February 21– American scientists use a 3D printer to create a living lab-grown ear from collagen and animal ear cell cultures. In the future, it is hoped that similar ears could be grown to order as transplants for human patients with ear trauma or amputation.[14]
May 20 – The latest EF5 tornado in the United States hits Moore and several other surrounding areas near Oklahoma City, resulting in 24 deaths and many injuries.[36]
May 31 – The largest tornado ever recorded hits El Reno, United States. This rain-wrapped, multiple-vortex tornado was the widest tornado ever recorded, and results in eight deaths, including four storm-chasers. Measurements from mobile weather radars revealed extreme winds up to 296 mph (476km/h) within the vortex, among the highest observed wind speeds on Earth. As it crosses U.S. 81, the tornado grows to a record-breaking width of 2.6 miles (4.2 km).[38]
August 14– Following the military coup in Egypt, two anti-coup camps are raided by the security forces, leaving 2,696 dead.[53] The raids were described by Human Rights Watch as "one of the world's largest killings of demonstrators in a single day in recent history".[54]
October 10– Delegates from some 140 countries and territories sign the Minamata Treaty, a UNEP treaty designed to protect human health and the environment from emissions and releases of mercury and mercury compounds.[61]
Euromaidan pro-EU demonstrations begin in Ukraine after President Viktor Yanukovych rejects an economic association agreement between the European Union and Ukraine in favor of closer ties to Russia.[68]
Kotz, Deborah (April 24, 2013). "Injury toll from Marathon bombs reduced to 264". The Boston Globe. Archived from the original on March 31, 2019. Retrieved May 3, 2013. It turns out that we had double-counted some patients who were transferred from 1 hospital to another, so we reviewed our spreadsheets and cleaned up the duplicates
National Weather Service Weather Forecast Office in Norman, Oklahoma (2013). Oklahoma Event Report: EF5 Tornado (Report). National Centers for Environmental Information. Archived from the original on May 12, 2018. Retrieved May 11, 2018.
Walker, Martin (July 22, 2013). "Snowden's best refuge". United Press International. Archived from the original on July 26, 2013. Retrieved July 27, 2013.
Eastley, Tony (September 8, 2013). "Kevin Rudd concedes defeat"(transcript). AM. Australia: ABC Radio. Archived from the original on February 16, 2015. Retrieved February 7, 2015.