Yahoo News explains: What's the other cause impacting global warming?

Kate Murphy

The past four years have been the warmest on record, according to NASA.

And that trend is likely to continue, according to a new scientific forecast published in Nature Communications journal.

The authors of the study predict a 58 percent chance that the next few years will be “anomalously warm,” with a 69 percent chance that earth’s oceans will be too.

The study found that that warming trend is not just the result of a steady increase in human-made climate change driven by emissions of greenhouse gases.

What else is involved?

This forecast for the remainder of 2018 through 2022 is derived from a projection of how natural factors known as the climate’s “internal variability” will play out.

The study used data from 10 climate-change models and found that natural variabilities were the cause of a global warming “hiatus” in the early 2000s.

That was when surface temperatures didn’t significantly rise, even though the ongoing climate warming trend continued.

It was found that internal factors like oscillations in oceans helped keep the planet cooler than what it might have been otherwise.

“Global warming is not a smooth, monotonous process,” the study says.

Even though there’s an overall warming trend, that doesn’t necessarily mean every year will be warmer than the last, because individual years vary on how hot they get.

And scientists say a warmer year doesn’t signify that it will be hot everywhere for everyone. The forecast covers only global temperatures, not regional ones.