CO2 increase! Atmospheric CO2 acts like fertilizer for trees

Why are U.S. trees growing faster?

By Dennis Avery Saturday, April 10, 2010

Trees in the U.S. are growing 2–4 times as fast as their long-term norm. The Smithsonian Environmental Research Center at Edgewood MD says it is because of global warming, according to a recent press release. Don’t bet on that.

Smithsonian researchers measured a series of forest plots at different stages of growth from 5 to 225 years of age. They found that more than 90 percent of the trees grew 2-4 times faster over the past 20 years than predicted from baseline growth rates.
Helpfully, lead author Geoffrey Parker tells us that there are three main possibilities why the trees might be growing faster:
A) the official temperatures in the region have increased about 0.3 degree C over the past 20 years;
B) There’s been a small expansion of the growing season; and
C) CO2 levels have risen about 12 percent over two decades.

Dr. Parker seems to have chosen A), higher temperatures, as the correct answer. But do facts support the choice?
First, we have to question how much the Maryland forest temperatures have actually increased over the last 20 years. Meteorologist Joe D’Aleo charges that the official U.S. temperature record has been systematically shorn of its low-temperature stations—those at high altitudes, high-latitudes and/or in rural areas. It’s as though NOAA has decided to record only the temperatures at heat-retaining airports and fermentation-warmed sewage treatment plants. D’Aleo warns that a major part of the reported increase in recent U.S. surface temperatures is due to this deliberate bias.
So, where did Dr. Parker get his regional temperature measurement? From Baltimore-Washington International Airport!
How important is this? A recent comparison of rural and urban sites by physicist Charles R. Anderson used NASA’s published data to pair 28 rural-urban thermometer sites across the U.S., with the rural sites 20–50 miles from their urban pairing. Anderson found that since 1900 the urban thermometers have trended upward about 1.5 degrees C. The rural thermometers show no upward trend! Forests are by definition “rural areas.â€