Over the past decade or so, global temperatures haven’t risen as steeply as some expected, recently calling into question the basis for climate change.
But that will soon change, say researchers. This could be the last decade before humans experience "an entirely new climate," when the coldest year is warmer than the hottest year in the past. They call it "climate departure."
Waking up to a blue, clear sky with calm winds and pleasant temperatures feels like a gift. And it is.
Published last week in Nature, "The Projected Timing of Climate Departure From Recent Variability," is the first study to zero in on the year when the mean climate at any given location on Earth will shift continuously outside the most extreme records experienced in the past 150 years.
"The results shocked us: 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," says Dr. Camilo Mora, lead author of the study and a professor at University of Hawaii, Department of Geography.
Parts of the earth that have historically had the smallest variability in temperature reach the point of no-return first. The world’s oceans reached this turning point in 2008 and the tropics are next – within 10 years.
Unabated heat already threatens coral reefs and the biodiversity they harbor.
"Tropical species are unaccustomed to climate variability and are therefore more vulnerable to relatively small changes. The tropics hold the world’s greatest diversity of marine and terrestrial species and will experience unprecedented climates some 10 years earlier than anywhere else on Earth," the study says.
Even though the Arctic and Antarctic poles are experiencing the greatest extremes in temperature changes, because species are accustomed to wide variability they can adapt somewhat better. In the tropics, even a small amount of warming makes a big difference.
Since many tropical nations are major food suppliers to global markets, there could be ripple effects across economies, way before industrialized nations exceed the bounds of their historical climate, Mora says.
By 2047, under a business-as-usual scenario, the average location on Earth will experience a radically different climate. If the world manages to stabilize emissions – an optimistic scenario – the global mean climate departure will be postponed to 2069.
The extra 20 years would buy time for much deeper emission cuts and new technologies that could be crucial for many species’ survival.
As a raft of previous studies have found, "Our results suggest that countries first impacted by unprecedented climates are the ones with the least capacity to respond," says coauthor and researcher Ryan Longman. "Ironically, these are the countries that are least responsible for climate change in the first place."
In the "business as usual" scenario, 5 billion people are affected in developing countries; in the optimistic scenario, over one billion people are impacted before 2050.
"Scientists have repeatedly warned about climate change and its likely effects on biodiversity and people," says 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."
Read the research paper:
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