Glen Peters Profile picture
Research Director @CICERO_klima on past, current, & future trends in energy & emissions. Projects: @V_ERIFY_H2020, @4C_H2020, @ParisReinforce, @CoCO2_project
Duncan Noble Profile picture Jean-Marc Desperrier Profile picture Pietro Monticone Profile picture Herve Moal Profile picture 💉💉AZ💧Warwick Tweedie Profile picture 11 added to My Authors
27 Jun
I interpret this as CO₂ emissions & removals as practically symmetric.

A 100GtC (366GtCO₂) experiment gives ~3% asymmetry (bigger pulse, bigger asymmetry) & symmetric in temperature.

We currently emit 40GtCO₂ (net) & scenarios remove ~10GtCO₂ (net). We are unlikely to be in a symmetric situation with emissions & removals. 40GtCO₂ net removal unlikely & also displaced in time.

We may have bigger gross emissions, but the atmosphere sees net emissions.

How to interpret such big pulses?

These experiments are 100-500GtC (366-1800GtCO₂), which we may emit over 10-50 years.

I see these experiments as more like the long-term response (say >50 years).

Read 5 tweets
22 Jun
Bioenergy is complex...

One of the reasons is that emissions are given as zero in the energy sector (reported as a memo), which means it is necessary to model the land sector to analyse bioenergy (or material substitution).

Short presentation

2. There is a real opportunity cost.

Increasing forest harvest, e.g. to increase bioenergy or material substitution, all else equal, means a smaller land sink. But, a land sink is needed to help reach net zero (may not be possible to get all emissions to exactly zero).
3. The forest sink is mainly from forests remaining forests, so carbon uptake comes from management or environmental factors (CO₂ fertilisation, climate change).

Afforestation can be increased & emissions from other land use types & transitions can be decreased.
Read 12 tweets
19 Jun
What does China have to do in a 1.5°C pathway?

Based on the new NGFS scenarios, up to a 60% drop in fossil CO₂ emissions by 2030. This includes a pathways with divergent polices (Divergent Net Zero).

(Different colours, different IAM).
EU & US reach net zero around 2040-2060, depending on model and scenario.

For the lingo, "Net Zero 2050" is an orderly transition to 1.5°C & "Divergent Net Zero" is a disorderly transition to 1.5°C, implying policies are implemented immediately, but not uniformly.
Don't ask about India...

[Technically, I guess the rebound in MESSAGE is since carbon prices stop growing (& decline) after net zero, which allows India to emit more. That would be my hypothesis... Is this rebound believable?]
Read 4 tweets
14 Jun
The penny just dropped...

Guarantee of Origins (GoOs) are basically a Non-Fungible Token (NFT)……

There is no physical transfer of electricity, just a digital transaction with some $.
A GoO is basically a certificate to say that some renewable electricity was produced, & the certificate is then sold onward to an entity. The entity then claims they are using renewable electricity, even if they are connected only to a coal power plant.
The average consumer that is physically using the renewable electricity generally has no idea about this virtual transaction. So, Norwegian's think they are using Norwegian hydropower & German's think they are using Norwegian hydropower. I guess no one is using the coal then?
Read 6 tweets
14 Jun
The EU has a LULUCF sink of ~250MtCO₂/yr:
* ~300MtCO₂/yr is forests remaining forests (a share of which is due to climate change & CO₂ fertilisation)
* ~50MtCO₂/yr is land converted to forests
* ~50MtCO₂/yr is increased storage in wood products
* The rest is a source

This sink has a huge policy significance, as the sink allows to offset emissions in hard-to-mitigate sectors & reach net zero in 2050.

But, using forests could also help reach net-zero by displacing some fossil fuels?

Just focusing on forests, the EU could increase harvest, weakening the sink, & use the harvest to displace materials (e.g. cement in construction) or fossil fuels (e.g., bioenergy).

[hypothetical numbers]

According to the JRC, this is probably worse!

Read 5 tweets
11 Jun
"IAMs are built on an oversimplified logic"...

But here lies the problem. The tendency is then to make models more complex. This does not solve the problem. Models are so complex barely anyone can understand what drives what.

Reform is needed so "researchers can examine the trade-offs between making models tractable & making them more useful for real-world decisions"

To me, this means you need different types of models, different types of tools & approaches, not bigger models.

Overwhelmingly, it seems most research funding is aimed at building more complex models. And nearly all funding is tied up by the big modelling groups.

Imagine an ERC or EU project, "here is my simple toy model". Laughed out of the room, but this is what is needed.

Read 7 tweets
11 Jun
Increasingly scenario users are interested in 'where we are heading' as a baseline, rather than no climate policy scenarios (light grey) & SSP5-85 (RCP85).

"Current policies" are high-end for some users...

This is quite consistent with our comment:…

Current policies may take the world to ~3.2°C (10-90% range 2.3-4.4°C due to climate uncertainties), which is much less than >5°C in SSP5-85.

The bold lines are from the NGFS scenarios used by financial institutions for 'stress testing', the thin lines are from IPCC SR15.

