New climates, unknown consequences ahead

IPCC - global surface temperature now and in the future.
Aggressive climate action ASAP (left figure) minimizes future warming. Inaction (right figure) results in catastrophic levels of warming, 9°F over much of U.S. (Via ClimateProgress, IPCC)

If the Intergovenmental Panel on Climate Change’s fifth assessment report didn’t scare you, a study in the journal Nature should do the trick. It may have a dull title (“The projected timing of climate departure from recent variability”), but it makes up for it with alarming findings.

The abstract is, as abstracts tend to be, clinical:

Ecological and societal disruptions by modern climate change are critically determined by the time frame over which climates shift beyond historical analogues. Here we present a new index of the year when the projected mean climate of a given location moves to a state continuously outside the bounds of historical variability under alternative greenhouse gas emissions scenarios. Using 1860 to 2005 as the historical period, this index has a global mean of 2069 (±18 years s.d.) for near-surface air temperature under an emissions stabilization scenario and 2047 (±14 years s.d.) under a ‘business-as-usual’ scenario. Unprecedented climates will occur earliest in the tropics and among low-income countries, highlighting the vulnerability of global biodiversity and the limited governmental capacity to respond to the impacts of climate change. Our findings shed light on the urgency of mitigating greenhouse gas emissions if climates potentially harmful to biodiversity and society are to be prevented.

What’s this really saying?

These researchers considered the long-term average temperatures places all over the world, and then figured out how far into the future they would have to go until global warming pushed the average temperature in these places above the hottest of the 145 years from the end of the Civil War through 2005. When your hottest year becomes your average year, you’re in a new climate.

Alastair Doyle of Reuters explained it this way:

Billions of people could be living in regions where temperatures are hotter than their historical ranges by mid-century, creating a “new normal” that could force profound changes on nature and society, scientists said on Wednesday.

 

Temperatures in an average year would be hotter by 2047, give or take 14 years, than those in the warmest year from 1860-2005 if the greenhouse gas emissions continue to rise, with the tropics the first affected area, a new index indicated.

 

“The results shocked us. Regardless of the scenario, changes will be coming soon,” lead author Camilo Mora of the University of Hawaii said. “Within my generation whatever climate we were used to will be a thing of the past.”

 

The data suggested the cities to be hit earliest included Manokwari in Indonesia, which could shift to a new climate from 2020 and Kingston, Jamaica, from 2023 under the fastest scenario of change.

 

At the other extreme, Moscow would depart from historical variability only in 2063 and Anchorage in 2071.

The year 2047 isn’t that far away. My kids will be about my age then. I may still be alive, even. My kids will have every right to be angry with me for my part in all this.

Maybe it’s the federal shutdown, maybe it’s the fossil-industry-funded denier machine, maybe I was closer to it in 2007 when I covered the IPCC’s fourth assessment report as a writer for the Daily Camera in Boulder. But it feels like there’s less interest in these kinds of stories now than there was six years ago, despite carbon-dioxide concentrations having risen and its consequences becoming irrefutably clear.

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