The concept of a Zero Emissions Commitment (ZEC), defined as the change in global mean surface temperature under net zero carbon dioxide emissions (following a set amount of cumulative emissions), has been used as framing to illustrate the benefits of rapid decarbonisation. The Zero Emissions Commitment is estimated using idealised climate model simulations where only atmospheric carbon dioxide emissions are modified. The mean estimate of Zero Emissions Commitment after 50 years under net zero carbon dioxide emissions, following 1,000 Petagrams of carbon cumulative emissions, is −0.07 °C (90% confidence interval of −0.36 °C to 0.29 °C)1. That global mean temperatures are projected to change very little after decarbonisation has been widely used in communications to demonstrate the importance of achieving net zero emissions2,3.

Nevertheless, other aspects of the climate, such as the oceans and the cryosphere, would potentially continue changing more substantially. This is known among climate scientists, but has not been the focus of a great deal of study on net zero carbon dioxide emissions climates4,5.

Figure 1 summarises some of the anticipated Earth System changes under net zero carbon dioxide emissions and similar decarbonization pathways highlighted in the literature5,6,7,8,9,10,11,12. Reduced average temperatures and heat extremes are expected in some typically wealthy regions of the northern mid-to-high latitudes7,9, but not elsewhere, especially in land areas of the southern mid-to-high latitudes which will likely continue warming. Many observed and projected climate changes during the 21st century are expected to continue for centuries under net-zero emissions. These include sea level rise13, ocean warming (especially sub-surface warming), and Antarctic sea ice decline6, albeit at slower rates than under continued high greenhouse gas emissions.

Red circles represent projected changes that are continuations of current trends (albeit at slower rates), blue circles represent projected changes that represent reversals of current trends, and grey circles represent uncertain changes where there is model disagreement.

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In addition to expected long-term changes, many potential future changes are uncertain. Large-scale patterns of climate variability fall into this category. For example, the dynamic of El Niño-Southern Oscillation, the leading mode of interannual climate variability in the Pacific, could significantly change in a future with net zero emissions, but the direction of such a change is still unclear6,11. Similarly, the Atlantic Meridional Overturning Circulation, the main ocean current system in the Atlantic Ocean, is projected to decline under 21st century emissions scenarios, but the sign and magnitude of the change under net zero emissions strongly differs across models7.

The variety of climate changes projected under net zero emissions, even while global temperature changes may be minimal, causes challenges in presenting climate information at global warming levels. Global warming level-based climate projections have become popular in reports such as the Sixth Assessment Report of the Intergovernmental Panel on Climate Change14. However, there are significant differences between the transient projections based on 21st century scenarios and the stabilised projections aligned with the Paris Agreement under net zero emissions even at the same global warming level6,15. Net zero emissions pathways are associated with continued changes in different parts of Earth’s climate system that balance out to limited changes in global average surface temperature. This means that global warming level-based projections for the 21st century, such as in the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, bear little similarity on local and regional scales to global warming level-based climate projections consistent with the Paris Agreement. These differences are particularly problematic for slowly evolving aspects of the climate, such as ocean temperatures, sea level and sea ice extent, which change over many centuries even under net zero emissions, but the differences also extend to local land-based temperatures and precipitation patterns6,15.

The problematic use of 21st century-based projections for inferring Paris Agreement aligned climates is also amplified in the Southern Hemisphere. Continued warming under net-zero emissions across much of this region could lead to maladaptation if not considered in decision-making processes.

Scientists should avoid limiting communication around post-net zero emissions changes to global temperatures and clearly acknowledge other changes that would result from humanity achieving its goals of limiting global warming to low levels. This includes not shying away from difficult subjects for public communication, such as the millennial-scale warming in the oceans, unavoidable sea level rise, and reductions in Antarctic sea ice extent that are now inevitable.

While a focus on decarbonization is critical to limit global warming and avoid even worse climate impacts, governments and public and private sector organisations should consider their exposure to risks from the continued evolution of the climate under net zero emissions and develop targeted adaptation strategies.

The presentation of climate projections requires careful framing because of the continuing changes anticipated under net zero emissions, particularly in the Southern Hemisphere. The next Intergovernmental Panel on Climate Change report provides an opportunity to revisit communication on the consequences of net-zero emissions to future climate changes. The uptake of information from climate projections continues to grow. Scientists have a responsibility not to over-simplify results by glossing over the difference between 21st century climates and those from the long-term future.