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Tuesday, August 19, 2003

Hot Summers, Climatic Change, CO2 and the Arctic Ice Cap

Sometimes I can't help asking myself why I don't keep my big mouth shut. Not content with suffering the heat, I have now found myself condemned to an afternoon's idle reading trying to justify a throwaway comment. The source of the problem: CO2 gas emmissions. My inculpator on this, as on so many ocassions, is of course my German alter-doppleganger, Joerg:

German TV showed a report on British wines last week. Have you tasted any? Any recommendations I might feel tempted to act upon?

Yes, there obviously is some warming going on. But the causality is not at all clear (this is about the only topic where I seem to be on the same page as Bush). First, we have to look at our current experience in its global and historical context. Just do some googling and you will see that in places like Peru, Zimbabwe and Illinois temperatures seem to have never before been as low at this time of year as they are now. 800 years ago there were vineyards in Britain, too. Shortly after that, a "mini ice-age" began. The oceanographers at Woods Hole in the U.S. theorize that it came about due to long-term cyclical changes affecting the gulfstream - which, they think, might go through another iteration within 10 to 150 years, again freezing rivers climatologists last saw covered with ice on 17th- and 18th-century paintings.

Then there is the cosmic-ray-flux business...The big hole in the carbon-dioxide theory is that it cannot account for what happened on earth during its early history when the sun was 30% cooler than it is now. Scientific progress on this front is not at all being furthered by political comments from climatologists in the "Guardian" about global warming being a weapon of mass destruction that unfortunately Bush and Blair do nothing about: One of the variables affecting cosmic ray flux is the position of the solar system in our galaxy - I am afraid there is not much we can do about that. However, even in the context of the cosmic-radiation hypothesis there is room for supposing that carbon dioxide may be a secondary driver of (possible, but not yet proven) global warming that we should try to get rid of in the long term. But that means that the EU will have to rethink its stance on nuclear energy (certainly getting more hot water out of it than originally calculated doesn´t amount to an objection - there must be uses for that). We won´t get ahead on the road to Kyoto if we muse about every bird killed by wind rotors, every dam flooding a valley and every extra gallon of hot water.

I'll leave, if I may, the wine jibe to the end, and maybe I should start with the easy bit first: my comments about the external overheating of the French nuclear industry was not intended as being either in favour or against nuclear plant as such, it was simply an observation about how even the best made calculations can often ignore some apparently trivial details which later turn out to be important. Now on the CO2 emmissions front, I will be the first to own up to having no special scientific expertise, that was why I used the term 'best guess', since that is what we 'the people' have to do all the time in a democratic society in a technological age. To take another example, I have no knowledge of whether stem cell research will be as important to the future of genetics as its advocates claim, but as long as I have no special problem with the idea that it will be, then I have no problem with a change in the law that makes it possible. In holding opinions we are forced to do this sort of thing every day (in fact I may be wrong, but taking sides in the CO2 debate is easier for me than deciding what really should have been done about Iraq): I simply read up on the best available information I find, and make a judgement, a judgement which may or may not be well founded.

Fortunately I am not alone in doing this:

Before last year's elections Frank Luntz, the Republican pollster, wrote a remarkable memo about how to neutralize public perceptions that the party was anti-environmental. Here's what it said about global warming: "The scientific debate is closing [against us] but is not yet closed. There is still an opportunity to challenge the science." And it advised Republicans to play up the appearance of scientific uncertainty. But as a recent article in Salon reminds us, this appearance of uncertainty is "manufactured." Very few independent experts now dispute that manmade global warming is happening, and represents a serious threat. Almost all the skeptics are directly or indirectly on the payroll of the oil, coal and auto industries. And before you accuse me of a conspiracy theory, listen to what the other side says. Here's Senator James Inhofe of Oklahoma: "Could it be that manmade global warming is the greatest hoax ever perpetrated on the American people? It sure sounds like it." The point is that when it comes to evidence of danger from emissions — as opposed to, say, Iraqi nukes — the people now running our country won't take yes for an answer.
Source: Paul Krugman NY Times and PK Archive

All of which awakes Paul Philp over at Long Harvest from his all too dogmatic slumbers:

Global Warming a scientific certainty? Hardly. Global Warming isn’t science. The question of Global Warming and the impact of man made CO2 isn’t a scientific question. It’s an engineering question. It’s a think tank question. It’s a policy question. It is many things except science. When the apocryphal apple fell on Newton’s not-as-apocryphal head, Newton didn’t jump up and say “Why are apples falling? Whose fault is it? What, if anything, needs to be done?” Newton’s question was “What’s up with the falling apples?”. He was inspired by curiosity, what Richard Feynman calls “The Pleasure of Finding Things Out”. The science questions include “What’s the history of the atmosphere? How did it evolve? What’s the connection between the atomosphere and life?” and “What is climate? Where does it begin? and end? What endogenous features account for the climate’s dynamics? How does the climate change as the sun’s hear flow changes?”

