the fundamental drilling technology for retrieving deep ice cores for climatologic archives." Polar ice caps have been used to track current climate patterns but also patterns over the past several thousands years from the traces of and found trapped in the ice. In the past decade, polar ice caps have shown their most rapid decline in size with no true sign of recovery. Josefino Comiso, a senior research scientist at NASA, found that the "rate of warming in the Arctic over the last 20 years is eight times the rate of warming over the last 100 years." In September 2012, sea ice reached its smallest size ever. Journalist John Vidal stated that sea ice is "700,000 sq km below the previous minimum of 4.17m sq km set in 2007". In August 2013, Arctic sea ice extent averaged 6.09m km2, which represents 1.13 million km2 below the 1981–2010 average for that month. Mars In addition to Earth, the planet Mars also has polar ice caps. They consist of primarily water-ice with a few percent dust. Frozen carbon dioxide makes up a small permanent portion of the Planum Australe or the South Polar Layered Deposits. In both hemispheres a seasonal carbon dioxide frost deposits in the winter and sublimates during the spring. Data collected in 2001 from NASA missions to Mars show that the southern residual ice cap undergoes sublimation inter-annually. The most widely accepted explanation is that fluctuations in the planet's orbit are causing the changes. Pluto On 29 April 2015, NASA stated that its New Horizons missions had discovered a feature thought to be a polar ice cap on the dwarf planet Pluto. The probe's flyby of Pluto in July 2015 allowed the Alice ultraviolet imaging spectrometer to confirm that the feature was in fact an ice cap composed of methane and nitrogen ices. See also Cryosphere Ice age Polar climate References External links Geography of the Arctic Ice caps Polar regions