Taxonomy term

Two upcoming missions will provide the first systematic approach to searching the atmospheres of exoplanets for signs of life — and they could find it in the next several decades.

Oxidants in the troposphere, such as ozone and hydroxyl radicals, influence the life spans of other atmospheric components, including pollutants and greenhouse gases like carbon monoxide and methane. But how the abundance of tropospheric oxidants varies as climate changes is poorly understood. Part of the challenge is that these oxidants are too reactive to be preserved in paleo-records, such as ice cores.

Geologists are fond of the saying, “The past is key to the future.” Unfortunately, the past has been a poor guide when it comes to understanding modern climate change. Now, however, a new study suggests that one episode — a spike in global temperatures that occurred about 55 million years ago — may be a better analog than previously thought, and could yield insights into the planet’s future.

NASA’s Curiosity rover found evidence that one or more large and long-lasting lakes probably filled Gale Crater in the planet’s warmer and wetter early history. While investigating the lower slopes of Mount Sharp recently at an outcrop called the Murray Formation, the rover photographed thick rock stacks featuring numerous layers of lithified sediment. Such stacks are typical of lake environments, where sediments slowly settle to the bottom and transform into rock over time.