The facts are pretty clear: our world is changing.
A few years ago, we worked with Bloomberg News to explain why we’re so sure humans are causing global warming. Using a sophisticated computer model of the Earth system, we calculated the effect of each individual factor in isolation. The graphic they made is wonderful, and whenever it starts trending on Twitter again it’s a good sign some prominent politician has said something silly about climate change. It’s the clearest explanation I’ve ever seen of who’s responsible for rising temperatures.
The data we used for this project extended only to 2005. But warming has continued through the 21st century. 2015 was the hottest year on record… until 2016. Last year was the hottest year ever measured to not have an added boost from a natural El Niño event. Greenhouse gas emissions have continued to increase, and they continue to be the prime suspect behind global warming.
We’ve seen human fingerprints all over the planet. The oceans are warming and becoming more acidic, the atmosphere contains more water vapor, and heat waves are becoming more frequent and intense. The science of climate change detection and attribution—climate detective work—has advanced to the point that we can now confidently blame human activities for some individual extreme events.
It’s always possible scientists have made a serious mistake here. But if you don’t believe people have affected the climate, you need a coherent alternate explanation for the changes we’ve seen.