CMIP7-ScenarioMIP: gridded Emissions 2022-2100 (all markers); version IIASA-IAMC-*-1-1-1

[jkikstra]

This is the place to discuss the gridded emissions data for ScenarioMIP CMIP7-ScenarioMIP.

Version 1.1.1 is on ESGF for all marker scenarios recommended for use in CMIP7 Fast Track:

• IIASA-IAMC-h-1-1-1
  • Description: gridded emissions for a high emissions scenario, produced by the GCAM team
• IIASA-IAMC-hl-1-1-1
  • Description: gridded emissions for a high-to-low emissions scenario, produced by the WITCH team
• IIASA-IAMC-m-1-1-1
  • Description: gridded emissions for a medium emissions scenario, produced by the IMAGE team
• IIASA-IAMC-ml-1-1-1
  • Description: gridded emissions for a medium-to-low emissions scenario, produced by the COFFEE team
• IIASA-IAMC-l-1-1-1
  • Description: gridded emissions for a low emissions scenario, produced by the MESSAGEix-GLOBIOM-GAINS team
• IIASA-IAMC-ln-1-1-1
  • Description: gridded emissions for a low-to-negative emissions scenario, produced by the AIM team
• IIASA-IAMC-vl-1-1-1
  • Description: gridded emissions for a very low emissions scenario, produced by the REMIND-MAgPIE team

More information:

• brief documentation, version history with changes compared to earlier testing data, and global sums on Zenodo: https://doi.org/10.5281/zenodo.17981824
• input4mips website [link]
• a journal publication and citation guidance is under preparation

Should any comment/question you leave here be left unanswered for longer than you wish, please contact Jarmo Kikstra (kikstra@iiasa.ac.at).

[digbyr]

Hi all! We at the CCCma are starting to look at the ScenarioMIP aerosols and I was wondering if anyone can explain the trends in the highlow and medium aviation emissions:

The highlow aviation emissions seem implausibly high up to 2065, and then their decrease seems implausibly rapid. For the medium scenario, the BC emissions are anomalously high while the OC and SO2 are flat like in the mediumlow scenario. These results do seem consistent with the diagnostics at https://zenodo.org/records/19730076, but I am wondering whether the odd behaviour might just have slipped through the cracks since aviation is such a small fraction of the total emissions.

I am also curious about the trends in forest burning in the verylow and lownegative scenarios. Here are total openburning BC emissions in all of the scenarios, where we can see that the verylow and lownegative scenarios have much more variable emissions than the others:

and here are the emissions for lownegative broken down by sector, so we can see that the irregularity comes specifically from the forest burning.

I previously looked into the verylow burning emissions and found that the relative difference between Southeast Asian forest burning emissions in the H and VL scenarios changes sign as you step through time. In the 2020s and 2060s, SEA forest burning emissions are higher in the VL scenario, and in the 2040s and 2080s they are higher in the H scenario, see attached.

Does anyone have insights into these?

[shinichirofujimoriKU]

For AIM-LowtoNegative scenario, we basically use Fire model which can be found in the following studies.
https://iopscience.iop.org/article/10.1088/1748-9326/ad1b7d/meta
https://www.sciencedirect.com/science/article/pii/S095937802300033X

The main drivers of the fire occurence is land-use and GDP/capita. The formulation can be found in the above references.
Basically, GDP/capita growth would decrease the fire rates but in the meantime, the fores area is the key increase factor under mitigation scenarios. They are offsetting each other and the degree depends on the regions but probably the the increase in mid century would be due to the situation where the latter factor becomes larger than former one.

[digbyr]

Thanks @laurinks and @shinichirofujimoriKU, this is really great information!

[digbyr]

For the highlow scenario, I also wanted to ask about the shipping (and possibly the waste?) in addition to the aviation results posted above. Here I am showing emissions by sector for highlow in blue with high in orange for comparison. The 2070 reduction in shipping emissions is astonishingly rapid! Is this deliberate, relating to something like an IMO2020-style policy change?

But my biggest concern remains the aviation emissions in highlow (BC, OC, SO2) and medium (BC only) scenarios. Both shipping and aviation show precipitous drops in 2070, but the aviation emissions in particular seem implausibly high leading up to that point.

