Title: 2. How has climate changed? | Australian Academy of Science
Headings: 2. How has climate changed?
2. How has climate changed?
Past climate has varied enormously on a variety of time-scales
Past records demonstrate that global climate is sensitive to small but persistent influences
Box 2.1: How do we detect climate change?
Box 2.2: Has climate warming recently stopped?
Global average temperatures have increased over the past century
Changes are evident in many parts of the climate system
There are regional differences to climate change including within Australia

Content: The temperature of the oceans has also risen. More than 90% of the total heat accumulated in the climate system between 1971 and 2010 has been stored in the oceans. The greatest ocean warming has taken place close to the surface, with the upper 75 m of the ocean warming by an average of 0.11°C each decade between 1971 and 2010. Changes are evident in many parts of the climate system
Changes consistent with an increase in global temperature have been observed in many other components of the climate system. Mountain glaciers have been shrinking and contributing to global sea-level rise since about 1850. Melting accelerated significantly in the 1990s. The Greenland and West Antarctic Ice Sheets have both lost ice since 1990, further contributing to sea-level rise as discussed in Question 6. This is from increased discharge of ice into the ocean, and also increased surface melting in Greenland. The rate of loss from Greenland appears to be increasing. The area of the Arctic Ocean covered by sea ice has decreased significantly since 1987 throughout the year and particularly in summer.