Outlook: Warm, Grim, Cloudy: My story on global warming and extinctions in tomorrow's NY Times

In tomorrow’s New York Times, I take a look into nature’s crystal ball. Scientists have long been warning that we may be headed into Earth’s sixth mass extinction. But most projections just carry forward the causes of recent extinctions and population plunges (overfishing, hunting, and the like). Global warming is already starting to have an effect on many species–but it’s a minor one compared with the full brunt that we may experience in the next century.

I’ve written in the past about studies scientists have carried out to project what that impact will be like. I decided to revisit the subject after reading a spate of provocative papers and books recently. While the scientists I talked to all agree that global warming could wreak serious havoc on biodiversity in coming decades, they’re debating the best way to measure that potential harm, and the best way to work against it. We all crave precision in our forecasts, but biology is so complex that in this case we may well have to live without it. Check it out.

[Image: Photo by DJ-Dwayne/Flickr]

4 thoughts on “Outlook: Warm, Grim, Cloudy: My story on global warming and extinctions in tomorrow's NY Times

  1. You’ve may have made a small error, here’s a quote from the Irish Elk paper (http://ib.berkeley.edu/labs/barnosky/BARNOSKY_QR_1986.pdf) “It was not Holocene warming, but a brief cold spell just before warming, that eliminated M. giganteus from Ireland ”

    (via http://wattsupwiththat.com/2011/04/04/all-the-climate-news-thats-fit-to-misprint/)

    I’m interested on your take on CO2.

    Do you think it’s the primary driver of climate change and do you think raised levels of CO2 are, on balance, bad for biodiversity?

    Obviously some species are vulnerable to any change, but given the increased growth of food crops and other plants, plants growing in dryer climates such as the Sahel, much of the world being cold and cold climates being less biodiverse, there’s an argument that it is a good thing.

    What do you think?

    [CZ: Boris, since you cite Tony Barnosky, whom I interviewed for this article, I’d suggest you read his 2009 book, Heatstroke: Nature in an Age of Global Warming, where he writes at length about his work on Irish elk. “Irish elk were just one of the casualties that occurred the only other time that Earth ran the natural experiment of rapidly growing the numbers of the people on the planet at the same time the globe warmed by some 5 C (9 F). The elk went extinct along with two-thirds of all the largest animals in a geologically short span of time, that, depending on where you were in the world, started around 50,000 years ago and mostly ended around 11,500 years ago,” he writes.

    The cooling you mention was the Younger Dryas, a period of lowered temperatures that’s most clearly documented in Northern Europe. It was brought on by earlier global warming: melting glaciers delivered fresh water to the Atlantic, rerouting the ocean currents so that Europe no longer received warm air. When the currents recovered, the temperature in Europe continued to rise. Barnosky found that in Ireland, the Younger Dryas led to a shift in vegetation in Ireland that could no longer support their growth. The elk had come to Ireland when it was linked to Europe thanks to low sea levels. But they became isolated as sea levels rose–due to global warming. Thus, when the ecology of Ireland changed, they had nowhere to go and became extinct–in Ireland. They did continue to survive in Europe and Asia for thousands of years more, however, and their fossils show how their range tracked with the changing climate. But their numbers dwindled as the climate warmed, until only a pocket of Irish elk were left in the Urals, 7,650 years ago. Those animals were then hunted to extinction.

    The full story of the Irish elk amply demonstrates the concerns of scientists I outline in my article: rapid climate change alters ecosystems, posing a challenge to some species in those ecosystems. One response is simply to move. But moving may not be possible for several reasons, including geography (being stuck on an island) or the presence of humans. What’s more, human activity–in this case, hunting–can combine with climate change into a double whammy.

    As for whether CO2 is “good” for biodiversity, that’s not actually the issue at hand. The issue at hand is whether the rapid climate change caused by CO2 and other greenhouse gases that’s projected to push conditions far beyond what many species alive today have experienced is going to threaten some large fraction of those species. The answer appears to be yes, as I explain in my article. That doesn’t mean that some species won’t thrive at some points during that climate change. But just looking at one thriving species (like poison ivy, for example) misses the bigger picture.]

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