by Gary Berg-Cross
We're heard bits and pieces of this before. Bill McKibben wrote on it in 1989 The End of Nature. More recently in Eaarth he asked us to:
" Imagine we live on a planet. Not our cozy, taken-for-granted earth, but a planet, a real one, with dark poles and belching volcanoes and a heaving, corrosive sea, raked by winds, strafed by storms, scorched by heat. An inhospitable place. It’s a different place. A different planet. It needs a new name."
There have been noted declines in some species which has evoked imagines of past mass extinctions, some of which seem to have been climate related. Anthony Barnosky, professor of integrative biology at the University of California, Berkeley, was one of the voices on this topic earlier including his 2009 book, “Heatstroke. ” Well Barnosky and the hard science on the issue has moved along. Anthony Barnosky is now lead author of a review paper appearing in the June 7 issue of the journal Nature adds to the dark tipping point image of what we are facing in a few generations with both climate change and increased human population. The rate of species loss is faster than it ever has been over evolutionary history, especially if the species currently listed as “threatened” aren’t rescued.
Mass extinctions for amphibians could take as little as 240 years, 540 years for birds, and 330 years for mammals.
"It really will be a new world, biologically, at that point. The data suggests that there will be a reduction in biodiversity and severe impacts on much of what we depend on to sustain our quality of life, including, for example, fisheries, agriculture, forest products and clean water. This could happen within just a few generations."
Mass extinctions seem especially likely for larger animals like tiger, elephants & bears, who are icons for us. There is also the problem of “shifting baselines”, where it depends on what we are comparing present conditions to. We may consider species richness to be quite normal now, when it is in fact very low, compared to pre-human times, based on the fossil record. So we start from a deficit.
One can't dismiss this paper authored by 22 internationally known scientists who describes an urgent need for better predictive models. Their detailed understanding is based on an empirical look back to how our biosphere reacted in the distant past to rapidly changing conditions. This includes a look at how climate affects human population growth.In the Nature paper they compared the biological impact of past incidences of global change with processes under way today and assess evidence for what the future holds. It's timely and will appear in an issue devoted to the environment just in advance of the June 20-22 United Nations Rio+20 Earth Summit in Rio de Janeiro, Brazil.
Of course the result of such a major shift in the biosphere would be mixed, with some plant and animal species disappearing, new mixes of remaining species, and major disruptions in terms of which agricultural crops can grow where. NASA-built Landsat missions confirm that more than 20 years of warming temperatures in northern Quebec, Canada, have resulted in an increase in the amount and extent of shrubs and grasses. It's good for the weeds too.