Global warming is real and human activity is the main cause. The consequences are mainly negative and headed toward catastrophic, unless we act. However, the good news is that we can meet this challenge. It is not too late, and we have everything we need to get started.

This is by far the most serious crisis civilisation has ever faced.

You can push your local communities to adopt more sustainable sources of energy and environmentally-friendly practices.

It's an important point, and every little bit helps not least because those who make those kinds of changes are more likely to make their voices heard as citizens. But the ultimate solutions are going to come through policies.

Where solar energy is concerned - and wind energy and battery storage and electric vehicles and efficiency technologies - that is what we are now seeing. So, yes, I'm very optimistic, but anyone who works on the climate crisis has an internal struggle between hope and despair. I won't deny that, but hope has always prevailed in my outlook.

The climate crisis requires a bottom-up, grassroots demand for solutions because the elites in many parts of the world are under the influence of old industry.

All of us can make changes, but the changes that are most needed are not light bulbs and windows but laws and policies and treaties. So, yes, we are in a phase of this (climate protection) struggle where civic and political action is at the top of the list.