The last time the Arctic warmed up, the climate changed. Now it is happening again.

The Arctic is heating up very fast. It has happened before. Then the climate changed in half the world. Will the same happen now?

• Climate throughout the Northern Hemisphere, even as far away as the tropics, is affected by what happens around the North Pole.
• The Arctic may be facing extreme climate change that will affect all life and climate in the Northern Hemisphere.
• The new findings surprise researchers. The situation may be much more acute and serious than the UN Climate Panel warned.
• The Arctic is already in the midst of extreme and very rapid climate change.

It’s not the first time the Arctic has been warming

The smaller and thinner sea ice in the Arctic will be important for what summers and winters will be like for our children and grandchildren, new Norwegian research shows.

Over the past 40 years, the temperature over land and sea north of Norway and Siberia has increased by more than 1 degree per year. decade. It is very fast and more than four times the average global warming on earth. In Svalbard, warming has occurred faster than anywhere else.

But this is not the first time.

Such abrupt climate changes have occurred many times before in world history. But it’s been a long time since the last time.

Extreme changes in the ice age

Professor Eystein Jansen is a climate researcher at the Bjerknes Center and the University of Bergen. He is a specialist in past climatic changes.

Together with colleagues from Norway and Denmark, he has studied the past to find answers:

– We begin with a comprehensive analysis of what has happened in the Arctic in the last 40 years after good and systematic satellite measurements began. We find very rapid warming north of Norway and Siberia, somewhat less on the other side of the Arctic. So we compare this with what we know about past climate change in the north, he says.

Read the full scientific article here.

Ice core samples taken from the depths of Greenland’s glaciers have documented extremely rapid and large-scale climate change during the last ice age, between 10,000 and 60,000 years ago.

– We found that what is happening now has happened before, but only in periods of extreme and very abrupt climate change. At that time, it led to changes in ocean currents and weather systems and to major changes in nature both on land and in the sea, says Jansen.

Much faster than IPCC alerts

The researchers describe the changes as extreme and believe they will affect all life in the Northern Hemisphere. The strong warming of the Norwegian Sea, the North Atlantic and Greenland caused the sea ice to disappear very quickly.

The changes are much greater than the UN Climate Panel has estimated in its simulations and have occurred much faster than climate scientists have previously thought.

Why haven’t climate scientists discovered this before?

– Climate models are not good enough. They have too coarse a mesh and their knowledge of the physical mechanisms of the Arctic Ocean is too poor. They have not been able to predict what has happened in recent decades, nor can they predict what will happen in the future. Almost everyone has underestimated speed, says Jansen.

The warm water of the deep

Current models have heralded gradual changes, where sea ice gradually disappears and where nature can adapt.

– Based on what happened during the ice age, it is more likely that we are facing sudden and extreme changes in the Arctic, he says.

– If global warming continues as it does now, we will risk a complete reorganization of ocean currents, and the biology and climate of the entire Northern Hemisphere may change rapidly.

A layer of cold water is still in the upper part of the Arctic Ocean, and large parts are still covered by ice in both summer and winter. The lower it is, the higher the temperature. During sudden climatic changes during the ice age, this stable divide collapsed and the entire sea between Norway and Greenland, which had been covered in ice, suddenly warmed up.

– We do not know if the same is happening now in the Arctic Ocean, but the similarities are many. If that happens, all the sea ice will disappear very quickly. Much faster than the climate panel and other investigations that are the basis of the Paris Agreement have announced.

The new research is published in the scientific journal Nature Climate Change.