Thursday, September 14, 2006

Important news

An interesting news report is circulating around the blogosphere today. Allegedly, the Bush administration is going to propose we limit CO2 to 450 ppmv by the year 2106.

If true, this as an incredibly important event --- it will move the debate from "should we take action?" to "what action should we take?" In other words, the debate will evolve into a discussion of what the target should be --- and this is (in my opinion) exactly what we should be talking about.

The long lifetime of CO2 in the atmosphere means that we cannot wait for 50 years to start reducing emissions if we want to hit 450 ppmv. In fact, we need to start deviating from our baseline in the next 10 years or so in order to avoid having to make large and disruptive cuts later. And the near-term actions required are pretty much the same for a wide range CO2 targets and timelines. Thus, while some will critize the target date of 2106, it will be one or several decades before actions in pursuit of this target preclude more ambitious targets.

ps: I've turned on "comment moderation" on the blog as a test, so your comments might take a few hours to appear. Your patience is appreciated.

[Note added later: The more I think of this alleged proposal, the more puzzled I am about it. The target (450 ppmv) and the time period (2106) are not really consistent. It is almost certainly the case that in order to stabilize CO2 at 450 ppmv at the beginning of the 22nd century, one has to be close to or at that target in the middle of the 21st century. So why put the target date 50 years later? Perhaps this is a cynical election year ploy, as suggested by several commenters. Or maybe there's something I'm not considering. Any thoughts on this are welcome.]


coby said...

this as an incredibly important event

I fear it is just "incredible", and not an event at all. But time will tell.

D. B. Paul said...

I will say up front that I am skeptical that human produced CO2 has much of an effect at all on global temperatures.

How can we go about setting CO2 targets in a scientific way? I agree it would be nice to reduce CO2 output - it would mean much greater efficient fossil fuel consumption and probably development of alternative energy sources, both very good things. However, how do the global warming advocates know how much CO2 is too much? I have heard that each 1 ppm increase in atmospheric CO2 should cause a temperature increase of 0.002 C, so it would take a 1000 ppm increase in CO2 to cause temperatures to rise 2 C, which is much less severe than what many models call for, especially if we are talking about increases in the 100-200 ppm level. I don't know if that number is accurate or not, but when I think of climate science, I would think it would be possible to objectively measure (in the laboratory) how much incremental additional heat retention if caused by an incremental increase in CO2, without considering other factors. In fact, I would think that would be the first thing scientist would do - measure the heat capacity of CO2 absent of any other correcting mechanism. If the incremental change is truly miniscule, like I wrote above, and responsible only a small fraction of the measured warming, then we should not be spending precious resources to control something which has little affect on climate. From what I have learned, water vapor and methane are far more potent greenhouse gasses and CO2 concentration changes barely make a dent in the total greenhouse capacity of the earth's atmosphere because of the abundance of water vapor.

Dano said...

I must say, Andrew, that you sure do get some interesting denialists.

Anyway, I agree with Coby. It's too close to elections to be believeable; this is the outfit that hired George Deutsch - we're supposed to believe this??



Mark UK said...

It is good news, even if it is because of elections. It shows politicians now realize that people care...

Steve Bloom said...

Call me cynical (along with Coby and Dano), but of course the nature and timing of this announcement are designed to obtain political advantage while still ensuring that Bush will do *nothing* on global warming during his final two years in office.

Dano said...

I don't think you want anyone to call you Dano, Steve - think of the increased trouble you'll have then ;o) .

But upon reflecting on the number and the year, 450 ppmv by 2106, well, this is a crock. We'll be at 450ppmv ~2050 at these rates. I understand what Andrew is saying, but I think the date is bo-o-gus.

It's, in effect, saying 'more study needed'.



George Landis said...

Steve, coby and dano, I agree and I certainly hope you are right.

coby said...

DB Paul,

Why don't you try some basic research on the topic before arriving at such misinformed opinions? I highly recommend starting with the IPCC report and it's overiews of how the climate system works.

Suffice to say that all those things "you would think" climate scientists would study have been studied and your figure of warming per ppm CO2 is incorrect, hence your predicted climate change is incorrect.

Why do people assume climate scientist are all total idiots?

D. B. Paul said...

Hey Coby,

I never said or assumed all climate scientists were idiots. I came to this forum looking for answers myself and self-righteous people like make it impossible to carry on a reasonable debate. If you read my post carefully, I was questioning the numbers I presented and not presenting them dogmatically. I was wondering where the analysis of the heat content of CO2 was - I have never seen it before. I didn't make any predictions either. I was just asking. All I hear from the likes of you is dogma without proof.

George Landis said...

db paul, if your assumption is as coby indictes, it would of course be correct and highly perceptive of you. Yes, the UN is a great storehouse of wisdom and science, who could possibly doubt that? Look at all the things the UN has accomplished for the world.

