Following 2016 and 2017, 2018 is likely going to set another heat record in many parts of the world. Already, the first six months have set high-temperature records for the US, the National Oceanic and Atmospheric Administration (NOAA) reported yesterday (July 9).

The extreme weather in the US, however, pales in comparison to the abnormalities along the Arctic coast. Last week, Nick Humphrey, a meteorologist living in Nebraska, wrote on his blog that temperatures rose to 90°F (32°C) in northern Siberia—some 40°F warmer than average for this time of year.

Other parts of the extreme north are hot, too—cities in Scotland and Northern Ireland are also hitting records of almost 90°F, the Washington Post reports. In Quebec, Canada, excessive heat reaching similar temperatures killed 70 people last week, and thousands were left without electricity due to overheating power wires.

“It is absolutely incredible and really one of the most intense heat events I’ve ever seen for so far north,” Humphrey writes.

What’s even more alarming, though, are the long-term effects of these high temperatures in this particular region that eventually extend down into lower latitudes. As temperatures remain above average, Arctic sea ice—already thin from weeks of abnormally high temperatures—melts, Humphrey explains. Instead of the sun shining on light white ice, it reflects down onto dark ocean water, which absorbs some of the heat that the ice would normally reflect. Collectively, this process speeds up the warming of the Arctic, called the Arctic Amplification, and ends up weakening the polar jet stream, which usually protects lower latitudes from the cold temperatures up north.

The result? More extreme weather in both directions—which could mean more repeats of the extreme cold North American faced this winter as a result of an “arctic outbreak” of freezing air.

“2018 has unfortunately been a prime example of global warming’s effect on the jet stream,” Humphrey writes. He predicts that warm temperatures will continue to melt sea ice, and could eventually effect permafrost, or ground that stays frozen permanently (as it’s name suggests). The thawing of permafrost releases more greenhouse gases into the atmosphere, adding to global warming, and potentially releasing frozen pathogens that have lay dormant for years into the atmosphere.

Correction: The article text and the headline previously stated that a heatwave has pushed Arctic temperatures 80% higher than usual when measured in Fahrenheit. In fact, it is wrong to measure percentage rise in either Fahrenheit or Celsius, which are both relative temperature scales. The absolute rise measured in Kelvin would be 8%. The error, however, does not mean that what’s happening in Siberia is not an anomaly.