Countries mull promise to peak pollution in 2025

Climate summit negotiators are tossing around making a promise: that global emissions will peak by 2025.

A peak would be a significant milestone, since climate pollution has stubbornly risen year after year. Climate experts warn this peak must come ‘‘before 2025 at the latest’’ for a shot at limiting warming to 1.5C – reducing the chances of much worse climate damage.

However, some global energy boffins now expect carbon emissions to peak in 2025 anyway, meaning a promise could be little more than greenwash.

New Zealand’s lead climate ambassador Kay Harrison said an agreement for ‘‘global peaking’’ of emissions by 2025 was a conversation topic at events leading up to the COP27 summit.

‘‘That’s not something that’s in the Paris Agreement or in the rulebook but there is a suggestion from what the science has been telling us that this is something we could galvanise around and act on,’’ she told stakeholders at a briefing in October.

A Ministry of Foreign Affairs and Trade spokesperson confirmed some countries ‘‘are pushing to build on’’ previous summits and ensure global efforts are ‘‘grounded in [the] best available science’’.

The world is already 1.1C warmer than the pre-fossil-fuel era, and this has already caused more severe and deadly floods and heatwaves. Climate scientists have warned that heating above 1.5C could turbocharge the impacts.

For this reason, COP leaders are aiming to keep heating inside 1.5C.

Earlier this year, global expert body the Intergovernmental Panel on Climate Change (or IPCC) recalculated greenhouse gas trajectories and stressed carbon dioxide emissions must ‘‘peak before 2025 at the latest, and be reduced by 43% by 2030’’ for the world to have a decent shot at 1.5C. (The body also said methane would need to fall ‘‘by about a third’’.)

Paul Winton – founder of the 1point5 project – said aiming to peak by 2025 would reflect ‘‘the edge of the science’’.

All paths compatible with 1.5C peaked between 2020 and 2025, he added. ‘‘It’s the end of the end of the end.’’

Carbon emissions must fall sharply after a peak to stay under 2C, Winton said. ‘‘It’s really what happens after that that matters. It’s how steep we go down.’’

Have New Zealand emissions peaked? ‘‘We don’t know that yet. In the last couple of years with very messy data, it’s hard to infer too much ... We haven’t yet seen any substantive emissions reduction programmes kick in. Some of the ones put in place – that are great – are soft.’’

But Winton thought a ‘‘global peak’’ commitment could act as a focal point.

‘‘It’s easy to visualise. If we say: we should have peaked in 2020 – then everyone becomes dismayed and we do nothing. I think there’s some really important messaging around hope, and the possibility of change.’’

In the lead-up to COP27, the International Energy Agency (IEA) found carbon dioxide emissions are likely to peak soon.