Archive for January, 2010

Arctic Circle Traverse 2010

Saturday, January 23rd, 2010

With colleagues from Utah, I’m planning a 700 km traverse across the Greenland ice sheet along the Arctic Circle 23 April – 12 May, 2010. We’re towing a radar to measure snow accumulation rates; drilling ice cores to calibrate the radar data; and having an airborne radar overflight of our ground traverse line to calibrate that towed-radar. Calibration of the airborne radar should facilitate to map snow accumulation rates elsewhere across the ice sheet.

C-5 Galaxy landing   (click here to open a new window with this photo in computer wallpaper format)

I’m flying north with 2 new snow mobiles on the enormous C5 aircraft.

2009: Second Warmest Year on Record; End of Warmest Decade

Friday, January 22nd, 2010

below is verbatim from a 21 Jan 2010 press release from NASA GISS…

2009 was tied for the second warmest year in the modern record, a new NASA analysis of global surface temperature shows. The analysis, conducted by the Goddard Institute for Space Studies (GISS) in New York City, also shows that in the Southern Hemisphere, 2009 was the warmest year since modern records began in 1880.

10-year average global temperature index
The map shows temperature changes for the last decade — January 2000 to December 2009 — relative to the 1951-1980 mean. Warmer areas are in red, cooler areas in blue. The largest temperature increases occurred in the Arctic and a portion of Antarctica. (Image credit: NASA)
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graph of the land/ocean temperature index
Except for a leveling off between the 1940s and 1970s, Earth’s surface temperatures have increased since 1880. The last decade has brought the temperatures to the highest levels ever recorded. The graph shows global annual surface temperatures relative to 1951-1980 mean temperatures. As shown by the red line, long-term trends are more apparent when temperatures are averaged over a five year period. (Image credit: NASA)
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graph comparing hemispheric temperatures
As seen by the blue point farthest to the right on this graph, 2009 was the warmest year on record in the Southern Hemisphere. (Image credit: NASA)
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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. The past year 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.

“There’s always an interest in the annual temperature numbers and on a given year’s ranking, but usually that misses the point,” said James Hansen, the director of GISS. “There’s substantial year-to-year variability of global temperature caused by the tropical El Niño-La Niña cycle. But when we average temperature over five or ten years to minimize that variability, we find that global warming is continuing unabated.”

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. High air pressures in the Arctic decreased the east-west flow of the jet stream, while also increasing its tendency to blow from north to south and draw cold air southward from the Arctic. This resulted in 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.

“Of course, the contiguous 48 states cover only 1.5 percent of the world area, so the U.S. temperature does not affect the global temperature much,’ said Hansen.

In total, average global temperatures have increased by about 0.8°C (1.5°F) since 1880.

“That’s the important number to keep in mind,” said Gavin Schmidt, another GISS climatologist. “In contrast, the difference between, say, the second and sixth warmest years is trivial since the known uncertainty — or noise — in the temperature measurement is larger than some of the differences between the warmest years.”

Decoding the Temperature Record

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 since 1880, but these gases are not the only factors that can impact global temperatures.

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 these effects are not enough to account for the global warming observed since 1880.

El Niño and La Niña are prime examples of how the oceans can affect global temperatures. They describe abnormally warm or cool sea surface temperatures in the South Pacific that are caused by changing ocean currents.

Global temperatures tend to decrease in the wake of La Niña, which occurs when upwelling cold water off the coast of Peru spreads westward in the equatorial Pacific Ocean. La Niña moderates the impact of greenhouse-gas driven warming, 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.

An especially powerful El Niño cycle in 1998 is thought to have contributed to the unusually high temperatures that year, and Hansen’s group estimates that there’s a good chance 2010 will be the warmest year on record if the current El Niño persists. At most, scientists estimate that El Niño and La Niña can cause global temperatures to deviate by about 0.2°C (0.36°F).

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, which can cause the total amount of energy given off by the Sun to decrease by about a tenth of a percent, typically spur surface temperature to dip slightly. Overall, solar minimums and maximums are thought to produce no more than 0.1°C (0.18°F) of cooling or warming.

