BEN BOVA: Sept. 4, 2011... A slice of irony about global warming

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It’s an ill wind that blows no good.

Measurements have shown that the global-warming trend of the past several decades has slowed considerably since the year 2000.

Global warming is caused, in large part, by the greenhouse gases that we humans pour into the atmosphere every year, mainly carbon dioxide from smokestacks and automobile exhausts.

Sunshine goes through our planet’s atmosphere and warms the ground. The ground re-radiates much of this energy back into the atmosphere in infrared wavelengths. Some of this infrared energy is trapped in the atmosphere by carbon dioxide and other greenhouse gases, making the atmosphere warmer. Like a greenhouse.

This sort of climate change is nothing new in Earth’s history. Our world has gone through ice ages and periods when the global temperature was considerably warmer than it is today.

What is new is that human activities are adding to the natural causes of global warming. Our greenhouse gases are making the warming trend more intense.

Or, at least they were, until about the year 2000. What’s caused the slowdown in global warming?

In part, natural processes are responsible. The oceans that cover three-fifths of our planet’s surface are absorbing some of the heat. Volcanic eruptions spew dust particles into the air, and these particles reflect incoming sunlight, helping to reduce the warming trend.

But just as human activities have helped to exacerbate the warming, human activities are now helping to reduce it. Coal-burning power plants spew megatons of soot into the atmosphere, along with carbon dioxide. Like volcanic ash, these particles of soot reflect incoming solar energy back into space.

China is building new coal-fired power plants at the rate of one per month, and will continue to do so for many years to come. This is part of that nation’s drive to modernize its economy and bring electrical power to the billion or so people spread across China’s vast hinterland.

In essence, Chinese and other nations’ coal-fired power plants are inadvertently producing a global parasol that shades us from some of the sun’s energy and helps to level off global warming.

It’s an ill wind that blows no good.

Soot from coal-burning power plants has usually been regarded as air pollution. It’s bad for the lungs and is a risk factor in many killer diseases, including tuberculosis. I remember my own childhood in South Philadelphia, where a nearby coal-fired power plant coated the neighborhood with gritty soot. My bronchial asthma was especially severe in those days.

But now, in an ironic twist of environmental fate, the coal-burners’ soot is apparently helping to ease the global-warming trend.

The story doesn’t end there, though.

Because of the health problems stemming from coal burning, the Chinese government has promised to install scrubbers that will remove the soot from their power plants, easing the air-pollution problem. But that will also remove the “parasol” effect that has helped to flatten the global-warming trend. Moreover, scientists are seeing serious problems arising from the warming of the oceans. Fish species, corals and other forms of sea life are endangered by the warming waters. The oceans are growing more acidic, too, as they absorb all that carbon dioxide.

The oceans can’t keep storing carbon dioxide forever. Sooner or later, they will reach a limit and start to release the CO2 back into the atmosphere. When that happens, global temperatures will start to soar again, probably faster and steeper than ever before.

At that point we could see a tipping point, where the world’s climate suddenly becomes much warmer. Within a few decades — not centuries — glaciers in Greenland and Antarctica could melt down, sea levels rise disastrously, droughts parch farmlands and tropical storms become much more frequent and severe.

It isn’t a choice between increasing sooty air pollution or catastrophic global warming. The warming will happen, sooner or later, unless we wean ourselves off fossil fuels and turn to cleaner sources of energy.

Probably we will do nothing of the sort. We will continue to burn coal and oil and natural gas. We will continue to hold meetings and issue warnings. Until that tipping point is reached.

Then we will die. By the tens of millions.

Among Bova’s 124 books is “The Green Trap,” a technothriller about developing hydrogen fuel. Bova’s website address is www.benbova.com.

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Comments » 1

JohnB writes:

So we are causing global warming and you say at the same time we are causing to to cool. And you wonder why more and more people are not buying it.

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