We keep learning new facts that make our future less secure. The latest wild card is perfluorotributylamine (PFTBA) in the air, which is 7100 times as potent a greenhouse gas as CO2 over 100 years.
At the same time, a significant number of respected climate scientists don't see a connection between Arctic warming and wild weather from jet stream changes.
Because the Arctic is warming so quickly – about twice as fast as as the rest of the planet – the difference in temperature between the Arctic and the lower latitudes is narrowing.
That temperature difference drives the jet stream; when it shrinks, the jet stream slows and undulates more. It also moves more north-south than east-west (its usual flow), and can get stuck in patterns that last for much longer than they did even a few years ago.
And when that happens, the waves of the jet stream slow down and become larger and more sluggish. When they increase in size thanks to Arctic amplification, they move eastward more slowly, allowing the weather associated with them to stick around longer.
Still, not all climate scientists accept the linkages between long-term global warming, thinning Arctic sea ice, and weather events like this weekend's. The science around attributing weather events at lower latitudes to what happens in the Arctic is still very new, and scientists are far from consensus on whether such a link exists. [emphasis mine]
Some influential climate scientists don't see a physical mechanism to explain what's happening in the past 5 years, only a possible correlation which remains unexplained. Climate is noisy, with interacting cycles and oscillations, and they want 30 year's worth of data to be sure Arctic warming is our causing wild weather. Of course in 30 years, being sure will be too late.
Andrew Freedman describes it poetically,
... a weaker polar vortex moving around the Arctic like a slowing spinning top, eventually falling over and blowing open the door to the Arctic freezer ...
Not being a climate scientist, it's mysterious to me how basic physics could not provide a mechanism. Isn't the jet stream something like a convection cell of a pot of water at rolling boil? The temperature difference makes it turn over faster. If there's less difference, the cell currents slow and wobble. The parts highlighted in red above seem obvious to me.
I admit to impatience over integrating new, scary, discoveries with existing climate science to predict the coming decades. If climate can shift 5°C in 13 years, but climate science takes over a decade to be sure of a cause, we'll all be twisting in the wind. Politicians will wait for the science to be settled, and then vetted by every country, before they'll begin to start formulating policies to prevent wild weather.
The best easy to understand explanation of how Arctic warming causes weather extremes by Jennifer Francis.