Misguided Hopes and Global Warming

Here’s a thought: Planting more trees won’t save us from global warming, contrary to the thinking of the Kyoto Accord. We’re just gonna have to reduce the amount of greenhouse gases that we’re spewing in the air. One of them in particular, carbon dioxide, is expected to double by 2010 if we don’t change our evil ways….

Carbon Dioxide Theory Doubted
Originally published Tuesday, June 1, 2004
The Washington Post

Many scientists hope the rising concentration of carbon dioxide (CO2) in the atmosphere will be offset by greater growth of plants on the Earth’s surface. A study in the journal Science suggests this may be wishful thinking.

Plant matter is made up largely of carbon-based molecules synthesized when plants capture CO2 from the air during the process of photosynthesis. The forests, grasslands and phytoplankton of the oceans are all huge “sinks” for carbon in the environment. If plants grow faster or bigger in the presence of more CO2, theoretically they could drain off some of the excess carbon entering the atmosphere through the burning of fossil fuels and other human activities.

A research team led by Bruce A. Hungate at Northern Arizona University studied what happened to Galactia elliottii@, a vine in the bean family that grows in coastal Florida, during a seven-year experiment in which enclosed but roofless plots of land were exposed to elevated concentrations of CO2.

To accumulate carbon in the form of biomass, the vines also have to accumulate — or “fix” — nitrogen, another essential element in living matter. Hungate and his colleagues used nitrogen fixation as a yardstick for growth.

In the first year of the experiment, the vines doubled their nitrogen fixation — clear evidence they were flourishing in response to the higher CO2 levels. That response fell off rapidly, however. In the past three years, the elevated CO2 levels suppressed nitrogen below normal fixation

Why did this happen?

It turns out the vines were running out of molybdenum, a trace metal captured from soil that they need for one of their nitrogen-fixing enzymes. When molybdenum became scarce, the excess CO2 became unusable.

“In a study in grasslands in Switzerland, plants ran out of phosphorus,” Hungate said in an interview. “Plants require many different elements. Restriction of any one of them could restrict their ability to fix more nitrogen — and that could limit future carbon uptake by land ecosystems.”

Here’s another article on the subject:

Smithsonian scientists are studying how a rise in carbon dioxide – a common pollutant – will affect the Earth’s vegetation.

Although politicians argue about the effect, scientists agree that increases in greenhouse gases are warming the planet. And one gas in particular – carbon dioxide – has been rising steadily since the Industrial Revolution began in the 19th century. Scientists expect carbon dioxide levels to nearly double by 2100, and an understanding of the effects of that increase remains elusive.

For example, studies over the past decade have shown that rising carbon dioxide produces increased vegetation, which in turn might absorb much of the carbon dioxide being pumped out by the world’s cars and industries.

But a study published last month in the journal Science – based on field work at the Smithsonian’s satellite facility in Florida – found that increased carbon dioxide levels actually crippled the growth rates of some plants raised in the sandy soils of Coastal Florida.