Friday, August 10, 2007

Astronomy, Global Warmth, and Trees

While technically we're reaching the end (tomorrow) of the dog days, I've always considered August as a whole to be the warmest month of the year. The "dog days" originate in the ancients' idea that Sirius, in the constellation of Canus Major, the large dog, since it is the brightest star in the sky after the Sun, also heats the earth. In late summer the rising and setting of Sirius and the Sun together was thought to produce extra-hot weather.

Speaking of weather (and climate), there was an excellent article in First Things about global warming: "The Politics of Global Warming" by Thomas Sieger Derr. The entire article is excellent, but I can't reprint the whole here, so I'm at pains to excerpt the best part. The overarching problem is censorship, of which Derr cites several outrageous examples. A couple of the tamer remarks: "[Dissenters'] articles are denied publication in Science and Nature, those two so-called flagship science journals of high reputation despite some embarrassing lapses.... Newspapers who seek balance in their reporting are told that they are doing a disservice to the public, to truth, and to the survival of the human race." It's ironic that censorious environmentalists cite non-scientific motivations ("being in the pay of the oil companies") to explain away the opposition, but it is really they who have extra-scientific motivations: how else would they have formed their prejudiced conclusion that global warming must be anthropogenic? It's a matter of faith for these people.

There are plausible alternative explanations to the planet's warming climate that aren't allowed to be heard. Here is one:

So what’s going on? There is a significant body of scientific opinion that finds the sun to be the principal climate driver. The sun’s output is variable and complex, more and less intense at different periods. A German team has shown an almost perfect correlation between air temperatures and solar cycles for the past 150 years. A Danish team likewise has constructed a multi-era match of solar activity (measured by sunspots) to global temperatures. Nigel Weiss of Cambridge University, a mathematical astrophysicist and past president of the Royal Astronomical Society, also correlates sunspot activity with changes in the earth’s climate. Because solar activity is cyclical, he expects that a downturn is coming and will usher in a cooling climate for earth in, maybe, three decades. Actually, global average temperature seems to have plateaued since 2000, though it is probably too soon to expect the downturn to have begun. Still, Richard Lindzen, a distinguished atmospheric physicist at MIT and a leading doubter that human activity is driving warming, thinks the odds are about 50 percent that the earth will be cooler in twenty years—due to natural cycles.

It may or may not be significant, but it is suggestive, that NASA’s instruments calculate that Mars, Jupiter, Pluto, and the Titan moon of Neptune are warming, suggesting a solar-system-wide phenomenon. To be sure, this is not hard evidence; other factors (axis tilt and wobble on Mars, for instance) may be a cause. Still, it may be a clue to what is happening here on our planet.

We think so much of ourselves and our technological accomplishments that we forget that nature has her own dynamics that we must respect, which means not only that we must refrain from meddling unnecessarily but also we must avoid underestimating her power. For all the braggadocio about science (Copernicus) having put man in his puny place in the universe1, it seems that we are more self-centered than ever.

But regardless of what we think of nature, we still need to foster open consideration of all scientific possibilities.

Some caveats are in order. Human activity may add something to the natural cycle, though how much is hard to tell. I have seen a paper that estimates the human contribution at 3 percent and another that gives it at 0.28 percent, for an almost undetectable effect on climate. The principal greenhouse gas, some 97 percent of the total, is water vapor, which leaves little for CO2 and other trace gasses. Scott McIntosh, of the Southwest Research Institute in Boulder, says that warming caused by CO2 compared to the effect of solar magnetic fields is like a flea’s contribution to the weight of an elephant.

We do know, however, that atmospheric emissions can affect climate—for example, the serious consequences of the ash cloud thrown up by volcanic eruptions; so perhaps there is something to the greenhouse-gas theory. People can also argue about the historical record and try to modify the data that shows natural climate cycles. There may be problems with the sun theory; climate is also affected by ocean currents, meteor impact, the tilt of the earth’s axis, cosmic rays, precipitation systems, and other factors. And so on. Those of us who are doubters will not complain when we in turn are doubted. Debate is healthy and must not be choked off.

Indeed, free discussion of the issue is essential. We must eschew the "faith-based" approach that censorious environmentalists insist on.

The Miracle of Trees

In a matter tangentially related, let me suggest that one long-term solution for summer heat is planting more trees where you live and work. (No, I'm not touting this as the solution to global warming, just the solution to local warming.)

Let's forget about the aesthetic value of trees, they're simply a practical solution to the overwhelming summer heat of cities and other inhabited areas. Think about it: when the sunlight hits a city there aren't many places it can go. No matter how much you reflect back into space, a good fraction of the solar energy will be absorbed, usually by asphalt, and released as heat into the air (most noticably at night). Trees do more than just block the solar energy and produce shade, that is, they don't simply shift the energy elsewhere. Rather trees capture the solar energy. Instead of re-radiating heat, trees turn the sun's energy into plant structure (and along the way give off oxygen, which is always nice to have). The sunlight is not simply converted to heat or stored, but converted into something entirely different. And the great thing about deciduous trees is that they shed their leaves in fall, allowing the scarce winter sunlight to reach the ground. All this happens almost automatically—naturally! What elegance!

The "coolest" use of trees I've seen is in Malaga, Spain. The wide avenues are completely covered by a canopy of enormous shade trees. That's a way to cool a city that requires very little human intervention (only people to maintain the trees) and is powered by the very energy that needs to be dissipated. Contrast this elegance with the ubiquitous ham-fisted technological solution: the air conditioner. A/C simply moves the heat from one place to another (typical superficial solution: just shifting the problem somewhere else)... and requires energy input to do so.

What are the obstacles to more trees? The problem is that for individuals plunking down the money for an air conditioner at the nearest Walmart is much easier than controlling the number of trees in their workplace or apartment-dwelling. Planting trees is a more radical solution and requires more societal coordination. Private individuals are free to do so on their own properties. Everyone in a city or town shares the same air, but everyone must individually bear the burden of caring for his own trees. The tragedy of the commons is all too real here. To have an effect on local temperature, we need a large number of people unafraid of bearing this burden for their locales and looking to the elegant, natural solution to keeping cool in summer: plant trees and stay cool.


1. Actually in the Ptolemaic universe, man wasn't so much at the center as at the bottom: the earth was a cosmic sump, and the truly excellent things were exalted in the aethereal trans-lunar heavens. (This is why Dante put the devil at the center of the earth—because it's the lowest, most dishonorable place.)

Thomas Sieger Derr, "The Politics of Global Warming," First Things (August/September 2007), 17-19. Subscription required.