Earth’s water must have arrived here earlier than we thought

The arrival of water on our planet is shrouded in mystery. Our leading theory says icy meteorites brought it here after most of the planet and its core had formed, about 4.5 billion years ago. But now an analysis of isotopes from meteorites seems to imply that the wet stuff got here much sooner. Read more.

New evidence reveals climate change killed the big animals of Australia’s ice age

During the Ice Age, things were a bit different than they are today in the land of Sahul. If the name Sahul doesn’t ring a bell, it is probably because it isn’t a place anymore. It is the landmass that includes Australia, Tasmania, and New Guinea—all once connected. At times of lower sea level when water is locked up in ice, the continental shelf is exposed and merges all of these seemingly separate swathes of land.

During this last glacial maximum, the continent was teeming with giants like 500-pound kangaroos, massive fuzzy wombat-relatives, and 20-foot-long crocodiles. But around 30,000 years ago, these enormous land dwellers had almost disappeared. A whopping 88 species of mammals went extinct in Sahul between 500,000 and 30,000 years ago, but why? Read more.

Reconstructing Greenland’s climate

It is not easy to reconstruct past temperature changes beyond the 150-year time frame of recorded observations, but Takuro Kobashi at the University of Bern has developed a tool that can do just this. In a two-year fellowship, completed in April 2016, Kobashi reconstructed the precise temperature of Greenland over the past millennia using ice cores. In a contrast to conventional methods, he collected data from argon and nitrogen isotopes trapped in air bubbles within ice cores. Read more.

Stone tools to skeletons: how to uncover an ancient object’s age

In his latest explainer, Jake Port explores a few of the techniques in an archaeologist’s and palaeontologist’s toolkit to date samples from thousands to billions of years old

When a piece of bone, spearhead or rock is dug from the ground, a long process begins to work out where it came from and how it got there. An important part of this investigation is determining the age of the specimen, for which there is a wide array of dating methods available. If you want to know the precise age of something, absolute dating techniques are the only option. They work by analysing the activity of elements and their decay over time. Read more.