THREAD (to get you prepared for the #IPCC Special Report on 1.5°C #SR15)

What are the origins of 1.5°C?…
1987: President of the Maldives: "We know, & yet we keep delaying action. The time for just talking is over."
1988: James Hanson testified "99% confidence"
1988: The #IPCC is born
1990: IPCC First Assessment Report (FAR)
1990: Alliance of Small Island States (AOSIS)
1992: UNFCCC "to prevent dangerous anthropogenic interference with the climate system"
1997: Kyoto Protocol
2007: Bali Road Map gives new hope
2008: A limit well below 1.5°C (Tuvalu, AOSIS)
2008: 1.5°C to stay alive
2009: Copenhagen Accord enshrined 2°C in climate politics
2010: Cancun Agreement commits to "review" 2°C
2011: @CFigueres "If we are not headed to 1.5°C we are in big, big trouble"
2015: 2°C is inadequate (Structured Expert Dialogue)
2015: High ambition coalition was born
2015: The Paris Agreement to pursue efforts to 1.5°C
2016: IPCC agrees to a Special Report on 1.5°C
...(scientists overworked for 2 years)...
2018: The #SR15 to be released 8 October, after the the final part of the report "Summary for Policy Makers" is agreed between scientists & policy makers.

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More from @Peters_Glen

Aug 31, 2018
Impressive new study on the carbon intensity of crude oil production by field. Average life-cycle emissions are 10.3gCO₂-eq/MJ or 1.7GtCO₂-eq (5% global energy GHG emissions), with huge variation by field / country. 1/5… ($)
Flaring (red), heavy oil (blue), or both (yellow) are key factors increasing emissions. Flaring is 22% of average weighted carbon intensity, but much higher in some places (over 50%). Heavy oil can be very emission intensive, but not always. 2/5
This will excite Norway: "Although some giant North Sea offshore fields have shown rapidly increasing per-barrel emissions due to depletion, they have low upstream GHG intensities when compared to many other global oil fields." 3/5
Read 6 tweets
Aug 28, 2018
What is the role of oil in a 2°C world?

THREAD on my presentation at #ONS2018 #CentreCourt (Monday), where I (try to) explain why there is potentially space for some new oil & what constrains the amount 1/…
It is important to remember, that every molecule of CO₂ that enters the atmosphere causes the temperature to increase. To stop temperature rising, either stop emitting CO₂ or, if you must, take out what you put in. 2/
Because it is unlikely we can get to zero emissions in 10-20 years (1.5°C) or 30-40 years (2°C), we have to remove CO₂ from the atmosphere. The more removed, the less radical the short-term reductions. Radical mitigation AND CO₂ removal is key. 3/
Read 13 tweets
Aug 8, 2018
A #HothouseEarth THREAD

The standard headline & interpretation: We are doomed, the Earth's climate will runaway to 4-5°C even if we slash emissions.

Well, that is not what the paper says (actually, it is a Perspective), & I don't see this framing as particularly helpful!
The paper does not seem to define "Hothouse Earth", this seems to come from the press material? I don't see much on 4-5°C or 10-60m in the paper, if so, it is very indirect?
The paper "explores" if we "could" instigate feedbacks, they "could" cascade, & they "could" lead to a hothouse earth (whatever that is). "We cannot exclude" this happening at 1.5-2°C. The closing paragraph says we should investigate these issues!…
Read 10 tweets
Jun 20, 2018
THREAD on the climate sensitivity (& carbon budgets)...

After decades of research, the equilibrium climate sensitivity has remained fairly close to 3°C for a doubling of pre-industrial CO₂ concentrations.…
The range has remained stubbornly wide (1.5°C-4.5°C), despite many individual studies claiming to narrow it (particularly recent instrumental-based methods). Though, @AndrewDessler could argue that in the 1970's the range was underestimated & today it is overestimated (maybe).
Most methods have a similar range, but instrumental methods are certainly lower. Many reasons why the instrumental record may be low (aerosols, variability, temperature estimates, ocean heat content, etc, etc).
Read 9 tweets
Jun 19, 2018
This thread seems to get two things wrong
1. Emissions need to be as close as possible to zero AND CO₂ removal is needed in addition (it is not either/or)
2. Mitigation is currently FAR cheaper than removal (removal may help costly mitigation, like air to fuels for aviation)
If CO₂ removal was used to just offset existing emissions (instead of reducing emissions), it is far cheaper to deploy energy efficiency, solar, batteries, CCS, etc, then recapture emissions directly from air (expensive). Even if social cost was $80/tCO₂, still take cheapest?
In emission scenarios (shown for 1.5°C), CO₂ removal has two roles:
* Small: Offset hard to mitigate sectors (the brown does not go to zero, need CO₂ removal)
* Big: Offset earlier emissions (already emitted too much, which gets worse if we don't mitigate drastically today)
Read 5 tweets
Jun 19, 2018

What are climate scenarios?

We use scenarios to explore the consequences of uncertainties (social, political, technical, climate).…
Climate scenarios are generally separated into two categories:
1. Transition risks related to the transition to a lower-carbon economy
2. Physical risks related to the physical impacts of climate change
Both types depend on different tools & methods
Scenarios should cover a range of possible outcomes. In practice, scenarios often focus on particular outcomes (levels of radiative forcing, policy characteristics, technology portfolios, behavioural change) meaning that a large part of the scenario space can be left unexplored.
Read 8 tweets

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