NASA SAYS IT’S GETTING HOTTER
2009: Second Warmest Year on Record; End of Warmest Decade
January 21, 2010 (NASA/Goddard Institute for Space Studies)
"2009 was tied for the second warmest year in the modern record, a new NASA analysis of global surface temperature shows…[The] Goddard Institute for Space Studies (GISS) [study also showed]…that in the Southern Hemisphere, 2009 was the warmest year since modern records began in 1880.
"Although 2008 was the coolest year of the decade, due to strong cooling of the tropical Pacific Ocean, 2009 saw a return to near-record global temperatures…[It] was only a fraction of a degree cooler than 2005, the warmest year on record, and tied with a cluster of other years — 1998, 2002, 2003, 2006 and 2007 1998 and 2007 — as the second warmest year since recordkeeping began…"
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"January 2000 to December 2009 was the warmest decade on record. Throughout the last three decades, the GISS surface temperature record shows an upward trend of about 0.2°C (0.36°F) per decade. Since 1880, the year that modern scientific instrumentation became available to monitor temperatures precisely, a clear warming trend is present, though there was a leveling off between the 1940s and 1970s.
"The near-record temperatures of 2009 occurred despite an unseasonably cool December in much of North America…[because of]…an unusual effect that caused frigid air from the Arctic to rush into North America and warmer mid-latitude air to shift toward the north…In total, average global temperatures have increased by about 0.8°C (1.5°F) since 1880…Climate scientists agree that rising levels of carbon dioxide and other greenhouse gases trap incoming heat near the surface of the Earth and are the key factors causing the rise in temperatures…but these gases are not the only factors that can impact global temperatures."
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"Three others key factors — including changes in the Sun's irradiance, oscillations of sea surface temperature in the tropics, and changes in aerosol levels — can also cause slight increases or decreases in the planet's temperature. Overall, the evidence suggests that [effects like El Niño and La Niña] are not enough to account for the global warming observed…La Niña moderates the impact of greenhouse-gas driven warming…[It] lingered during the early months of 2009 and gave way to the beginning of an El Niño phase in October that's expected to continue in 2010…[Climate scientists think it likely] 2010 will be the warmest year on record if the current El Niño persists…
"Warmer surface temperatures also tend to occur during particularly active parts of the solar cycle, known as solar maximums, while slightly cooler temperatures occur during lulls in activity, called minimums…A deep solar minimum has made sunspots a rarity in the last few years. Such lulls in solar activity…typically spur surface temperature to dip slightly…[but] are thought to produce no more than 0.1°C (0.18°F) of cooling or warming…Small particles in the atmosphere called aerosols [like sulfate aerosols from volcanoes] can also affect the climate…But volcanic eruptions in 2009 have not had a significant impact…[O]ther types of aerosols, often produced by burning fossil fuels…probably counteract about half of the warming produced by man-made greenhouse gases…"
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"To conduct its analysis, GISS uses publicly available data from three sources: weather data from more than a thousand meteorological stations around the world; satellite observations of sea surface temperature; and Antarctic research station measurements…These three data sets are loaded into a computer program, which is available for public download from the GISS website. The program calculates trends in temperature anomalies — not absolute temperatures — but changes relative to the average temperature for the same month during the period of 1951-1980…"
[James Hansen, head climate scientist, NASA:] "There's a contradiction between the results shown here and popular perceptions about climate trends…In the last decade, global warming has not stopped."