Consider the current coronavirus crisis. In December 2019, it became apparent that Covid-19 was threatening public health in a major way. Several mathematical models predicted how the virus would spread, and that a worldwide pandemic was a distinct possibility. Data were scarce and not always reliable, so decision makers had maybe 50% of the information needed to make 100% of the decisions. For various reasons, the authorities were slow to acknowledge the extent of the problem, and precious time was lost to implement effective measures that could have mitigated the impact of the pandemic. The results were devastating: social life was disrupted in a major way and the economy came close to collapsing.
Now consider the climate crisis. In the 1980s, several scientists warned that increasing CO2 emissions resulted in global warming, which could have serious consequences for our weather and future climate. While there was some uncertainty, by 2010 the scientific community had arrived at a consensus: climate change was real, it was happening now, and it was the result of human activities. Decision makers had almost 100% of the information they needed to develop and implement a strategy to keep the temperature rise to no more than two degrees C. The Paris agreement was signed in 2015, where each nation committed to reduce carbon emissions through government action. Today, only 50% of the proposed measures has been implemented, and the window to keep the temperature rise to no more than two degrees is rapidly closing.
It is fair to say that the climate crisis is today where the coronavirus epidemic was in the early months of 2020. What will happen next is clear. Assume for a moment that our climate will reach a new equilibrium state, where the global average temperature is two, maybe three degrees warmer than today and the atmospheric CO2 concentration is at or slightly above current levels. This climate will be similar to the climate during the Pliocene Epoch, the period from 5.3 million to 2.6 million years before present. The climate was mild, especially at high latitudes, and certain species of both plants and animals existed several hundred kilometers north of where their nearest relatives exist today. What is less well known is that less ice at the poles also resulted in a sea level that is thought to have been about 30 meters higher than today’s. Do we need more warnings?