Good news:
we are doing increasingly better closing in on 2°C
Bad news:
it is still far from meeting the goals of the #ParisAgreement
A short thread (1/n)
The @UNEP#emissionsgap report takes stock of current pledges of countries and compares them to where emissions emissions should be going to limit warming to 1.5°C or 2°C.
The difference is called the emissions gap.
(2/n)
The latest @UNEP#EmissionsGap Report finds new and updated Nationally Determined Contributions only take 7.5% off predicted 2030 emissions compared to previous commitments. Reductions of 30% are needed to stay on the least-cost pathway for 2°C and 55% for 1.5°C. (3/n)
Various countries contribute differently to this reduction in the #EmissionsGap, with Brazil actually counteracting the decrease. (4/n)
For the first time ever, the @UNEP gap report also looks into #NetZero targets.
It finds that a total of 49 countries plus the EU have pledged a net-zero target, covering over half of global greenhouse gas emissions, over half of GDP and a third of the global population. (5/n)
#NetZero targets should not be considered in isolation. Clear near-term plans a targets should accompany them to put countries and the globe on a clear path towards achieving the net zero target. (6/n)
The reports dives deeper into the various aspects by which #NetZero targets are being distinguished, and looks into whether the near-term NDCs of countries already put them on a clear path towards achieving their net zero targets. (7/n)
(Figure 3.3)
What does all this mean for global warming?
If current NDCs and pledges are achieved by 2030, and climate action continues at the same level of ambition thereafter, warming over the course of this century will only with a 2-in-3 chance be kept to 2.7°C (range: 2.2-3.2°C). (8/n)
Achieving, in addition, the announced #NetZero targets are achieved, would reduce this these projections by about half a degree. (9/n)
In the most optimistic case:
If all conditions that are included in NDCs (such as access to finance, technology transfer, capacity building) are met and also #NetZero targets are met, we are projected to en up with a 2-in-3 chance below 2.1°C (range: 1.9-2.4°C).
(10/n)
That is closer, but still not in line with the #ParisAgreement.
Finally, these single number hide some of the variation and risk in the global warming projections. Therefore, the report also shows the full distribution. (11/n)
Under current pledges there is about a 1-in-5 chance that warming still exceeds 3°C, whereas when considering the #NetZero targets in addition, this risk is strongly reduced but still a bit more than a 1-in-8 chance remains that warming would exceed 2.5°C until 2100. (12/n)
Finally, as every year, the @UNEP report also highlights way of reducing the #EmissionsGap and this year it highlights:
- The importance of a green #COVID19 recovery
- The potential additional contributions of #methane cuts
- The role of market mechanisms.
(13/n)
After yesterday, we now landed on changes in extremes🌡️⛈️🥵🧺!
And although I don't like to pick favorites, I do like this visual very much.
Too big for a single tweet, this one shows how hot extremes over land change compared to when our great-grandparents were alive. (2/n)
Did you notice in the previous figure: a heat extreme that our great-grandparents would have experienced once in their lifetime, will occur about once every 4 years in a 2°C warmer world. It will be the norm in a 4°C warmer world.
Carbon budgets tell us how much CO2 we can still emit while keeping warming below specific limits.
The latest @IPCC_CH report provides updated estimates of these budgets.
Here’s an insider's view with a deep dive looking at how they have changed since previous reports. (1/n)
I have been involved in the estimation of carbon budgets since the IPCC Fifth Assessment Report in early 2010s.
And since the first IPCC estimates published in 2013, we have learned a lot and have gotten much better at estimating remaining carbon budgets. (2/n)
The scientific basis underlying a carbon budget is our robust scientific understanding that global warming is near-linearly proportional to the total amount of CO2 we ever emit as a society.
This is shown in Fig. SPM10, both for the past and future projections. (3/n)
EXPLAINER: new projections for the next 5 years by @metoffice and @WMO indicate that there's a high chance that one of these years is 1.5°C warmer than average preindustrial levels.
The 1.5C level in the @metoffice announcement should not be confused with the 1.5C limit in the Paris Agreement.
The Paris targets refer to global warming - that is, the temperature increase of our planet once we smooth out important year-to-year variations (see👇)
(2/n)
Even in a stable climate, global temperatures differ from year to year because of noise in the climate system.
A detailed look at the report shows that @IEA has done a thorough job.
Modelling choices underpinning the pathway are well argued, reliance on speculative technologies is limited, and the carbon budget is in line with the most ambitious pathways available in the literature (2/n)
In addition, the report also presents a unique collaboration between two of the core flagship teams of @IEA: The World Energy Outlook and the Energy Technology Perspectives.
The @Science_Academy's analysis starts from carbon budgets reported in @IPCC_CH's 1.5°C Special Report's Table 2.2 (orig. below).
Then makes adjustments & updates.
Having had the pleasure to compile Table 2.2 for #SR15, let's compare and try to make sense of the numbers
(2/n)
The @Science_Academy's table starts from IPCC's 1.5C carbon budget for a 50% chance.
(Note1: the table quotes either a wrong likelihood or a wrong number, but that's a detail)
(Note2: IPCC Table 2.2 is in GtCO2, the table below in GtC. Multiply by 3.6 to convert to GtCO2)