Thanks everyone for the input on these!

[MathijsHarmsenPBL]

Hi @digbyr, thanks for noticing. IMAGE has aviation pollutant emissions for BC, but not for OC and SO2, since these seemed to very minor when we implemented this. So OC and SO2 follow the constant emission rules when these emission categories are missing in a model. For BC, we don't have any air quality policies in place, since this information was not available to us (i.e. it was not in the GAINS data). This means that BC aviation emissions follow the trend in aviation kerosene use in our case. I think this is not unreasonable. There are some options to reduce soot (sustainable aviation fuel, better engine combustion, but I also read these show mixed results). I hope this helps. Best, Mathijs

[digbyr]

Thanks for the explanation @MathijsHarmsenPBL.

[laleluia]

Thanks for noticing this. While shipping reductions are comparable to past Sulphur policies and consistent with HL narratives, we have found a problem on the harmonization of the aircraft emissions. We are trying to solve this issue. We will get back to you.
thanks
best
The WITCH team

[laleluia]

Follow-up to my earlier comment.

We re-checked the WITCH HL post-harmonization output. It is consistent with the HL storyline in Van Vuuren et al. (2026, GMD): rapid, coordinated mitigation in the second half of the century under high technological capacity.

On the magnitude of aviation growth up to 2070: this is consistent with the SSP5 socio-economic development, namely high economic growth, energy-intensive lifestyles, associated with rollback of climate policy (H/HL). Without an effective international mitigation regime, aviation is hard to abate. The harmonized level sits within the range expected for an SSP5-anchored high scenario.

The WITCH team will document extensively the harmonization choices and the aviation pathway in detail alongside the scenario release.

[digbyr]

@laleluia thanks for this extra context! I am curious, though, why the aviation in the HL scenario would increase so much more rapidly than that in the H scenario prior to the 2070 reductions. In the figures I posted above, H is the blue line and it is nearly flat compared to the rate of increase in HL (orange).

I'm also not sure if your team is the one to ask about the M emissions or if that's a different group, but the BC aviation emissions in that scenario are not consistent with the corresponding OC or SO2 emissions.

[digbyr]

@laleluia just following up on this - do you know why the HL aviation emissions are so much higher than the H emissions up to 2070?

[jkikstra]

Hi @digbyr just chiming, although I'm not the developer of the scenario, perhaps it provides a pointer until @laleluia comes back.

One key difference between H and HL, I think, is the underlying economics:
*H has SSP3, with slow economic development. I assume that aviation activity growth slows down a lot. While there is, especially in the near term, still some improvements in emissions intensities of fuels.
*HL has SSP5, with very fast economic development. I assume that aviation activity would grow increasingly fast. More rich people, less worry about environmental damage, more flying.

[ccmi1-test]

Hello @jkikstra.

I have just been processing the NOx_em_anthro emissions for the Medium-to-Low (ml) scenario for our runs to produce the specified ozone forcing. I noticed that the International Shipping (sector 7) is constant for all years from 2024 to 2100. I can see it in the v1-1-1 files I am working with and it can also be seen in the global totals that are provided on Zenodo. Since it is a bit suspicious, I wanted to check with you whether this is a problem or if it is supposed to be this way. Thanks.

[vnaik60]

Hi @jkikstra, could you confirm that the constant aircraft/shipping emissions for ML scenario are by design? Thanks!

[jkikstra]

Hi @ccmi1-test and @vnaik60, thanks for the multiple pings, and sorry I missed this in my inbox earlier! I was on leave most of July and then missed this.
I do believe this is all as intended, but I will also now immediately check in with the COFFEE team (who produced ML) to confirm.

[Angelkorte]

Hi @ccmi1-test, @vnaik60, and @jkikstra,

We confirm that the constant aviation and shipping NOₓ emissions are expected for this scenario and are consistent with our assumptions. The current results can therefore be used as provided.

[vnaik60]

Thank you @Angelkorte and @jkikstra!

[ccmi1-test]

Same from me. Thank you @Angelkorte and @jkikstra for confirming things are as they should be. It is good to hear!