Memo to media: If countries go no further than their current global climate pledges, the earth will warm a total of 3.5°C by 2100.
A very misleading news release from the U.N. Framework Convention on Climate Change (UNFCCC) — coupled with an opaque UNFCCC report on those pledges, which are called intended nationally determined contributions (INDCs) — has, understandably, left the global media thinking the climate talks in Paris get us much closer to 2°C than they actually do.
Indeed, the news release contains this too-cleverly worded paragraph quoting UNFCCC Christiana Figueres, Executive Secretary:
The INDCs have the capability of limiting the forecast temperature rise to around 2.7 degrees Celsius by 2100, by no means enough but a lot lower than the estimated four, five, or more degrees of warming projected by many prior to the INDCs,” said Ms. Figueres.I’m a fan of Figueres and all that she has accomplished in the lead-up to Paris. Indeed, as I’ve written, “the INDCs have bought us another five to 10 years of staying close to the 2°C path,” which is the defense line against very dangerous-to-catastrophic global warming.
But, to repeat, assuming countries meet their current global climate pledges — but go no further — the earth will warm a total of 3.5°C by 2100 (but see note at the end). Climate Interactive has added up the latest commitments and here is where they lead:
Significantly, while China has agreed to peak CO2 emissions by 2030, “total GHG emissions are likely to continue increasing until 2030, as China has not yet implemented sufficient policies addressing non-CO2 GHG emissions (methane, nitrous oxide, HFCs etc.),” as the analytical team at Climate Action Tracker explains. Also, India has specifically not committed to peak its CO2 emissions yet (nor have some other developing countries that are not yet at India’s stage of economic growth).
I have no doubt that countries will make stronger pledges in the future — indeed, China just announced with France that it wants every country to have five-year check-ins to assess progress on the climate commitments. But those pledges have not been made yet, we do not know what they might be, and we certainly should not count them in any analysis of what Paris will achieve.
So why does Figueres say the Paris pledges will limit warming to 2.7°C by 2100? In fact, she doesn’t say that. She says they “have the capability of limiting the forecast temperature rise to around 2.7 degrees Celsius by 2100.” What does that mean?
It means that the overwhelming majority of the pledges end by 2030 — but most of them imply a rate of reduction in CO2 emissions between now and 2030. So, if you assume countries will commit in the future to keep reducing emissions after 2030 at the rate they did before 2030 — and make a bunch of other optimistic assumptions — you can limit warming to 2.7°C in 2100.
Here’s a quick analogy. You weigh 400 pounds with many weight-related health problems, and a team of doctors say you need to cut your weight sharply. You agree to go on a supervised weight loss regime for two years that will take you down to 300. Should you start telling all of your friends that you’ll weigh 200 pounds in 4 years?
Of course not. You’ve got a long way to go. Heck, you’re not even at 300 yet.
Actually, it is worse than that because the 2.7°C scenario requires a whole other level of effort. Here’s one possible 2.7°C pathway:
As you can see, India would have to plateau around 2030 (as would other developing countries). India has has not made such a commitment yet. One of the country’s leading politicians says it can do it. Indeed, I believe the combination of ever worsening climate impacts and rapidly dropping costs for clean energy make it all but inevitable that India will ultimately do so — and that the vast majority of other countries will also make stronger pledges in the years to come.
But India has not made a pledge to peak yet, nor have other major developing countries, nor has China agreed to start slashing emissions in 2030, nor has our country agreed to steady reductions in CO2 emissions post-2025.
Here’s another analogy. You weigh 400 pounds with weight-related health problems, and a team of doctors say you have to lose weight sharply. But you are still gaining 10 pounds a month. You agree to go on a supervised diet and exercise regime that will stop your weight from rising beyond 450 pounds in twelve months. Should you tell everyone that you’ll weigh 300 pounds in 3 years?
Of course not.
And the UNFCCC understands all this, which is why, immediately after Figueres’ quote in the news release, the very next paragraph is:
The secretariat report does not directly assess implications for temperature change by the end of the century under the INDCs because information on emissions beyond 2030 is required. However, other independent analyses have, based on a range of assumptions, methodologies and data sources, attempted to estimate the impact of the INDCs on temperature leading to a range of average estimates below, at or above 3 degrees C.That means the UK Guardian had the story wrong when they wrote:
“Pledges by most of the world’s countries on climate change are likely to lead to less than 3C of global warming over the century, analysis of the data by the United Nations suggests.”The UNFCCC never made any such analysis or claim. And the only way to make such a claim is to go far beyond the current pledges. But, again, the mistake is understandable since the news release was very misleading on this point.
The best we can say right now is that, if we consider the Paris climate pledges and nothing further, the earth will warm a total of 3.5°C by 2100. Of course, we can continue to say that keeping total warming to 2°C is super cheap because we know that is also true.
Note to nerdtastic readers: Yes, the 3.5°C calculation does assume that no unmodeled carbon cycle feedbacks kick in — such as the permafrost melting. I’ll cover issue that in a later post.
