HOUSTON (CBS Houston) — A massive asteroid slammed into the Earth 66 million years ago, setting off a decades-long “impact winter” in which a blanket of ash blocked sunlight and caused a severe drop in global surface temperatures, new sediment research concludes.

The study from Johan Vellekoof and his team at Utrecht University in the Netherlands concludes that the space rock’s impact some 66 million years ago caused a vast blanket of ash and silt to block out the sun. The ashy darkness halted photosynthesis, caused sea surface temperatures to fall an average of 2 degrees and ultimately led to the demise of the dinosaurs.

The asteroid collided with Earth near present-day Chicxulub, Mexico, and the researchers studied ocean microbe lipids preserved within the silt in the Brazos River region of central Texas in order to reconstruct sea surface temperatures from the dinosaur period.

The data showed that waters were warm before the impact, around 30 degrees Celsius. But in the decades following, sea surface temperatures dropped an average of 2 degrees as light and heat from the sun were blocked by the blanket of dust blasted skyward by the asteroid collision.

“All models predict a resulting short-lived severe drop in global surface temperatures, the so-called ‘impact winter.’ The various scenarios suggest that the period of reduced solar radiation may have lasted anywhere between six months to more than a decade,” Vellekoop writes on his Utrecht University page.

Vellekoops says that the sudden, dark chill that spread over the earth was followed by a period of global warming, acid rain and massive hurricanes that contributed to the deadly effects of the “impact winter.”

“When the dust-veil had lifted, an increase of CO2 in the atmosphere led to a longer period of pronounced warming,” writes Vellekoop, adding that the “post impact greenhouse phase” may have lasted thousands of years and caused mass extinctions and vast ecosystem rearrangement.

Vellekoop characterizes this Cretaceous period as one characterized by the “mass extinction event,” although he says that additional research is still necessary to reconstruct temperatures and environmental consequences.


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