however, decisions to take action are typically made with much less evidence. In most cases, waiting decades until all the data are in is simply not an option. In some cases, perhaps, the bar for evidence is set too low. In a recent book, Dick Cheney is quoted as saying:

Even if there's just a 1 percent chance of the unimaginable coming due, act as if it is a certainty.

As you can see, policy decisions (at least about war!) can be and typically are made with a much lower standard of proof than would be required in a scientific forum.

Which brings us back to climate change. There are significant uncertainties in our knowledge of the climate system. As long as there is much we do not know about the climate, as a scientist I cannot say "the science of climate change is settled." In fact, the number of scientists working on the climate problem clearly indicates that major scientific problems remain.

When the science is settled, you'll see scientists moving into other fields, as they did when we finally settled the science of ozone depletion.

But many people, looking at what we do know, have concluded that it's time to take action now to head off climate change. Thus, from a political standpoint, the science is settled.

By confusing the standards of evidence in these two arenas, Hayward makes an attractive but ultimately flawed argument. The science is not settled, but we know enough to start taking action now.

For story: Is the science of climate change settled?
20 Comments | Post a Comment

The elephant in the room

The issue is that greenhouse gas forcing is the elephant in the room, so large that the rest are just details and greenhouse gas forcing is probably the best understood of all the possible forcings, the longest lasting (hundreds of years for CO2 and zillions for perfluorides and ok, hydrocarbons are a few years before they oxidize to CO2). So to get a ballpark of the future temperature rise, pretty much all you have to know is the ghg forcings.

Of course, a lot of the devil and the damage are in the details, such as the rate that the Greenland ice cap melts at

by EliRabett at 11:02 AM on 09 May 2007

Gore's movie also distorted science please explain

You said that Gore's movie also distorted science for the case of advocacy. While I can believe this, I think this is a claim that you should back up, especially when posting to this site. I have heard claims that An Inconvenient Truth incorrectly stated that melting ice caps on Kilimanjaro was due to global warming, and that the movie left out the fact that it would be 100 years or so before sea levels rise to the degree mentioned in the movie.

If these are the only misrepresentations, then they are relatively minor and do not effect the thesis of the movie. And, as you mention, they pale in comparison to what Hayward did.

Regardless, this is something that I think you should have mentioned or linked to in your post.

Andrew Eisenberg
The gateway project is wrong---http://www.livableregion.ca

by Werdna at 11:53 AM on 09 May 2007

More or less

The science is pretty well settled on "Warming is happening, and manmade emmisions are primarily the cause"

What isn't settled is the exact degree of warming, and the exact severity of the fallout that will occur.

And rather than the skeptics actually having solid evidence, they just mention that until we solve all the secrets of the universe then it's not possible to take any precautions.

Reminds me of a british TV clip :P
http://video.google.com/videoplay?docid=-1829764711340977 ...

-David Ahlport

by GreyFlcn at 12:29 PM on 09 May 2007
[ Parent ]

Gore's inaccuracies

First, let me say that I liked Gore's movie. On the whole, it's quite accurate and I think it's done a lot to further the policy discussion of AGW.

However, he does push the "impacts" side of the science a bit beyond what the scientific community says: e.g., he basically says that Katrina and the spectacular 2005 season was caused by AGW, and he talks about a 20-ft rise in sea level, but does not give a time frame. I agree these are relatively minor issues ...

Thanks!

by Andrew Dessler at 1:39 PM on 09 May 2007

Impacts

However, he does push the "impacts" side of the science a bit beyond what the scientific community says.

True, but thats back onto the degree of warming, and the fallout.

Which doesn't have much to do with "Is it manmade".

-David Ahlport

by GreyFlcn at 1:56 PM on 09 May 2007
[ Parent ]

And these "groups" are whom?

In science, important and novel claims are repeatedly tested by independent scientific groups.

And you are referring to whom?

What other "group" tested and verified the IPCC claims?

In fact, who ever "tested" Global Warming?

How can it be tested? That's my big gripe with this whole thing...it's only based on computer simulation, no hard real world data.

And what historical data there is all points to the Modern Warming being a relatively mild maximum compared to the Medieval Warming.

