My friend Mark Boslough presented a fascinating analysis last month at AGU comparing the risks of climate change to big rocks from space hitting Earth:
One objective way to compare the relative magnitude of the impact threat to that of anthropogenic climate change is to estimate the long-term worldwide fatality rate. For asteroids, the average is about a hundred deaths per year–about half of which are climate-change related. By contrast, the World Health Organization (WHO) has estimated that 150,000 deaths per year are currently attributable to anthropogenic climate change.
From the AGU poster:
The risk of global catastrophe is dominated by low-probability, high-consequence occurrences. The asteroid threat community has been much more successful than the climate change community in characterizing the dominant “worst-case” scenarios and communicating them to policy makers, the media, and the public–even though the climate change threat is more than a thousand times greater. Media focus on exceptionally unlikely impact scenarios is common, whereas focus on high-consequence climate scenarios is often unfairly labeled as “alarmist”. Quantitative comparison of climate change to asteroid impact is a valuable way to put both threats into perspective.