I have a new column this week on OnlySky. It’s about some news worth celebrating: we’ve avoided the worst-case scenario for climate change.
Several years ago, the Intergovernmental Panel on Climate Change released a range of scenarios, dubbed the Representative Concentration Pathways or RCPs, that set out a range of different visions for the future, depending on how much progress humanity made toward curbing greenhouse gas emissions. The worst of these, known as RCP8.5, painted an apocalyptic picture of a world so hot and chaotic that billions would be at risk from heat waves, coastal cities would flood, agriculture would be starved by drought, and mass migrations would spark war. Civilization would be at risk of utter collapse. That was the future we were headed toward until recently.
The good news is that this dire scenario now looks like it will never come to pass. Despite the best efforts of rich petrostates and science deniers, humanity has made solid progress toward decarbonizing the economy and replacing fossil fuels with green energy. While we waited too long to act and as a consequence have already missed the best-case scenario of a world that completely avoids climate change, there’s reason to believe that worst-case scenario is off the table as well.
Read the excerpt below, then click through to see the full piece. This column is free to read, but members of OnlySky also get special benefits, like a subscriber newsletter:
The RCP8.5 scenario represents 4°C or more of warming. As a reference point, this is roughly the same magnitude as the temperature difference between today and the last glacial maximum, when northern Europe and North America were buried under mile-thick ice sheets. Try to picture a future that’s as much hotter than the present as the present is hotter than that.
Fortunately (or unfortunately), you don’t need to use your imagination. Climate scientists have sketched a picture.
In a world with 4°C of warming, 4.7 billion people would be exposed to potentially lethal levels of heat over the course of the year. Summer temperatures in equatorial regions like the Middle East and North Africa could reach 60°C (140°F) on the hottest days. Southern Spain would become a desert. Cities like Karachi and Kolkata would become uninhabitable. As journalist David Wallace-Wells put it in a famous article: “At four degrees, the deadly European heat wave of 2003, which killed as many as 2,000 people a day, will be a normal summer.”
4°C is a nightmare scenario. That’s why it should be a vast relief to hear that this isn’t the path we’re on.
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