Monday, February 5, 2007

The Global Warming Controversy

As far as I can tell, the controversy surrounding global warming is much too hot for what it really deserves at this point in time. But there will always be people who overreact, especially if they think the issue is important. Climate scientists understand the consequences and are amazed that much of humanity is willing to go ahead in complete innocence like a bunch of proverbial lemmings blinded by their day-to-day activities. On the other hand, green activists hijacked the issue and made it part of their extreme-left agenda. As a result, many people with a minimum of economic education have become skeptical that maybe the whole story is nothing else but green propaganda. In this shaky context, oil companies, which have a vested interest in postponing as long as possible any attempt to tackle the issue, have used this understandable skepticism to prop up their own propaganda; they have sought and brought into the public attention those few scientists who still doubt the reality of the global warming phenomenon.

The public, unacquainted with how the scientific community works, thinks that the existence of those doubting voices is a big deal. It is not. The history of science is actually quite used to such exotic characters. And it is worth remembering that they were always wrong. (A famous example is Ernst Mach who still doubted the existence of atoms half a century after most physicists had accepted them. Another similar contemporary example is the "intelligent design" scientists.) There's nothing mysterious about the fact that such exotic characters have been and probably always will be wrong: science advances by increasing the empiric accuracy of the theories and as a result it is quite hard for an old theory to be better than a new one (science isn't just about creating stories, it's a quantitative endeavor); moreover, the whole scientific community is usually very conservative, they're not willing to jump to conclusions en mass. This is why it is very unlikely that such "reactionary" characters, of which the scientific community will always have its share, will ever be right. But today we see such characters transformed into superstars by various political forces that don't like what the science is truly saying.

Moreover, the so-called public debate has turned into a "he said that / he said otherwise" kind of "debate". This is utterly ridiculous. What matters are the facts and whether they are interpreted in a reasonable manner. That's what we should focus on and not the literary criticism of various statements made by X or Y (no matter who those are, no matter who's funding their research etc.). So, let me try to give you an overview of why I think our activities are causing global warming and why this is somewhat worrying (especially if we don't do anything about it - however, sometimes the proposed "solutions" are more worrying than the problem itself!).

Some well established theory (I think): The variations in earth's climate depend foremost on tiny variations of earth's orbit and, to a smaller degree, the variations in sun's activity. We obviously have nothing to do with these. Earth's climate also depends on the planet's albedo (how much sunlight is reflected by the atmosphere back into space) and on the composition of the atmosphere (in particular the concentrations of greenhouse gases). The question is whether our activities have a significant impact on the earth's global climate compared to the uncontrollable astronomical factors.

Some facts (disclaimer: I'm a plasma physicist not a climatologist, so I wouldn't know how to react if you deny that these facts are real, because I have neither the time, nor, quite frankly, the inclination to read the actual scientific literature on climate change):

1. Greenhouse gases do absorb heat; it can be demonstrated very easily in the laboratory and we can also determine how much heat each absorbs.


1.bis. There exists a correlation between average global temperature and carbon dioxide concentrations (
link).

2. The amount of greenhouse gases in the atmosphere (especially carbon dioxide) has increased very much in the past century. How much? "Highest value [of carbon dioxide] measured in an ice core: 323 ppm, corresponding to around 1969 levels. So even the pure ice core data show values higher than any seen in 650,000 years [highest value on EPICA graph ~290 ppm]." (
link, comment 27-30) Highest in 650,000 years sounds pretty impressive to me!

3. Human activities (such as burning fossil fuels) do release carbon dioxide into the atmosphere.

4. The industrial revolution took pace around 150 years ago and earth's most populated regions started to industrialize only in recent decades.

Interpretation 1: Given how much carbon dioxide is today in the atmosphere compared to its natural oscillations (fact 2), and given that our activities produce carbon dioxide (facts 3, 4), it isn't such a leap of faith to assume that we are responsible for it (i.e. natural warming does cause a rise in carbon dioxide, which feed-backs the warming, but not to the extent that it's now observed - therefore we are responsible for the fact that there is so much carbon dioxide today in the atmosphere).

Furthermore:

5. The average global temperature today is the highest in 400 years (the last decades being the hottest on record) and probably the highest in 1100 years. (
link)

Interpretation 2: Taking into consideration fact 1 and interpretation 1, it is likely that we humans are the cause behind fact 5 (the rise in the global temperature). How are we doing it? By releasing anomalously large quantities of carbon dioxide into the atmosphere - anomalous on a time-scale of hundreds of thousands of years, i.e. three or four times longer than the time our species has spent on Earth so far.

Is global warming something to worry about? (regardless of whether it's natural or artificial) Some predictions (a prediction is some additional facts + global warming):

p1. Warmer water has a larger volume, thus global warming implies a rise in sea levels.
p1.1. It's estimated that the most populated areas (such as Bangladesh) will sink. If we're to believe Al Gore, other regions include Florida, parts of New York and Shanghai; probably also Venice and Netherlands.

p2. Many water supplies in Africa come from mountain glaciers. The glaciers are melting due to global warming (link) which will cause wide spread droughts. The levels of precipitation are also changing, and not for the better (
link).

p3. Large quantities of methane are now trapped in the Siberian permafrost. As this melts, methane will be released into the atmosphere causing a further increase in global warming (methane is a more powerful greenhouse gas than carbon dioxide). Moreover, the frozen permafrost stores large quantities of yet undecomposed organic materials; as the temperature rises this starts to decompose releasing in the process large amounts of carbon dioxide into the atmosphere (
link). (The melting of the permafrost seems to have also played an important role in past global warmings, being responsible for the observed correlation between temperature and carbon dioxide. Our activities however are adding more carbon dioxide in this story, and the permafrost hasn't even melted yet - this is why the current global warming is unlike any other that existed in the past.)

p4. The ocean temperature is correlated to hurricane and typhoon energy, thus global warming implies more powerful and longer lasting hurricanes and typhoons (although not necessarily more frequent). (
link)

p5. Greenland is melting and flows into the Atlantic Ocean. This causes an increase in sea levels (because the ice that was on land now gets into the ocean) and might cause the North Atlantic current to stop (this current is responsible for the mild climate of Western Europe). It is known that this has happened in the past (
link) and that the current has been diminishing in strength in the past decades (link).

p6. The current climate change happens so fast that animals don't have time to adapt (natural selection works rather slowly). For example caterpillars in Europe appear earlier, before the migratory birds' chicks are born, leaving them with less food (
link). Thus, global warming tends to diminish biodiversity as many species (such as migratory birds) fail to adapt. This favors however the more robust species, such as the agricultural pests (which are left with fewer natural predators) or the mosquitoes which carry malaria (they are now spreading to higher and higher altitudes on African mountains in regions that have been too cold for them in the past). (Or maybe not.)

Another idea:

Maybe a common ground between (anthropogenic) global warming believers and unbelievers could be reached with the help of economics. After all the whole problem is a risk management problem at the global scale. It's not so much of a black/and/white issue as it is a matter of how likely the bad effects are and how bad they are estimated to be. I think that a major road block on the path toward a
viable solution is the fact that the discussion has been hijacked by extremists on both sides (on one hand by those thinking that global warming is such a big threat that we should even give up civilization if that's what it takes to curb it, and those thinking it's just a hoax).

(Apart from trying to stop global warming, maybe the UN could establish an insurance fund for the potential victims of global warming, a fund that will be dissolved if global warming doesn't happen in 100 years.)

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