If no-one does anything the result will be bad for everyone.
If only a small number of countries (or global regions) do something and the rest of the planet does nothing the effect will be minimal or negligible of a global scale. The greater the number of regions doing something useful, the greater the effect and the benefit.
For an impact to be made globally, a critical mass of regions needs to do something useful.
If your country does something and its neighbors don't, parts of your country may have better local conditions. It also depends on what other countries, elsewhere are doing. We are all in a canoe being moved by a strong current. We need everyone to paddle to get us to safety, not just a small number of people paddling.