The Paris Climate Talks, Explained Using Star Wars


The buzzword of the moment at the Paris climate talks is “ratchet.” Will the nations of the world agree to ratchet up their carbon pollution reduction commitments every five to 10 years — as will be required if we are to avoid catastrophic global warming?

The ratcheting could be thought of like episodes in a long-running movie series.

A lot of people — most recently President Obama — have been declaring premature victory in the fight to avoid catastrophic climate change. They are making it seem like the Paris climate talks are Episode Six in the Star Wars series, “Return of the Jedi,” where the dark side appears to have been thoroughly defeated.

At the same time, some have prematurely declared the Paris climate talks a defeat, as if we were stuck in the interminable and opaque interplanetary trade negotiations of Episode One — and as if climate change itself were “The Phantom Menace.”


The truth lies in between. We are much closer in spirit to Episode Four, “A New Hope.” There are many battles ahead — indeed, it looks like we’re headed toward nine episodes now! — but at least the fight has been joined and there is cause for hope that homo sapiens might yet avert catastrophic levels of warming.

Here is where we are right now, if we add up the impact of the goals to limit carbon pollution that countries have already put on the table for Paris — the intended nationally determined contributions (INDCs). Researchers at Climate Interactive and the MIT Sloan School of Business find they would limit total warming to 3.5°C (6.3°F) — assuming countries neither go beyond what they have committed, nor backtrack.

For instance, the European Union cuts total emissions 40 percent below 1990 levels by 2030 — and then keeps emissions constant at that level, much as the U.S. does after we cut greenhouse gas (GHG) emissions 26 to 28 percent below 2005 levels by 2025. China plateaus CO2 by 2030 — as it has pledged to do — but total GHG emissions continue to slowly rise.

Here is how global emissions this century look under this scenario of INDCs “frozen” at Paris levels (broken down by the contribution of the major emitters):

Inexplicably, some in the media continue to push the myth that the Paris commitments are “utterly inconsequential,” which I and others debunked when confusionist Bjorn Lomborg first started pushing it.


Yet, at the same time, an even more widespread misconception holds that the Paris climate talks put us on track for 2.7°C warming. In fact, just before departing Paris, President Obama himself asserted “if you add up all the pledges and they were all met right now, we would be at a estimated 2.7°C increase in temperature.”

That is simply not accurate. As previously discussed, hitting 2.7°C requires many major developing countries countries, like India, to substantially ratchet up their current commitments and actually plateau around 2030, something they have explicitly not committed to do yet.

Here’s one possible 2.7°C pathway:

As you can see, this pathway also requires many of the biggest emitters — including both the U.S. and China — to make entirely new commitments, which result in steady reductions after the 2025–2030 period.

The problem with overstating what Paris is accomplishing is that it can create the impression the world doesn’t have much more work to do — since 2.7°C seems so very close to the 2°C “defense line” the world’s top climate experts warn against crossing. The president himself created that impression as he continued:

That’s too high. We wanted to get 2°C or even lower than that. But if we have these periodic reviews built in, what I believe will happen is that by sending that signal to researchers and scientists and investors and entrepreneurs and venture funds, we’ll actually start hitting these targets faster than we expected, and we can be even more ambitious. And so when you look at the cumulative targets that may exist 10 years from now, we may well be within the 2°C increase.

In fact, while I firmly believe the U.S., China, and most other countries will hit targets faster than expected, there is essentially no possibility that “cumulative targets that may exist 10 years from now” could bring us “within the 2°C increase.”

You can see that clearly from this fairly typical 2°C pathway:

Again, we are going to need to ratchet things down decade after decade (explainer video here). The chances that by 2025 all of the major nations of the world will come to the table with firm, credible pledges that extend through 2100 and bring us “within the 2°C increase” is about the same as the chances that … the Star Wars series was going to end with Episode Five.


Bill McKibben, the founder of, has it right in his new Foreign Policy piece. He writes that the Paris pledges, “when you add them up, would warm the planet 3.5 degrees if they were kept.” He puts that in perspective: “That’s historic, that’s remarkable — and that’s also a disaster. A world that warms 3.5 degrees would not be a world with civilizations that resemble ours.”

So the nations of the world will have to ratchet up their targets again and again to keep total warming below 2°C (3.6°F). The good news is that doing so will be super-cheap — according to every major independent economic analysis and all of the world’s leading governments, as I discussed back in January. And that’s without counting some $300 trillion in avoided climate damages — and $18 trillion in health and productivity co-benefits.

But we’re much nearer the beginning of this epic fight than the end. There’s new hope, for sure, but we have many battles yet to come.