U. TEXAS-AUSTIN (US) — Global warming is affecting the environment, but trying to tease apart specific contributions of greenhouse gas to extinctions or declines is misguided and a waste of financial resources.
From the perspective of wildlife, it doesn’t matter what proportion of climate-change impacts are caused by humans, according to a commentary published in Nature Climate Change “that argues “A changing climate is a changing climate, irrespective of its cause.”
“Yes, global warming 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 Camille Parmesan, associate professor of integrative biology at the University of Texas-Austin.
Biologists are urged to dissect how much of the changes observed in wild species are due specifically to greenhouse gas driven climate change versus other possible factors, including natural changes in the climate.
But limited research funding 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 greenhouse gases, the authors write.
The focus ought to be placed on the interactions of climate change with impacts of other human activities, such as air pollution, invasive species, 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,” Parmesan says. “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.”
An example is the Quino checkerspot butterfly which became endangered in the 1980s mainly because of growth of Los Angeles and San Diego. A handful of populations that remain in the U.S. suffer from a complex of factors.
A warming and drying climate is shortening the life of host plants, causing caterpillars to starve and 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 Michael Singer, professor of integrative biology. “Climate change is definitely part of the context for this butterfly in this system, but it isn’t the only driver.”
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 note recovery is worse in areas that have been hit directly by human activities, such as over-fishing, introduced species and water pollution.
To make appropriate, and at times immediate intervention, conservation biologists and policy makers need to understand local driving forces. 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,” Parmesan says, “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, etc. Those are things you can and should do something about in the short term.”
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