Thread by @ClimateBen

Did you know?

1. If greenhouse gas emissions don't peak and fall sharply by soon after 2025, climate change will likely be severe enough to kill many billions by 2055.

2. Governments and corporations plan on increasing fossil fuel production well beyond 2025.

Let that sink in.

'The Met Office ran 17 different models with these feedbacks. All concluded a 4°C world by 2055 was likely if emissions continue to rise. Even if we are lucky, we are still likely to hit 4°C by 2070.'
newscientist.com/article/dn1786…

'a 4°C world might only support one billion people'.

climatecodered.org/2019/08/at-4c-…

It would appear, therefore, that billions would likely die by around 3.5C.

To avoid 3C we'd need to slash emissions in the 2020s.

To avoid 3.5 we'd need to slash emissions by 2025 - 2035.

To avoid 4C by 2055, we'd have to slash emissions before 2039.

theguardian.com/environment/20…

The Production Gap Report, released by a group of research organizations including the United Nations Environment Programme, found the world is set to produce about 50 per cent more fossil fuels in 2030 than it will take to limit warming to 2C.
nationalobserver.com/2019/11/20/new…

The 4C by 2055 - 2070 projection assumes very high emissions, strong carbon cycle feedbacks, and high climate sensitivity. All these are entirely possible. Some say current policies lead us away from this nightmare scenario, but production plans suggest otherwise.

This recent (2017) peer-reviewed research confirms that 3.5 - 4C by 2055 is a real danger.

'warming under the two baseline scenarios can exceed 3.5–4°C by 2050'

pnas.org/content/114/39…

'if emissions don't peak and fall sharply by soon after 2025, climate change will likely be severe enough to kill many billions by 2055'

Let me just explain why I feel my choice of words here is reasonable:

1. We are set for 2C by around 2040 (2030-2045). If emissions keep on

rising beyond 2026-2029, this very much suggests that by 2055 we'll hit 2.5- 3.5C or even 4C. It's extremely hard to imagine that this wouldn't threaten the lives of billions in terms of crop failures, water scarcity, ecosystem collapses, extreme weather events, etc.

2. Isn't
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it slightly missing the point to quibble over the exact likely temperature rise by 2055 (2.8? 2.9? etc) in the extreme scenario of emissions increasing into the late 2020s and 2030s? The danger to billions is clear if we're to go from 1.3C to 2.5- 3.5C (or more) in just 35 years.

2. 'soon after 2025' means what to people? 2026-2027? Later? To me it means 2026- to the 2030s, not least because 'soon' in the context of this abrupt climate change (faster than anything known in 65 million years) could easily mean 5 to 10 years!

3. So, is 'likely' the best...

word to use? Well, should we only ever use 'possible', just because it is beyond science to say for sure whether rapid warming from 1.3C to 2.5- 4C in just 35 years in this specific unique moment in geological history will kill many billions? That makes no sense to me. I'm not

against using the word 'possible', of course. But it is acceptable to feel that emissions are likely to keep rising given political and economic structures, and that feedbacks are likely worse than generally thought (see permafrost thaw and forest fires since 2019), and that

climate sensitivity will be high enough to combine with the other factors to threaten half of humanity with death and destruction at 2.5-4C.

Just think of the droughts and rainfall patterns in such a scenario.

Even at 1.5-2C they will become so dangerous.agupubs.onlinelibrary.wiley.com/doi/epdf/10.10…

Climate change impacts on global corn/maize yields, world's most widely grown crop (precipitation changes ignored: "We took a conservative approach")

🔺% risk increase of 4 maize-exporting countries simultaneously suffering a bad year:

2°C: 7%
4°C: 86% ⚠️phys.org/news/2018-06-w…