Today's featured article
An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Cores are drilled with hand augers (for shallow holes) or powered drills; they can reach depths of over two miles (three kilometres), and contain ice up to 800,000 years old. The physical properties of the ice and of material trapped in it can be used to reconstruct the climate over the age range of the core. The ratio of oxygen and hydrogen isotopes provides information about ancient temperatures, and the air trapped in tiny bubbles can indicate the level of atmospheric gases such as carbon dioxide. Greenland ice cores contain layers of wind-blown dust that correlate with cold, dry periods in the past. Radioactive elements, either of natural origin or created by nuclear testing, can be used to date the layers of ice. Some volcanic events that were sufficiently powerful to send material around the globe have left a signature in many different cores that can be used to synchronise their time scales. Climate models can be constructed by piecing together all the available data. (Full article...)
In the news
- The Syrian Democratic Forces declare victory in the Battle of Raqqa.
- The first observation of a neutron star merger in gravitational waves as well as gamma-rays and visible light is announced.
- Sooronbay Jeenbekov (pictured) is elected President of Kyrgyzstan in the first peaceful transfer of power after a full term in the country's history.
- Twin bombings kill at least 320 people in Mogadishu, Somalia.
- Flash floods and landslides from a tropical depression kill more than 50 people in Vietnam.
- Wildfires in Northern California kill at least 40 people and destroy thousands of buildings and other structures.