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Amidst the usual riff-raff of comments on my previous post, I received at least one good suggestion, which was to look at the web site realclimate.org, and in particular their FAQ page.

One question asks, Just What is the Consensus?. The answer is


1. The earth is getting warmer...0.17 oC/decade over the last 30 years
2. People are causing this...
3. If GHG emissions continue, the warming will continue and indeed accelerate...
4. (This will be a problem and we ought to do something about it)

The last point is in parentheses, because "whilst many would agree, many others (who agree with 1-3) would not, at least without qualification. It's probably not a part of the core consensus in the way 1-3 are."

My impression of the Al Gore movie, based on the trailer, is that it is designed to beat up on anybody who disagrees with any of the consensus, including (4). I think that the movie takes the climate issue away from people like those at realclimate.org, who strike me as rational and capable of admitting to imprecision and alternative courses of action, and makes it a religious issue, in which imprecision and alternative courses of action are punishable offenses.

Another FAQ post deals with the issue of whether or not climate modelling is truly a science. Read the whole thing. I will comment on some selected excerpts.


Climate is complex. Since climatologists don't have access to hundreds of Earth's to observe and experiment with, they need virtual laboratories that allow ideas to be tested in a controlled manner. The huge range of physical processes that are involved are encapsulated in what are called General Circulation Models (or GCMs). These models ... are based on physical theories and empirical observations made around the world. However, some processes occur at scales too small to be captured at the grid-size available in these (necessarily global) models. These so-called 'sub-gridscale' processes therefore need to be 'parameterised'

...This means that validating these models is quite difficult. (NB. I use the term validating not in the sense of 'proving true' (an impossibility), but in the sense of 'being good enough to be useful'). In essence, the validation must be done for the whole system if we are to have any confidence in the predictions about the whole system in the future. This validation is what most climate modellers spend almost all their time doing.


This does in fact sound like the way that major macroeconometric models were constructed. There were many problems with these models. However, in my opinion, the biggest issue is that there are many more parameters than data points. In macro, there really are only a few interesting episodes, such as the Great Depression, the 70's stagflation, and the disinflation of the 1980's. There are many causal variables that could be implicated in these episodes.

When there are many more variables than true data points, it is impossible to rule out competing hypotheses. This problem can be glossed over as long as there is a consensus among the model-builders, which there was in the 1960's. If everyone agrees on an approach to building a model, the models will tend to provide broadly similar answers.

But as it turned out in macro, the consensus proved fragile, and it fell apart in the late 1970's. By that point, we had people publishing papers pointing out that the data could not distinguish between an economy obeying a 200-equation macro model and one obeying a univariate random walk. There was a paper saying that every business cycle was an oil shock (that was James Econbrowser Hamilton's Ph.D dissertation). There was even a famous paper, alluded to here, which argued that sunspot activity was as useful an explanation of the business cycle as any major macro-econometric model.

My take on macro is that the neo-Keynesian approach, which underlies the big econometric models and which is taught in intro econ courses, may still be correct. But so could a number of other models, some of which have very different implications for how macroeconomic policy affects unemployment and inflation. Anyone who insists on one particular model is a religious zealot, not a scientist.

My guess is that I would look at climate modelling the same way. The complexity of the process far exceeds the availability of data needed to verify the model. Even a broad consensus may prove fragile.

I have no alternative to the climate models. I think we ought to take their results seriously. But my instinct is that we should be prepared for the possibility that they are way off base.

I believe that the climate models will tell you that a lot of the global warming predicted for the next few decades is "baked in," if you will pardon the expression. That is, even if we held human CO2 emissions to current levels, or reduced them by 10 percent, the trend of temperatures would be up rather than down.

In fact, the question of how sensitive future global warming is to our CO2-producing activities is one that I wish were addressed more directly in the FAQ. My impression is that the models show relatively small effects, which means that it takes a relatively large reduction in CO2 emissions to get a small reduction in the path of global temperatures. In turn, this suggests that policies to fight global warming now have a large buck and a small bang. We may be in a better position to address global warming in ten years, with better technology (and perhaps with better climate models).

The choice that we face on global warming is not "either-or." It is not, "either we believe in global warming and rescue the planet or we all die." It is a largely a choice between how much action we do pro-actively now and how much we do in response to climate change in forthcoming decades.