Andrew Dessler said...


The canonical wisdom is that a doubling of CO2 (from 280 to 560 ppmv) causes a temperature increase of about 3 deg C. That translates into about 0.01 deg C/ppmv. I'm not sure where you got your number, but it seems a bit low to me.


coby said...

A quibble, one that Andrew knows much better than I: CO2's effect on temperature is not linear, thus it does not really make sense to attribute any number of degrees warming to any fixed increment of CO2. .01oC/ppmv will only work as an approxiamation while levels are where they are now. The higher the concentration, the lower the effect of each additional ppm increase.

d.b.paul, what dogma? I only pointed you to the best online resource for everything from the overview and introduction down to the nitty gritty technical details of climate science.

BTW, for a direct answer to your thought that H2O far out dominates CO2 in radiative forcing, you might find these articles informative:

D. B. Paul said...

coby mentioned "The higher the concentration, the lower the effect of each additional ppm increase." I have read that as well, and of course that observation is in conflict with my original question if the GH effect were linear at 0.002 C/ppm CO2. In regards to the non-linear idea, which does make sense to me, I have read that because of this non-linearity, a doubling of CO2 from where we are today at 380 ppm would only increase the GH effect due to CO2 by 10%. If this is true, I am not sure how we can have a runaway GH effect as some have predicted. If these numbers are correct (does someone have different numbers?), or close to correct, and if the effect is that non-linear, I don't see the benefit of setting CO2 caps.

ttyler5 said...

Dr. Dessler,

As I have noted here before, I am engaged in studying climate science and have withdrawn from any public debate over global warming until such time as I feel competent to discuss the science which is actually behind the public discussion.

However, as a citizen deeply concerned with our national security as well as with our national economic well-being, I am very much interested in seeing our nation begin to move substantially away from fossil fuels, beginning now.

Obviously such concerns overlap significantly with concerns over global warming, including the timetable for action.

Have you considered the ultimate persuasiveness of a case for action now based on all three of these areas of concern combined?

Andrew Dessler said...


Obviously there are multiple issues revolving around energy policy in addition to climate change. I am also concerned about energy security. I think that any policy we adopt to address climate change should also address the other issues, e.g., energy independence, regional air pollution, etc.


Dr. J said...

db paul, it is useful to understand that CO2's direct effect on climate is not linear since there are a dozen or more major factors that also change climate, some up, some down. The climatologists need to quit implying that this single factor correlation (weak at best)proves attribution, and thus implying that temperatures will move in lock step with CO2, it just isn't that simple, or true and cannot be proven scientifically. I'm sure Dr. D is not trying to mislead you in that, but I know others do, and it is intellectually dishonest.

Andy said...

I'm guessing that the Bush Administration's plan would to be to allow the global community to greatly overshoot the 450ppm target and then come back down to it by the 2106 deadline. Essentially requiring nothing in the way of action right now.

I have a question about the recent reports of accelerating ice cap loss. What, if any, would the loss of floating ice mass be on Texas sea levels? Would the loss of this much mass at the poles allow oceanic waters to be released from polar regions via the loss of gravitational pull and migrate towards lower latitude seas like the Gulf of Mexico?

coby said...


The GHE raises the earth's temperature 33oC above where it would otherwise be. A 10% increase would then mean 3.3oC warming, which is pretty close to model derivations of climate sensitivity. All indications are that this is a very rapid and large climate change for the globe. That is why emissions reductions are urgently needed.

I am not aware of any scientifically supported prediction of a runaway GH warming. There are potential (almost certain) feedback effects, but none indicate any danger of a Venus like situation on Earth.

EliRabett said...

Dear DB, ln(1+x) ~ x for small x. Forcing in [CO2] is logarithmic at least for small intervals.

Dr. J said...

Andy, please do not worry about sea level rise doing anything within your or any of your relatives lifetimes for many, many generations. Look at this data of sea level rise since the last ice age:

And remember, this cycle has happened many, many times in earth's history.

Now, look at the part that is due to natural variations of climate untouched by human SUVs (before 1975), and then look at the few inches (at most) that are possibly due to humans in the last few decades. It is astonishing and disappointing to me as a scientist that anyone could possibly worry about sea level changes caused by human induced warming given the huge amount caused by nature. The human noise is totally overwhelmed by nature's much more powerful and cyclical signal. Please Andy, do not worry, your beach property may be wiped out by a hurricane, but it will not be flooded by sea level rising from satanic human gases.

Andrew Dessler said...


Loss of floating ice has virtually no effect on sea level. Greenland, however, has enough ice to raise sea level by 20 ft. However, our best guess is that it would take several centuries to melt Greenland.