That is why I don't think any of this is "science" -- it's more like engineering. You guys build models and then go around saying, "but the model says" -- and then when real data comes in, you shift all the variables by +2 and then claim, look "Look, Rocky, watch me pull a rabbit out of my hat...this time for sure!".

by jabailo at 2:45 PM on 09 May 2007

re: Jabailo

In science, important and novel claims are repeatedly tested by independent scientific groups.
And you are referring to whom?
What other "group" tested and verified the IPCC claims?

1. Australian Academy of Sciences
2. Royal Flemish Academy of Belgium for Sciences and the Arts
3. Brazilian Academy of Sciences
4. Royal Society of Canada
5. Caribbean Academy of Sciences
6. Chinese Academy of Sciences
7. French Academy of Sciences
8. German Academy of Natural Scientists Leopoldina
9. Indian National Science Academy
10. Indonesian Academy of Sciences
11. Royal Irish Academy
12. Accademia Nazionale dei Lincei (Italy)
13. Academy of Sciences Malaysia
14. Academy Council of the Royal Society of New Zealand
15. Royal Swedish Academy of Sciences
16. Royal Society (UK)

http://www.logicalscience.com/consensus/consensus.htm

-David Ahlport

by GreyFlcn at 3:13 PM on 09 May 2007

Beware the need for "balance"

Andrew,

... he basically says that Katrina and the spectacular 2005 season was caused by AGW, and he talks about a 20-ft rise in sea level, but does not give a time frame ...

He does not say Katrina was caused by AGW -- go back and watch. He quite carefully doesn't say that. Perhaps he could be charged with allowing audiences to leave with that impression, but he cannot be charged with stating a falsehood.

As for not giving a time frame for sea-level rises and flooding, he's talking about non-linear positive feedback cycles (sudden melting of Greenland ice sheet, etc.). Nobody knows when that might happen. We just know it's possible, and the chances are rising as CO2 rises. Again, you might charge him with allowing audiences to think such changes are inevitable or imminent, but he doesn't give a time frame because there is no time frame.

My point is, allowing the impression that danger is looming (by leaving out technical discussions) is not an "inaccuracy," nor is it comparable to the asserted and false inaccuracies in Hayward's slideshow. Even if you say Gore's was closer to the truth, I think you're still leaving people with the impression of equivalence, and that, more than anything, is what Hayward wants.

grist.org

by David Roberts at 3:40 PM on 09 May 2007

Nice Post Andrew

Yes the cause of global climate change is very unsettled

>> accepting an incorrect claim can be quite costly >>

who needs money when y'all extinct.

This outcome is an almost certainty.

Let them argue, let them look, let them pocket money, let them all die in my mind. Deliberately overlooking critical data will lead us all over the cliff like lemmings.

Bring on the DAEBATE, and let me blast these phonies and posers out of the water.

omegafour.com

by Zarkov at 3:50 PM on 09 May 2007

You Canna No A Foola Me

Here is a press release from the National Academy of Sciences (USA) which opens with the words "Climate Change is real". It's conclusion begins with "We urge all nations, in the line with the UNFCCC principles, to take prompt action to reduce the causes of climate change, adapt to its impacts and ensure that the issue is included in all relevant national and international strategies."

All these guys agreed to is that "climate change is real". Sheeesh...of course it's real. Climate is always changing.

Again, this is not scientific verification, this is a bunch of bureacrats leaning on each other like wasted fighters in the 9th round, waiting to see who'll fall first.

by jabailo at 4:16 PM on 09 May 2007
[ Parent ]

No, it's not settled

The science is pretty well settled on "Warming is happening, and manmade emmisions are primarily the cause"

There is no scientifically verifiable link between CO2 emissions and global warming.

None.

Zero.

Nada.

And the historical record shows that as well.

There is no experiment that has ever been done showing the link between CO2 and global warming.

There is no experiment showing that the Modern Warming is no more than part of the same 1500 cycle that produced the Medieval Warming.

The only "evidence" is on the computers of ecological modelers who get funded if their models show disaster, and who get zilch if there models show the truth -- that we're in a perfect climate right now and it will stay that way for a long time.

by jabailo at 4:19 PM on 09 May 2007
[ Parent ]

There is no scientifically verifiable link between CO2 emissions and global warming.

Even Richard Lindzen disagrees with this statement.

