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takyon [soylentnews.org] writes:

Scientists have placed tighter constraints [bbc.com] on the amount of material expelled into the atmosphere by the Chicxulub impact:

Scientists say they now have a much clearer picture of the climate catastrophe that followed the asteroid impact on Earth 66 million years ago. The event is blamed for the demise of three-quarters of plant and animal species, including the dinosaurs. The researchers' investigations suggest the impact threw more than 300 billion tonnes of sulphur into the atmosphere. This would have dropped temperatures globally below freezing for several years. Ocean temperatures could have been affected for centuries. The abrupt change explains why so many species struggled to survive. "We always thought there was this global winter but with these new, tighter constraints, we can be much more sure about what happened," Prof Joanna Morgan, from Imperial College London, told BBC News.

Quantifying the Release of Climate-Active Gases by Large Meteorite Impacts With a Case Study of Chicxulub [wiley.com] (open, 9DOI: 10.1002/2017GL074879) (DX [doi.org])

Potentially hazardous asteroids and comets have hit Earth throughout its history, with catastrophic consequences in the case of the Chicxulub impact 66 Myr ago. Here we reexamine one of the mechanisms that allow an impact to have a global effect—the release of climate-active gases from terrestrial sedimentary rocks after the high-velocity impact. We estimate that 325 ± 130 Gt of sulfur and 425 ± 160 Gt CO₂ were ejected into the atmosphere at velocities > 1 km/s. These numbers have to be used in global climate models to quantify possible changes of solar irradiation, surface temperature, and duration of stressful conditions for biota.

Also at the American Geophysical Union [agu.org].

Original Submission