Our Blue Planet is in the grips of the Sixth Mass Extinction: The best-case scenario projects that humans will add 300 gigatons of carbon to the oceans by 2100, while more than 500 gigatons will be added under the worst-case scenario, far exceeding the critical threshold. In all scenarios, says Daniel Rothman professor of geophysics and co-director of MIT’s Lorenz Center, by 2100, the carbon cycle will either be close to or well beyond Earth’s threshold for catastrophe.
“SS 433 is an unusual star system and each year something new has come out about it,” said Segev BenZvi, physicist at the University of Rochester. “This new observation of high-energy gamma rays builds on almost 40 years of measurements of one of the weirdest objects in the Milky Way. Every measurement gives us a different piece of the puzzle, and we hope to use our knowledge to learn about the quasar family as a whole.”
Selecting a landing site for a rover headed to Mars is a lengthy process that normally involves large committees of scientists and engineers. These committees typically spend several years weighing a mission’s science objectives against a vehicle’s engineering constraints, to identify sites that are both scientifically interesting and safe to land on.
“How can you really compare these great events in the geologic past, which occur over such vast timescales, to what’s going on today, which is centuries at the longest?” says Daniel Rothman professor of geophysics and co-director of MIT’s Lorenz Center,. “So I sat down one summer day and tried to think about how one might go about this systematically.”
In the past 540 million years, the Earth has endured five mass extinction events, each involving processes that upended the normal cycling of carbon through the atmosphere and oceans. These globally fatal perturbations in carbon each unfolded over thousands to millions of years, and are coincident with the widespread extermination of marine species around the world.