How do we halt global warming? Reaching net zero carbon dioxide (CO2) emissions is understood to be a key milestone on the path to a safer planet. But how confident are we that when we stop carbon emissions, we also stop global warming? The Zero Emissions Commitment (ZEC) quantifies how much warming or cooling we can expect following a complete cessation of anthropogenic CO2 emissions. To date, the best estimate by the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report is zero change, though with substantial uncertainty. In this article, we present an overview of the changes expected in major Earth system processes after net zero and their potential impact on global surface temperature, providing an outlook toward building a more confident assessment of ZEC in the decades to come. We propose a structure to guide research into ZEC and associated changes in the climate, separating the impacts expected over decades, centuries, and millennia. As we look ahead at the century billed to mark the end of net anthropogenic CO2 emissions, we ask: what is the prospect of a stable climate in a post-net zero world? Reaching net zero carbon dioxide (CO 2) emissions is understood to be a key milestone on the path to a safer planet. But how confident are we that when we stop carbon emissions, we also stop global warming? The Zero Emissions Commitment (ZEC) quantifies how much warming or cooling we can expect following a complete cessation of anthropogenic CO 2 emissions. To date, the best estimate by the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report is zero change, though with substantial uncertainty. In this article, we present an overview of the changes expected in major Earth system processes after net zero and their potential impact on global surface temperature, providing an outlook toward building a more con fident assessment of ZEC in the decades to come. We propose a structure to guide research into ZEC and associated changes in the climate, separating the impacts expected over decades, centuries, and millennia. As we look ahead at the century billed to mark the end of net anthropogenic CO 2 emissions, we ask: what is the prospect of a stable climate in a post-net zero world? Our current models and understanding of relevant processes support the argument that if global carbon dioxide (CO 2) emissions from human activities are brought back to ‘net zero ’ (i.e., we emit into the atmosphere no more than our activities absorb from it), the increase in global surface temperature may be halted. In other words, by no longer adding CO 2 to the atmosphere, we may cautiously expect that global warming can be stopped. The sixth assessment (AR6) of the Interg overnmental Panel on Climate Change (IPCC) ( 7) supports this key geophysical insight, and this understanding underpins the many ‘net zero’targets that countries and companies have announced over recent years. The Zero Emissions Commitment (ZEC) describes the net change to global surface warming after a complete cessation of anthropogenic emissions, in many cases with a focus on CO 2.I n combination with the transient climate response to cumulative emissions (TCRE), it de fines the total amount of global surface warming for a given amount of CO 2. In turn, this total expected warming determines the carbon budget: the amount of carbon dioxide that can be released before reaching a certain temperature threshold. A positive ZEC indicates additional surface warming after net zero, a negative ZEC a drop in surface temperature, and a zero ZEC no further averaged surface temperature change (Figure 1 ). ZEC is defined by two dimensions: the time since the onset of net zero CO2 emissions, and the global surface temperature change that occurs over this pe riod. Though prone to false equivalence in wider climate communications, ZEC is distinct from the ‘constant composition commitment ’, which describes the temperature change expected when atmospheric composition and hence radiative forcing ( 14, 15) is kept fixed at its present-day Palazzo Corner et al. 10.3389/fsci.2023.1170744 Frontiers in Science frontiersin.org02 value for multiple centuries. Owing to the relatively short atmospheric lifetime of most anthropogenic greenhouse gases and aerosols compared to the atmospheric lifetime of CO 2 on centennial timescales, ZEC for all anthropogenic forcing agents largely depends on the response to CO 2 (3, 27). Recent model experiments designed to quantify ZEC have thus focused on CO 2 emissions only ( 28). In addition, while strategies to reduce global CO2 emissions to net zero have been identi fied in the broad climate change mitigation scenario literature, no existing pathways show a complete elimination of methane (CH 4), nitrous oxide (N 2O), or aerosol emissions (29, 30). Reflecting this context, we consider ZEC for CO 2 only. Even a zero ZEC scenario will not stop regional temperature change (35), long-timescale environmental consequences of climate heating, and Earth ’s natural long-term climate variability. For example, global sea level rise will continue owing to mass input from ice sheet dynamics and volume expansion from deep ocean warming driven by past anthropogenic emissions, with centennial to millennial time-lags until ocean heat uptake and ice sheet mass adjustment reach new steady states ( 11). ZEC modeling Studies of how much warming could be expected under particular conditions originated in the 1980s with early analyses of response timescales by Hansen et al. Thus, declines in CO 2 fertilization, due either to increased nutrient limitation or declines in the growth rate of atmospheric CO 2, lead to a reduction of the land carbon sink (70). When CO 2 emissions reach net zero, the speed with which terrestrial ecosystems respond to the change from rising to falling atmospheric CO 2 concentrations (by slowing or potentially stopping their net carbon uptake) will strongly in fluence the land contribution