Step #1: Educate yourself. Learn more about climate change, and how by taking shorter, colder showers, using mass transit, etc., we can feel empowered and part of the solution, even if we are part of the problem at the same time.
Step #2: Help motivate politicians to work at the local, national and international level to change the way we do business. Help retool those industries that need it, help retrain the unemployed to work in the businesses of the future, businesses that are environmentally sustainable.
Step #3: Come up with an interim plan in Copenhagen, and be doing the studies and research needed to implement more focused, long term plans in the near future.
The site below has been invaluable to me in learning more about what's going on in a global climate change world. The "Climate Change News" section is unparalleled.
There is no simple solution, but there are solutions.