10 October 2013 — The myth that climate change will be the problem of another generation has been debunked by a comprehensive study published today [10 October] in Nature.
The study provides an index of the year when the mean climate of any location on Earth will shift continuously outside the most extreme temperatures experienced over the past 150 years – when “the coldest year in the future will be warmer than the hottest year in the past”, according to lead author Camilo Mora.
For Sydney, this new climate will here in 2038; Perth and Brisbane in 2042; and Melbourne in 2045.
Within 35 years, the analysis of all climate models found, even the lowest monthly dips in temperatures will be hotter than anything experienced in the past 150 years, which could have profound effects on local ecological and social systems.
The researchers used a collection of global climate models to estimate when the climate in a given area was likely to change beyond the previous norms of variability from 1860–2005.
Under a business as usual situation, unprecedented climates will occur globally in 2047. If an emissions stabilisation scenario is taken, the change will be delayed until 2069.
“The results shocked us,” said Mora. “Regardless of the scenario, changes will be coming soon. Within my generation, whatever climate we were used to will be a thing of the past.”
Changes were not uniform, however, and most Australian cities unfortunately came ahead of the global trend.
For Australia’s major cities, Sydney was predicted to be the first to transition into unprecedented climates in 2038, followed by Perth, Brisbane and Darwin in 2042, Canberra and Melbourne in 2045, and Adelaide in 2049.
Some areas in the tropics were expected to head into unchartered territories within the next decade, which would have catastrophic effects on biodiversity.
Tropical species are unaccustomed to climate variability and are therefore more vulnerable to relatively small changes, the study authors said. This was of serious concern, as the tropics hold the world’s greatest diversity of marine and terrestrial species.
“This work demonstrates that we are pushing the ecosystems of the world out of the environment in which they evolved into wholly new conditions that they may not be able to cope with,” said Ken Caldeira of the US Carnegie Institution for Science’s Department of Global Ecology. “Extinctions are likely to result.”
The study authors also noted that countries first impacted by the changes would be poorer ones with the least capacity to respond.
“Ironically, these are the countries that are least responsible for climate change in the first place,” said study coauthor Ryan Longman.
“Scientists have repeatedly warned about climate change and its likely effects on biodiversity and people,” said Mora. “Our study shows that such changes are already upon us.
“These results should not be reason to give up. Rather, they should encourage us to reduce emissions and slow the rate of climate change. This can buy time for species, ecosystems and ourselves to adapt to the coming changes.”