'Climate change is here' — but is it to blame for the extreme weather this summer?

It's been a record-breaking summer when it comes to the weather around the world. In Canada alone, we've been hit by severe heat in the prairies, wildfires on the West coast, and storms on the East coast. Over 90 deaths have been linked to a heat wave in Quebec.

Now, an international group of scientists is working to identify when extreme weather is caused by climate change, and when it isn't.

Climate change is not a future concern—it's already here

"It's very important for people to understand that climate change is already affecting them. It's affecting the weather they experience from day to day," Miles Allen, a member of the World Weather Attribution team and a climate scientist out of the University of Oxford, told Quirks & Quarks host Britt Wray.

"It's incorrect to blame every instance of extreme weather that happens on climate change, but at the same time it's misleading to say climate and weather are different."

"That's what this research is all about. It's about establishing which of the events we see have been made more likely by climate change and quantifying the size of that effect."

His colleague Friederike Otto recently led the study looking at the causes of the current heat wave across Europe. Heat waves have happened throughout history, but Otto's weather attribution study found that localized heat waves were five times more likely under climate change. Because of that, the risk of simultaneous heat waves — like the ones currently affecting Europe — increases even more.

"If we load the weather dice to double the risk of a six, we actually increase the risk of a double six by a factor of four and we increase the risk of a triple six by a factor of eight," said Allen. 

"So the odds of these coincidences of many heat waves happening, widely dispersed in different parts of the world, happening at once, are going up even faster than the odds of an individual heat wave happening in one location."

He cautions that while not all extreme weather is caused by climate change, it's important to know the difference.

"It's about understanding cause and effect. Lots of things contribute to weather events — many of them natural," he said. "But it's a very important element in the story because unlike other factors, which might go away next year, climate change is with us to stay, and we have to get ready for it getting worse."

Hothouse Earth

On Monday, a group of 16 scientists published a worst case scenario report, saying if our carbon emissions are left unchecked, we could be headed toward "Hothouse Earth conditions," warming our planet by 4 to 5 C.

"That would mean melting of an awful lot of ice, which would mean sea level rise of between 10 and 60 metres," said Katherine Richardson, professor in biological oceanography at the University of Copenhagen and one of the study co-authors. 

"It would mean heat waves like we've never seen before. It would mean large areas of the planet where humans no longer could live and grow food. It would mean much wilder storms. It would mean that the world that we know it would be no longer here."

Allen says that we can still prevent such a future from happening.

"We do have a choice. We can keep this an exceptional summer or we can accept it becoming the norm, and what we need to do is very simple. We need to stop dumping carbon dioxide into the atmosphere."

To donate your computer power to the Weather Attribution team and join the world's largest climate modelling experiment, go to climateprediction.net.

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Daily climate change forecasts in the future?

Allen suggests that meteorologists start including climate change details in their weather reports, to clearly indicate when it is playing a role in a particular weather pattern. CBC asked Environment and Climate Change Canada to see if they had any plans to include climate change reports in their forecasts. This was the department's response:

Event attribution is an important research topic that the Climate Research Division (CRD) at Environment and Climate Change Canada (ECCC) has been active on. It aims to determine the extent that human influence may have had on the likelihood of a class of extreme weather or climate events similar to (or worse than) the event just occurred. Such studies help to understand the causes of extreme events. For example, a recent published study indicates that the risk for extreme fire weather that resulted in the Fort McMurray Wildfire in May 2017 has increased due to human-induced warming.

ECCC's Climate Research Division is currently working with the National Research Council in developing future projections for climate extremes such as extreme temperature, intense storms, snow accumulation etc. Such information will be available for the public and will be used in the development of Canada's building codes, bridge and highway codes.

Meteorological Service of Canada (MSC) will be following with interest what the German Weather Service does with climate attribution. MSC will be guided by Canadian research and the experiences of national meteorological services around the world with whom we work in close collaboration on this and other issues of global interest.

MSC has a focus on providing Canadians with advance warning of extreme weather events to help them prepare and respond to the risks they represent. It operates world-class computer prediction systems that are improving weather forecasting in both the short and longer time ranges.  These systems are enabling us to provide increasingly reliable early notification of significant weather events to Canadians and public authorities who manage and respond to extreme events.