This morning (Korean time), @IPCC_CH’s Special Report on keeping global warming below 1.5°C was published. You find its Headline Statements here:…

“Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate.”
That’s what would probably happen if we keep global emissions flat. It already gives a sense of how fast we should reduce emissons to stay below 1.5°C.
Even global warming of 1.5°C would result in more hot temperature extremes in most inhabited regions, heavier precipitation in several regions, drought and precipiation deficits in some regions. But less so than 2°C.
“By 2100, global mean sea level rise is projected to be around 0.1 metre lower with global warming of 1.5°C compared to 2°C.”
A relatively small, but meaningful difference in terms of human and ecological adaptation. I'd expect a much larger difference over (more) time.
“Limiting global warming to 1.5°C is projected to reduce risks to marine biodiversity, fisheries, and ecosystems, and their functions and services to humans, as illustrated by recent changes to Arctic sea ice and warm water coral reef ecosystems"
“Climate-related risks to health, livelihoods, food security, water supply, human security, and economic growth are projected to increase with global warming of 1.5°C and increase further with 2°C.”
“In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO2 emissions decline by about 45% from 2010 levels by 2030.”
Meaning we need to reduce global CO2 emissions by 45% from *2010* levels, within 12 years from now, to keep global warming below 1.5°C.
And since global CO2 emissions still went up since 2010 (by about 10%), that means we'll need to halve global CO2 emissions between now and 2030, to keep global warming below 1.5°C! In index values:
2010 = 100
2017 = 110
2030 = 55
“Pathways limiting global warming to 1.5°C with no or limited overshoot would require rapid and far-reaching transitions in energy, land, urban and infrastructure (including transport and buildings), and industrial systems.”
“These systems transitions are unprecedented in terms of scale, but not necessarily in terms of speed, and imply deep emissions reductions in all sectors, a wide portfolio of mitigation options and a significant upscaling of investments in those options.”
“All pathways that limit global warming to 1.5°C with limited or no overshoot project the use of carbon dioxide removal (CDR) on the order of 100–1000 GtCO2 over the 21st century.”
Sometimes called negative emissions. Needed on top of those strong emission reductions.
In keeping global warming below 1.5°C, “Avoiding overshoot and reliance on future largescale deployment of carbon dioxide removal (CDR) can only be achieved if global CO2 emissions start to decline well before 2030.”
“Mitigation options consistent with 1.5°C pathways [have] multiple synergies and trade-offs across the Sustainable Development Goals (SDGs).The total number of possible synergies exceeds the number of trade-offs.”
That’s those measures with multiple benefits we should aim for.
“Strengthening the capacities for climate action of national and sub-national authorities, civil society, the private sector, indigenous peoples and local communities can support the implementation of ambitious actions implied by limiting global warming to 1.5°C.”
“International cooperation can provide an enabling environment for this to be achieved in all countries and for all people, in the context of sustainable development. International cooperation is a critical enabler for developing countries and vulnerable regions.”
That concludes my thread on the Headline Statements of @IPCC_CH’s #SR15 report on #1o5C. You can find the Summary for Policy Makers here:…, and the various chapters of the report itself here:
Essential stuff for our common future!

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More from @Sustainable2050

Aug 11, 2018
In discussions on the climate ‘hothouse’ paper, it’s interesting to see how annoyed some people get by the word stewardship. It’s labeled as anti-conservative, socialist, etc.
To me, stewardship is a positive word, and I remember it was e.g. often used by christian-democrats in this country. Checking it in the dictionary, I found this. Seems rather appropriate, given the climate crisis we’re causing.
Maybe the annoyance that "Earth system stewardship" causes has to do with the need for international cooperation it implies, for those who love competition?
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Jul 7, 2018
“What if we started economics not with its long-established theories, but with humanity’s long-term goals, and then sought out the economic thinking that would enable us to achieve them?”
The central question in @KateRaworth’s Doughnut Economics.
@KateRaworth Today, we have economies that need to grow, whether or not they make us thrive: what we need are economies that make us thrive, whether or not they grow.
@KateRaworth in Doughnut Economics
@KateRaworth Simon Kuznets, creator of the concept of Gross National Product, growth of which became the overriding economic goal: “Objectives should be explicit: goals for “more” growth should specify more growth of what and for what”. In 1962...
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Jun 4, 2018
By end-2017, renewables produced 26.5% of the world's electricity, up from 24.5% one year before! Fast growers: wind (4.0 → 5.6%) and solar PV (1.5 → 1.9%).
@ren21's new report:
Share of wind+solar PV in total 2017 electricity generation highest in Denmark (57%), followed by Uruguay (30%), and 4 European countries above 20%: Germany, Ireland, Portugal, and Spain.
The amazing growth curve of global solar PV capacity continued in 2017, reaching 400 GW by end of the year. This year the 500 GW mark will be passed, and around 2022 the first TW will be there!
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May 11, 2018
Confirmed: Atmospheric CO2 measured at Mauna Loa averaged 410.3 ppm in April. First time a monthly mean exceeded 410 ppm, just four years after the 400 ppm line was crossed.
Since I was born, CO2 at Mauna Loa crossed:
320 ppm in May 1960
330 in May 1972
340 March 1980
350 May 1986
360 May 1993
370 April 1999
380 April 2004
390 May 2009
400 April 2014
and 410 ppm in April 2018
I apologize for any inconvenience caused.
Years it took us to drive up CO2 by 10 ppm:
320 → 330: 12
330 → 340: 8
340 → 350: 6
350 → 360: 7
360 → 370: 6
370 → 380: 5
380 → 390: 5
390 → 400: 5
400 → 410: 4
That’s making the climate crisis worse faster.
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