Rapid decline of Arctic sea ice a combination of climate change and natural variability

Arctic sea ice, as seen from an ice breaker ship in 2014.

Arctic sea ice in recent decades has declined even faster than predicted by most models of climate change. Many scientists have suspected that the trend now underway is a combination of global warming and natural climate variability. A new study finds that a substantial chunk of summer sea ice loss in recent decades was due to natural variability in the atmosphere over the Arctic Ocean.

‘Black swan’ events strike animal populations

A black swan (Cygnus atratus) seen in New Zealand. The black swan metaphor refers to a previous assumption that the birds did not exist, but later were found in the wild — signifying a surprising change of thought.

Black swan events are rare and surprising occurrences that happen without notice and often wreak havoc on society. The metaphor has been used to describe banking collapses, devastating earthquakes and other major surprises in financial, social and natural systems. A new analysis by the University of Washington and Simon Fraser University is the first to document that black swan events also occur in animal populations and usually manifest as massive, unexpected die-offs.