An article published in the journal “Proceedings of the National Academy of Sciences” describes a simulation of the events that led to the mass extinction of the end of the Creataceous period, which also led to the extinction of the dinosaurs. A team of researchers from the National Center for Atmospheric Research (NCAR), in Boulder, Colorado, and NASA used a computer model to find out what climatic conditions followed an asteroid impact.
Approximately 66 million years ago, the impact of an asteroid with a diameter estimated at over 10 kilometers off today’s Yucatan Peninsula began a series of catastrophic events that shocked the whole world. The direct destruction caused in the area near the impact was followed by tsunamis and the introduction of huge amounts of soot in the atmosphere that darkened the sky.
According to some research, such as the one published in October 2015 in the journal “Science”, the impact of the asteroid might have shaken the whole planet enough to trigger a strong volcanic activity in India in the Deccan Traps. According to the authors, toxic dusts and fumes that were released for thousands of years by volcanic eruptions made the catastrophe even worse.
A team led by Charles Bardeen of NCAR used the Community Earth System Model (CESM) software, written specifically to model global climate processes, to simulate the consequences of the presence of soot but also of water vapor introduced in the atmosphere directly or indirectly. Part of those materials came from the impact area, meaning from the asteroid itself and the affected area, the crater called Chicxulub. Another part was generated during the fires that followed the global impact.
The amount of soot in the atmosphere was estimated at between 15 and 35 billion tonnes. These were small particles called spherules formed by condensation of rocks vaporized in the impact of the asteroid and projected at high altitudes into the Earth’s atmosphere reaching the whole world. Falling on the surface, the spherules were heated by friction enough to trigger global fires.
This catastrophic event certainly hit the organisms that were living on the mainland and it’s possible that many species were quickly brought to extinction but the species that digged underground burrows and even more marine species or at least amphibians could escape that devastation. However, the team led by Charles Bardeen also looked at the long-term consequences of soot in the atmosphere.
According to the simulation, soot in the atmosphere caused a further catastrophe, damaging the ozone layer, affecting the climate and darkening the sky stopping the photosynthesis process. Blocking sunlight meant lowering the temperature to the ground, with a drop up to 28° Celsius (50° Fahrenheit) on the mainland and up to 11° Celsius (20° Fahrenheit) in the seas. The length of that dark and cold period is connected to the amount of soot in the atmosphere and could have reached two years.
The model used was designed to predict the evolution of today’s climate so its application to a catastrophic event in the past may have provided inaccurate results. However, the results seem consistent with those of other research on the consequences f that asteroid’s impact. According to Charles Bardeen, that model could also give an idea of the consequences of an atomic war, hoping it will remain a simulation.