What scientists don’t understand, but fear, about climate change in Europe – POLITICO

This is the first chapter in The Road to COP26 series.

It’s clear global warming will have a major impact on Europe, but there may be climate demons lurking that scientists are much less certain about.

A POLITICO review of the latest climate science, including a draft of a major new report from the U.N. Intergovernmental Panel on Climate Change, offers a troubling vision of the future for Europe and the wider world, even under temperature rises that are practically inevitable. 

But while scientists are increasingly confident of these findings, there are still phenomena and potential impacts that are relatively understudied or harder to predict. We asked some leading scientists to give a sense of the nagging impacts they fear, but don’t fully understand. 

Disaster pile up

We know unsettlingly little about what happens when extreme events arrive simultaneously or in rapid succession. Is it just another car crash, or would it cause a pileup that pushes our carefully organized societies over a cliff?

That’s bugging Friederike Otto, associate director of Oxford University’s Environmental Change Institute, whose work revolutionized the role of climate change in individual weather events.

Almost all research into the impacts of climate change on society has considered just one risk factor at a time. But these “are not necessarily those aspects of a changing climate we are most vulnerable to,” said Otto.

The lack of research may be in part because these confluent events have previously been so rare.

Droughts in Central Europe in 2018 and 2019 were the first such back-to-back events in 250 years. What impact would it have on city water supplies or the forestry industry when several such events come in quick succession? How can we predict and prepare for the deadly combination effect of heat waves that drive up the use of air conditioning, which in turn spreads coronavirus through a building?

These compound events might be a trendy topic at climate science conferences, Otto says, but real scientific inquiry “hasn’t gotten much further than that … No one really knows what they are” or the impacts they might have on societies.

Migration may not happen

It’s a long-held assumption that climate change will drive mass migration into Europe.

Many have suggested climate change was one cause of the Syrian civil war, from which thousands fled to Europe, triggering one of the deepest crises in the EU’s history. But that connection is heavily disputed.

As scientists look more closely at the factors driving migration, they remain uncertain that climate change would spark a rush for safety in the EU. In its draft, the IPCC is inconclusive.

“That is not saying that it’s not possible,” said Otto, but the reasons that people move or stay home are extremely difficult to run through scientific models. How do you compare the power of kinship ties with the willingness to gamble everything for a better life?

A review of scientific literature by a group of Austrian scientists found “climate change will not systematically generate mass migration from Africa to Europe and other continents.”

One of the elements the researchers considered was the means to migrate. They concluded that people will only attempt the desperate and dangerous crossings if they have a certain level of resources. No matter how badly they are affected, those who are too poor will be unable to seek sanctuary in Europe.

Arctic nightmares

Europeans have for too long ignored the catastrophe unfolding to their north, says Johan Rockström, director of the Potsdam Institute for Climate Impact Research. The Arctic is warming faster than anywhere else — up to 3 degrees, as opposed to the global average of roughly 1.25 degrees. 

“What this shows is that ground zero … is really in the Arctic, that’s where things are changing fastest,” said Rockström. 

That could have huge and hard-to-understand effects on Europe’s weather. 

First, there’s growing fear about the warming and melting of Arctic sea ice and the ice sheets of Greenland that are slowing down the jet stream — a high altitude current of air that circles the North Pole. That in turn creates great wobbles that block the movement of weather patterns across the planet leading to what Rockström calls “extreme lock ins” of hot and cold air. It could mean more of the extended heat waves and cold snaps that are increasingly familiar to Europeans.

“We do not know this for certain,” said Rockström. “But there’s a number of scientific papers now out there.”

Even less certain but more frightening is what could happen to the Gulf Stream, the current bringing warm water from the Gulf of Mexico to European shores. What scientists refer to as the “North Atlantic warming hole” is a patch of the world that is actually getting cooler. That’s caused by cold, fresh water sluicing off Greenland and it is slowing the conveyer that keeps Europe from freezing. The Gulf Stream “is what makes it possible to have — basically — modern civilizations in Scandinavia,” said Rockström. 

It’s not clear if that portends disaster.

“No science is suggesting that the Gulf Stream would stop,” said Rockström. If it did it would plunge Europe into a mini ice age, even as the rest of the world continued to heat up. But we don’t know if the slowdown has implications for Europe’s weather in the near term. “I think the jury’s still out there.”