Expert: Jayendra Upadhye - 7/20/2005

Question
Could a meteorite colliding with Earth cause a climate increase? I know that it could cause a climate decrease (as in an ice age) but could it cause the landscape of a planet to become a desert? Thanks!

Answer
Hi Sarah that is a very difficult question.
When mount Krakatoa towards the beginning of the 19th century, exploded in the sunda straits, it blasted 2/3ds of the island a mile high into the sky. The dust blocked sunlight for months (yielding multihued sunrises and sun sets, and the explosion was heard in australia!
 An asteroid impact would compare with that as a nagasaki type nuclear device of 20 kiloton yield with many megaton thermonuclear explosion of an h-bomb!
 The impact that wiped out the dinosaurs left an all pervading layer of iridium all over the earth! It is known better as the KT boundary (Kretacius tertiary age boundary, and can be seen exposed in the california fault line (san andreas). (from what i read and remember).
 Such impacts if they occur in the middle of large continents, (say an impact in the urals that divide european ussr from asian one), tend to fragment the continent itself. The radio-active heating from potassium isotopes normally weakens the middle of continents due to accumulated heat (just above the magma layer).
Any mighty shove can be the last straw on the camel's back, as may have happened when mighty PANGAEA broke up 225 million years ago!
 In a sense these breaks ups lead to deserts forming where land was once green and vice versa!
 So you could be right..but again you could be wrong too!
You see, however large the impact, in the long run, (several centuries after the impact) the climate which is decided more by latitude and relative distance from the sea, returns to what it was like before. Weathering starts its inescpable eraser action, and things become "same as before"..but if the tectonics has been affetced then over a million years what you say comes true!
hence..you could be right..but again you could be wrong too!
it all depends on your perspective!
Jayen