As far as your suggestion that the Bush plan allows CO2 to overshoot 450 ppmv and then bring it back down, that doesn't really work out. The lifetime of CO2 in the atmosphere is a few centuries, so if you overshoot 450 by any significant amount, you cannot bring it back down to 450 by 2106.


ankh said...
Much of recent sea level rise has been attributed to global warming.
Temperature changes during a similar period and possibly responsible for causing the observed sea level rise.

EliRabett said...

There is incresing evidence that we don't have the mechanics of ice flow right, and that the rise can be much more rapid than foreseen in the TAR.

See for example this and this.

Dr. J appears eager to play bet your grandkid's life.

Dr. J said...

Ah yes, of course Dr. Hansen again. He was the science consultant for Al Gore, who in his movie stated that a 20 foot rise in sea level is a realistic, short term probability. However, you will find very few scientists who share that notion.

Let me again point to the scientific data that shows this: Natural warming and climate variations since the end of the last ice age have increased sea level by 130 metres, most all of that in a 5000 year span (say 2.6 cm/year). Now human CO2 has risen sea level (even if we say 100% is due to humans with 100% probability, an impossible certainty) by, at most, 19 cm over the last 120 years (say 0.16 cm/year, and the graph doesn't show any hockey stick recently). Now tell me what is more important, human CO2 or natural variations in sea level rise over the last 14,000 years? You blindly homocentric people out there need to use your brains for something other than to declare humans the most powerful force on earth, we aren't even close.

Oh, I know, but now is different, we can just ignore all that historic data because humans are now responsible and dirty and the last few decades are all we need to know or study, along with computer output, since that must be right. Again, look out your window and see if you see the earth's curvature, if you don't then why believe anything beyond your human view? That is the same as ignoring millions of years of scientific data and the power of nature, it's unscientific, among other things.

EliRabett said...

Well, Dr. J. is in his drive by van again. Hansen WAS NOT THE SCIENCE COMSULTANT Al Gore's Inconvenient Truth, either the book or the movie.

Put up or shut up Julius, which is street for reference please.

And, oh yes, if the movie or book used information from Hansen's publications, that does not make Hansen a consultant to Gore, anymore than any other reference.

Dr. J also needs to understand that we may be entering a regime change for ice dynamics, something the earth has not encountered for hundreds of thousands of years.

Mark UK said...

DR J seems to think all processes in nature are linear? That's the ptoblem. They are not...

Dr. J said...

No Mark UK, I do not and I have never said that, so go put your words in somebody else's mouth, like your own, since you are not understanding me.

References? How about this one, just read where Dr. Hansen admitted to reviewing and commenting about the science on Gore's presentation (at Gore's request)that soon became his movie. Doesn't that mean he acted as a consultant? Or are you parsing denialist words again Mr Rabett?


Mark UK said...

I think Gore's movie is mostly very good. As did the vast majority of scientists whose opinion was asked about it. Just like the vast majority of scientists supports the science indicating AGW.

I am not putting any words in your mouth J. You do that perfectly well yourself.

Mark Uk said...

As far as Hansen being a consultant for Gore or not... I don't see what difference it makes to the science?

Mark UK said...

It must be a difficult time for a GW skeptic. More evidence all the time for AGW and more evidence throwing out sun spots as the cause.

Add to that the fact that even the Economist, Republicans and right wing Christians are deciding to accept main stream science... Tough times indeed

EliRabett said...

Let us review the bidding here. Dr. J's claim was that:

"He was the science consultant for Al Gore, who in his movie stated that a 20 foot rise in sea level is a realistic, short term probability. However, you will find very few scientists who share that notion."

I replied

"Well, Dr. J. is in his drive by van again. Hansen WAS NOT THE SCIENCE COMSULTANT Al Gore's Inconvenient Truth, either the book or the movie."

First of all, Gore NEVER said that a 20 foot rise in seal level is a realistic SHORT term probability. It is a long term probability if AGW continues.

Second, if you look at the URL J provided , Hansen wrote

"My next interaction with Vice President Gore was in January 2006 in a meeting at his request to discuss current understanding of global warming. In this meeting he apologized (I presumed it was in regard to the request for an Op-Ed article), said that he would like me to be on a board overseeing a campaign to alert Americans to the dangers of global warming, and asked if I would critically review his slide/PowerPoint global warming presentation. I did not agree to be on the board, but I subsequently (February 6) reviewed and offered scientific comments on his presentation."

The film was shown January 24, 2006 at Sundance. Books also need to be finished before they are printed most places in the universe, so clearly Hansen was not science advisor to the movie or the book, although he did offer personal science advice to Gore once in 2006. Offering advice does not make one an advisor.

It is worth looking at Hansen's opinion on sea level rise

Hansen points out that it may only take centuries. That is a short enough time that if you hurry up and buy your Hummer now you may be able to screw your great grand kids. In Hansen's words:

"A 20-meter sea level rise is not required to wreak havoc with civilization today. Three-quarters of a meter each from Greenland and Antarctica would do the job quite well."

