The Next Two Decades Will Make or Break Humanity — Why Are We Waiting to Fight Climate Change?

We must make fundamental choices now that will shape our future economy and climate.

By Nicholas Stern / The MIT Press

We stand at a crossroads where, consciously or otherwise, we must make fundamental choices that will shape our future economy and climate. Over the next two decades we will see a remarkable coincidence of two vital transformations in world history. First, it is in this period that we will largely determine whether or not we have a reasonable chance of avoiding dangerous climate change, usually defined as holding the increase in average global surface temperature to less than 2 ° C above nineteenth-century levels. The link between emissions of greenhouse gases and climate change should be well known. Our activities cause the emission of these gases (among which carbon dioxide is particularly important) which are not fully absorbed by the earth and which thus accumulate in the atmosphere, thereby raising concentrations of the gases. These concentrations prevent energy from escaping, resulting in global warming and climate change. We have a period-by-period “ ratchet effect ”of flows of emissions into concentrations in the atmosphere because carbon dioxide, in particular, is very long-lasting in the atmosphere.