Half of animals face extinction

Animals, plants may vanish from many parts of the world unless action is taken, writes Douglas Main

AS scientists recorded the highest level of CO2 in human history, experts have predicted that unless greenhouse gas emissions are significantly reduced, about 50% of plants and one third of animals are likely to vanish from half of the places they are now found by 2080.

These losses could lead to local extinctions of species, according to Rachel Warren, a researcher at the University of East Anglia in England.

In the study, published in the journal Nature Climate Change, researchers looked at the likely effects of global warming on 50,000 species around the world. The study used a computer model that calculated the desired climatic zone that these plants and animals live in, and analysed how these zones, and the organisms’ accompanying ranges, are likely to shift in the future.

In many cases, these shifts are likely to cause extinctions, as warming temperatures force animals and plants to move to points beyond which they cannot go, such as up mountain tops and toward coastlines into the ocean, said Warren. However, plants and animals with limited ranges were excluded from this study, because the goal was to gauge climate change’s effects on common species, she said. If you include total extinctions — which this study did not — the impact of climate change on global biodiversity looks even worse.

It’s not too late to do something to prevent the loss of species. The study found that if emissions are slowed and begin being reduced by 2017, about 60% of the losses can be avoided, Warren said. If emissions peak in 2030 and are reduced after that, about 40% of the losses could be avoided.

The losses are likely to be particularly severe in Central and South America, Australia, North Africa, and South-East Asia, said Warren. These areas are vulnerable to declines in rainfall and increasing temperatures, according to the study.

A decline in plants and animals means a decline in the services they provide, such as recycling of nutrients, purification of air and water, pollination, as well as draws for ecotourism and recreation, she added.

Some species are likely to be more tolerant than others, but the study is that it didn’t focus on any one plant or animal, or specific high-profile creatures like polar bears, she said. “The important message I want to get across is that there are large effects on a large proportion of species.”

Warren said she considered the estimates conservative, since the study didn’t take into account interactions between animals and plants, which could exacerbate declines; if an animal’s preferred plant food disappears, it too could bite the dust. The research also didn’t consider the effect of extreme weather that many models project will become worse with global warming, she said.

“There will be winners and losers in the natural world as species respond to climate change,” said Lee Hannah, a senior fellow in climate change biology at Conservation International, who wasn’t involved in the research. “This study shows that we can greatly reduce the losers among common, well-known species by taking action to reduce climate change.”

This “phenomenal” study “scared me to death”, said Terry Root, a scientist at Stanford University who wasn’t involved in the research. “What it is showing is how many species we are actually affecting by putting carbon dioxide in the atmosphere.”