I think that there is time to have a reasonable discussion and to make rational decisions. If that's the way people want to approach the issue, that is.


Comments and Sharing





COMMENTS (33 to date)
Clear the Air writes:

More reading on this subject since yeaterday than I had planned...

Over at the Scientific American blog site there is a discussion of global warming (April 15) that had a 420,000 year temperature chart of the Vostok (Antarctica) ice core from the Carbon Dioxide Information Analysis Center (CDIAC) at the Oak Ridge National Laboratory.

This chart shows 5 temperature peaks.
It shows us at a relative high point now with the most recent prior peak being about 130,000 years ago.

Link to chart:
http://cdiac.ornl.gov/trends/temp/vostok/graphics/tempplot5.gif

Note: Time on this chart runs from right to left and BP seems to mean Before Present.

Distilling a lot of stuff down to a few short sentences...

It appears that manmade CO2 may be augmenting a "natural" peak ("natural" meaning not completely understood and similar peaks have occurred prior to a significant human presence.)

Points:
1. Global warming in the present era is real.
2. Much or most of it may NOT be due to our actions.
3. It will not take much more warmth before before we match the prior peak.
4. At that time sea level was about 18 feet higher than it is today. (There is enough ice in Greenland and Antarctica to provide the water to do this)
5. If the water rises lots of folks will have to move.

conchis writes:

"My impression is that the models show relatively small effects, which means that it takes a relatively large reduction in CO2 emissions to get a small reduction in the path of global temperatures. In turn, this suggests that policies to fight global warming now have a large buck and a small bang."

This depends in a big way on your discount rate, particularly as it seems likely that there are always going to be significant lags involved between any remedial action and its effect. I'm not sure I'd be comfortable with the idea that we should never do anything about global warming because we won't see the results for a decade (assuming for the moment that the phenomenon is real, and we can do something about it).

It also depends on whether there are feedback processes at work that mean that acting/not acting now could impact our ability to do anything about warming in the future. I know that some people have suggested such processes may be at work, and while I don't know anywhere near enough about it to comment on whether the suggestion has merit, if it does, then preserving that option value may be important.

On a separate note, it does strike me that not enough thought seems to go into the possibility that letting global warming happen, and dealing with the consequences could be a more cost effective option than trying to fix it now. Whatever the old adage might say, prevention isn't inherently superior to cure (or palliatve care, or whatever).

Lord writes:

If climate change is large, fast, and envitable, there is no point to change. If it is small or slow, there is no reason to change. Only if it is significant, but not too rapid, and that speed can greatly slowed by changes is there reason to change. I don't know of anyone who believes it could be prevented, but even this is possible with technology. New technologies could greatly alter the level of emissions. If gas stays over $3/g, solar/wind/nuclear/hydrogen should become competitive and that will greatly reduce emissions. Leveling, or even falling population will greatly reduce growth in emissions. Simply targeting levels regardless of the costs of achieving them is wishful thinking.

T.R. Elliott writes:

Al Gore is a politican. His goal is to convince people. To vote for him, to like his programs. No different than a politican like Bush. As far as science is concerned, he can both can ignored. Regarding science policy: sure. But those are entirely different issues.

Since the post is about climate science, we can ignore Al Gore.

I agree that there are uncertainties. Climate science is complex. But efforts to attack scientists who are performing reputable science that may deliver undesirable results is bad. It is occuring because there are many in politics and positions of influence who care little for the truth. Let's face it: on the conservative end of the spectrum, we have politicians who believe that (a) the earth was created in 6 days; (b) evolution is a myth and (c) the end times are near. Many who attack climate scientists are the same people.

Regarding complexity: There are many models that are complex. All you are saying when you compare macroeconomics with climate science is that (a) both are complex; (b) both require significant data and (c) both models can include a variety of parameters (and one must always consider the amount of data versus the number of parameters).

What these two theories are modeling, human agents in aggregate versus what is basically a large scale thermodynamic consideration (climate science) are entirely different.

Comparing the two in terms of analogy is fine, it provides a very very crude historical comparison, but that's about it. It's also convenient: pick an economic theory that fell apart. Find a relation to climate science. Then claim that climate science may similarly fall apart. It's mostly rhetorical or analogical in nature.

