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August 06, 2015


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Global Warming is inevitable. I think I've been beating that drum since at least 2007.

And its going to take millennia for the environment to recover /and/ the temperature rise/climate has a long tail: even if we halted adding CO2 to the atmosphere, climate change will continue for another century afterwards.

Yeah, I think we're pretty much looking at 8°F by the end of the century. You've never written that post telling us what that might mean in concrete terms ... the popular books are terrible vague.

The reason I haven't written up the climate of 2100 us largely due to the uncertainty of precipitation. The Neo Oligocene and the Neo Eocene scenarios (hot, dry vs hot wet) are really, really different. And there's no consensus on which it will be.

How similar are the temperature plats?

The first-order worry is food security, no? Here's my thinking: take the modal case for the Neo-Oligocene forecasts. An absence of precipitation is more expensive for human civilization to deal with than an abundance. Additionally, cost figures for irrigation and desalination are known.

Then compare the modal Neo-Eocene forecast. Here, the damage to human agricultural productivity will be due to variability. Wet rice cultivation has the highest yielding grain per area.

The plats are variable, but largely similar: its a question of what happens to clouds and their formation. We're at least 6 years away from the simulations are fine grained enough to do accurate modeling for precipitation.

As for what the plats will be, you might say the problem is about when the plat takes place. It will NOT take place in the 21st century under any scenario. Barring some sort of successful sequestration that is.

We're generally looking at a 5 to 10 C plateau depending on the model. There is a lot of overlap between the two scenarios. Note, when I say Neo Oligo and Neo Eo, that is with very broad strokes. There are a lot of variation and the whole world doesn't get the same fate. The exception seems to be Oz: the place gets screwed no matter what.

The primary concerns are food and water security, but not only those. An increasingly dry world would be harder pressed to sequester more carbon. That would be rather bad.

For that matter, what do you do with the populations of the Western States when you have very little snow pack? NM without snow pack gets rather dicey. California with a permanent snow pack can be handled (desalinization), but I bet it throws a dent into the economy and population. Central Valley agriculture is definitely toast.

While there's often the discussion of San Francisco will have the climate of San Diego circa 2100. This is far too simplistic. A wet temperature profile SD is rather different than one of a dry one.

I've always thought the Neo Eo more likely. However, while I tilt that way still, I am less convinced than I was.

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