Think globally, but act locally when studying plants, animals, global warming

Mar 20, 2011
The endangered Quino checkerspot butterfly experiences pressures in Southern California from climate change, but also urban development, invasive species and pollution. Credit: Lawrence Gilbert and Michael C. Singer. The University of Texas at Austin.

Global warming is clearly affecting plants and animals, but we should not try to tease apart the specific contribution of greenhouse gas driven climate change to extinctions or declines of species at local scales, biologists from The University of Texas at Austin advise.

Camille Parmesan, Michael C. Singer and their coauthors published their commentary online this week in Nature Climate Change.

"Yes, is happening. Yes, it is caused by human activities. And yes, we've clearly shown that species are impacted by global warming on a global scale," says Parmesan, associate professor of integrative biology.

Policy makers have been recently pressing biologists to dissect how much of the changes observed in wild species are due specifically to greenhouse gas driven climate change verses other possible factors, including natural changes in the climate.

However, research funding is limited, and the scientists feel it should be directed more toward studies on species adaptations and conservation of compromised species rather than trying to figure what percent of each species' decline is due to rising . One reason is that, from the perspective of wildlife, it doesn't matter what proportion of climate-change impacts are caused by humans.

"A is a changing climate, irrespective of its cause," write the scientists.

They argue that the focus ought to now be placed on the interactions of climate change with impacts of other human activities, such as , , urban sprawl and pressures from agriculture.

"Effects of climate change are everywhere, but they act on top of all these other stresses faced by wild species," says Parmesan. "What we need to do now is to focus on extensive field experiments and observations that try to understand how multiple factors, such as exploitation or habitat fragmentation, interact with a changing climate to directly affect these species."

Take, for example, the Quino checkerspot butterfly in Southern California.

The butterfly became endangered in the 1980s principally because of growth of Los Angeles and San Diego. Only a handful of populations remain in the United States, and they suffer from a complex of factors. A warming and drying climate is shortening the life of host plants, causing caterpillars to starve. The plants themselves are suffering from competition with introduced Mediterranean geraniums, likely encouraged by nutrients in rain falling through polluted air.

"All of these things have been happening, so when we see one of these populations wink out we suspect them all," says Singer, a professor of integrative biology who has been working on this species since the 1960s. "Climate change is definitely part of the context for this butterfly in this system, but it isn't the only driver."

The scientists offer another example in corals. Incidences of coral bleaching have increased since the 1970s due to unusually high ocean temperatures associated with global climate change. Corals can recover from bleaching, but biologists have noted that recovery is worse in areas that have been hit directly by human activities, such as over-fishing, introduced species and water pollution.

For conservation biologists and policy makers, it's critical to understand those local driving forces, so they can make appropriate, and sometimes immediate, interventions. Tackling climate change itself is a problem on a different level.

"Think globally about climate change and how that's going to affect your national park, or your reserve or your endangered species," says Parmesan, "but in terms of action, you've got to think locally about what you need to do in terms of habitat restoration, removing invasive species, assisting species migration, etcetera. Those are things you can and should do something about in the short term."

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debolton
not rated yet Mar 20, 2011
I live in southern California and this is the biggest broadcast of total nonsense. Mediterranean geraniums are species grown in gardens on purpose. They are sold in stores from WalMart to the local nursery & many grocery stores. The smog problem is at the lowest level since the 30's; in fact, we only have a couple of smog days a year. In my opinion, these quasi-scientists are trying to make something out of nothing. They haven't noticed out 40,000 year climate cycle? Perhaps they should read Psysorg.com news.
Au-Pu
5 / 5 (1) Mar 21, 2011
Associate Professor Parmesan is being dishonest.
We are in an interglacial period and we have not reached its zenith. Once we do the long process of cooling will commence until such time as we reach its nadir, when the process again reverses.
So we are in a naturally occurring period of global warming.
The question we should be looking at is: "Are we contributing to the speed of global warming and if so to what extent?"
Which should then lead us to try to remove our input into the process.
But there is absolutely nothing we can do to halt or reverse this process. Indeed we should not even attempt to try to interfere. Any attempt by us to interfere with this process is doomed to failure and is likely to produce disastrous results.
We need to understand what we can influence and what we cannot and we need to concentrate our efforts on those things we can influence.
That does not mean we don't investigate, what it means is that we need to know when something is presently beyond us.
3432682
not rated yet Mar 21, 2011
We are past the peak of warming for the current interglacial. 90% of the period was warmer than today. We are just out of the little ice age, one of the three coldest periods in the last 10,000 years. If we can produce global warming, it will be extremely valuable when the next ice age comes.

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