Climate science is not a religion. It is a science no different than cosmology, for example. I'm not saying I'd make policy according to cosmology, and I'd be concerned about making policy according to climate science (I don't think humans will be willing to change anway--they don't have the collective will), I'm not going to argue against cosmology's conception of the big bang because some fundamentalist doesn't like big bangs. And I'm not going to call those who believe in the big bang members of a new religion called cosmologism.

Slinging the term religion at those who are concerned with environmental issues is no different that slinging the same term at cosmologists. Which, with that comparison, shows just how silly some people are when they make the comparison. It's an attempt to be snide in a subtle way.

JohnJ writes:

Wait. If a degree more would raise water levels 18 feet, what was the world like when it was eight degrees colder? Was the water level lower by 150 feet?
That's not meant to be a sarcastic question, though it does sound like one, and I do doubt that the water level was ever that low for the same reason I doubt water levels would rise by 18 feet with any more significant warming. I would also like to point out that, according to the graph, we've been in this "hot period" for over two thousand years, well before people started producing GHG's at the current rate.
Other than that, I agree.

T.R. Elliott writes:

Lord: I've been studying energy from several perspectives for the past few years, looking at the economics and physics of a host of energy technologies: solar, coal, nuclear, you name it. The reality, as I see it right now, is that there is no technological fix in the near future. Granted, prediction is difficult (just ask Lord Kelvin and his predictions at the turn of the last century). But also consider Richard Smalley's work. There seems to be no easy fix. Gas is $3/gallon and it's probably going to get more expensive. Then we'll see demand destruction start, the final demise of the gas guzzling car. Then increased effort and R&D towards coal liquifaction, tar sands, nuclear. All will require significant investment. Solar will fill a nitch. Requires significant investment. Wind power a much smaller nitch. Hydrogen is not an energy source so discussions of it are red herrings.

In summary, I see no magic bullet, just demand destruction and improved efficiencies where possible. Right now the world has perhaps an additional few easy million barrels/day of production that could be put online if not for political problems (e.g. Iraq, Nigeria, Venezuela), but after that, with other source of production in decline, we're going to see a massive amount of investment needed to maintain production, let alone increase it.

So the upside is that more expensive energy will drive efficiencies (including the guy who just won the midas commuting award for driving 7.5 hours every day to and from work--186 miles each way). But the down side is that reliance on coal will lead to increased production of CO2. There are ideas on what to do with it. None of them will scale very well.

It's quite possible the world will be a much different place in 2100. I don't see a panacea to solve our energy problems, and science has progressed to the point that we may have hit certain limits--e.g. there are no hidden forces waiting to be discovered--it requires to much energy to do so.

Every large system reaches some sort of limit asymptotically, when growth slows. That's why you can make more money with small cap stocks that with large cap stocks. The question that must asked: has the human enterprise, including our scientifically unexplored areas, reached these limits. It's possible. Julian Simon would say no. But he's dead. And that was his one idea. It's been used. It won't provide us with more energy. It's really faith.

Other than some quantitative advances in nanotechnology, which could--and I mean just could, in the Kurzweil Singularity sense--make a difference, I see no panacea jumping out from the near future.

Clear the Air writes:

For JohnJ -
Indeed during the last ice age the sea level was down as much as 400 feet! You could walk from Europe to England.

Clear the Air writes:

more for JohnJ

Actually if you look at the graph linked in comment #1 above the current warm period is about 12-13 Thousand years. Given our human sense of time and existence perhaps we should call this a plateau rather than a peak.

If I recall correctly the most recent Ice Age was about 18,000 years ago.
Pause to go check...

I just hopped over to wikipedia and here is a nice chart of sea levels for 140,000 years.
http://upload.wikimedia.org/wikipedia/en/c/c0/Sea_level_temp_140ky.gif

You can also see that within the recent couple thousand years the Sea Level has been 10 meters HIGHER than it is right now.

Silas Barta writes:

Note: Dignifying T. R. Elliot's input is a waste of time. S/he has shown repeated unwillingness to back up his/her claims and seriously confront the issues. To this day s/he is unwilling to back up his/her claim that threatening to screw over current and potential customers is a viable strategy for increasing the price of your servies. See here:

http://econlog.econlib.org/archives/2006/03/economic_fallac.html

To give just another of many examples, T. R. Elliot also considers the distinction between physical productivity and value productivity (how much your produce vs. how valuable what you've produced is) to be a meaningless distinction. See here:

http://econlog.econlib.org/archives/2006/04/scientific_cons_1.html

and find the April 17, 2006 10:39 PM response.

