evidence: 1. Human-induced global warming of 1.1 degrees C has spurred changes to the Earth’s climate that are unprecedented in recent human history. [...] Additional warming will increase the magnitude of these changes. Every 0.5 degree C (0.9 degrees F) of global temperature rise, for example, will cause clearly discernible increases in the frequency and severity of heat extremes, heavy rainfall events and regional droughts. Similarly, heatwaves that, on average, arose once every 10 years in a climate with little human influence will likely occur 4.1 times more frequently with 1.5 degrees C (2.7 degrees F) of warming, 5.6 times with 2 degrees C (3.6 degrees F) and 9.4 times with 4 degrees C (7.2 degrees F) — and the intensity of these heatwaves will also increase by 1.9 degrees C (3.4 degrees F), 2.6 degrees C (4.7 degrees F) and 5.1 degrees C (9.2 degrees F) respectively.