Here I illustrate how the emerg­ing climate crisis would be viewed by those in the medical comm­un­ity who are used to dealing with fuzzy categories and their closing windows of opportunity for effect­ive action. I hope to provide a better intellectual toolkit for facing up to the climate crisis, largely borrowed from what medical school professors teach med students about dealing with emergencies.

Focus your mind for a moment on the tradit­ional bath­room light switch, where a gradual increase in finger pressure sud­den­ly triggers a flip and a click, flooding the space with painfully bright light.

Climate can flip as well and, so far, we lack a dimmer device to slow down the five-year transition time. Yet we keep assuming the overheating is like pushing a dimmer switch, where results are linearly proportional to the push.

But for five types of extreme weather, something did flip between 2002 and 2010. It was regime change. Unlike storm surges, the Big Five did not go away. Sustained changes everything— now we need to actually back up, cooling via taking the excess CO₂ out of circulation.

The Big Five

The extreme weather of the last twenty years has featured five sustained surges, where an aspect of extreme weather suddenly got much worse. None have flipped back.

A. Severe windstorms (billion-dollar-plus events are up 600% from pre-2009). This NOAA count does not include TCs/hurricanes.

B. Inland floods (billion-dollar-plus events are now up 220% from 2010). Again, this count does not include TCs/hurricanes.

C. There was a 260% increase in big fire weather episodes after 2006. Overall damage (big and others) surged 500% after 2016.

Because the annual count of all wildfires did not trend up, the increase in big ones appears to be a matter of acres burned, which in turn suggests a step up in "fire weather" episodes (hot, dry, windy).

Besides these three big ones whose annual rates suddenly increased more than 200%, there are two more that qualified on the basis of severity.

D. Two mega heatwaves so far; the 2003 mega in Europe killed 70,000 people; the 2010 mega in Russia killed 56,000 and set off the bread riots of the 2011 "Arab Spring" by ruining crops.

E. Stalled hurricanes such as 2017 Harvey, which stuck around Houston for five days, rather than passing over in five hours, a 24-fold increase in dwell time.

Also, a year’s worth of rain arrived in five days; the onshore winds kept it from running off.

These are the five types of extreme weather that qualified under my arbitrary criterion of increasing at least 200% in either recurrence rate or severity. Two other types are worth noting, though they fail to reach 200%.

The annual count of TCs/­hurricanes, those causing at least $1b in damages, seemed unchanged until 2020, despite the consensus that TCs were becoming more powerful. If sustained a few years, it would rate as a step up.

Billion-dollar droughts are a runner up, showing about a step of 50% about 2005, when costs tripled for the first time.

Jet Stream Loopiness

The five big extreme weather surges are all expected consequences of the long jet stream loops, though they may have other causes as well. The polar jet stream follows the path of the rising air curtain that is produced by northbound warm-moist air colliding with southbound Arctic air.

The standing wave drifts east, unless it encounters a blocking high. Then it buckles into a hairpin turn a few hundred km across.

A hairpin turn is especially effective at setting up the Big Five types of extreme weather.

Continue to 4. Mindset


  1. Most of the data comes from NOAA National Centers for Environmental Information (NCEI). U.S. Billion-Dollar Weather and Climate Disasters.

  2. is NASA's jet stream video from 1988.

  3. William H. Calvin (2021). Extreme Weather and What to Do About It. Preview PDF edition at

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  8. J. A. Francis, N. Skific, S. J. Vavrus (2018). North American weather regimes are becoming more persistent: is Arctic amplification a factor? Geophysical Research Letters 45, 11414;

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  13. Dim Coumou, Vladimir Petoukhov, Stefan Rahmstorf, Stefan Petri, and Hans Joachim Schellnhuber (2014). Quasi-resonant circulation regimes and hemispheric synchronization of extreme weather in boreal summer. Proceedings of the National Academy of Sciences 111, 12 331–12 336,