For this reason, responding to T. R. Elliot is tantamount to encouraging a troll rather than getting an honest response from the opposing side.

[A continuation of this comment has been edited out for ongoing, inappropriate, ad hominem remarks.--Econlib Ed.]

T.R. Elliott writes:

Silas silas: We're not getting along. Are we? I had high hopes we could be pals. We'd get together to discuss neoliberal economics together. I guess I was premature in that thought.

Anyway, I find it impossible to answer your completely hypothical questions. In a question about the distribution of earnings to employees, you've simply drawn upon a term "value" to create a nonsolution on why capital and executives are rewarded for improved earnings but not employees. Axiology is a tough philosophical topic, and "value", along with morality, is so slippery that I agree: you can define away any sharing of productivity gains with employees.

So let's put that one to rest. Now, your hypothetical question about changing prices in a grocery store has no relation to unionization. Unions have existed and operated well for well on 100 years. I'm not familiar with any stores that change the prices as I shop, upon selecting the product but before hitting the checkout.

It's nonsense.

There, I've responded.

Can we be friends now?

Brad Hutchings writes:

If this were a harbor that man was polluting, we'd be talking about how to clean it up right along side how to keep it from getting more polluted. Gregory Benford addressed this 8 years ago. Of course, that whole concept is apostasy for the global warming crowd.

Silas Barta writes:

Anyway, I find it impossible to answer your completely hypothical questions. In a question about the distribution of earnings to employees, you've simply drawn upon a term "value" to create a nonsolution on why capital and executives are rewarded for improved earnings but not employees. Axiology is a tough philosophical topic, and "value", along with morality, is so slippery that I agree: you can define away any sharing of productivity gains with employees.

I didn't "define it away". I invoke the distinction as part of a broader explanation. I took issue with your denial that the distinction (between physical and value productivity) exists at all. You need to first admit that such a denial is in error.

Now, your hypothetical question about changing prices in a grocery store has no relation to unionization. Unions have existed and operated well for well on 100 years. I'm not familiar with any stores that change the prices as I shop, upon selecting the product but before hitting the checkout.

It's one hundred percent relevant, as I have explained several times. When a grocery store tries to jack up prices after you have made significant investment in gathering the goods but before you pay, that appears to you exactly as it appears to investors when unions try to jack up wages through strikes (and with it, blocking entrances). With the grocery store, you would mentally discount all claims of "great values here!" in your estimation of the merit in purchasing from the store. In precisely the same way, as an investor, you would discount the productivity of unionized workforces.

(Note that it's not *merely* the quitting, but being kept from continuing with replacements that causes the most problems.)

It is not nonsense, and the fact that grocery stores aren't stupid enough to do this, while unions are, is no response.

You have not responded because, quite simply, you have never seen the issue in this light, and to it shatters your current worldview to see it this way. It's a "bummer" in other words, that you don't feel obligated to take seriously, because it's so unsettling.

T.R. Elliott writes:

Whew. Silar is still talking to me. Perhaps friendship does lie in our future?

Value: I don't deny that what someone produces has value, which is measure in a variety of ways. And my twenty years of experience producing consumer products (including cell phones and games to run on those phones) makes me understand this in practical terms. But that said, you've defined away the sharing of productivity increases with employees by stating that they've obviously not added any value. It's not a response. It's a word. I think capital and executives are rewarding themselves and not employees for productivity gains because they can get away with it. Wouldn't you?

Unions and that pesky supermarket with changing prices. Apples and oranges. Doesn't compute. We'll just have to agree to disagree on this one.

OK. Friends again? Pal oh buddy.

Silas Barta writes:

Readers: please note the above as further proof of T. R. Elliot's intellectual laziness and trolling.

[Silas: Please email us at webmaster@econlib.org if you wish to reinstate your posting privileges.--EconLog Editor.]

Barkley Rosser writes:

I wish to commend realclimate.org as an excellent source. One aspect of it that is quite good is that while the people who run it have a definite position (they are "global warmers," part of that "global warming crowd" that Hutchings is so dismissive of), the critics are allowed on and there has been a long and healthy debate at a highly informed level of the issues involved.

I would note that one of the people who run it, Michael Mann, has been accused of some improper scientific work in regard to the (in)famous "hockey stick" controversy. That is still a matter of much dispute, although many feel that Mann was not treated properly.

