Study confirms carbon pollution has ended the era of stable climate

We have rapidly warmed past the warmest periods of the last 11,000 years.

Temperature change over past 11,000 years (in blue) plus projected warming over the next century on humanity’s current emissions path.
Temperature change over past 11,000 years (in blue) plus projected warming over the next century on humanity’s current emissions path.

Recent temperatures experienced across Europe and North America are unprecedented in the past 11,000 years, a new study in the journal Nature finds.

Significantly, the new study found that the average temperature of the last decade (between 2007 and 2016) exceeded the warmest centuries of the last 11,000 years by more than 0.5°F — which is much larger than century-scale changes have been over the pre-industrial era.

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This research confirms findings from 2013 that human-caused carbon pollution has ended the stable climate that enabled the development of modern civilization, global agriculture, and a world that could sustain a vast population (see top chart).

That 2013 study, published in the journal Science, was the most comprehensive reconstruction of global temperatures over the past 11,000 years ever done. Temperature reconstructions are done by looking at proxies for temperature such as tree rings for which we have records going back thousands of years

The Science study found that “during the last 5,000 years, the Earth on average cooled about 1.3 degrees Fahrenheit — until the last 100 years, when it warmed about 1.3 degrees F.” We are warming at a pace never before experienced during modern times.

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The new research focused only on North America and Europe, but had very complementarily findings. As lead author Dr. Jeremiah Marsicek explained in a news release, “we learned that the climate fluctuates naturally over the last 11,000 years and would have led to cooling today in the absence of human activity.”

In fact, if the Earth hadn’t been in a cooling phase when humans massively disrupted the system with tens of billions of tons of carbon pollution from burning fossil fuels, we’d be nearly 1°F warmer today than we already are.

The key takeaway is that, thanks primarily to carbon pollution, global temperatures have soared outside of the slow-changing, relatively stable conditions that existed when humans were figuring out where the climate — and rivers and sea levels — were most suited for living and farming.

We could keep total warming over the next century close to 4°F — and avoid the worst consequences — but only with a very aggressive effort to shift away from fossil fuels and to clean energy. Under President Donald Trump’s policies of promoting fossil fuels at the expense of clean energy, however, we are headed for 7 to 11°F average global warming, and the extreme impacts that will come with this.