Cape Town, May 20 : A 3.2 degree Celsius increase in the Earth's temperature could see 47 per cent of insect species, 26 per cent of vertebrate and 16 per cent of plant species lose at least half of their geographic ranges, an expert on global change has said.
Professor Guy Midgley, a world-leading expert on global change and its impact on biodiversity, warned that this might be the outcome if global temperature increase cannot be restricted to 1.5 degree Celsius above historical pre-industrial levels.
In an insight article published in the journal Science, he said that higher levels of warming would lead to systemic ecological simplification, a process where many "climate losers" are replaced by far fewer "climate winners".
"Warming by more than two degrees will take the world into a temperature state that it has not seen for several millions of years," Midgley added from his office in the Department of Botany and Zoology at Stellenbosch University, South Africa.
According to a report from the Tyndall Centre for Climate Change Research at the University of East Anglia in the UK, if the global temperature is allowed to rise with 2 degree Celsius, it roughly doubles the risks associated with warming for plants, animals and insects.
But even if governments and industries manage to limit warming to 1.5 degree Celsius, large tracts of land would have to be made available for capturing and storing carbon: some estimates are for up to 18 per cent of the land surface or 24-36 per cent of current arable cropland by the end of this century.
"We need to stay as close to 1.5 degree Celsius as possible. So here is the irony: In order to achieve the 1.5 degree Celsius target, we may well damage many of the habitats that support biodiversity in order to achieve a target that will save biodiversity," he said.
He said that very high carbon dioxide concentrations could change the ecosystems of the world irrevocably.
"If we increase carbon dioxide to over a thousand parts per million, over the next fifty to sixty years -- which we are quite capable of doing if we fail to reduce our dependence on fossil fuels -- we could literally move the world back 20 to 30 million years in the space of a century. It is like moving ecosystems backwards in time at the speed of light," he warned.
Midgley said only if humans succeed in solving the nexus between climate security, land use and biodiversity conservation, "will we be able to ensure a sustainable future in the long-term."