JohnJ,

Not just walking from England to Europe, but from Asia to America across the Bering Strait. Also, what is now the Chesapeake Bay was simply the extension of the Susquehanna River in those days, with the Potomac, the James, and others being simply tributaries of the Susquehanna.

OTOH, the shoreline has been higher, with the fall line being a long time shoreline inland from the current one. Today is neither the coldest nor the hottest the earth has been in relatively recent geological time.

Also, thanks to the editors for spotting the real troll and putting him out to pasture for the time being.

James writes:

T.R.,

I think you are a bit too modest regarding your predictive accuracy when you write "It's quite possible the world will be a much different place in 2100."

Anyway, you are right that the rising cost of energy, global warming, etc, may be problems that the market can't "solve" in a cost effective manner. That would mean every single person on earth, exchanging costs for benefits as best they know how, can't solve those problems. In that case, I think it rather odd to imagine that governments somehow could solve them. The only unique option available to governments is to engage in loss generating activities over somewhat longer periods than private actors could. (When bankruptcy would cancel the plans of private actors, governments can keep on going and have taxpayers cover the loss.)

Drew writes:

Of course they say I have no degree in meteorology and I am therefore not qualified to speak. But I have studied their climate models and know what they can do. The models solve the equations of fluid dynamics and do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry and the biology of fields, farms and forests. They do not begin to describe the real world that we live in.

The real world is muddy and messy and full of things that we do not yet understand. It is much easier for a scientist to sit in an air-conditioned building and run computer models than to put on winter clothes and measure what is really happening outside in the swamps and the clouds. That's why the climate model experts end up believing their own models.
- Freeman Dyson on Global Warming

Also:
- Video: Freeman Dyson: Carbon Dioxide in the atmosphere: the balance between vegetation and atmosphere
- Video: Freeman Dyson: Carbon Dioxide in the atmosphere: global warming and stratospheric cooling
- Video: Freeman Dyson: Carbon Dioxide in the atmosphere: conclusions

I think we can control the carbon dioxide rather easily--it's a question of land management essentially. The amounts that are involved in the vegetation are so large, that if you merely change some of the forest management practices--or do a little more irrigation in some places--it's quite likely you can absorb all the carbon dioxide you want at a cost that is far less than stopping burning coal and oil

JohnJ writes:

That's too funny! This graph was obviously drawn from the temperature graphs! You can't use this to correlate the other, since this used the other as a source!
Let me try to explain better. If the temperature graph was A, then they used A to get B, the water level graph. Therefore, B cannot be used to support A, since B is conjecture drawn from A!
At least as far as it seems to me. If there was a better explanation with the graph, maybe I could understand better.

Clear the Air writes:

for JohnJ
The Temperature graph was derived from the Vostok ice core project done by the Russians in the 1970s and 80s. Do a Google search on Vostok Ice Core and temperature.

The water level graph was from Wikipedia. I found it on-the-fly as I wrote the posting and did not do any work to determine how it was drawn.

That there is a strong positive correlation between the 2 graphs does not mean somebody just did the water level drawing from the temperature drawing but it is possible to fake data that way. I came to my understanding of water levels years ago from other sources.

Here are a few items you can decide are true by your own research.
1. The total mass of water on the earth has not changed much over the recent history.
Some creation and loss by processes such as fire and chemical reactions.

2. The extent of the ice coverage during ice ages is well known from the geologic record.

3. Fossil records all over the place have indicated that some things now "high and dry" were once underwater and vice versa.

4. If you make ice you have less liquid water.
Thus a massive ice sheet will drop ocean levels.
Coverversely if you melt ice that is on land (Greenland & Antarctica) the oceans will rise.

Brad Hutchings writes:

Barkley writes: part of that "global warming crowd" that Hutchings is so dismissive of

Well FYI, I actually had a college course tag team taught by Rowland and Cicerone, the big scientific brains behind the CFC ban. You know, the reasons we can't have warm Big Macs and arguably a contributing factor in the loss of Space Shuttle Columbia. Cicerone is now a lead gloom and doomer on the global warming front. Basically, his schtick in that "honors" physical science course (1991) was to whip all the sorority girls into a frenzy over the skin cancers they and their kids would have as a result of the ozone hole and what horrible deaths they would have because of them.

