Sunday, March 14, 2010

Hansen's book and sea level increase

Reading James Hansen's book, Storms of my Grandchildren, has convinced me that AGW (anthropogenic global warming) is a real problem. I won't attempt to summarise the book except to say that it is an outstanding  example of clear science communication to the public.

I haven't looked closely at the issue of species extinction yet but Hansen and other research convinces me that the threat of rising sea levels is real and that the IPCC estimates are conservative. Sea level rise is difficult for humans to adapt to since so many people and important cities are located around the coastline. I hadn't thought about this much before. I had thought that Climate might or might not be changing but the IPCC maximum projection of 59cm in the next century was a maximum and was sufficiently far off in the future to be not a major problem.

Hansen points out that sea level stability has been with us for approximately 7,000 years and that this provided enormous advantages for the emergence of civilisation, such as increased fish breeding around the coasts providing a high protein diet for a settled population. He also uses paleoclimate data to point out that in the previous interglacial, the Eemian, 140,000 years ago, at one stage the climate was only 1 degree Celcius warmer and the sea level was 4-6 metres higher. See Fig. 3 (source)

My thinking was guided by the idea that everything changes continually anyway and in general new technological discoveries can be used to overcome new problems as they arise. I still think this is correct as a generalisation but I can't think of anyway in which new technologies would overcome a significant sea level rise for millions of people. Of course, it's possible / probable that sea level will rise anyway, sooner or later,  and we will have to adapt. But it seems that we have reached the point where we do have some control over the climate and should collectively exercise that control.

Back to the present, the evidence from the GRACE satellites (Gravity Recovery and Climate Experiment) and other data indicates that the ice sheets in Antarctica (especially West Antarctica) and Greenland are losing mass at an accelerating rate. The GRACE figures are in gigatonne per year and the mass loss is accelerating over the period measured (2002-09) on both sheets:
In Greenland, the mass loss increased from 137 Gt/yr in 2002–2003 to 286 Gt/yr in 2007–2009, i.e., an acceleration of −30 ± 11 Gt/yr2 in 2002–2009. In Antarctica the mass loss increased from 104 Gt/yr in 2002–2006 to 246 Gt/yr in 2006–2009, i.e., an acceleration of −26 ± 14 Gt/yr2 in 2002–2009.
- source
A central issue is the inertia of the oceans and the ice sheets. Ice begins to melt slowly but the rate accelerates over time. Ice in the wild has different dynamics. Ice flows, ice can get dirty, moulins can form to accelerate the destruction etc. With oceans the warming process is much slower overall but the quicker part is early rather than late. These combined inertias create the threat that if you go past a tipping point, which we can’t predict, then you can’t recover from it. We may be letting systems which are controllable to an extent slip out of control. With so many people living in coastal regions then anything faster than the IPCC predictions would be a real concern for future generations.

I still think that economic and industrial development is very important for everyone, especially for the developing world. Since we have the nuclear energy option I don't see any reason for pessimism about the long term energy future for humans.  However, the present problem is that nuclear is more expensive and subject to excessive regulation owing to the widespread fear of anything nuclear. These issues have been and are being discussed in detail at Barry Brook's  blog, Brave New Climate.

At the moment I'm particular interested in the threat of rising sea levels. I found another excellent blog, Getting skeptical about global warming skepticism which has a series of posts about this question. This amazing page lists 94 skeptical arguments and links to responses to all of them based on reviews of peer reviewed papers by John Cook, a Queensland physicist. Here are some of the links to Cook's blog which directly or indirectly look at the issue of rising sea levels:

Sea levels aren't rising
Ice isn't melting
How much will sea levels rise in the 21st Century?
Is Greenland gaining or losing ice?
It's the ocean
Arctic ice melt is a natural cycle
Does ocean cooling prove global warming has ended?

Reading these references makes me think that the IPCC maximum estimate is a conservative one and the sea level may well rise faster than that. This video provides an illustration of how the ice sheet dynamics might work, explains the reasons for IPCC conservatism and looks at some of the paleoclimate data. The section right at the end is overly alarmist but overall it's worth watching:


Mark Miller said...

The thing that has frustrated me about the pro-AGW argument (particularly the "anthropogenic" part. The "global warming" part I have no problem with) is it has always boiled down to anecdotes and data correlation, which are very weak from a scientific perspective; or an argument about probability, that the probability is extremely small that it's natural given the conditions over the past 10,000 or 100,000 years (let's keep in mind that the current configuration of our atmosphere has existed for about 400 million years). The question I keep coming back to is "Where is the thermal evidence?" If the greenhouse effect is increasing we should be able to detect that where it takes place; in other words, the heat source itself, not just in the receivers of heat. To my knowledge no one has been able to do this. Does Hansen show warming in the troposphere in his data? If so, I'd like to take a look at his book myself.

