Give to 350.org, an international grassroots movement working to end fossil fuel use and stop new fossil fuel projects around the world. The organisation coordinates local campaigns and mass mobilisations across dozens of countries rather than running its own conservation projects.
If you'd rather fund grassroots organising and advocacy against fossil fuels than direct conservation projects, this is a different kind of climate gift than most others on this list. Coordinating local campaigns across dozens of countries rather than running its own projects also means your gift supports a global network of organisers, not a single operation.