So yeah, experience has taught me to be dismissive of scientists, no matter how intelligent and prestigious, who want to translate their theories to controlling the rest of us. You all know brilliant people you wouldn't trust with your TV remote. Maybe we ought to be skeptical of entrusting our economy and our future to them too without a little bit of debate.

JohnJ writes:

CTA, true. I'm not disagreeing with any of that except that it is not backed up by enough research to make policy decisions regarding. It seems to me to be conjecture that is often market-driven, i.e. disaster sells. If the evidence is so valid, why is it so hard to find? For instance, the global temperature has risen by nearly a degree in the last one hundred years. How has this correlated to the rise in the water level?

Roger M writes:

On the "validity" of climate models, check out this story on the hockey stick effect: http://news.bbc.co.uk/2/hi/science/nature/4349133.stm

I've read that water vapor and methane have a far greater impact on warming than CO2, but few people talk about them because we can't control them.

Boonton writes:
In turn, this suggests that policies to fight global warming now have a large buck and a small bang. We may be in a better position to address global warming in ten years, with better technology (and perhaps with better climate models).

This may in fact be true, however just as uncertain as climate models there is uncertainity as to how bad global warming will be (if it happens).

It seems an incremental approach would be to aim to start reducing CO2 and then either step up or step down the incentives as evidence becomes available. Simply hoping that in ten or twenty years someone will invent a magical 'no CO2' machine is foolish. Technology to reduce greenhouse gasses ten years from now will come because people will start investing in R&D today. They will start investing in R&D today if there are incentives (aka costs) for releasing greenhouse gasses.

TGGP writes:

In the BBC page McIntyre & McKitrick say that the old model exaggerates hockey shapes. Here: http://www.technologyreview.com/articles/04/10/wo_muller101504.asp
it is claimed that it generates a hockey stick from random, trend-less data.

pj writes:

Realclimate.com greatly overstates the consensus. Number 2 should read, "People are causing some part of this." Both realclimate's and my statements are statements of faith, however, and not based on observation. We simply don't know how much of the warming is due to anthropgenic greenhouse gases. All we have is a theory. Statement 3 is simply wrong. The temperature response to rising greenhouse gases is logarithmic. In other words, each additional ton of CO2 emitted leads to less warming than the previous. For example, preindustrial concentrations of CO2 was about 290 ppm. A doubling to 580 ppm causes a 2 percent increase in radiative forcing. To increase radiative forcing another 2 percent would require another doubling to 1160 ppm. So there's simply no way that warming will accerlate.

Roger M writes:

On the models, I saw an article in the late '90's in which the researcher input data from the first half of the 20th century and 4casted the weather for the next half. According to the model, the '90's should have had avg temps of about 20 deg F higher than they were. As we the large econ models, that climate model was terrible at 4casting out of sample.

Roger M writes:

Why isn't anyone talking about methane? It's a much bigger problem than CO2. We could stop all the CO2 and GHG's would still build up because of methane and water vapor. In fact, some research came out last month that the rainforests contribute to GW because the aninmals and bacteria that decompose organic matter emit so much methane. Methane bubbles up from the ocean. Cow farts alone contribute more to global warming than all of the cars in the US!

Clear the Air writes:

for JohnJ
Actually the two points I was addressing most recently (water levels and 400,000-year temperature history) seem to be beyond our control and beyond most folks comprehension.

The effect of human activity on the temp chart from the Vostok ice core project is like frosting on a layer cake - a small percentage of the overall height.

BUT - one issue that worries folks is the narrow threshold of certain critical points.
example: normal human body in 98.6 degrees F.
How do you feel at 99, 100 etc.

ice melts above 32 degrees (+/- a few factors which we can ignore). IF your temps are right near the critical point a small change one way or the other can tilt the direction from Ice-building-up to Ice-decreasing.

on one side or the other your next item of interest is the rate of increase/decrease.
Slow? - we cope
Very fast? - we hustle and cope.

BTW - did you know the output of the sun itself is now thought to vary - beyond the 11-year sunspots cycle you may already have known about?

Bob Knaus writes:

And finally for JohnJ who seems a bit of a skeptic, I invite you to come to the Bahamas some day. It's an ideal place to see evidence of rapidly changing sea levels, in fairly recent times, with your own eyes.

