Thread by @Peters_Glen

What will be the temperature increase in 2100 if emission pledges are implemented to 2030 & "with an extrapolation of implied effort beyond 2030"?

According to one scenario comparison: 2.3-3.2°C (median across IAMs).

THREAD

db1.ene.iiasa.ac.at/ADVANCEDB

2. It is not clear exactly how "with an extrapolation of implied effort beyond 2030" is implemented.

Depending on the IAM, GHG emissions either decline ~50% by 2100 or remain flat.

3. The carbon price to meet the outcomes varies considerably across IAM, but generally rises through to 2100 (and remains relatively low).

4. Despite these low carbon prices, a rather significant amount of carbon capture and storage is used, one model has ~50GtCO₂/yr in 2100.

I do not see why, with such low carbon prices, such high levels of CCS would be needed. What drives this?

5. The levels of coal, oil, gas, & biomass vary considerably across scenarios:
* Coal is flat, but then rises in many IAMs (due to use of coal with CCS)
* Oil is flatish, then declines slowly
* Gas continues to rise, in some cases flat
* Biomass grows

Some models are outliers!

6. Non-biomass renewables has only modest growth (solar, wind)

Nuclear has a steady increase in most scenarios, though strong in IAMS that prefer nuclear

7. Negative emissions are significant:
* Land-use change becomes afforestation by ~2050
* Bioenergy with CCS cross up to 9GtCO₂/yr in 2100

Not sure why models seek such levels of negative emissions in a moderate scenario. Is BECCS cheaper than mitigation, at low carbon prices?

8. I find these results rather intriguing. The aggregated pathways for GHG seem plausible, but the underlying energy system does not seem plausible.

Is it possible in IAMs to model out pathways at moderate carbon prices that don't include large-scale CCS & other crazies?

/end