Scientists believe annual temperatures over North America, Europe and East Asia could rise 2-4 degrees C by 2065
Scientists from Stanford University say the rate of change in the climate over the next 100 years could be 10 times faster than in the past 65 million years.
They say that without reductions in greenhouse gases linked to global warming, this could lead to a 5-6C temperature spike by the end of the century.
Noah Diffenbaugh and Chris Field, both Working Group II lead authors on the forthcoming UN climate science IPCC AR5 report, warn this will place significant stress on ecosystems all across the planet.
“It’s not easy to intuit the exact impact from annual temperatures warming by 6 C,” Diffenbaugh said in a statement.
“But this would present a novel climate for most land areas. Given the impacts those kinds of seasons currently have on terrestrial forests, agriculture and human health, we’ll likely see substantial stress from severely hot conditions.”
The study, published in the latest edition of Science, suggests that with continued emissions of greenhouse gases â€˜at the high end of the scenariosâ€™, annual temperatures over North America, Europe and East Asia could rise 2-4 degrees C by 2065.
Basing their research on paleoclimate studies, the authors calculated that 55 million years ago, carbon dioxide in the atmosphere was elevated to a level comparable to today.
The Arctic Ocean did not have ice in the summer, and nearby land was warm enough to support alligators and palm trees.
But they stress that the current level of warming is faster than in the past, and argue that added â€˜stressorsâ€™ such as cities and pollution did not exist.
Reviewing results from â€˜two-dozen climate modelsâ€™, they conclude extreme weather events, such as heat waves and heavy rainfall, are expected to become more severe and more frequent.
They also conclude that the next few decades are already “baked into the system,” making cutting emissions in the next decade more important.
“There is already some inertia in place,” Diffenbaugh said. “If every new power plant or factory in the world produced zero emissions, we’d still see impact from the existing infrastructure, and from gases already released.”
“There’s no question that a climate in which every summer is hotter than the hottest of the last 20 years poses real risks for ecosystems across the globe.
“However, there are opportunities to decrease those risks, while also ensuring access to the benefits of energy consumption.”