This was the sixth-highest crest since measurements began in the first half of the 20th century.

The measurements began in 1978 and ran until mid-1990.

August 2009 was the warmest month since official measurements began.

Electronic measurements began in 1948 and improved further in the early 1970s.

This glacier has been constantly receding since measurements began in 1780.

The 2007 dead zone is one of the largest since measurements began in 1985.

Reliable measurements of sea ice edge begin within the satellite era.

Reliable measurement of sea ice edge begin within the satellite era in the late 1970s.

In such cases, doctors disagreed about when measurement of the breathing time should begin.

This is the lowest lake elevation since measurement began in 1882.