DENVER -- Record drought in 2002 spelled disaster for Colorado.

The Hayman Fire, the state's largest wildfire in recorded history, burned nearly 138,000 acres in just three weeks and cost almost $40 million to suppress. Agricultural losses throughout the state were significant. Mountain snowpack was well below average.

New research is providing insight that the drought's impact has implications that extend well beyond that lack of precipitation.

In essence, the drought had the effect of adding the polluting emissions of 200 million automobiles to the atmosphere.

A new study from the National Oceanic and Atmospheric Administration shows how a prolonged drought in North America in 2002 cut the continent’s natural uptake of carbon dioxide (CO2) in half, leaving more than 360 million tons more of the heat-trapping greenhouse gas in Earth’s atmosphere. The amount not absorbed that year is equivalent to annual emissions from more than 200 million U.S. automobiles.

Scientists from NOAA's Earth System Research Laboratory in Boulder base their conclusions on new powerful data and modeling system called CarbonTracker, released earlier this year by NOAA.

The study presents the first objective estimate of net atmospheric CO2 exchange across North America every week from 2000 to 2005. The estimate is based on 28,000 global atmospheric observations.

Two billion tons of carbon as CO2 is released into the atmosphere each year through the burning of fossil fuels and manufacturing cement in North America alone. About a third of those emissions are absorbed by forests, grasslands, crops and soil.

During the 2002 drought, however, the amount of carbon taken up by vegetation and soil plunged by half. At the time, most of North America was experiencing one of the largest droughts in more than a century. Conditions over nearly 45 percent of the United States were classified as "extreme" or "exceptional."

"Scientists often look at the role of greenhouse gases in producing climate extremes," said scientist Wouter Peters, who led the study at ESRL and is also affiliated with Wageninen University and Research Center in The Netherlands. "Here we show the reverse is also true. Climate extremes can have a major affect on the amount of carbon dioxide in Earth’s atmosphere."

Drought and other climate variations can disturb the natural uptake of CO2 by changing regional temperatures, rainfall, soil moisture and even the length of the growing season. The problem is not unique to North America. The widespread drought and heat wave that struck Europe in 2003 left more than 500 million tons of extra carbon in the air that year.

"Disruptions to natural carbon uptake can have enormous environmental and economic effects, possibly even erasing efforts to reduce fossil fuel emissions in a given year," Peters said. "CarbonTracker not only tells us when and where such disruptions occur, but also suggests why."