Feb. 23, 2001

Model research for climate change





What will the results of the "greenhouse effect" be in five, 10 or 50 years? On the world? On the United States? On the Tri-Valley specifically?

What would happen if one or more of the suggested steps to stem this effect were taken by California, the entire United States or by the world?

These questions, and more, are the focus of the Lab’s Climate and Carbon Cycle Modeling Group. Thanks to the unique supercomputing capabilities here, scientists Philip Duffy (group leader), Starley Thompson, Ken Caldeira and Jose Milovich, with assistance from Mike Wickett and Bala Govindasamy, are modeling myriad variables in the greenhouse effect — climate changes due to man-made carbon dioxide accumulation in the atmosphere from burning fossil fuels.

The results of their research will be one of many highlights in the upcoming Science Day, March 21, in the Bldg. 123 auditorium. The day will celebrate the Laboratory’s science and technology by including a daylong schedule of presentations, as well as a poster session that will highlight a broad spectrum of Laboratory research and development. (For more information, see the Website at http://stars.llnl.gov/ ScienceDay/ ).

"Our work is going to play a critical role in determining the importance of carbon management," said Caldeira. "If we’re to develop reliable predictions, which can be relied upon by governmental policy makers, we’ve got to thoroughly and accurately develop this modeling capability.

"Global-level answers are necessary if governments are to establish comprehensive policies on carbon emissions."

The Lab’s ASCI-level computational power has enabled this team to model the needed global patterns. Their simulations, which are increasingly accurate and varied, are showing atmospheric carbon to be truly a global issue.

"The benefit of our digital modeling is the motivation to clean up the atmosphere on a global level," said Thompson. "To really make an impact in atmospheric carbon levels, everyone must cut emissions. No one country or region can solve the problem."
However, local-scale modeling is proving to be equally as important, for more political reasons.

"In each world region, the politicians, who hold the purse strings, want to know ‘How’s this going to affect my area?’ " said Caldeira, "or ‘Why should we pass control laws if others don’t?’

"Each climate center typically has to answer questions to their government about pollution on a local scale, but everyone’s combined contributions to global carbon pollution is the real problem."

Currently, different groups around the world are studying different options, but the nature of government funding has kept most of these projects from working on a global scale.

"We work with other modeling centers," said Thompson. "There is sort of an emerging consortium as we work in cooperation to produce more detailed models. It’s certainly a process that’s in a state of continuing development."

The team’s work addresses two main areas: How will human activities impact the atmosphere and climate, and what can we do to minimize the human impact on the carbon dioxide concentrations and ultimately on the climate?

To answer these questions they model various scenarios and possible solutions.

"We’re looking at several options," said Caldeira. "Reducing carbon emissions through reducing energy demand (for example, through increased product efficiency or lifestyle changes), producing power from non-carbon sources (such as wind, solar or nuclear power), and carbon sequestration — storing the excess carbon where it won’t affect the atmosphere. Sequestration can be accomplished by burying the carbon in deep geologic reservoirs, planting forests to absorb it, or by sending it into the deep oceans."

Thompson continued, "Our modeling is so complex because we must take into account the constant interaction between varying carbon dioxide levels and the uptake of that carbon by the global carbon cycle. Studying the effect of increased carbon dioxide on the climate alone, as some have done, is not accurate because as climate changes, the amount of carbon absorbed by the land and ocean components will change.

"For example, one model forecast shows the Amazon rain forest drying out and dying, which would be a huge change and would substantially increase the atmospheric carbon."

Further modeling details can get far more specific. Forestation modeling must even take into account the species of trees to be planted, as a dark forest absorbs more heat and the earth becomes even warmer.

"We’ve been able to test ourselves in the development of our models by modeling a known time period, such as the 1980s, and then comparing our models against the actual 1980s data," explained Thompson. "The Europeans are a little ahead of us in their modeling applications, but we are catching up. Communication between researchers around the world is generally very good, although there is a sense of competition, too. The Hadley Center in London is currently the world leader, but the Germans are also doing some good work. Their governments are putting a lot of money into it."

Group Leader Philip Duffy credits DOE and the Lab’s LDRD program for enabling the progress the team has accomplished. "The DOE supports part of our modeling efforts and we anticipate that they will move more into coupled climate and carbon cycle modeling in the future," he said. "Much of our work has been done through LDRD and institutional commitment, enabling us to position ourselves for more external support in the future."

In a forecast of another sort, Thompson predicted that as computing capability grows, the experimental high-resolution modeling that the Lab team does now will be the norm everywhere in 10 years.

"But we’re the ones with the equipment and knowledge to do it here and now," he said.