2.7C by 2100 under current policies, albeit with a fair bit of uncertainty.

Thankfully there is no plausible world where we get to 2.9C by 2050.

Thanks, it’s one of my favorites.

Me to. That probability is also contingent on their central emissions outcome. I wish the UNEP report provided a combined uncertainty estimate here…

They are my figures; here is UNEP's one with whiskers (albeit only for the values in this report).

Hopefully under 3C (the new UNEP report gives a ~80% chance for the central estimate of current policy emissions), but big uncertainties remain.

For more details, see Carbon Brief's coverage here: www.carbonbrief.org/...

And the full UNEP Emissions Gap report here: www.unep.org/resourc...

Here is how estimates of future warming have changed over the past four UNEP reports. The estimates are down slightly from last year (largely due to methodological updates) but there isn't really a trend down in future warming estimates in recent years.

Yep, global.

PFAS is bad but not a greenhouse gas.

Not sure it buys us time; most SLCP emissions today will be long gone when we reach peak warming even under optimistic scenarios.

It’s good to cut them, just not to use them to justify emitting more CO2 (e.g. as offsets by themselves).

So lets take stronger action to cut SLCPs; lets just not do it in a framework that allows more CO2 emissions. Because ultimately its CO2 that is driving long-term warming of the climate system. SLCP's alone cannot credibly neutralize CO2 emissions; they need to be coupled with future carbon removal.

This makes methane both a powerful lever to have a strong near-term climate effect, but also a potentially dangerous distraction if we prioritize it over CO2 as we trade short-term benefits for longer-term harms.

This has a few important implications. First, we are stuck with warming from CO2 more or less forever; we would have to remove CO2 we previously added to cool down the climate. We can, however, undo past warming from methane emissions by simply cutting emissions.

Short-lived climate pollutants (SLCPs) have a strong near-term impact on global temps, but have a short atmospheric lifetime. They represent "flow pollutants" where the amount in the atmosphere depends on the rate of emissions, while CO2 is a "stock pollutant" that depends on cumulative emissions.

Hah, I made the same typo 🫥 bsky.app/profile/haus...

To be clear, there is a lot of reasonable stuff in Gate's new memo, but I chafe a bit at the assumption that putting resources toward mitigation and development/public health have to be zero sum tradeoffs.