The thermal evidence is one of the lynchpins in the anthropogenic argument. Without it it's very difficult to justify an assertion that industrial and/or agricultural activity is the cause of the warming. There are other reasons to worry about both of these sources of pollution. I don't mean to take them off the table. And I think the scientific conclusions that can be drawn will tell us how soon we need to act to avoid catastrophe as a result of these pollutants, but IMO we need to be realistic about it.

Bill Kerr said...

hi mark,

Hansen uses paleoclimate data as his main evidence, current observations second and computer modelling third. He says models are unreliable, good for some things but limited.

I checked the index just then and troposphere is not there. I then checked the skeptical of skeptics site and found this article (Satellite measurements of warming in the troposphere ) which addresses the issue you raise and delivers some satisfaction but is not conclusive. I don't think that issue is central to Hansen's argument since it relies on computer models.

Mark Miller said...

The conclusion at oversimplifies what the executive summary from the U.S. Climate Change Science Program says. In one part of the executive summary it says (which skepticalscience does not quote):

For observations during the satellite era (1979 onwards), the most recent versions of all
available data sets show that both the low and mid troposphere have warmed. The majority of these data sets show warming at the surface that is greater than in the troposphere. Some of these data sets, however, show the opposite - tropospheric warming that is greater than that at the surface. Thus, due to the considerable disagreements between tropospheric data sets, it is not clear whether the troposphere has warmed more than or less than the surface.

Like you were saying, inconclusive.

Perhaps I'm misunderstanding you. You say that the "issue is not central to Hansen's argument, because it relies on computer models." If you're talking about tropospheric warming, the conclusions that AGW proponents have used does rely on computer models, as I think you're saying, but the issue itself--the actual phenomenon--is crucial to any argument about AGW if we're concerned about the actual physics of it. The only exception to this I can think of is if there's some other radiative forcing phenomenon, apart from what is known as the greenhouse effect, which is human induced, and which has not been discovered yet.

I've come around to the idea that there is reason to criticize the current state of our civilization. Kenneth Clark called the era we've been in since the 20th century "Heroic Materialism". In his view the beauty of human creations was replaced by almost purely functional, utilitarian things; gigantism bereft of any aesthetic, certainly any sense of harmony with Nature. He said in the 19th century the philosophies of Malthus and Ricardo took precedence over what was otherwise sensible thought at the time, and their legacies have persisted to this day. It seems to me the movements to try to change things have been efforts to find a workable alternative to this. I'd prefer something along the lines of the Age of Enlightenment and the Renaissance, while still maintaining notions of freedom (though it's hard to say if that's possible, based on history), but humanity has chosen a different path.

Bill Kerr said...

hi mark,

I think what Hansen's book demonstrates fairly clearly is:
-human greenhouse gas forcings have increased to the point where we do influence climate, see Fig 1
- small climate temperature changes, even 1 degree Celcius, do have a large influence on sea levels and species, which are migrating towards the poles (I hadn't been clear about that, the demarcation b/w climate and weather)
- the paleoclimate record shows that sea levels have 4-6 metres higher with only 1 degree Celcius higher difference (some cause for alarm here if it going to happen quickly or if the process becomes irreversible)

At this stage I'm not going to do further deep research into the troposphere issue. I still think that political economy is our main problem and want to spend more time researching that. I agree that parts of the science are still uncertain. However, it does seem fairly clear that the Greenland and West Antarctic ice sheet are beginning to melt, ocean temperature is increasing and sea level rise has accelerated (slightly but significantly). Hansen is an alarmist and I'm not sure that is justified (he does have as much right as anyone to become politically involved) but I do think there is a real problem based on an overview of the science evidence. I don't see how uncertainty on one point about the troposphere is a knockout punch against AGW.

I think the real important issue is how the science, politics and economics connects to each other. I might spend some more time researching that. Check out Roger Pielke's blog, he has some good material on those issues.

Mark Miller said...

If the concern is just about changing from dirty energy sources to cleaner ones, regardless of the existing circumstances, then I can see it becoming a matter of economics, though there are more clear environmental reasons to switch away from certain energy sources. I would think that if AGW is a real problem then it's not a matter of economics, but of survival.

The reason I pressed the issue of the troposphere is if we're concerned about AGW then we're concerned about the greenhouse effect. The two terms are practically synonymous. The difference being that there's a natural GH effect, and then there's the question of our contribution to it. I've already talked about where the GH effect takes place. AGW alarm is primarily concerned with the amount of heat that is being trapped by this layer of air--"trapped" meaning the portion of the energy which is radiated from the surface that is absorbed and then radiated by GH gases, before it finally escapes into space.

