Climate change is happening, whether one chooses to link that
to anthropogenic greenhouse gases or not.

Some may prefer the theory
put forward by Vladimir Shaidurov of the Russian Academy of Sciences
who believes that the Tunguska Event–when the Tungus meteorite
exploded in the sky of remotest Siberia with the force of 15 atomic
bombs and flattened 60 million trees in an area of more than 2,000
square kilometers on June 30, 1908–has perturbed the levels of water
vapor in the atmosphere. According to Shaidurov’s theory, this
mysterious event is responsible for the present warming trend (a
preprint of a paper outlining this idea is available here.)

Whatever the cause, the warming is real, as the readers of the Nunatsiaq News, the local paper of the Canadian Arctic,
well know. Residents there face eroding towns, longer springs and
shrinking Arctic sea ice cover as a result of the warmer temperatures,
facts backed up by NASA research. This warming puts all the residents of the Arctic at risk,
especially the large mammals, such as polar bears and reindeer. And the
problem may not stem solely from the nearly 6 billion metric tons of
carbon dioxide–the most ubiquitous greenhouse gas–spewed by the
Arctic’s southern neighbors in the U.S. It may also arise from the smog
we produce in abundance in the lower 48 states, according to a new report from NASA’s Goddard Institute for Space Studies.

Burning
fossil fuels, making cement–there are a host of ways humans produce
ozone, known as smog when it lingers too close to the ground (and known
as the ozone layer when it protects us from harmful UV radiation in the
upper reaches of the atmosphere). In winter and spring, the ozone
produced by countries like the U.S. migrates north and settles over the
Arctic, where, in the absence of sunlight, it does not break down. This
thick layer of smog may be responsible for as much as half of the
observed warming trend, the NASA scientists report.

This means
that the Bush administration is taking action on climate change after
all, albeit unknowingly. Under the Environmental Protection Agency’s
Clean Air Interstate Rule, power plants across the country are cutting
back on the nitrogen oxide pollution that leads to smog. The program
employs a cap-and-trade approach wherein an overall level, or cap, is
set for a given pollutant and then companies are permitted to trade
allowances to meet that limit. Of course, that is the same approach for
a different pollutant–carbon dioxide–adopted under the Kyoto
Protocol, which the U.S. government rejected. But in the case of smog,
electricity producers in the U.S. have been trading allowances to emit
the stuff for two years now, under a declining cap set up by the EPA.
And that cap will get even more restrictive going forward (just how
much is a matter of some debate).

Of course, this may prove
too little, too late in the grand scheme of climate change–nitrogen
oxides account for less than 6 percent of U.S. greenhouse gas
emissions–but it is better than nothing. And it could eventually lead
to a cap-and-trade program for carbon dioxide in this country. If that
tighter cap fits, we should wear it, no matter how warm it is outside.

By David Biello
ScientificAmerican.com