Climate Change Is Here to Stay, for Centuries

Carbon dioxide already in the atmosphere has locked the world into at least a 3.6-degree Fahrenheit global temperature increase that will last for millennia, according to a new report released by the National Research Council. Marilyn Raphael, a UCLA geography profesor and member of the report committee, urges action and not despair.

By Alison Hewitt for UCLA Today

THERE IS ALREADY enough carbon dioxide in the atmosphere that the world is locked into at least a 3.6-degree Fahrenheit global temperature increase that will last for millennia, according to a new report released by the National Research Council.

Marilyn Raphael, a UCLA geography professor who helped write the report from the National Academy of Sciences, said the implications were sometimes frightening even to her committee of mostly experts from government and academic institutions that teamed up to develop "Climate Stabilization Targets: Emissions, Concentrations, and Impacts Over Decades to Millennia." The team collected previously published scientific reports to compile their report on climate change.

UCLA Geography Professor Marilyn Raphael

UCLA Geography Professor Marilyn Raphael

"I think most of us were really taken aback by the length of time that we're locked into climate change," Raphael said. "Previously the conversation has been about the next generation or two, but now we're looking at millennia. It's sobering and a little frightening."
To prevent the global average temperature from increasing more than 3.6 degrees, carbon dioxide emissions would have to be reduced by 80 percent now, the report said. "I think you'll agree, that's not likely to happen," Raphael said.
So, not to put to fine a point on it, but is the world screwed?

"Yes. We're locked into a temperature change," she said. "It doesn't mean we give up or lose hope. On a personal level, it does make me think about personal choices I can make to reduce my carbon footprint."
As the world's population continues to emit CO2, it will be locked into higher and higher temperature increases, the report explained. But the sooner emissions are reduced, the authors wrote, the sooner that temperature climb will level off, or stabilize. "Stabilization" doesn't mean the world will cool back down – it will just stop getting hotter, Raphael explained.
Because carbon dioxide takes so long to dissipate from the atmosphere, the current levels of CO2 are going to be with us for thousands of years, no matter how much people reduce their emissions, the report said. Today's CO2 measurements – 390 parts per million – will culminate in a 2-degree Celsius, or 3.6 F, increase in the Earth's average temperature, Raphael said.
"That doesn't sound like much, but it will change things," she said. "Think of the warmest summer you've experienced in your lifetime. You can expect that to become the norm for summer."
As the world's average temperature rises, the report found that for each degree Celsius:

  • The Mediterranean, the southwestern U.S. and southern Africa will face 5-10 percent less rainfall;
  • Arctic sea ice will melt 15-25 percent;
  • Alaska and other far-northern regions will face 3-10 percent increases in heavy rainfall;
  • Food crops will falter by 5-15 percent;
  • Rivers like the Rio Grande will dwindle 5-10 percent;
  • Wildfires will consume two to four times as much land.

While the report anticipated current carbon dioxide levels will create a 2 C increase and therefore multiply each of those effects by two, worse is yet to come, the document said. Emissions must be cut by 80 percent to prevent that 2-degree increase from growing – but scientific articles predict CO2 will continue to accumulate.
"Carbon dioxide concentrations could double or nearly triple from today's levels by the end of the century," which would eventually cause warming of 5 C, or 9 F, the report warned.
The National Academy of Sciences committee that developed the report included scientists from the National Oceanic and Atmospheric Administration (NOAA); Stanford University; the University of Washington, Seattle; Texas Tech University; the Electric Power Research Institute, Inc. in DC; Concordia University, Montreal; and others in addition to UCLA.
"It's important that people realize that what we have done to the Earth has an impact not just on our lives and our children's lives, but generations of children to come," Raphael said. "People have to use this information to decide what steps to take next. It's information to act on, not to give up on."

Published: Tuesday, August 24, 2010