Radio Script
2003

George Somero is a physiologist who studies how organisms adapt to climate change. (Courtesy Hopkins Marine Station.)

Adapting to Climate Warming
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INTRO: As the world's climate slowly, but almost surely, heats up, creatures everywhere will have to adapt or die. Doug Schneider reports in this week's Arctic Science Journeys Radio that some critters may not be able to adapt fast enough.

STORY: Scientists have spent a great deal of time studying the effects of a warmer climate on the environment—on such things as glaciers, sea level and changing vegetation. But few scientists have studied just how animals might be adapting to a warmer planet. One scientist who is, is George Somero. Somero is a physiologist and director of the Hopkins Marine Station in Pacific Grove, California.

SOMERO: "We're trying to develop some general conclusions about how global change is going to affect organisms. We've looked at a number of different marine species that have different evolutionary histories to see if some general patterns of thermal effects and thermal adaptation occur."

Somero says that, in general, animals adapt to a warmer climate in one of two ways. They either evolve over long periods of time to changes that occur slowly, or they acclimate to short-term changes in temperature. Somero says many animals are capable of adjusting to changes in temperature for short periods, such as between winter and summer. But he says most organisms have evolved to live within a narrow range of temperature. Somero says raise the temperature by just a degree or two and some organisms simply cannot cope.

SOMERO: "Organisms are not really pre-adapted or overengineered to deal with rising temperatures. For a lot of organisms, they are currently living right at their thermal limits."

This may be especially true of cold-blooded animals such as snails, crabs and fish that maintain a body temperature close to that of their surrounding environment. Somero says the marine organisms he studies that live in areas that are already quite warm may not be able to acclimate to the even higher temperatures expected from climate warming.

SOMERO: "Curiously enough, the organisms that we studied that are currently living in the hottest areas are the ones that have the least ability to acclimate to even higher temperatures. It seems counterintuitive that if an organism that lives high on the rocks in a tidal zone is getting pretty high body temperatures. They can be as warm as our body temperatures. They can be up around 37 to 40 degrees Celsius. You might say well that organism isn't going to be bothered by climate change because it's so warm-adapted. But it's living right on the edge of its thermal tolerance right now, and further increases in temperature are probably going to push it over the edge where you may get local extinctions of populations."

Somero says there is no single body function that is unaffected by temperature. Everything from heartbeat to respiration to metabolism and even reproduction is sensitive to temperature. He says that fact makes it much harder for animals to adapt to a warmer climate.

SOMERO: "There's no one thing that could be fixed through adaptation. You'd have to tinker with all of the different systems. One example is that if we look at heart function in crabs, which is a very convenient study system, we find that for crabs living at the highest temperatures—these are ones that occur relatively high on the rocks in the intertidal zone. Let's say these crabs die at around 30 degrees Celsius. Their hearts conk out at the same time, so in one sense these animals are dying of heart failure at temperatures that they may see on a very hot day during low tide. We also find that their nerve function conks out at about this temperature. In other organisms like snails, or some of the mussels, their ability to make proteins conk out. So there's a very high sensitivity to temperature."

George Somero's studies focus on identifying the particular proteins that help control an organism's body functions in response to heat. More recently, he's begun work to identify specific genes that might be altered due to a warmer climate. He says it's important to understand how invertebrates, fish and other cold-blooded organisms will cope with the changes.

SOMERO: "There were two papers published in January of this year that were meta-analyses of a large number of studies that showed the broad ecological effects that are already evident in global warming. And yet there haven't been a lot of studies at the physiological level that show what the mechanisms are behind these changes."

George Somero is currently in Alaska, where he is this year's Irving-Scholander guest lecturer at the University of Alaska Fairbanks. He'll present a public lecture April 14th entitled, "A Physiologist's Perspective on Global Warming." This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences. I'm Doug Schneider.

Thanks to the following individual for help preparing this script:

Dr. George Somero, Director
Hopkins Marine Station
Stanford University
Oceanview Boulevard
Pacific Grove, CA 93950-3094
Phone: 831-655-6200
Email: somero@stanford.edu

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Related websites

Hopkins Marine Station

Dr. George Somero profile

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