Apres J le Deluge or, what has posterity ever done for J pretty much sums it up. But to succeed he has to anyone who would stand up to his tictacs.

Some more from Hansen's statement:

"In my “Iowa talk” (available at above website) I indicated that my favorite for President in 2004 would have been John McCain, but he was not on the ballot. I appreciated the priority he gave to both decreasing the power of “special interests” in politics (campaign finance reform) and global warming, in addition to the fact that he calls a spade a spade and is an American hero. I indicated that I would vote for John Kerry because he recognized the global warming problem and he said that he would work with industry leaders to address it, but I also noted that I had reservations about Kerry (citing his appeal to Nevada voters to have no nuclear waste disposal there).

As for “ties reaching to the top of the Democratic Party”, early in the first Clinton/Gore term I was invited to and attended in the White House a “breakfast with the Vice President” (along with Joyce Penner and Bob Charlson), which was my only meeting with Gore during his eight years in the White House. In the middle of the Clinton/Gore administration, after publication of an Op-Ed in the New York Times (by Greg Easterbrook, I believe) that Vice President Gore objected to, it was suggested to me (via an intermediary) that I write an Op-Ed article to dispute the published Op-Ed article. I declined to do that. My next interaction with Vice President Gore was in January 2006 in a meeting at his request to discuss current understanding of global warming. In this meeting he apologized (I presumed it was in regard to the request for an Op-Ed article), said that he would like me to be on a board overseeing a campaign to alert Americans to the dangers of global warming, and asked if I would critically review his slide/PowerPoint global warming presentation. I did not agree to be on the board, but I subsequently (February 6) reviewed and offered scientific comments on his presentation.

I have great respect for Vice President Gore and his dedication to communicating the importance of global warming. He has a better understanding of the science of global warming than any politician that I have met, and I urge citizens to pay attention to his presentation, which I understand will come out in the form of a movie. Even if you don’t agree with Vice President Gore’s politics, you should pay attention to his climate message. He knows what he is talking about."

Andy said...

Hey, this is great. I appreciate the dialogue.

Another question about sea level rise but first some background on what I do. I'm a coastal wetland ecologist. A single foot of eustatic sea level rise will cause major changes to occur throughout the Gulf of Mexico tidal and supratidal wetlands let alone a meter or multiple meters. Right now much of our coastal wetland bounty appears to be a geologic legacy of slightly higher (a meter or so) sea levels in the recent past (1,800 years BP) that receded and left us with millions of acres of incredible marshland. Texas and Louisiana host many of the Nation's wildlife refuges, the bulk of which are less than a meter above sea level. Less than a foot of relative sea level rise (from subsurface water withdrawal) caused the loss of essentially all of the tidal wetlands at one of Texas' State Parks for example. At another site about 4 inches of elevation loss precipated soil changes that caused the loss of hundreds of acres of marsh. So you can see my interest is in the here and now of sea level rise.

Most geologists don't appreciate the biologist's perspective that even relatively tiny amounts of sea level change can have huge adverse effects on today's coastal flora and fauna. These impacts are made catastrophic because human development has: 1) broken apart the natural means by which marshes are formed (riverine deposition and longshore drift of shoreline sediments), and 2) almost all lands above the marshes are developed and unavailable for marsh retreat.

My question is: how do we keep track of eustatic sea level rise? Tide levels vary on not wholly predictable 20-30 year cycles in the Gulf of Mexico and these natural cycles tend to mask eustatic changes. I don't want to wait 60 years to be able to definitively tell folks what the current rate of sea level rise in
Texas is. Is there a dependable way to detect eustatic sea level change that is essentially instantaneous other than change of volume relationships (ie.estimates based on volume of ice loss)? Is this information available?

Andrew Dessler said...


Most of our long-term records of eustatic sea level rise come from the global collection of tidal gauges. Adjusting for rise or fall of the land as well as tidal effects is an issue, so there is some uncertainty in the measured rise.

In the last decade or so, we've been able to measure sea level from orbiting radar. This is vastly superior and has really improved our knowledge of sea level. See for more about this.

The bottom line is that sea level is going up. Unfortunately, we really can't predict how much with much accuracy. A canonical number is around half a meter over the next hundred years, but that number is a few years old and might significantly underestimate the real rise.


Bill F said...

In terms of the sea level along the Texas coast, you should be far more worried about coastal subsidence than sea level rise. Subsidence is occurring in most areas of the Gulf Coast at a rate that far exceeds the rise of sea level. That isn't to say that sea level rise won't be a threat in the future, but it is quite likely that subsidence (and lack of subsequent replenishment due to changes in coastal hydrology and sediment deposition) will claim more wetlands than sea level rise for at least the next 2 decades.

EliRabett said...

Subsidence and global sea level rise, the daily double.