From the article "But it is only last year that we successfully drilled into the impact site, and only now, for the first time, do we really understand why the impact was so fatal. And if the meteorite had arrived ten minutes earlier, or ten minutes later, it would still no doubt have inflicted devastation, but the dinosaurs would still be here and you wouldn't."
> The drilled cores give us the answer. As I mentioned earlier, they are surprisingly deficient in gypsum, although gypsum is abundant both in the more recent sediments, and in nearby sediments laid down before the impact. So the missing gypsum must have been destroyed by the heat of the impact, sending sulphur dioxide gas up into the atmosphere.5 We already know from studies of volcanic eruptions that over months or years this sulphur dioxide would slowly react in the atmosphere to form a haze of sulphuric acid droplets, scattering sunlight and cooling the Earth. That haze, rather than simply dust, is how the Mt Pinatubo eruption affected climate.
> Extrapolating from Mt Pinatubo and other recent eruptions, and taking into account the enormous volume of gypsum sediments in the impact zone, we can estimate that the haze produced by the Chicxulub impact would have blocked enough sunlight to reduce temperatures worldwide by more than 10oC (18oF), while acid rain would also have contributed to the death of much marine life. On land, trees would have shed leaves and shut down as if for what would turn out to be an unusually long winter. The dinosaurs, hugely diverse and successful as they had been through some 180 million years, had no such way of adapting. The herbivores, and the carnivores that fed on them, perished.
> Where did those ten minutes come from? From the rotation of the Earth. The asteroid is falling towards Earth on a fixed trajectory, but the Earth itself is spinning beneath it, one revolution every 24 hours. This corresponds to around 1,000 miles an hour in the region of interest. So arriving ten minutes earlier or later would have placed the impact some 150 miles further to the East or West. And if this had happened, the asteroid would have missed the shallow gypsum-rich continental shelf, and encountered only the oceans on either side. No gypsum in the impact zone, no sulphuric acid haze, no long deep winter. While things might have been pretty rough for anything living within a couple of thousand miles or so, the rest of the world would hardly have noticed.