Another organisation that has been doing work on 'where we are heading' is the @climateactiontr, which has quite consistent numbers as the NGFS (though quite different methods).
* NGFS is based on modelling
* CAT is more a statistical approach…

Read 8 tweets
9 Jun
I had a poll the other day on "Orderly" versus "Disorderly" energy transitions. This wording comes from the @NGFS_.

I have troubles with saying immediate implementation of global 1.5°C climate policies is orderly. Perhaps in a model but not in reality.

A few thoughts...

A global carbon price of 150 or 200$/tCO₂ in 2025 is the difference between Orderly & Disorderly? (blue versus purple). You are kidding me?

Or a delay of 10 years and then a carbon price of 250$/tCO₂ is disorderly?

This is reduction in coal in the various NGFS mitigation scenarios.
* Which one looks orderly?
* Which country would find implementing an economy wide climate policy overnight orderly?

Read 8 tweets
4 Jun
How does the global average temperature increase compare to atmospheric CO₂ concentrations in the last ~100 years?

It is quite a linear relationship, with a 2.7°C increase for a doubling of CO₂ concentration.

This includes non-CO₂ effects, which approximately cancel.

This tweet was inspired by a comment by @GregFlato based on this figure by @RARohde

"If you multiply by 270ppm to make it comparable to TCR & ECS, you get something we might call ‘instantaneous climate sensitivity’ (ICS) which comes out to be 2.7C"

Greg mentioned it was not useful, but a discussion followed...

(try to follow the discussion on the various threads)

Read 6 tweets
31 May
Global CO₂ emissions grew at 2.6%/yr in the 2000s, but this dropped to 1.0%/yr in the 2010s.

Can we see this in the atmosphere?

If emissions growth continued at 2.6%/yr in the 2010s, it would lead to ~0.3ppm difference in 2019, or cumulatively 1.3ppm over the 2010s.

1/ Image
How did I do this?
1. Assume emissions continued at 2.6%/yr from 2010
2. Get difference with current emissions
3. Multiply by airbourne fraction (AF, estimated 1960-2010, 0.43) to estimate atmospheric increase
4. Convert to ppm (1ppm = 2.124GtC, GtCO2 = 3.664 GtC).


We should see this in the atmosphere, but how confidently given variability?

The effective difference in growth rates is ~2%, which we should be able to detect after 5-10 years. Though, note in the commentary, we compared 1% & -1%, not 2.5% & 1%.

Read 4 tweets
28 May
Norway's oil industry on defensive after IEA report as polls loom

One report can change the debate & potentially tip the scales in an election year!

A good summary of why the @IEA's Net Zero 2050 report could be transformational, by @olehelgesen7.

"It is not obvious that the cheapest resources with the lowest carbon footprint lie in the resources already discovered... To stop exploration at this time would cause a major threat to the world's energy security", are the arguments from the Norwegian Oil & Gas lobby

"Recent polls have shown that 60% to 70% of voters continue to support future Norwegian oil & gas production"

[Perhaps the political niche is threading the needle between investment for old & new fields, taking the IEA's lead]

Read 8 tweets
25 May
THREAD: Bioenergy use in the @IEA Net Zero 2050 scenario

I have seen a few comments that the IEA uses loads of bioenergy. Let's have a look...

First up, overall, bioenergy use is lower than in equivalent scenarios assessed by the IPCC, particularly in 2050.

2. An important detail is that the IEA assumes traditional biomass is gone by 2030. Traditional bioenergy "is unsustainable, inefficient & polluting, & was linked to 2.5 million premature deaths in 2020"

The IPCC only has a slow drop, so the IEA must build up modern bioenergy.
3. In terms of modern bioenergy, the IEA has similar levels as the IPCC up until 2050.
* Rapid growth to 2030 is to compensate traditional bioenergy
* Slowdown to 2050 is to limit to 100EJ per year, view by many as sustainable.
Read 11 tweets
19 May
The IEA Net Zero 2050 scenario uses quite a lot less Bioenergy with Carbon Capture & Storage (BECCS) than scenarios assessed by the IPCC.

Consequently, all else equal, the IEA NZE2050 uses less fossil fuel in 2050 than most IPCC SR15 scenarios.

The IEA, in contrast, has a decent (not huge) amount of Direct Air Capture (DACCS) of 0.6GtCO₂/yr.

Not many scenarios assessed by the IPCC SR15 use DACCS (4 out of 53 have non-zero data, the other 2 marked have zero DACCS)

The scenario with high DACCS is from MERGE-ETL.

Since IEA NZE2050 reaches net-zero CO₂ emissions in 2050, the removals (tweets 1 & 2) must balance with (residual) emissions in 2050.

The NZE2050 clearly has far less fossil fuel use in 2050 than most IPCC SR15 assessed 1.5°C scenarios.

Read 7 tweets
18 May
The new @IEA Net Zero by 2050 report is crystal clear on what is needed.

"All the technologies needed to achieve the necessary deep cuts in global emissions by 2030 already exist, & the policies that can drive their deployment are already proven."…

"Clean energy innovation must accelerate rapidly, with governments putting R&D, demonstration and deployment at the core of energy and climate policy."

