Thread by @ChrisScottWx

Western Canada's historic heat wave is so far off the charts, it's like suddenly meeting a 10 foot tall human when you thought the tallest people were only 7 feet. We meteorologists immediately ask, How? Climate change? Stay with me to the end 🧵 1/

https://twitter.com/ScottDuncanWX/status/1409260376408178690?s=20

The jet stream is to blame for creating this incredible #heatdome. @pppapin offers a great explanation. And a virtually invisible spin of low pressure off the California coast is key to locking in the heat dome and roasting the coast 2/

https://twitter.com/pppapin/status/1407849632621764610?s=20

So is this mega ridge in the jet stream enhanced by climate change? Maybe. Theories like Quasi Resonant Amplification suggest it's possible. But the link between wavy jet streams and climate change is not clear. A great read here 3/ met.reading.ac.uk/~williams/publ…

So, it's all just natural variability? A whacked jet stream? Let's use a different lens. Canada's Changing Climate Report shows that summer temps have warmed by 1-2 C on average as a result of human caused global warming, and hot extremes are increasing 4/ nrcan.gc.ca/climate-change…

It seems reasonable then to say 1-2 C is because of global warming. But this oversimplifies things. We simply can't unravel and separate the human cause from the natural cause. No question though, our current climate makes extreme heat waves more likely 5/

https://twitter.com/AndrewDessler/status/1408500237182947333?s=20

At these extreme temperatures, each degree can mean a much bigger impact on health and infrastructure. Attribution science tries to quantify how climate change impacted a given extreme weather event 6/

https://twitter.com/ClimateOfGavin/status/1408416547530493953?s=20

Keep in mind, attribution of climate change to weather events is pretty complex stuff and there are pitfalls, but it's safe to say that for a heat wave like this, there will be studies showing it was more likely/intense due to climate change 7/ link.springer.com/article/10.100…

It's worthwhile thinking about the flip-side: severe cold. Texas endured an incredible cold snap this year. Did climate change make this worse? It seems likely that climate change lessened the likelihood and intensity of this historic event. 8/

Most previous extreme cold events studied have been shown to be LESS likely and LESS intense due to climate change. This rarely gets discussed as we have a tendency to want to simplify the narrative to 'bad weather = climate change' 9/ worldweatherattribution.org/analysis/cold-…

For a country like Canada, one could look at future climate projections and see the positives - longer growing seasons, less severe cold. And we have the resources to mitigate some of the negatives like extreme heat. 10/

But this misses the forest for the trees. As a global community, the negative impacts of climate change far outweigh the positives. The good news here is that there is increasing alignment across society for positive change. 11/

It's important to put this extreme heat event into context as well. It does not mean we've crossed some threshold and will see events of this intensity every few years in Western Canada. While heat waves will become more common, this likely won't be repeated anytime soon. 12/

And we should be positive in how we communicate this to children. Yes, our world has a big challenge with climate change. However, there is great opportunity to be part of solutions for adaptation and mitigation. 13/

To all those in BC, Alberta and US Pacific NW: stay safe and check on your neighbours. We will get through this. Stay with @50ShadesofVan @KyleTWN @jwhittalTWN @weathernetwork for updates 14/14