As difficult as it is to eliminate the risk of nuclear warfare, it requires fewer changes to the global economy than does averting or reversing climate change.

Political parties often take advantage of denial and fear in a moment of change. This is a well understood phenomenon that often leads to scapegoat-ism: blaming outsiders, such as immigrants, or racial and religious minorities. The phenomenon is behind Brexit and the violence in the political cycles in the US and EU.

The new markets that arise from ecological constraints will dominate the 21st century economy, and so will markets for knowledge.

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.

Signs of a poorly understood but treatable house fire requires action, not inaction.

We know that the warming rising seas will swallow entire island nations that are about 25 percent of the UN vote and perhaps at the end, even our civilization. This realization is traumatic and the first reaction to trauma is denial. Since there is some remaining scientific uncertainty, a natural response is to deny that change is occurring. This is natural but it is very dangerous.

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.