We know little of the consequences of the geoengineering process, such as spraying particles into the atmosphere that shade the planet from the sun's rays and could decrease its temperature. But this process is how dinosaurs disappeared from the Earth about 60 million years ago, by particles spewed by a volcano or a giant meteorite impact, and our species could follow suit.

We need a transformation of the world economy and of how we use and share the Earth's resources. We are running out of time. We are truly at the point of no return.

We have to remove the CO2 that the industrial economy has already emitted, which otherwise will remain in the atmosphere for hundreds of years and alter the Earth's climate irreversibly. It is possible to do this.

Changing the world's oceans to increase their uptake of CO2, as other geoengineering solutions propose, is equally dangerous, as the increased resulting acidity of the oceans kills tiny crustaceans, such as krill, that are the basis of the pyramid of life on the planet as we know it.

Carbon negative power plants can provide energy while they overcome poverty and change economic values in the right direction.

Even if we planted a tree on every square yard available in the planet by the end of the century we would only capture at most 10 percent of the CO2 we need to reduce. This does not mean that we should not plant trees; we should, for biodiversity's sake, and for our long-term future together with the other species.

We are in the midst of the 6th largest extinction event in the history of the plant and the first caused by human action.