Carbon dioxide buildup seen accelerating

Carbon dioxide, mostly from burning of coal, gasoline, and other fossil fuels, traps heat that otherwise would radiate into space. Global temperatures increased by about 1 degree Fahrenheit during the 20th century, and international panels of scientists sponsored by world governments have concluded most of the warming probably was due to greenhouse gases.

The climatologists forecast continued temperature rises that will disrupt the climate, cause seas to rise, and lead to other unpredictable consequences -- unpredictable in part because of uncertainties in computer modeling of future climate.

Before the industrial age and extensive use of fossil fuels, the concentration of carbon dioxide in the atmosphere stood at about 280 parts per million, scientists have determined. Average readings at the 11,141-foot Mauna Loa Observatory, where carbon dioxide density peaks each northern winter, hovered around 379 parts per million on Friday, compared with about 376 a year ago.

That year-to-year increase of about 3 parts per million is higher than the average annual increase of 1.8 parts per million over the past decade, and markedly more accelerated than the 1-part-per-million annual increase recorded a half-century ago, when observations were first made here.

Asked to explain the stepped-up rate, climatologists were cautious, saying data needed to be further evaluated.

The Intergovernmental Panel on Climate Change projects that, if unchecked, atmospheric carbon dioxide concentrations by 2100 will range from 650 to 970 parts per million.