# How Much Hotter by 2030?

I’ve been trying to figure out if the dire predictions for the world that Guy McPherson keeps scaring us with are actually true. Or whether he is one of these guys who simply adopts every whiff of a worst case scenario as established fact. So here’s what I’ve found out so far.

Guy Mac’s claim:
Global average temperature is going to increase by 4°C by 2030.

This would be catastrophic. He points out that 2°C is enough to cause 6°C of overall temperature increases from various feedbacks, like CO2 from drought and fires and methane from melting permafrost and methane hydrates. It begs the question, what kind of feedbacks would 4°C give us?

My findings:
Nope. It’s more like 1° to 1.5°C by 2030.

Here’s why.

If you’re not a scientist and just rush off to Wikipedia, like I did, here’s what you’ll find. In the last hundred years, the Earth’s average surface temperature rose by 0.74°C (1906–2005). Projected from August 2013 to August 2030, if the rate stayed the same, we could expect an increase in global temperature of  ~.13°C , or a tenth of a degree. No biggie, right?

Then we read that things are warming a lot faster now than they were in 1906. The rate of warming over the last 50 years was almost double that for the period as a whole (.013°C/year, vs .007°C /year). So, in the next 17 years, you could expect a ~.22°C increase. Worst case (just for the sci-fi fans), let’s double that and say, half a degree more by 2030.

But let’s put Wikipedia and our DIY projections aside for a second and look at the kind of math that actual scientists are doing.

MIT researchers calculate that without effective policy to mitigate climate change, we’re headed for 5.2°C by 2100. That’s just over 1°C by 2030. Their worse-case scenario, given no action at all (which is seeming more and more likely) gives us +7°C. Assuming the sci-fi temperature of 7.5°C, we can expect around 1.5°C more heat worldwide by 2030.

Notice I’m cherry-picking worse-case numbers here. Let’s not do that and go with “most likely”. MIT suggests an increase of 5.2°C by 2100 in a No Policy scenario. That’s where governments and corporations can’t get their act together and stop carbon emissions completely in the next couple of decades. Given their track records and the amount of inertia in our global systems of government and commerce, I could probably take that No Policy scenario to Vegas and come back a winner. Which means a bankable 1°C by 2030.

Notice that none of these numbers (.5°C , 1.5°C , 1°C ) are anywhere near 4°C by 2030. The only way 4°C is going to happen is if something completely unexpected unfolds. I’m not ruling that out, but I’m not going to bet my mortgage on the “completely unexpected” either.

So if we’ve already warmed the planet about a degree C since 1850, we can probably expect it to warm to 1.5 or 2 degrees C by 2030. What exactly does that mean?

It means that by 2030, whatever effect the additional 1 degree has had on the climate will be nearly doubled. That’s not necessarily double the number of storms or storms twice as violent. But it certainly ain’t good. The point is, only really bad feedbacks are going to change this little bit of math.

Being conservative with these estimates still gets you some clear conclusions. If you’re living in a drought prone area, it might be time to think about a dugout or a cistern. If you’re living in a flood plain, maybe you should get into boating. Soon.

I’m not a doomsday prepper kind of guy. But I am practical. It is nice to look the future in the face and plan for it realistically. Guy McPherson has the dates too soon. (Yeah, yeah, climate feedbacks might shift those dates in his favor, but that’s pretty unlikely.) What that means is, the fight now, today, is about not being severely wounded as opposed to dying on the battlefield. The enemy does not have a thermonuclear device. He has a bomber and a bunch of cruise missiles. And yes, they’re still aimed at you and me.

Here are a couple of scary-assed links on credible scenarios.

An Illustrated Guide to the Science of Global Warming Impacts