The Bahamas are remarkably stable platforms composed of marine deposited carbonates. You can Google "Bahamas carbonate platform" for many interesting hits, as this area has been intensively studied. Core samples show the effects of multiple sea level changes ranging from about 10 feet higher than present to about 300 feet lower than present.

I can show you fossilized coral reefs eroding from soft limestone rock that were formed within the last few thousand years at the post-glacial sea level peak. I can show you "blue holes" that lead to underwater caverns, complete with stalactites, formed when the sea level was much lower.

If you doubt the ability of rock to quickly form and fossilize to record sea level changes in this area, I can show you shipwrecks eroding from solid limestone... until the hurricanes of 2 years ago, I could have shown you a D-cell battery eroding from the rock!

For a slighly more advanced Googling adventure, try finding climate records (based on cores from Haitian and Gulf Coast lakes) which show that about 1500 years ago Katrina-sized hurricanes hit the Gulf Coast 3 to 5 times more frequently than they do today.

Daublin writes:

T.J. Elliot wrote: "Let's face it: on the conservative end of the spectrum, we have politicians who believe that (a) the earth was created in 6 days; (b) evolution is a myth and (c) the end times are near. Many who attack climate scientists are the same people."

Meanwhile, there are people on the liberal end who think (a) global warming caused Hurricane Katrina and (b) the Kyoto Protocol would have stopped global warming.

Shouldn't reasonable people stay away from both of these silly politics-driven stances? I think so. I am far more scared by the insane positions that come out during political brawls, than the issues these brawls are about. What hope do we have, when our best people join sides with idiots for tactical reasons?

AK says: "But my instinct is that we should be prepared for the possibility that they are way off base."

Either way?

The guesses the climate scientists make are the best guesses there are at the moment. My layman's understanding is also that the basic assumptions in climate models are more solid than those in market models, since physical assumptions can not be affected by what we believe about them, whereas assumptions of human behaviour can.

Also, Don said something interesting in the previous post that I'd like to comment: "But if the 'consensus' is as strong as many claim, aren't there lots more smart folks on the 'right' side of the question? Even if a particular argument takes more time to refute than to make, the amount of available brainpower should make refutation straightforward."

That is true, especially in this case, where a lot of people are concerned about it. If you were a severe , but uneducated critic of some aspect of paleontology, paleontologists wouldn't rush to the defense unless they felt that you were really effective at spreading your unorthodox ideas directly to the public. That is a threat to any system of experts. An other thing that could provoke a response was if the research had immediate, serious consequences that the researchers were concerned about. Both applies to climate science - denialists get a lot of publicity, and the researchers genuinely believe that their lives 30 years from now will depend a lot on the decisions made on the basis of their research today.

The consenscus is big, and there are "lots more smart folks on the 'right' side of the question". That's a prerequsite for getting a site like realclimate, with famous climate scientists making intelligent answers to tough questions. But it's not enough in itself: they would get more money (and peer esteem) for their skills elsewhere, so they probably do this because they are actually worried.

But you don't get to tap into this "avaliable brainpower" unless you go looking. Many things that have been mentioned in this thread, like McKitrick and McIntyre's criticisms of Mann et al., are answered on realclimate. They have a whole folder on the hockey stick, as have other prominent blogs like a few things ill condsidered and deltoid.

Also, I repeat what I said in the previous post that who you are does matter in science. You have to be a peer at some level before criticism is worth listening to. McKitrick is an example of the people I mentioned, who can make a hundred ridiculous statements in a week, when it takes ten years to explain to the public why they are wrong. That may be a "type M" argument or what you may call it, but it's actually relevant. You have to get rid of noise and amplify the signal, peer review is science's way of doing it.

Blogs usually do it by banning someone for trolling.

Barkley Rosser writes:

One thing that really is not known is the nature of certain nonlinearities and possible associated tipping points. These can cut both ways, to heighten the chance of a sudden movement to greater warming, or to suddenly offset it and halt it. Most of these are poorly modeled and not in the existing climate models.

I would note on the worrisome side that the geological evidence does suggest that movements both into and out of glacial periods in terms of temperature changes was pretty quick in geological time, like maybe 100 years. And this was with no humans around to aggravate things. One "positive [destabilizing] feedback" that has been suggested involves albedo, surface reflectiveness. As more ice accumulates, more sunlight is reflected off and cooling is accelerated. The opposite can happen during warming, as like now. Glaciers melt reducing reflectiveness, thereby accelerating warming...

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