He agrees there is a link, but that the effect is small. (ASSUMING you leave out any potential for climate feedbacks)

-David Ahlport

by GreyFlcn at 4:30 PM on 09 May 2007
[ Parent ]

You Go,Denier Guy

John, We need to keep beating these folks who have swallowed the bait,hook ,line and sinker.We are of course in a period of global weather and processes that repeats itself,just as I have previously completely explained many times on this Grist forum.These folks choose to accept the "Science" of those accredited institutions that were never taught proper earth science for a reason.Their models and prognostications are like a freight train when the buzz words and buzz personalities get on the band wagon and wail.This period of warming will abate in a few short years and it will get cooler than average for a while as the energetic system pulls our grid energy away as it recedes.These are just plain and simple facts.Global co2 just does not greenhouse our heating,it just does not.Its a ruse to raise our energy price as far as I am concerned as many know the story. The media shills that many of you have become scream them down.Thank you for being so malleable by their system, that you have shut down your processing ability folks.Glaciers melt from below from magma heat.Get with it.The serious weather is from the extra energy input into our grid.Get with it.Stop using mathematical modelers to insist that they are science,they are just evidence of process,and thats it.You people,you people,you people. WAKE UP.!!!

Earth Shaman

by Earth Shaman at 4:52 PM on 09 May 2007

Al Gore = Art Bell

I used to listen to Art Bell every night when he was on KOMO radio. It was like War of the Worlds, each and every show had some type of doomsday effect that the guest was sure would destroy the planet by 2000, 2001, 2002...yeah, you get it...like every millenarian movement the day comes around when the earth is supposed to end and...glory be...it's still there.

That's about what will happen to Al and his Village...

by jabailo at 5:36 PM on 09 May 2007
[ Parent ]

For those lurking

The statement made by commenters on this thread that there's no evidence connecting human activities with climate change is non-sense.

The IPCC lays out the peer-reviewed evidence in great detail. Those who argue that no evidence exists have not read the IPCC report.

You can find the carefully constructed argument at www.ipcc.ch. Why should you believe it? Read this.

by Andrew Dessler at 6:16 PM on 09 May 2007

The same issue

Dave-

I think you've confused science with politics. I agree that Gore's presentation is effective, and as an advocate he can and should utilize the most effective arguments he can muster. If he can get away with stretching the science, and it's effective, then more power to him. But that does not make those arguments scientifically right.

As far as your argument that my post contributes to equalizing these presentations, I suppose you're right. From a scientific point of view, I do see them as roughly comparable (although I see Gore's presentation as slightly superior). I suspect that what really makes you mad (and me, too) is Hayward's conclusion that we don't need to do anything to head off climate change. But that's a normative policy decision, not a scientific one.

Thanks!

by Andrew Dessler at 7:05 PM on 09 May 2007

Science and politics---Andrew D and Dave R

It's a good conversation to have: what makes a scientific argument vs what makes a political argument and when is it justified to use one or the other.

Clearly, it is only justified to make a political argument when you have the science to back it up.

Also, clearly, a political argument is one that tries to persuade us to take action and so it will have to play to our emotions.

I think Andrew D's argument is that both Gore and Hayward have science on their side. But, that Gore makes a better emotional/political argument because it is less misleading.

That's where I disagree. You are implying that the more emotional an argument is, the more scientifically misleading it is.

The point is that scientists make scientific arguments (because that's all they are trained to do). We need to rely on non-scientists (or some very few, multi-talented scientists) to make emotional appeals to the general public to spur us into action.

Even without Gore's minor omissions in the film, I think he makes an excellent visceral argument for why AGM is a huge problem.

ps- apologies for over-philosophizing, but that's what I do as a (computer-)scientist.

Andrew Eisenberg
The gateway project is wrong---http://www.livableregion.ca

by Werdna at 7:58 PM on 09 May 2007

Andrew,

I don't want to belabor this, but I resist the way you're framing it.

You want to say that Gore's an advocate on one side, Hayward's an advocate on the other, they're both abusing the science in service of their preferred policy goals, and you're the disinterested observer who only cares about the science. You're not "on a side." I, being on a side, condemn Hayward but not Gore, because my only goal is advancing "my side." You, being above such petty concerns, won't play along. (You'll note that this is extremely reminiscent of the way a certain "policy scholar" we know and love tries to spin things.)

