The facts about climate change are clear, the goals are scientifically supported: to limit global warming to 1.5 °C, greenhouse gas emissions must be reduced by around 50 percent by 2030. This calls for committed action, especially from the largest emitters. Since U.S. President Biden took office, many have been counting on his commitment to climate policy and diplomacy. The recent stricter reduction targets of many major emitters, together with China’s commitment to climate neutrality and phasing out coal, give reason to hope that cooperation in the spirit of the Paris climate agreement is possible. Not only the United States, but also its “system competitor” China need to adopt a leading role. Despite many lines of conflict and areas of dispute, they must not allow geopolitical rivalry to interfere with their common goal of climate protection. This requires: 1. a willingness to invest heavily in economic transformation and to support those countries that cannot afford to do this on their own; 2. binding long-term commitments and treaties that survive changes of government; and 3. an understanding of the numerous security risks associated with climate change. The humanitarian costs of unchecked climate change, i.e. global warming in excess of 2 °C, would far outweigh the efforts required now. In combination with an incentive and penalty mechanism that still has to be put in place, there is an opportunity to hold those states to account that refuse for various reasons to protect the climate. Significant steps in this direction should be taken at the COP26 climate summit in Glasgow.