Disasters come in many shapes and sizes. One way of looking at them are by their scope: how much of the world and the future do they affect? And by their severity: how bad are they?
Global catastrophic risks are those that affect the entire world, while existential risks are those that threaten all future generations – typically extinction risks. There are many potential threats in these categories, ranging from asteroid impacts to nuclear war. Most are fortunately unlikely to spell our doom… but there are enough of them to make us rightly concerned about our well-being.
While natural risks are unlikely to cause an end of humanity, human-made risks are. What is the role of climate change in this? Direct extinction by a changed climate is very unlikely: it takes very extreme heat to stop an adaptive, technological species that is spread worldwide.
But climate change poses a systemic threat. By stressing nearly every part of the world as we move into a century with many other risks, powerful emerging technologies, and an interconnected and fragile global system, it can amplify other dangers and make them more likely to coincide into vast disasters.
Climate change may not be the end of the world, but it can certainly help it along. Conversely, some (but not all!) ways of handling climate change can reduce large risks.