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| 2005 was the warmest year since the late 1800s, according to NASA scientists. 1998, 2002 and 2003 and 2004 followed as the next four warmest years. Credit: NASA |
The year 2005 may
have been the warmest year in a century, according to NASA scientists studying
temperature data from around the world.
Climatologists at NASA’s Goddard
Institute for Space Studies (GISS) in New York City observed that the highest
global annual average surface temperature in more than a century was recorded in
their analysis for the 2005 calendar
year.
Some other research groups that study
climate change rank 2005 as the second warmest year, based on comparisons
through November. The primary difference among the analyses, according to the
NASA scientists, is the inclusion of the Arctic in the NASA analysis. Although
there are few weather stations in the Arctic, the available data indicate that
2005 was unusually warm in the Arctic.
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| This colorful global map of 2005 average temperatures shows areas that have warmed the most in red, to the areas that have cooled (in blue). Note that the Arctic has warmed significantly. These temperatures are from Dec. 2004 through Nov. 2005. Credit: NASA |
To check
whether the Earth is cooling or warming, the scientists use temperature data
from weather stations on land, satellite measurements of sea surface temperature
since 1982, and data from ships for earlier years.
Previously,
the warmest year of the century was 1998, when a strong El Niño, a warm water
event in the eastern Pacific Ocean, added warmth to global temperatures.
However, what’s significant, regardless of whether 2005 is first or second
warmest, is that global warmth has returned to about the level of 1998 without
the assistance of an El Niño.
The NASA study suggests that a strong underlying
warming trend is continuing. Global warming since the middle 1970s is now about
0.6 degrees Celsius (C) or about 1 degree Fahrenheit (F). Total warming in the
past century is about 0.8* C or about 1.4* F.
“The five warmest years over the
last century occurred in the last eight years,” said James Hansen, director of
NASA GISS. They stack up as follows: the warmest was 2005, then 1998, 2002, 2003
and 2004.
Over the past 30 years, the Earth has warmed by 0.6* C or 1.08*
F. Over the past 100 years, it has warmed by 0.8* C or 1.44* F.
Current
warmth seems to be occurring nearly everywhere at the same time and is largest
at high latitudes in the Northern Hemisphere. Over the last 50 years, the
largest annual and seasonal warmings have occurred in Alaska, Siberia and the
Antarctic Peninsula. Most ocean areas have warmed. Because these areas are
remote and far away from major cities, it is clear to climatologists that the
warming is not due to the influence of pollution from urban areas.
Recent warming coincides with rapid
growth of human-made greenhouse gases. Climate models show that the rate of
warming is consistent with expectations . The observed rapid warming thus gives
urgency to discussions about how to slow greenhouse gas emissions according to
NASA.
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