Source:     Lawrence Livermore National Laboratory     
Date:     2005-11-02
URL:     http://www.sciencedaily.com/releases/2005/11/051101222522.htm
Modeling Of Long-term Fossil Fuel Consumption Shows 14.5 Degree Hike In 
Temperature

If humans continue to use fossil fuels in a business as usual manner for 
the next several centuries, the polar ice caps will be depleted, ocean 
sea levels will rise by seven meters and median air temperatures will 
soar 14.5 degrees warmer than current day.

These are the stunning results of climate and carbon cycle model 
simulations conducted by scientists at the Lawrence Livermore National 
Laboratory. By using a coupled climate and carbon cycle model to look at 
global climate and carbon cycle changes, the scientists found that the 
earth would warm by 8 degrees Celsius (14.5 degrees Fahrenheit) if 
humans use the entire planet's available fossil fuels by the year 2300.

The jump in temperature would have alarming consequences for the polar 
ice caps and the ocean, said lead author Govindasamy Bala of the 
Laboratory's Energy and Environment Directorate.

In the polar regions alone, the temperature would spike more than 20 
degrees Celsius, forcing the land in the region to change from ice and 
tundra to boreal forests.

"The temperature estimate is actually conservative because the model 
didn't take into consideration changing land use such as deforestation 
and build out of cities into outlying wilderness areas," Bala said.

Today's level of atmospheric carbon dioxide is 380 parts per million 
(ppm). By the year 2300, the model predicts that amount would nearly 
quadruple to 1,423 ppm.

In the simulations, soil and living biomass are net carbon sinks, which 
would extract a significant amount of carbon dioxide that otherwise, 
would be remaining in the atmosphere from the burning of fossil fuels. 
However, the real scenario might be a bit different.

"The land ecosystem would not take up as much carbon dioxide as the 
model assumes," Bala said. "In fact in the model, it takes up much more 
carbon than it would in the real world because the model did not have 
nitrogen/nutrient limitations to uptake. We also didn't take into 
account land use changes, such as the clearing of forests."

The model shows that ocean uptake of CO2 begins to decrease in the 22nd 
and 23rd centuries due to the warming of the ocean surface that drives 
CO2 fluctuations out of the ocean. It takes longer for the ocean to 
absorb CO2 than biomass and soil.

By the year 2300, about 38 percent and 17 percent of the carbon dioxide 
released from the burning of all fossil fuels are taken up by land and 
the ocean, respectively. The remaining 45 percent stays in the atmosphere.

Whether carbon dioxide is released in the atmosphere or the ocean, 
eventually about 80 percent of the carbon dioxide will end up in the 
ocean in a form that will make the ocean more acidic. While the carbon 
dioxide is in the atmosphere, it could produce adverse climate change. 
When it enters the ocean, the acidification could be harmful to marine life.

The models predict quite a drastic change not only in the temperature of 
the oceans but also in its acidity content, that would become especially 
harmful for marine organisms with shells and skeletal material made out 
of calcium carbonate.

Calcium carbonate organisms, such as coral, serve as 
climate-stabilizers. When the organisms die, their carbonate shells and 
skeletons settle to the ocean floor, where some dissolve and some are 
buried in sediments. These deposits help regulate the chemistry of the 
ocean and the amount of carbon dioxide in the atmosphere. However, 
earlier Livermore research found that unrestrained release of 
fossil-fuel carbon dioxide to the atmosphere could threaten extinction 
for these climate-stabilizing marine organisms.

"The doubled-CO2 climate that scientists have warned about for decades 
is beginning to look like a goal we might attain if we work hard to 
limit CO2 emissions, rather than the terrible outcome that might occur 
if we do nothing," said Ken Caldeira, of the Department of Global 
Ecology at the Carnegie Institution and one of the other authors.

Bala said the most drastic changes during the 300-year period would be 
during the 22nd century in which precipitation change, an increase in 
atmospheric precipitable water and a decrease in sea ice size are the 
largest when emissions rates are the highest. During the model runs, sea 
ice cover disappears almost completely in the northern hemisphere by the 
year 2150 during northern hemisphere summers.

"We took a very holistic view," Bala said. "What if we burn everything? 
It will be a wake up call in climate change."

As for the global warming skeptics, Bala said the proof is already evident.

"Even if people don't believe in it today, the evidence will be there in 
20 years," he said. "These are long-term problems."

He pointed to the 2003 European heat wave, and the 2005 Atlantic 
hurricane season as examples of extreme climate change.

"We definitely know we are going to warm over the next 300 years," he 
said. "In reality, we may be worse off than we predict."

Other Livermore authors include Arthur Mirin and Michael Wickett, and 
Christine Delire of ISE-M at the Université Montepellier II. The 
research appears in the Nov. 1 issue of the American Meteorological 
Society's Journal of Climate.

 

 

Editor's Note: The original news release can be found here.

This story has been adapted from a news release issued by Lawrence 
Livermore National Laboratory.