Geoscience Reference
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mountain glaciers, and Arctic sea ice are shrinking. The dominant cause
of the warming since the 1950s is human activities.” (AMS Statement on
Climate Change 2012).
Figure 18.1 shows a line graph of the globally-averaged land-ocean
temperature anomaly from 1880 to 2010, relative to the WMO (World
Meteorological Organization) recommended average temperature climate
reference period of 1951 to 1980. Black line connecting solid square symbol
shows the annual mean and the solid red line is the corresponding 5-year
running mean. The green vertical bars indicate uncertainty estimates.
Figure 18.1. Source: http://data.giss.nasa.gov/gistemp/graphs/.
Figure 18.2 shows a globally observed increase in the annually averaged
surface temperature during the decade 2000-2009, compared to the WMO
recommended reference period of 1951 to 1980. The most signifi cant
warming, shown in red, was in the high-latitude Arctic region.
Despite the inter-annual and inter-decadal variability, the observation of
the surface temperature of Earth points unequivocally to a warming trend,
with about 0.8ºC increase from 1901 to 2010, the period which includes a
relatively rapid increase of about 0.5ºC over the 1979-2010 period. With
over 100 years of instrumental temperature record on a global basis,
the 10 warmest years have occurred since 1997. Global climate models
indicate that these warming trends are projected to continue as CO 2 and
other greenhouse gases (such as CH 4 and N 2 O) are continually emitted
into the atmosphere from human activities (IPCC-AR4 2007). From the
meteorological measurements from stations located in the valley fl oors of
the central Canadian Rockies (Banff, Yoho and Jasper National Parks), it has
been found that an increase of around 1.4 to 1.5ºC in annual temperature
occurred from 1888 to 1994 (Luckman 1998, Luckman and Kavanagh 2000).
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