The way I understand science to work is that if scientists are noticing something happening, they theorize about what's causing it, and then explore that theory. I don't know of any field of legitimate science which says with a straight face something like, "We're generating more of a substance that we expect to trap more heat. We see certain effects happening (ocean warming, melting glaciers, etc.) which indicate that this is the heat source (which is a big assumption). We therefor conclude that the substances we're emitting are causing it." This represents a short-circuiting of the process, and almost sounds like circular reasoning. There isn't even a pause to test the theory. Most of what's being looked at are indicators of climate change with an implicit assumption of cause, not a theory of cause and effect.

Regardless of criticisms of Richard Lindzen's analysis of the evidence, in that presentation I referred you to earlier (called "Cooler Heads") he laid out some basic principles of science. One of them is in order for a theory to be validated scientists have to show that a theory fits the observed phenomenon well, and all other conceivable possibilities have been considered and eliminated through tests that failed, or come up with murky results with lesser certainty. Until that happens the best anyone can say is "We don't know what's causing it." Since, in the absence of this process, scientists are asserting anyway that "We do know what's causing it" (I recall Hansen saying years ago, "It's obvious that humans are causing it.") this indicates to me that there's something else besides science going on, perhaps indicating that the science isn't really that important to begin with.

Anyway, I know I'm emphatic about this stuff. I hope I'm not coming across as trying to pressure you to change your mind, because that's not what I intend. I just wanted to present a perspective that you had perhaps not heard. We all need to find our own answers to our questions.



Bill Kerr said...

hi mark,

I will look again at what Lindzen said and do some more research, at some time.

Hansen does have several sections about Lindzen in his book, which are very interesting. One of the things he does is outline 6 key differences he has had with Lindzen in an Appendix. He did this early on in the debate because he realised the debate would go on for decades. I thought this approach was great but as far as I can tell not all the loose ends from the Lindzen points are tied up, although some of them are.

Mark Miller said...

If you're interested in looking at the presentation I referred to earlier, you should go here. It was taken down from the old video source I had. This is CEI's own website. They were the sponsor of the presentation he gave.

Bill Kerr said...

hi mark,
I still haven't done a revisit of Linzen's lack of tropospheric warming argument but did come across this summary from Roger Pielke Snr, which includes a reference that the IPCC has overstated the extent, his point 5: Main Conclusions

I've subscribed to both Pielke Jnr and Snr blogs. I think they provide the best commentary on AGW issues.

Mark Miller said...

Hi Bill.

When I was intensely interested in looking at this issue, Pielke, Sr.'s blog was one of the sources I would consult. I was occasionally confused by his conclusions, but I think that was because they were nuanced, and he didn't always clearly communicate what lay behind the nuances. Perhaps my own understanding of the issue had been polluted. Among everyone else that I could see, his assessments were the most sober, and were firmly based in the scientific thinking process. The main thing I noted was the lack of presumptive assertions and hysterics. What pained me was to hear him talk about his encounters with the media, I guess newspapers in particular. He has often been painted as a "denier", or someone who should be disregarded because "he's in the minority", simply because he doesn't toe the party line, and is much more interested in what the evidence says. It seemed like the only reason they'd talk to him at all was so that they could say, "We listened to both sides." This approach not only showed a total lack of understanding of the discipline of science on the part of newspapers, etc., it also showed the total absence of critical thought going on in the public discussion of the issue. As I think you can see, Pielke is anything but a "denier" of the human influence on climate.

The dichotomy between Pielke, Sr. and Pielke, Jr. is interesting. I often got them confused because of their names. I assume they're related. Pielke is not a common name around here. From what I've seen, they each take a different tack on the issue, and they approach it from different angles. From what little I've seen of Pielke, Jr., he seems to think that AGW is likely a problem, but he's open to counter-arguments. From what I understand, Pielke, Sr. is a climate scientist. Pielke, Jr. is not. I may be mistaken, but it seems to me Pielke, Jr. has focused more attention on analyzing the public debate about AGW.

My interest in the issue was more driven by my concern for the integrity of science, and the public's trust in information that was derived scientifically (the "cry wolf" problem). Honestly, though, my heart wasn't really in it. I have decided to distance myself from it. I've had my fill of it for now. I realized that it was distracting me in a significant way from what I really love doing, which is studying computing and searching for a way to apply it that will be relevant and powerful to society.

Bill Kerr said...

hi mark,

Roger Pielke jnr is the son of Roger Pielke snr. Pielke snr is a climate scientist and Pielke jnr looks at the role of science in policy making. See the Q&A at Pielke jnr for more detail.

I think climate science is a fascinating area about the interaction of science with politics and policy making which is the focus of Pielke jnrs research. I will probably keep writing some things along those lines. I'm sure I'll never understand all the nuances of the science. As you imply it's more a matter of finding experts on these complex issues that you can trust. I think the Pielke's qualify.

Mark Miller said...

Hi Bill.

I'll continue commenting on it based on the research that I did--in the past tense. I'm just not going to devote time researching it more.