Does half a degree make a difference?

Even seemingly low levels of global warming can have serious consequences. For example, if Earth heats up by 1.5 degrees Celsius compared to preindustrial levels, 70 to 90 percent of the world’s coral reefs will likely die. At two degrees, practically all of them will die (98 to 99 percent).¹

We can expect to see a temporarily ice-free North Pole every 40 years or so with a temperature increase of 1.5 degrees Celsius, while the same phenomenon will likely occur every three to five years if the increase is two degrees Celsius.² If global warming amounts to 1.5 degrees Celsius, we can expect a storm surge that so far occurs statistically every 500 years on the North Sea coast near Cuxhaven to hit once every hundred years. At two degrees Celsius, the frequency of such a storm surge increases to once every 33 years.³ This explains why in 2018 the IPCC wrote in the foreword to its special report on limiting global warming to 1.5 degrees, “Every bit of warming matters.”⁴