In 2030 only existing technologies needed, by 2050 new technologies also come to market.

Net Zero 2050 is a jobs bonanza.


"The transition to net zero brings substantial new opportunities for employment, with 14 million jobs created by 2030 in our pathway thanks to new activities and investment in clean energy"

More jobs than losses...

Read 10 tweets
10 May
What explains the generally poor performance of solar in energy-system models (versus reality)?

* Type of organisation
* Type of model

* Cost
* Technology & policy assumptions

"IPCC scenarios consistently project lower PV adoption pathways & higher capital costs than non-IPCC scenarios"

Academics & researchers are behind the curve... (or are they just exploring the uncertainties?)

If you think the track record on PV costs are bad, then you have missed the elephant in the room

Model, model setup, model assumptions, etc, are more important. This is such a misunderstood issue.

Read 8 tweets
10 May
Norwegian electricity production is dominated by hydropower, & overall Norway is a net exporter of electricity (though, this varies throughout the year).

Hydropower production varies due to weather (green), but consumption is relatively constant (black line).

Total energy consumption is dominated by hydropower (figure shows generation, not consumption).

Nearly all the oil is used in transport, and nearly all the gas is used in oil & gas extraction.

Norway is already quite electrified...

The energy flow is dominated by electricity (hydropower, split between dispatchable & non-dispatchable).

As time passes, this figure will become even more dominated by electricity. Current policy is to electrify transport & oil & gas production...…

Read 4 tweets
7 May
There is a lot of confusion about net-zero GHG & CO₂ emissions, they are different.

The EU & US have a target of net-zero GHG emissions in 2050, which is ~20 years ahead of the global average (coincidentally, global net-zero CO₂ emissions is ~2050).

For developing countries to have a later net-zero GHG year, say 2090 (~20 years after the global average), it requires that developed countries are net negative to compensate developing countries & maintain net-zero GHG globally. (a point often made by @Oliver_Geden).

I think we all agree & accept developing countries will find their own path to net-zero, & one that is later than developed countries.

But, I also think many confuse the net-zero years for CO₂ & GHG emissions.

Many obsess on 2050, when there is actually a broad range!

Read 4 tweets
7 May
A 🧵 on carbon budget uncertainties (for walkers)...

It is 2km to the lake, which means it could be 1.5km or 2.5km given rounding.

If I have walked 1km, then it is 0.5km to 1.5km to go. That is a huge uncertainty!

Carbon budgets are often presented for 66% chance (of avoiding the target), which in this analogy, would say after 1km that if I walk 0.5km further there is a 66% chance I have not reached the lake.

Or after 1.5km, there is a 33% change I have still not reached the lake!

There are a few issues here. There will be a non-zero probability I have reached the lake after only 1km, which means the measurements were wrong.

Carbon budget uncertainties for 1.5°C also include negative carbon budgets, meaning it may already be too late to avoid 1.5°C!

Read 5 tweets
6 May
Keeping below 1.5°C requires rapid emission reductions at the global level.

What do scenarios imply for key regions?

In this thread, I show the fossil CO₂ emissions in key regions. These scenarios do not include equity considerations, these are cost-efficient pathways.

1/ Image
2. In the OECD, fossil CO₂ emissions are are already in a decline.

On average, from 2020, a 44% reduction by 2030 & 95% by 2050. This requires accelerating climate action beyond current levels. Image
3. Asia is a big challenge. Emissions are growing strongly now, but has to drop by 47% from 2020 to 2030 & by 88% to 2050.

This requires a dramatic reversal of current trends. In many respects, this makes the challenge harder in Asia (developing) compared to OECD (developed). Image
Read 9 tweets
5 May
EU27+UK GHG emissions (including LULUCF) have declined 30% from 1990 to 2019.

By changes by sector were:
* Energy: -28%
* Industry: -30%
* Agriculture: -20%
* Waste: -44%
* LULUCF: +37% (stronger sink)

The energy sector is the largest in terms of GHG emissions.

The changes from 1990 to 2019 were:
* Energy industries: -41%
* Manufacturing: -41%
* Transport: +20%
* Other (buildings, etc): -27%
* Fugitive: solid -73%, oil/gas -46%

Transport is a problem...

Considering only CO₂ emissions, emissions are nearly totally dominated by energy (see previous tweet for details), with some emissions from industrial processes (cement, etc) and LULUCF as a sink.

Read 9 tweets
4 May
Mitigation will cause the ocean sink to have reduced efficiency because of:
* reductions in carbonate buffer capacity in scenarios with intermediate or no mitigation
* reduced transport of anthropogenic carbon from surface to depth in 1.5°C scenarios.

2. Atmospheric CO₂ has grown exponentially over the industrial era. Under an exponential forcing regime, ocean anthropogenic carbon uptake also grows exponentially.
3. Since these conditions have held over the historical era, the ocean sink has historically maintained a high efficiency.

In future scenarios, regardless of the degree to which emissions are mitigated by 2080, efficiency of ocean anthropogenic carbon uptake will decline.
Read 4 tweets