of the Asteroid Impact
The devastation caused by such an event is difficult to imagine.
The asteroid would have hit with the force of 100,000 billion tons
of TNT. This would have generated an earthquake one thousand times
greater than the largest ever recorded, with winds of over 400 kph.
A massive fireball would have boiled nearby seas, destroying everything
for thousands of kilometers. Forests throughout most of North America
and some of South America would have been flattened by the shock
wave. Evidence of a giant tsunami has been found around the Gulf
of Mexico and Caribbean, as well as in Spain and Brazil. It may
have had an effect as far away as New Zealand.
Despite the enormity of the destruction from the initial impact,
the dinosaurs and their contemporaries might have survived and eventually
recovered, but the subsequent long-term effects of the blast were
even more deadly. Ninety thousand cubic kilometers of debris would
have been blasted into the atmosphere, some reaching into space
only to re-enter at high speeds. This could have heated the atmosphere
sufficiently to ignite global forest fires. While the heavier pieces
of ejecta settled back down on Earth, fine dust particles would
have remained in the atmosphere and significantly blocked sunlight,
causing an effect called an “impact winter”. There is
much debate about the duration and severity of the impact winter
following the K/T impact, but the darkness and cold temperatures
might have reduced photosynthesis and collapsed food chains globally.
The amount of carbon and sulfur contained in the rock at the impact
site would have aggravated these devastating effects. As much as
100 billion tons of sulfur and 10 trillion tons of carbon would
have been vaporized by the impact and blown into the atmosphere.
The resulting sulfate aerosols would have stayed in the atmosphere
for several years; the resulting carbon dioxide would have stayed
airborne for several hundred years. Initially the sulfate aerosols
would have contributed to global cooling by blocking out the sun,
before precipitating as acid rain. After the dust and sulfates settled
out and ended the cooling, global warming would have begun. The
carbon dioxide levels, being two to three times normal, would have
caused extreme greenhouse conditions, raising global temperatures
by as much as 10°C. Although some life forms may have survived
the years of darkness and freezing temperatures, many surely died
out in the subsequent centuries of heat.