“In 2009, it was clear that even the deepest solar minimum in the period of satellite data hasn’t stopped global warming from continuing,” said Hansen.

Small particles in the atmosphere called aerosols can also affect the climate. Volcanoes are powerful sources of sulfate aerosols that counteract global warming by reflecting incoming solar radiation back into space. In the past, large eruptions at Mount Pinatubo in the Philippines and El Chichón in Mexico have caused global dips in surface temperature of as much as 0.3°C (0.54°F). But volcanic eruptions in 2009 have not had a significant impact.

Meanwhile, other types of aerosols, often produced by burning fossil fuels, can change surface temperatures by either reflecting or absorbing incoming sunlight. Hansen’s group estimates that aerosols probably counteract about half of the warming produced by man-made greenhouse gases, but he cautions that better measurements of these elusive particles are needed.

Data Details

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.

Other research groups also track global temperature trends but use different analysis techniques. The Met Office Hadley Centre, based in the United Kingdom, uses similar input measurements as GISS, for example, but it omits large areas of the Arctic and Antarctic, where monitoring stations are sparse.

In contrast, the GISS analysis extrapolates data in those regions using information from the nearest available monitoring stations, and thus has more complete coverage of the polar areas. If GISS didn’t extrapolate in this manner, the software that performs the analysis would assume that areas without monitoring stations warm at the same rate as the global mean, an assumption that doesn’t line up with changes that satellites have observed in Arctic sea ice, Schmidt explained. Although the two methods produce slightly different results in the annual rankings, the decade-long trends in the two records are essentially identical.

“There’s a contradiction between the results shown here and popular perceptions about climate trends,” Hansen said. “In the last decade, global warming has not stopped.”

Related Links

Climatologist Gavin Schmidt Discusses the Surface Temperature Record

GISS Surface Temperature Analysis

GISS Annual Temperature Summation for 2008 and NASA News Release

Media Contact

Steve Cole, 202-358-0918, NASA Headquarters, Washington, D.C. stephen.e.cole@nasa.gov

Leslie McCarthy, 212-678-5507, NASA Goddard Institute for Space Studies, New York, N.Y., leslie.m.mccarthy@nasa.gov

Adam Voiland, 301-352-4631, NASA Goddard Space Flight Center, Greenbelt, Md.

This article is derived from a NASA Looking at Earth news feature.

colder here warmer there

Thursday, January 7th, 2010

Since December, a persistent extreme in regional atmospheric circulation is causing record-cold  in the US, northern Europe, and northern Asia. A friend at 70 deg. N in west Greenland yesterday complained 6 January of no possibility to dog sled because of above-freezing air temperature and insufficient sea ice formation. He was surprised to know that here Ohio, 3300 km to the south, air temperatures were 8 °C (14.4 °F) cooler! See the December 2009 departure from normal…

figure 4: air temp map for December 2009

Map of air temperature anomalies for December 2009. —Credit: National Snow and Ice Data Center courtesy NOAA/ESRL Physical Sciences Division. high resolution version.

“The regional contrasts in temperature anomalies resulted from a strongly negative phase of the Arctic Oscillation (AO). … The AO consists of opposing patterns of atmospheric pressure between the polar regions and mid-latitudes. In December 2009 the AO index value was -3.41, the most negative value since at least 1950, according to data from the NOAA Climate Prediction Center. ” – National Snow and Ice Data Center

Here’s a different projection of a more basic data set…besides the extreme cold especially in northern Eurasia, note the red areas where warmth has been prevailing.

LST anomalies WRT 1961-90
Land surface temperature departure from normal. – UK Met office


Is this cold period part of a pattern of climate change?

…one cannot judge with any certainty without understanding causes in extremes of the Arctic Oscillation. Further, weather and climate are not the same, occurring at different time and spatial scales. The current weather pattern that is bringing cold to the US and Eurasia, being persistent, seems to be straddling the spatial and temporal scales between weather and climate. That’s about all I can say without more study.

Stay warm out there (in the US and Europe) and keep cool there in Greenland! This pattern is expected to persist for weeks? longer!!