An update on the 1.5 °C warming threshold

Over the past few months I’ve discussed with a variety of guests the emerging idea of trying to keep global warming below 1.5 °C, and our family of journals has certainly been active on the topic, particularly with regard to feasibility and mitigation pathways.

From Paris Agreement climate proposals need a boost to keep warming well below 2 °C, Nature doi:10.1038/nature18307.
An example of the emissions required to get close to 1.5 (blue), versus unregulated emissions (red). There’s a lot of space in between! From Paris Agreement climate proposals need a boost to keep warming well below 2 °C, Rogelj et al., Nature doi:10.1038/nature18307.

But I thought it would be a good idea to find out what the IPPC is actually doing on the topic, as one of their three special reports. IPCC Working Group I co-chair Valérie Masson-Delmotte kindly agreed to come back on the podcast for a quick catch-up on the recent 1.5 scoping meeting held in Geneva.

At this point, discussions are extremely preliminary, but it is clear that the IPCC is undergoing a fairly huge change in culture, at least for the special reports. Most notably, the entire framing of the debates, questions, and approaches is taking place across the three working groups. Additionally, the author group chose to bring in outside scientific consultants to bolster their expertise, for example in ethics. As Valérie says, the scoping meeting was:

“… an opportunity to challenge, to question, the way AR5 was framed."

It’s still early days for the report, but I think it will provide an unusually broad discussion of the social and ecological issues that are inextricably intertwined with trying to reach any particular mitigation or climate goal. One notable point of discussion was the potential of the human, as well as climate, system to undergo abrupt change.

If you’re keen to read more on the 1.5 threshold, you can check out the across-journal collection from Nature, Nature Climate Change and Nature Geoscience.


Music: Stance Gives You Balance by Hogan Grip, Creative Commons license CC BY-NC-SA 3.0.


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