Human greenhouse gas emissions have caused major climate changes to happen already. Even if all greenhouse gas emissions stopped today, climate changes would continue to happen for at least several more decades. That’s because it takes a while for the planet to respond, and because carbon dioxide – the predominant heat-trapping gas – lingers in the atmosphere for hundreds of years. There is a time lag between what we do and when we feel it. But it may not be too late to avoid or limit some of the worst effects of climate change.
Responding to climate change involves a two-tier approach: 1) “mitigation” – reducing the flow of greenhouse gases into the atmosphere; and 2) “adaptation” – learning to live with, and adapt to, the climate change that has already been set in motion. Because climate change is a truly global, complex problem with economic, social, political and moral ramifications, the solution will require both a globally-coordinated response (such as international policies and agreements between countries, a push to cleaner forms of energy) and local efforts on the city- and regional-level (for example, Climate Action and Adaptation Planning at the City level). It’s up to us what happens next.