Thread by @ClimateHuman

A thread on the op-ed I just published in the @latimes. The Times considered it important enough to also publish a separate editorial today echoing my message. And they are right. This will be a civilization-defining topic for humanity in the years ahead.
latimes.com/opinion/story/…

We all know you can't fool physics, but nowhere is that more true than in the basic, brutal thermodynamics of global heating. All the excess energy pouring into our planet due to CO2 buildup has to go somewhere. It goes into hotter temperatures, which means - worsening heatwaves.

Hundreds perished in the PNW heatwave (which we should call Heatwave ExxonMobil) and it could have been far more. When I think about the "Big One" I'm thinking of a deadly fossil-fueled heat storm, not an earthquake. It is coming - THEY are coming. We just don't know when & where

Here is a great description of what it will be like: the first chapter of Ministry for the Future by Kim Stanley Robinson.

I URGE YOU TO TAKE A FEW MINUTES RIGHT NOW TO READ IT. (@DoctorVive did a great service to humanity IMO by putting it here for free)

OK, now that you've read that, let's talk about wet bulb temperature. Meteorologists should start reporting them from now on (cc: @WeatherProf). The idea is simple: take a thermometer and put a little moisture-wicking sock over the bulb. It's called a psychrometer and costs ~$20

You want good ventilation (wind) to evaporate the water (and fun fact, you can use the two readings to determine relative humidity.)

Why does this matter? Because our bodies are like the wet bulb. Our bodies don't care about heat alone, they care about moist heat.

As @AndrewDessler points out in this excellent thread, our bodies generate 100 watts (constant power output) in the form of heat, and we must dissipate that heat or else we heat up and die. When it get hot, we accomplish this by sweating.

But as humidity increases, the evaporation rate slows, and so you feel all the sweat just dripping down your back because it is not evaporating. And if it is not evaporating, it is not carrying away that heat energy from your body.

As heat and/or humidity continue to rise, at some point your body can no longer dissipate its 100 watts and your core temperature has no choice but to start increasing. Even in the shade. Even in a good breeze. Even with plenty of (ambient temperature) water to drink.

The theoretical upper limit for human thermoregulation is wet-bulb of 95°F (35°C). But many would perish if exposed to wet-bulb temps significantly lower than this - especially the elderly, children, people with underlying health conditions, and people working outside (exertion)

Until recently, it was thought that wet-bulb temps > 95°F (35°C) were not possible on Earth. But we now see them popping up here and there - infrequently, and not lasting too long. Here is a paper I link to that describes this.
advances.sciencemag.org/content/6/19/e…

And now for the bad news. If we allow the planet to keep getting hotter - if we do not rapidly end the fossil fuel industry - large swaths of the planet will become increasingly uninhabitable due to deadly humid heat beyond human tolerance.

The Global South will be hit hard but nowhere will be safe, as Heatwave ExxonMobil so dramatically showed. Here is another paper I linked to, from 2017. IMO still the best paper on projections of future deadly humid heat (though greatly needs updating). nature.com/articles/nclim…

Here are the three key figures. 1: days per year (2090-2100 mean) above a deadly humid heat threshold under "business as usual." 2: same, mostly w/o climate breakdown. 3: deadly humid heat threshold construction.

These areas will not necessarily be above TW 95°F (35°C) for that many days per year... instead they will be beyond the humid heat threshold where at least someone (more likely, many someones) will die. (Above TW 95°F/35°C, most everyone exposed for more than an hour or so dies)

As I write, "Regions that routinely surpass deadly heat thresholds will become increasingly uninhabitable by humans. And long before this occurs, extreme heat, especially when coupled with climate-induced drought, will lead to ever more intense wildfires and crop failures."

The point is, as moist heat continues to steadily increase like a juggernaut, lots of people will be affected and many will be forced to become climate migrants. A billion people live in India alone.

Climate migrants in large numbers - hundreds of millions? - would have profound impacts on global geopolitics. And all of this seems like it is already starting to play out. We have to put a stop to global heating as fast as we can...

It's super important to remember that things get worse the hotter humanity allows the planet to get. It's not an on or off switch. So please don't give up, keep fighting. No matter how bad it gets it can still get worse. There is NO "new normal" 😬 (until fossil fuel is gone)

It's also super important to remember that all of this is essentially irreversible. Whatever point we let climate impacts (heat, floods, sea-level rise, fires, etc.) get to, that is where they will stay for a very long time. We will not live to see them start to get better.

It will likely stay hot for hundreds of years (or more). Sea-levels will stay high for thousands of years (or more). And biodiversity will require millions of years to recover. Also, it's an awful idea to count on "negative emissions tech" which does not, and may never, exist.

Taken altogether, this points to one inevitable conclusion: humanity MUST phase out fossil fuel as quickly as possible... not as quickly as convenient. Radical policies for ending the fossil fuel industry are not nearly as radical as they seem.

It is a no-brainer to immediately end all fossil fuel subsidies. It should ALSO be a no-brainer to immediately impose a moratorium on all new fossil fuel infrastructure - which would end Enbridge's Line 3 pipeline... which it is absolutely INSANE to be building right now.

What can you do? Become a fire-breathing climate activist! Talk about it to everyone. Get involved in direct action groups. Get to know other activists. Get creative and use all the skills and resources at your disposal. And yes, also please stop or reduce flying, eating meat etc

Please read my op-ed and share it as widely as you can! Here are the the last three graphs.
latimes.com/opinion/story/…

*btw, we (scientists, publishers, funding institutions) should be ensuring climate papers of potentially great public interest like this are open access at this point!

*270 million people live in Indonesia, and the whole country is dark red under RCP8.5- every day per year beyond the deadly humid heat threshold by end-of-century

BTW, here is their editorial, which came out two days after my op-ed. @latimes has excellent climate coverage in their opinion pages, and I am grateful for this. Also, unlike some newspapers - cough @NYT 🤯
- they do not publish climate deniers
latimes.com/opinion/story/…