In his May 18 column [“Staying hopeful while facing the climate threat“], Russ Vernon-Jones shared good news on the climate. Here is some very hopeful news to add to his list. Recent studies confirm a major decrease in the chance that climate change will lead to an existential threat to human civilization.
Projections of temperature increase have been a key measure of the impact of climate change. A decade ago, the global community focused on maintaining the global temperature increase to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels. Some modeling analyses have projected temperature increases of about 5 degree C or higher by 2100; these are temperature increases that may put human civilization at risk.
Temperature projections come from computer models of the global atmospheric, ocean, and land surface system. One of the inputs to these models is a scenario of carbon emissions in each year for the rest of the 21st century. The highest temperature increases have been driven by emissions scenarios that assume very high fossil fuel usage, especially coal, and minimal growth of solar and wind power. Recently, climate scientists concluded that the carbon emission scenarios that led to the highest global temperature increases are implausible.
This determination was made by the science group that has developed a new set of emissions scenarios for the next round of official IPCC climate modeling. When input to the climate models, the results show a temperature increase by the end of the 21st century of about 3 degrees C. This is still highly disruptive to society at large and disastrous for vulnerable parts of the world, but the future is just a little less grim and the need to stay full-speed ahead on the transition to a non-fossil fueled future is even clearer.
David Ahlfeld
Amherst