I think that's off in a number of ways. It is simply not true that advocates, as such, have no concern for scientific accuracy. Some do, some don't. Nor is it true that scientists (or policy scholars) have only concern for scientific accuracy. They're all human; they all have values and goals that affect what they choose to say, to whom, and when.

Nor is it true that Gore and Hayward abuse science equally in service of their goals. Gore is extraordinarily careful about the science -- he's been studying it for decades. You keep saying his "arguments" are "scientifically wrong," but you don't identify any such arguments. He didn't say global warming caused Katrina. And he didn't give a time frame for sudden sea-level rise because there is no such time frame. If anything, he wasn't explicit enough about trying to head off possible misunderstandings -- that's your complaint, some errors of omission. But in the confines of a popular documentary, it's a miracle that that's the best you can come up with.

Contrast with Hayward, who is saying things that he knows are wrong -- or more accurately, he just doesn't care if they're wrong, or misleading. He's just attacking Gore. He's trying to take Gore down a notch.

Gore's goal is to educate people and rouse them to action to address a problem. Hayward's goal is to tarnish Gore. Gore is trying to reassert reality after decades of horseshit in the media and from the right wing. Hayward is trying to maintain a fog of confusion.

I don't just support Gore because he's on "my side," I support Gore because he's right -- about the science, and about the need for action. It's the reality I care about. It's the reality Gore cares about. Hayward's playing cheap politics. There is no equivalence.

grist.org

by David Roberts at 8:28 PM on 09 May 2007

Poor Little Andrew

All of the nay sayers(Thats me I presume) who say the IPCC report is hogwash are just not getting it in your opinion and you do the (In your mind) proper thing and lead us to a link of the report.Well ,I assure you ,I have read the report and I am in favor of them returning all of the public money they used for their transport and meals and lodging etc.And why so cranky(Or just a crank) you may ask.Well for centuries,we have not had climatologists.We,as a society seem to make up all of these new science fields just to run a subject to death.I am an old fart thats an earth scientist and always have wondered why so damn many fools attempt to understand earth science without any earth science background.Mathematical studies and graphs of evidence of previous weather/earth processes does not make an earth scientist.When your supposed Phd. heros do the damage I see daily with their IPCC nonsense,I just groan and task myself to beat all of you folks daily.If there was anyone here really interested in actual earth science/history they would peruse my posts.But you know ,I think we just have a bunch of journalists on board here who are un-paid dis-information shills.What else could I assume unless I shared the other secrets I know to be true as to why most people have trouble processing properly.Of course,I see that most folks here would not be interested in that science and prefer to not repair themselves.What a shame,but this anomaly will beat most of you guys up pretty bad before it passes from our sector,so maybe it will be more peaceful and just think,alot less carbon to worry about also except the methane produced from rotting flesh and vegetation.

Earth Shaman

by Earth Shaman at 9:10 PM on 09 May 2007

Good points

Dave

First, don't ever call me a Pielke. Thems fightin' words. In Texas, I think I could legally shoot you for that.

Second, my point is not that Gore abuses the science. He clearly does not. I'm quite certain, in fact, he knows more science than almost anyone who's not a climate scientist. However, if you watch Hayword's presentation carefully, most of what he says is also technically correct. That was really my point.

Overall, you make some good points. I suppose what got out of this exchange is that I probably shouldn't compare Hayword's and Gore's presentations. Because Hayword is defending the status quo, he actually has a much different goal in the debate. Maintaining the fog of confusion is a victory for him because it allows him to achieve his preferred policy option: to do nothing. Criticizing Hayword for misusing science is actually a victory for Hayword because it focuses the debate on science and contributes to policy gridlock.

Gore, on the other hand, needs to actively convince people to adopt new policies, which is far more difficult. Arguments about science do not help him, because they move the discussion away from talking about solutions.

Because of this, their presentations are not easily compared.

In the end, none of this was really what I want to talk about in this post. My main point was the "science is settled" argument and now it was not a very good argument.

Regards

by Andrew Dessler at 9:43 PM on 09 May 2007

Global Warming

I can't believe that there's people who don't trust that CO2 make global warming.
Even if it's wrong, we should admit that CO2 make a pollution. If we can lower the percentage of CO2 in the air, it is good, isn't it?
-- Yuhirocks from natural sleeping aids

by yuhirocks at 8:36 PM on 01 Oct 2008

ADVERTISING POLICY

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