Impact of global warming on biodiversity
The Australian science site NOVA, in a topic sponsored by the Australia Government’s Department of the Environment and Heritage, has a brilliant article headlined Impact of global warming on biodiversity that explains in quite some detail the known facts about climate change and looks at the effects of global warming on several species of Australian plants and animals.
To estimate the effect of climate change on species, scientists use what they call a climatic envelope (sometimes also referred to as a bioclimatic envelope), which is the range of temperatures, rainfall and other climate-related parameters in which a species currently exists.
As the climate warms, the geographic location of climatic envelopes will shift significantly, possibly even to the extent that species can no longer survive in their current locations. Such species will need to follow their climatic envelopes by migrating to cooler and moister environments, usually uphill or southwards in the southern hemisphere. There is some evidence that plants and animals are already responding to warmer temperatures. The treeline (above which there are no trees) near Mount Hotham in the Victorian Alps has reportedly moved up in altitude by 40 metres in recent years.
In many cases, however, such migration might not be possible because of unsuitable soils and other unfavourable environmental parameters, geographical or human-made barriers and competition from species already in an area. The mountain pygmy possum is particularly vulnerable to a loss of habitat linked to global warming.
It’s a fantastic article with lots of detailed information, presented in a clear and calm manner, that answers many of the questions people might have about global warming and why it’s not just longer summers and more German wines.
Global warming is predicted to take place faster in the next century than at any time for at least the last 10,000 years. Coupled with other factors, such as continued land-clearing, this could mean the extinction of species at a rate even greater than when the dinosaurs disappeared about 65 million years ago. Some species not under immediate threat of extinction might nonetheless suffer decreases in population size, diminishing intra-species’ genetic diversity (and therefore face increased vulnerability).
A diversity of species increases the ability of ecosystems to do things like hold soils together, maintain soil fertility, deliver clean water to streams and rivers, cycle nutrients, pollinate plants (including crops), and buffer against pests and diseases – these are sometimes called ‘ecosystem functions’ or ‘ecosystem services’. A loss of species could reduce this ability, particularly if environmental conditions are changing rapidly at the same time. It is therefore possible that as the climate changes and as species are eliminated from an area we will see a change in some ecosystem functions; this could mean more land degradation, changes in agricultural productivity and a reduction in the quality of water delivered to human populations.
Three quarters of the way down the page they make a rather controversial statement. Well controversial for an Australian Government department anyway.
Scientists agree that human-induced global warming is happening, and that the world will continue to warm for some time even if greenhouse gas emissions are somehow curbed. Some species, particularly insects, might be able to adapt to changing conditions or evolve in response to global warming. But for many, especially those that are already rare and have limited climatic envelopes, global warming could pose an insurmountable challenge.
Indeed it really seems that the Australian Government has understood the truth for quite a while, despite their Prime Minister’s mee too stance (’shoulderer to shoulderer’ as I prefer to describe it after a few glasses of wine), with the US on all issues ‘climate change’.
In Australia, action plans that have been prepared for a number of endangered species try to address the possible impacts of global warming. For example, the recovery plan for the mountain pygmy possum prepared by the NSW National Parks and Wildlife Service includes the development of a model to illustrate habitat suitability under current snow conditions and to identify key refugia for the possum under the predicted impacts of global warming.
You can’t just dream these models up overnight, they take years and years of scientific study and analysis to get them right. So now I am wondering, is it actually Australian Government policy that human-induced global warming is real. If so then that makes their “but we can’t afford it, and what about those Asians” refusal to back the Kyoto protocol a genuine ethical dilemma.
Some of the impacts of global warming may be sudden, but in many cases societies will have some years to adapt their management of biodiversity as conditions change. Increasing our understanding of the effects of climate change on biodiversity, and developing practical ways of mitigating such effects, are critical to limit the damage. Even so, the dangers are great – for humans as well as our native plants and animals.
That page was published in 2004 and discusses action plans for 2004 - 2007. Australian readers, please ask your local ministers about this seeming contradiction, and also about how the local flora and fauna is going to be safeguarded. — DS
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