By 2100, according to business-as-usual climate projections, temperatures will have risen by 4C and sea levels by a metre or so.
This is not true!
There are a number of projections about the future climate. All of those projections are “business-as-usual” projections. And those projections run the gamut from (to use the slightly older parlance) A1FI (Aiieee! We’re All Gonna Die!) to A1T and B1 (What the fuck was everyone worrying about?).
“Business-as-usual” refers to the interlay of population, economic growth and fossil fuel use…..without measures to change any of them. Without government measures that is. What are the possible interplays of technological, population and economic growth, without the politicians sticking their oar in?
“Business-as-usual” does not mean pick the very worst of that range of possibilities and insist that this is what will happen without intervention. But that is what is being done in near all discussions of this problem. That A1FI would be a bad out turn is accepted. That B2 would also be a bad out turn is accepted. But along with that we’ve got to also accept that B1 and A1T (looking purely at climate change that is) would be entirely acceptable out turns. A richer world, each individual vastly richer (from 5 to 11 times) and climate change nothing to worry about.
To repeat, all of these are “business-as-usual” outcomes.
And the one thing we absolutely know is that we’re not in fact going to have any at all of these “business-as-usual” outcomes. Because all of them depend upon the idea that we’re not going to have any government programs to limit emissions. Do we have government programs to limit emissions? Have we had vast sums ploughed into making solar cheaper, at a rate vastgly faster than even A1T assumes? Yes, yes, we have. Does the UK have something akin to hte carbon tax that Stern recommended? Yes, it does. Does the EU have cap and trade (however badly done)? Yes, yes it does. Do we see all sorts of people doing all sorts of things to limit emissions? Yes, yes we do.
The outcome is therefore going to be below “business-as-usual” then isn’t it? Below the range listed above?
Just to repeat once again, “business-as-usual” projections do not say 4 oC. One specific b-a-u projection says that, the worst one. Others say there’s no problem beyond something trivial.