Monday, December 17, 2007

'Carbon dioxide levels at 650,000-year high'

National Oceanic & Atmospheric Administration

WSJ (republished in Denver Post): Carbon dioxide levels at 650,000-year high

For a half century, sensors atop Mauna Loa on the island of Hawaii have captured the world-wide signature of increasing carbon dioxide in the atmosphere, due largely to burning coal, oil and natural gas. The carbon dioxide traps heat. For 50 years, these CO2 readings, known as the Keeling Curve, have been climbing steadily, setting and then breaking a new record every 12 months or so.

Global concentrations of CO2 in 2006, not surprisingly then, reached the highest level since the record-keeping began in 1958, the World Meteorological Organization recently announced in its annual greenhouse-gas bulletin. Based on samples from 40 countries, the level of carbon dioxide in the air reached 381.2 parts per million, up fractionally from 2005 — concentrations not seen in 650,000 years, scientists said.

This week, while diplomats from 180 countries argued over the cost of staving off predicted climate changes, the Mauna Loa readings started to approach even higher levels.

These annual measurements are the world's longest continuous record of CO2 concentrations and, plotted as data points in a rising arc, form one of the most important graphs in science.

By 1960, the data had provided the first clear evidence that carbon was accumulating in the atmosphere and implicated human activity. By inference, it also records how little has been done each year since to reduce greenhouse-gas emissions. "It is one of the iconic records of human influence on the planet," said atmospheric chemist Pieter Tans at the federal Earth Systems Research Laboratory in Boulder. "When you look at it, it is shocking how overwhelming the human influence has been on the atmosphere. It is the scientific basis for the whole anxiety we have about climate change caused by human beings." Climate scientists call the graph the Keeling Curve in tribute to a skeptical atmospheric chemist named Charles D. Keeling, who first began monitoring the pure air at two of Earth's most remote locations — Mauna Loa and the South Pole — in 1958. Oil then sold for $3 a barrel, a new fuel-efficient Ford Edsel promised 12 miles to the gallon, and no one thought the carbon released by burning fossil fuels, making cement or clearing land could have a measurable effect on Earth's climate.

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