How do the effects on climate of an asteroid hitting earth compare to the effects of man made emissions?

Answer 1

If it's big enough the effects would be instantaneous. This is the most popular theory as to dinosaur extinction right now. I believe the most awesome part is a wall of flame and super heated debris emanating from the epicenter to fully encompass the globe.

Answer 2

Actually, the debris from an asteroid will help to block the sun's rays, and COOL DOWN the Earth. Man-made emissions increase the magnitude of the greenhouse effect, and cause global warming, increasing the temperature.

But a large asteriod and global warming should both eventually cause the extinction of mankind.

Answer 3

This is a relevant question.

Fossil fuels are the result of plants storing solar energy in the form of hydrocarbons over hundreds of millions of years. How could it possibly be benign for us to release millions of years of stored carbon in the space of 150 years? On a geologic time scale our actions are nearly the equivalent of an asteroid strike. In a geologic instant, we have changed the balance.

Of the last five big extinctions, two were clearly caused by asteroids, but for the other three no smoking gun could be found. Here is the new theory - they were caused by CO2.

http://www.sciam.com/article.cfm?articleID=00037A5D-A938-150E-A93883414B7F0000&pageNumber=1&catID=2

Answer 4

It depends on how big the asteroid is. A small one would have less effect than humans. A big one would have much more extreme effects.