We shouldn't have stupid cars that use liquid fossil fuels. Come on, how outmoded is that? We have to get to the point where this is no longer a part of our experience.

We cannot ask others to do what we have not done ourselves.

We are just about to cross the 400 parts per million threshold.

We, the older generations, simply cannot leave a world for you, the younger generations, in which climate change impacts become ever more threatening to your survival. Still more public attention and action are needed. Solutions like renewable energy or energy efficiency need to fully power our collective future!

Connect with people, visibly and loudly showcase initiatives that reduce greenhouse gases emissions, nurture youth leaders, or spread the message by raising awareness through campaigns. I am convinced that your contributions will ensure that climate change solutions safely power our - and especially your - future.

In a perfect world global emissions would have peaked already. In a semi-perfect world we will peak on Dec. 31, 2020. The fact is, that's going to be difficult. We know that it's going to get more and more expensive the longer we delay.

This is probably the most difficult task we have ever given ourselves, which is to intentionally transform the economic development model, for the first time in human history.