Pathways to limiting global warming to 1.5°C

A super relevant point related to our climate future emerges from the IPCC Special Report on 1.5°C warming that I wrote about before. The report shows that our environment is likely to be much more hospitable for human habitation if we can limit global warming to the ambitious target of 1.5°C rather than the also ambitious 2.0°C warming targets that was the goal of the Paris Climate Agreement.

An interesting point arising from this report though was the understanding that to limit global warming to 1.5°C we will need ways to remove some of our past and ongoing greenhouse gas emissions from the atmosphere. In essence, the longer we delay in cutting emissions (as we are just now) the more we will need to rely on technologies to suck greenhouse gases out of the atmosphere. This is of massive significance, as  these technologies are not yet available at scale to do the work we require of them.

To break this down and explain it more, lets first have a look at the key graphic from the Report Summary for Policy Makers:

The 4 pathways shown are those with no or limited overshoot of 1.5°C warming, which requires that global net anthropogenic CO2 emissions decline by about 45% from 2010 levels by 2030 reaching net zero around 2050 in all cases.  However the way we achieve this is different in the 4 pathways.

Importantly, all pathways that limit global warming to 1.5°C with limited or no overshoot project the use of carbon dioxide removal (CDR) on the order of 100–1000 Gt CO2 over the 21st century.

There are 3 main categories of carbon dioxide removal strategies include carbon capture and storage (a.k.a. CCS), which is the process of capturing the CO2 released from the exhaust gas of fuel combustion or other oxidative process and depositing the CO2 in geological storages. Bio-energy with carbon capture and storage (a.k.a. BECCS) is the combination of bioenergy use and capturing and storing the biogenic CO2 leading to a net CO2 sink. These technologies are not yet up to technological and industrial readiness levels that would allow for deploying them on the kind of considered scale. The final option is to drawdown carbon from the atmosphere through changing practices in agriculture, forestry, and other land use activities (a.k.a. AFOLU).

A pathway in which we slash emissions immediately (P1) requires the least reliance on drawdown of greenhouse gases from the atmosphere, while if we delay reducing emissions, as we are currently, then the pathway represented by P4 sees us requiring substantial drawdown of greenhouse gases from the atmosphere. Clearly there is a serious message here: we need to slash our emissions but every day we delay on this requires us to be more technologically ready to  suck greenhouse gases from the atmosphere in large quantities and lock it away in soil, structures and any available long term store.


About lindsey

Environmental scientist. I am glaciologist specialising in glacier-climate interactions to better understand the climate system. The point of this is to understand how glaciated envionments might change in the future - how the glaciers will respond and what the impact on associated water resources and hazard potential will be.
This entry was posted in uncategorized. Bookmark the permalink.

Comments are closed.