Five really hot years on the way, scientists predict

The past four years have been the four warmest that humans have ever recorded — and now, according to a new scientific forecast, the next five will also probably be “anomalously warm,” even beyond what the steady upward pace of global warming would produce on its own.

That could include another record warmest year, even warmer than the current record year of 2016 — although it is still too early to be certain. It could also include an increased risk of heat extremes and a major heat event somewhere in the oceans of the sort that of late has triggered large die-offs of coral reefs across the tropics.

“What we found is that for the next five years or so, there is a high likelihood of an anomalously warm climate compared to anomalously cold,” said Florian Sevellec, a scientist at France’s National Center for Scientific Research, who co-authored the study published in Nature Communications with Sybren Drijfhout of the University of Southampton in the United Kingdom.

The Earth is warming, but it is becoming a cliche at this point to note that this does not mean that every year is warmer than the previous one. Rather, there is an overall warming trend.

One key determinant of an individual year’s temperature is what scientists sometimes call the climate’s “internal variability,” as As these people sunbathing on a beach in Barcelona, Spain, recently might have said, 2018 has been hot, but perhaps not as hot as the two years preceding it. A new modeling of temperature trends suggests that the next four years will be hotter still.

opposed to the contribution of human-released greenhouse gases. The new forecast for 2018 through 2022 arises from projecting how this internal or natural variability will play out.

During the so-called global warming “hiatus” during the 2000s, for instance, these internal factors, such as oscillations in the oceans, helped keep the planet somewhat cooler than it might otherwise have been and blunted the pace of warming — thereby launching a longrunning scientific debate and 1,000 political talking points.

Now, though, these same internal factors are poised to do the opposite, says the new research (whose authors also note that their technique accommodates the “hiatus”). And assuming that the

steady rate of global warming continues, that means already rising temperatures will get an added boost.

The study mines data from 10 existing climate change models, or simulations, to determine which do the best job of capturing how natural factors are contributing to the planet’s temperature. Then it projects forward using the same simulations to see how these factors will play out over the next five years.

It’s important to underscore that the result is a forecast based on probability — not a certain outcome. The study finds a 58 percent chance that the Earth’s overall temperature from 2018 through 2022 will be anomalously warm based on these factors, and a 69 percent chance that the Earth’s oceans will be.

Already, 2018 is shaping up to be a pretty warm year — although not recordbreaking. For instance, the period from March through May of this year was 1.57 degrees Fahrenheit above the planet’s average from 1951-1980, making that the third-warmest such stretch in the temperature record, according to NASA’s Goddard Institute for Space Studies.

The next 54 months (including this July, for which the temperature has not yet been reported by NASA) will definitively test the new forecast.

“It is one study, and what will be interesting is that now there will be a lot more that we’ll also test and try to see if our prediction is right or not,” Sevellec said.