The Rate of Change: July 8, 2019

We have too many fossil-fuel power plants to meet the 1.5° C target

Last year, we were given a carbon budget. This is the total amount of carbon dioxide that we can add to the atmosphere in the foreseeable future, to cap global warming to a few degrees Celsius. Think of it as the remaining balance in our carbon bank account.

So what’s our current balance? For a 50-50 chance (essentially a coin toss) of capping global warming at 1.5°C, our carbon budget is 580 billion tons of carbon dioxide. For a 2 in 3 (or 67%) chance of hitting this target, our budget is 420 billion tons.

How long does this buy us? Every year, we’re spending about 42 billion tons of carbon dioxide from our carbon bank account. It isn’t hard to do the math. Just divide 580 by 42 (or divide 420 by 42 if you want to play it safe). That’s how many years it’ll take us to spend our entire budget, assuming things don’t change. If you average these answers, you get 12 years.

In other words, at our current rate of emissions, we’re set to exhaust the 1.5°C carbon budget in a little over a decade.

And it gets worse. An important new study published last week in Nature argues that we’ve already committed to overspending this carbon budget. That is, if all the power plants, factories, vehicles, buildings and appliances in use today keep operating as long as planned.

Every coal or natural gas power plant that we build is like signing up for a new monthly payment plan with our carbon budget. By adding up the future payments for all the stuff that we’ve already signed up for, this study teaches us that we’ve already maxed out the 1.5°C carbon budget.

Stephen Leahy reports in National Geographic:

“Our study is dead simple,” said Steven Davis of the University of California, Irvine, a co-author of the paper published in Nature. “We wanted to know what happens if we don’t build any more fossil-fuel-burning stuff as of 2018.”

To answer that question Davis and colleagues looked at all the emissions from electricity, energy, transport, residential, and commercial infrastructure as of 2018.

[…]

Add up all those lifetime emissions from existing infrastructure, Davis and his colleagues estimated a total carbon commitment of about 658 billion metric tons of CO2. That’s

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