1299. Consideration of the Earth System-Scale Impact of Climate Change in Net Zero

Much of the discussion on climate change associated with achieving the goal of net-zero carbon dioxide emissions has tended to focus on the change in global average temperature after emissions are halted. However, the long-term impacts of climate change, such as sea level rise and ocean warming, are likely to continue, and need to be taken into consideration, even if rapid decarbonization is achieved.

Many countries around the world aim to achieve net-zero greenhouse gas emissions by the second half of this century in order to fulfill their commitments under the Paris Agreement, which aims to limit global warming to well below 2°C above pre-industrial levels, and ideally 1.5°C. However, even if we achieve net-zero emissions and prevent further increases in global mean surface temperature, the complex nature of the Earth system means that we cannot stop ongoing changes in many components of the climate system, such as sea level rise, melting sea ice, and warming in some regions.

An editorial in Communications Earth & Environment suggests that even if carbon neutrality goals are achieved, the scope of consideration should be broadened beyond global temperature changes to include other Earth system impacts to account for current and future climate change.

The concept of zero-emission commitments, defined as the change in global mean surface temperature under net-zero carbon dioxide emissions after a certain amount of cumulative emissions has been used as a framework to demonstrate the benefits of rapid decarbonization. Zero-emission commitments are estimated using idealized climate model simulations that change only atmospheric carbon dioxide emissions. The projection that global mean temperature will remain almost unchanged after decarbonization has been widely used in communications to demonstrate the importance of achieving net-zero emissions.

However, other aspects of the climate, such as the oceans and the cryosphere, may continue to change more significantly. This is recognized among climate scientists, but has not been a focus of research on a net-zero carbon dioxide emissions climate to date.

A decrease in average temperature is projected in some (typically wealthy) northern mid- and high-latitude regions, but not in others. Warming is likely to continue, especially over land in the southern mid- and high-latitude regions. Many climate changes observed and projected in the 21st century are expected to continue for centuries under net-zero emissions. This includes sea level rise, ocean warming (especially subsurface warming), and Antarctic sea ice loss, but at a slower rate than if greenhouse gas emissions continue at high levels.

While a focus on decarbonization is essential to limit global warming and avoid even more severe climate impacts, governments, public sector, and private sector organizations need to consider their exposure to risks from continued changes in the climate under net-zero emissions and develop targeted adaptation strategies. A careful framework is needed to present climate projections, as continued changes are expected under net-zero emissions, especially in the Southern Hemisphere.

(Reference)
King, A.D., Jones, C.D., Ziehn, T. et al. Enhancing communication of climate changes under net zero emissions. Commun Earth Environ 6, 526 (2025). https://doi.org/10.1038/s43247-025-02472-1

Contributor: IIYAMA Miyuki, Information Program