As COP26 comes to a close, its clear it will not put us on a path to 1.5C by itself. It does not ensure we remain below 2C, given gap between long-term ambition and near-term 2030 commitments.
But it does move the needle forward, and tee up another round of stronger commitments.
If folks were hoping for a dramatic breakthrough, this is not it. But nevertheless it is slow and steady progress towards a lower warming future, even if pace of action means that we may not avoid as much warming as we'd like.
At the end of the day every 0.1C still matters.
It also makes real progress on a lot of thorny issues that have bedeviled past negotiations, even though many outstanding issues still remain:
The draft final document is here, which will be the agreement barring any last-minute surprises. But its not final until the gavel drops and everyone heads home: unfccc.int/sites/default/…
(looks like the language of the final draft will be changed from "phase out" coal to "phase down" coal due to pressure from China and India. This is disappointing, but given the lack of a timeframe for either its unclear it will actually impact future NDCs and domestic policy)
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COP26 will not – by itself – put the world on track to meet Paris Agreement goals. But it does meaningfully move the needle. Commitments in the lead-up to COP26 likely reduced global temperatures by 0.2C and commitments during the conference by another ~0.1C.
Every 0.1C matters!
While long-term net-zero promises are encouraging, talk is cheap, and pledges around outcomes 30 to 50 years in the future are only meaningful if reflected in near-term commitments. The task as COP26 draws to a close is to ratchet these up to put us on a path to net-zero.
Future climate projections coming out of COP26 broadly consider three different scenarios: current policies, 2030 commitments (e.g. both unconditional and conditional NDCs), and longer-term net-zero promises. 2/
Four different groups have produced updated estimates of climate outcomes across these different scenarios: the @UNEP, @climateactiontr (CAT), @IEA, and the relatively new @ClimateRsrc (CR) team. 3/
There is a pretty strong claim here that anything without a 50/50 chance of avoiding 1.5C is "not compatible with the Paris Agreement". Well-below 2C was the main Paris goal with an aspirational goal of limiting warming to 1.5C, but this seems to conflate the two a bit.
Here is the actual language of the Paris Agreement: "Holding the increase in the global average temperature to well below 2C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5C above pre-industrial levels"
Of course, "well-below 2C" is not particularly precise. While some have defined it in the context of a 2/3 chance of avoiding 2C warming (e.g. in RCP2.6 or SSP1-2.6 scenarios), others have defined it more ambitiously (e.g. 90% chance of < 2C, which is effectively a 1.5C scenario)
CO2 emissions are flatting. This is good news, but it does not mean global warming will stop. Rather, it means that warming continues at the same rate rather than accelerating. To stop the world from warming we need zero emissions.
This is the brutal math of climate change.
We have become more confident in recent years that when emissions do reach zero (or net-zero), global warming will likely stop. There does not appear to be substantial additional warming "locked in" or "in the pipeline". carbonbrief.org/explainer-will…
At the same time, once we reach zero emissions global temperatures will not fall for many centuries to come. Reducing global temps would require humans to actively remove CO2 from the atmosphere. E.g. getting back to 1970 temps requires sucking out all our emissions since 1970.
Big news: recent CO2 emissions have been revised notably downward in the just-released @gcarbonproject dataset. The revisions – due to a major reassessment of land-use – suggest emissions have likely been flat rather than increasing over past decade: carbonbrief.org/global-co2-emi… 1/19
Global CO2 emissions come from a combination of fossil fuel emissions (~90% in recent years) and land use change (LUC) emissions (~10%) from deforestation and soil carbon loss. While fossil emissions have an uncertainty of +/- 5%, LUC emissions are much more uncertain. 2/
The Global Carbon Project (GCP) substantially revised their best estimate of LUC emissions in their newly released dataset. Rather than a 35% increase in LUC emissions since 2000 – as the data previously showed – the new version has a roughly 35% decrease instead. 3/
For what its worth, we have been projecting future warming since the first climate models in the late 1960s/early 1970s. We can look back to see how well they have performed. It turns out our models generally did a good job:
In case folks are interested, climate models are not trying to predict year-to-year variability which is mostly dominated by semi-stochastic El Nino and La Nina cycles. They are trying to project long-term responses to changes in radiative forcing from CO2 and other GHGs.