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Glen Peters Profile picture
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12 Feb, 10 tweets, 6 min read
1. “one of the most important sentences of the last few centuries”…

Did the IPCC SR15 change the debate, the IPCC just in the right place at the right time, or are some people just slow to get it?

Seriously...

bloomberg.com/news/articles/…
2. Why not put praise on the earlier Paris Agreement, which has a legal form & is the text countries agree to adhere too?

🤔 Perhaps many just do not know about the Paris Agreement (or was it Accord?), or confuse IPCC SR15 and Paris?
3. Scientists have been on net-zero for years. So have policy makers. The Paris Agreement did not happen in a vacuum, nor IPCC SR15, it built on the work over years, even decades.

IPCC SR15 is an assessment of the literature, not new science. Or is it?
4. IPCC AR5 was onto it...

Remember all those scenarios below zero, & complaints about BECCS?

And remember the high profile “carbon budget”, figure SPM10, that build on papers from 2009?

We knew about net-zero then...
5. Back in 2012 the Nordic countries were aiming for net-zero (carbon neutral) by 2050 (sorry, link is dead). It wasn’t cool then, no leader boards of x% of countries with net-zero targets…
6. @Oliver_Geden was writing about net-zero (carbon neutral) in 2010 swp-berlin.org/en/publication…

His 2016 article is more influential than many will give him credit nature.com/articles/ngeo2…
7. Even before the big carbon budget papers in 2009:

2008: @damon_matthews & @KenCaldeira: agupubs.onlinelibrary.wiley.com/doi/full/10.10…

2008: @KevinClimate & @AliceClimate
royalsocietypublishing.org/doi/full/10.10…

Lots more...

I am sure @jgkoomey back in the 1980s also...
8. Why weren't preeminent fossil energy experts lumping praise on IPCC AR5, earlier reports, early movers, & leading their industries out of fossil fuel dependence?

It is almost like people forgive GM for doing an EV ad...

🤷
9. The quoted IPCC SR15 text is great. Sharp, crisp, & I use it all the time. Hats off to the smart people that wrote it...

Though, we have known more or less the same for 20+ years, & failed to act.

And we are still failing to act...
10. I am not sure the IPCC focused on the net zero text anyway.

My favorite was: “Every bit of warming matters, every year matters, every choice matters”.

While not as catchy & more ambiguous, it will probably stand the test of time!

/end

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More from @Peters_Glen

Glen Peters Profile picture
13 Feb
Fossil CO₂ emissions are likely to remain flat through 2100 leading to ~2.8°C warming if countries continue historical CO₂/GDP trends.

If countries meet emission pledges & continue reductions, then ~2.3°C.

Not RCP8.5, nor RCP1.9 or RCP2.6...

nature.com/articles/s4324… Image
Though, note that these sorts of methods are very sensitive to assumptions (played with this before).

They had a similar study a few years back, some thoughts here
medium.com/@Peters_Glen/w…

And here is how the method performed...
Here is a Kaya based projection we did 7 years ago. If a country continues along historical trends, the method is ok. If the country changes trends, the method is useless. See China. We were way out.

Though, for the EU, we will much better than the other study.. ImageImage
Read 5 tweets
Glen Peters Profile picture
12 Feb
"If you gave the average CEO a multiple-choice question whether the Paris Agreement goal is 2°C or 1.5°C, I wonder what they would write"

Let's see... bloomberg.com/news/articles/…
According to @CFigueres chatting to @MLiebreich

The hard target in the Paris Agreement is “well below 2°C” (you have to do this). The soft target is 1.5°C (the aspiration, we would like to do this).

Listen to the whole Episode 6 liebreich.com/cleaning-up/
The Paris Agreement asked IPCC do to a Special Report on Global Warming of 1.5C. This was done in the Paris Agreement "decision" text. This was why there was a 1.5°C report (interestingly not a "well below 2°C" report)

unfccc.int/process-and-me…
Read 6 tweets
Glen Peters Profile picture
11 Feb
THREAD: Does rounding change 1.5°C carbon budgets?

Short answer: Yes

If the temperature is rounded 0.05°C, then the carbon budget changes 100GtCO₂ (~25% of the remaining carbon budget for 1.5°C)…

That is the tweet, now for the explanation…

1/
2. Global average temperature has a near linear relationship with cumulative CO₂ emissions, with a correction for non-CO₂ emissions.

This means we need net-zero CO₂ emissions.

It is also great for back-of-the-envelope calculations…

cicero.oslo.no/no/posts/klima…
3. Equations:

T = α ×ΣCO2+ T(non-CO₂)

α is the Transient Climate Response to CO₂ Emissions (TCRE)

Assume a small change, so that T(non-CO₂) is ~constant

ΔT = α×Δ(ΣCO2)

(here is some explanation, sorry for different notation)
rdcu.be/cdO5Q Image
Read 11 tweets
Glen Peters Profile picture
10 Feb
"Net-zero CO₂ or GHG emissions? Resolving terminological confusion..."

CEOs (& higher) are raising the climate rhetoric, but do they know what they are talking about?

Does imprecise language suggests it is more talk than action?

1/
bloomberg.com/news/articles/… Image
“It’s revealing that a lot of financial institutions are thinking about...But they aren’t being exposed to climate scientists who can make sure they get the details right.” @bencaldecott

I agree, but does missing details mean we are at talk & not action? @Oliver_Geden

2/
I coincidentally came across this: "confusion remains about concepts like carbon neutrality, climate neutrality, full decarbonization, and net zero carbon or net zero GHG emissions" from @JoeriRogelj

That was in 2015... iopscience.iop.org/article/10.108…

3/
Read 6 tweets
Glen Peters Profile picture
4 Feb
THREAD: Climate risks & scenarios
[based on a presentation]

Financial institutions are asked to assess climate risk “…, taking into consideration different climate-related scenarios, including a 2°C or lower scenario.”

So, which scenario(s) do they use?

1/
2. It depends on the risk!

Easiest to frame around where we are heading (black line - approximate)

Climate risk: We have risk already, but we are concerned about it getting worse

Transition risk: We are mitigating, but policy, technology, society might make that happen faster
3. There is likely a drop in emissions from COVID of ~7%, but the IEA (& others) expect a rebound. Most analysts think emissions will be flat(ish) in the next decade.

The goal is to get to net-zero CO₂ emissions. When? Short answer: the earlier the better...
Read 10 tweets
Glen Peters Profile picture
3 Feb
Oslo had a goal to halve emissions in 4 years (to 2020), but emissions have only gone down 2.5% over that time.

Perhaps some things are out of Oslo's control, or, perhaps, reducing emissions is not so easy 🤔...

1/
nrk.no/norge/de-rodgr…
Oslo had a plan that was distributed across sectors. It is fair to argue that some things were out of their control (CCS at Klemetsrud), but not all things.

There was meant to be a 40% reduction in transport, for example, with many local measures.



2/
Here is how transport emissions were meant to go down. Perhaps Oslo did well on the collective transport, but how was progress across other transport sub-sectors?



/3
Read 5 tweets

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