These are interesting questions which lead to interesting science. One noteworthy result is that the answer changes as we shrink and expand our time horizon. The science looks different when you focus on the climate with a 1 year lens or a 10 year lens or 1,000 year leans or a 1,000,000 year lens. The changes in the atmosphere and climate as life evolved on earth are wonderous. James Lovelock and Lynn Margulis proposed the theory that the ‘biosphere’ is a self-regulating, self-producing system which is far more complex and robust than are scientific models of the atmosphere and climate suggest. This is where science is happening.

It is frequently claimed that atmospheric CO2 is at an all-time high. This is blatantly false. Over the history of life on Earth, atmospheric CO2 is near an all-time low. Over the past century the CO2/O2 ratio has reversed trend reduction very slightly but there is no scientific consensus on the meaning or causes of this fact.

What is clear hear, and in this Philp is certainly right, is that there is no scientific consensus on this (and hence Frank Luntz is not an especially good source to lean on for authority), but since there is no consensus Philp has no more 'hard' justification for his views than Krugman has for his (or I for mine). Philp is in fact exploiting a rhetorical loophole to effectively say that since the role of CO2 isn't proven we can assume it isn't important. Well there are a hell of a lot of good scientists around who would want to disagree with that.

First of all, one thing is for sure, global temperatures are on the way up, even if this doesn't rule out that sometimes in some places it's cooler. At the same time CO2 emmissions have been rising steadily. This correlation has lead many scientists to draw the conclusion that there is a CO2 forcing effect, among them Jim Hansen, lead researcher on a climate warming study at NASA's Goddard Institute for Space Studies:

The GISS "SI2000" climate model provided a convincing demonstration that global temperature change of the past half-century is mainly a response to climate forcing agents, or imposed perturbations of the Earth's energy balance. This is especially true of human-made forcings, such as carbon dioxide and methane, which trap the Earth's heat radiation as a blanket traps body heat; thus they cause warming.

The computer model's ability to simulate the past 50 years of global temperature change provided confidence in understanding the causes behind climate changes that have occurred over that time period. The sensitivity of the "SI2000" model to a climate forcing is comparable to that of other climate computer models. Model results from 1951-2000 are in close agreement with observed changes; the surface has warmed by about .5ºC (0.9ºF) while the upper atmosphere (10-15 mile altitudes) has cooled by about 1ºC (1.8ºF).

The climate model was then used to simulate global temperature change during the next 50 years, under two contrasting assumptions for future growth of human-made forcings.

The first assumption for the emissions of GHGs is the "business-as-usual" scenario where GHGs continue to increase rapidly. This scenario leads to an accelerating rate of global warming, raising global temperature to levels that have not existed during the past several hundred thousand years.

In the "alternative" scenario, in which air pollution is decreased and fossil fuel CO2 emissions are stabilized, further global warming is limited to 0.75ºC (1.35ºF) in the next 50 years. Hansen cautioned that the 'alternative' scenario will not be easy to achieve. It requires that the world begin to reverse the growth of true air pollution (especially 'soot' and the gases that control surface ozone, including methane) and also that we flatten out and eventually begin to decrease CO2 emissions.

The climate forcing agents that Hansen and his co-authors include in their climate simulations are: (1) long-lived greenhouse gases such as carbon dioxide, methane and the chlorofluorocarbons; (2) stratospheric aerosols (fine particles) from volcanic eruptions; (3) variations in the Sun's energy indicated by sunspots; (4) ozone changes - both at the surface (a pollutant) and upper atmosphere (protects from the Sun's ultraviolet rays); (5) stratospheric water vapor and; (6) tropospheric air pollution aerosols, including black and organic carbon (soot) and sulfates.

Achievement of stable CO2 emissions, as required in the alternative scenario that yields minimal climate change, it is likely to require some combination of increased energy efficiencies, a growing role for renewable energies, capture and sequestration of CO2 emissions, and/or increased use of nuclear power. All of these possibilities are being addressed by the National Climate Change Technology Initiative.

"Decision-makers, including the public, may need to consider all of these options as climate change becomes more apparent and as our understanding of the climate forcing agents improves," Hansen said. "Halting and reversing the growth of air pollution is possible with existing and developing technologies. It would have other benefits, especially for human health and agricultural productivity."

Note the reference to variation in the sun's energy, this is also the topic of another piece of research at the Goddard Institute:

Since the late 1970s, the amount of solar radiation the sun emits, during times of quiet sunspot activity, has increased by nearly .05 percent per decade, according to a NASA funded study.

