There are critical tipping points that we will reach above a 1.5 C. degree warming, similar to a cascade of falling dominoes. Alarming signs are now occurring—the wildfires in California, growing cracks and crevasses in the ice shelves protecting two of Antarctica’s largest glaciers. The Greenland ice sheet is one example of a tipping point; it contains enough ice to raise global sea levels by seven metres, if it were all to melt. And it is prone to runaway melting.