"This trend is important because, if sustained over many decades, it could cause significant climate change," said Richard Willson, a researcher affiliated with NASA's Goddard Institute for Space Studies and Columbia University's Earth Institute, New York. He is the lead author of the study recently published in Geophysical Research Letters.

"Historical records of solar activity indicate that solar radiation has been increasing since the late 19th century. If a trend, comparable to the one found in this study, persisted throughout the 20th century, it would have provided a significant component of the global warming the Intergovernmental Panel on Climate Change reports to have occurred over the past 100 years," he said.

NASA's Earth Science Enterprise funded this research as part of its mission to understand and protect our home planet by studying the primary causes of climate variability, including trends in solar radiation that may be a factor in global climate change.

Oh and don't forget, there is also the problem of soot:

A team of researchers, led by NASA and Columbia University scientists, found airborne, microscopic, black-carbon (soot) particles are even more plentiful around the world, and contribute more to climate change, than was previously assumed by the Intergovernmental Panel of Climate Change (IPCC). The researchers concluded if these soot particles are not reduced, at least as rapidly as light-colored pollutants, the world could warm more quickly.............The researchers found the amount of sunlight absorbed by soot was two-to-four times larger than previously assumed. This larger absorption is due in part to the way the tiny carbon particles are incorporated inside other larger particles: absorption is increased by light rays bouncing around inside the larger particle. According to the researchers, the larger absorption is attributable also to previous underestimates of the amount of soot in the atmosphere. The net result is soot contributes about twice as much to warming the world as had been estimated by the IPCC. Black carbon or soot is generated from traffic, industrial pollution, outdoor fires and household burning of coal and biomass fuels. Soot is a product of incomplete combustion, especially of diesel fuels, biofuels, coal and outdoor biomass burning. Emissions are large in areas where cooking and heating are done with wood, field residue, cow dung and coal, at a low temperature that does not allow for complete combustion. The resulting soot particles absorb sunlight, just as dark pavement becomes hotter than light pavement.

So now you've got it haven't you, all these problems mean that things are going to warm up a bit aren't they? Well no, and here Joerg really has a point, the answer must surely be: it depends. For starters the global climate is subject to long term changes which we don't really understand. But secondly, and more interestingly in the present context, all this warming could be a prelude, via it's effect on gulf stream irrigation, to a significant cooling - at least in Europe:

The Arctic ice cap will melt completely within the next century if carbon dioxide emissions continue to heat the Earth's atmosphere at current rates, according to an international study. "Since 1978, the ice cap has shrunk by nearly 3 or 4 per cent per decade. At the turn of the century there will be no more ice at the North Pole in summer," one of the study's authors, Professor Ola Johannessen, said. "If the CO2 emissions continue to accelerate, that may occur sooner, but if we cut them back the process will be slowed," Professor Johannessen of the Nansen research institute in Bergen, Norway said. Observations of the Arctic by satellite show that the polar ice cap has shrunk by one million square kilometres over the last 20 years and is only six million square kilometres in the summer. According to Professor Johannessen, the total melting of the ice cap would set free a massive flow of cold water, which would strongly reduce warm surface ocean currents such as the Gulf Stream. The Gulf Stream is the reason behind Europe's temperate climate and a reduction in its influence would have serious consequences for climate and the ecosystem in the continent. However Professor Johannessen also said that contrary to received wisdom, a melting of the ice cap would not entail a rise in the level of the oceans. "Because the ice cap is already in the water when it is melting, you are not adding any mass," he said. "Only precipitation, discharge from rivers and the melting of glaciers can cause the water to rise," he said. He added that the disappearance of the Arctic ice cap would benefit maritime transport as it would create a new northern shipping route along Russia's northern coast which could save some 10 days in journey time between Europe and Japan. Ironically, the expanded ocean would also help absorb the carbon dioxide emissions which caused the ice cap to disappear in the first place. "The ocean will play a major role in absorbing CO2. Out of the seven gigatonnes of CO2 that we emit today, the ocean is absorbing 2.5 tonnes just naturally. The bigger the ocean is, the more CO2 it will be able to absorb," Professor Johannessen said.
Source: ABC News Online

So there we have it, we're either going up or going down, the least likely option is, it seems, that we stay where we actually are. If you want the original Johannessen paper you can find it here, and if you want a really good read on this and other topics you could start with William Calvin's A Brain For All Seasons.

Phew, this has been a hot post, so I think I'll end up with a nice British wine, a cool glass of Hereford white perhaps, or maybe something Scottish now I learn the gulf stream may be in danger.

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