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Climate Variability and Change

Posted on by Tassia Owen Posted in News and Events

For two weeks in late June and early July 2015, western Europe and the Pacific Northwest of North America endured record-setting heat and parched landscapes. Other parts of the world got a taste of the heat, too, as new temperature records were set on three continents.

The map above shows daytime land surface temperature anomalies in Europe from June 30 to July 9, 2015. Temperatures for those ten days are compared to the 2001–2010 average for the same period. Shades of red depict areas where the land surface was hotter than the long-term average; areas in blue were below average. White pixels were normal, and gray pixels did not have enough data, most likely due to excessive cloud cover.

This temperature anomaly map is based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. Observed by satellites uniformly around the world, land surface temperatures (LSTs) are not the same as air temperatures. LSTs reflect the heating of the land by sunlight, and they can sometimes be significantly hotter or cooler than air temperatures. Read more

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NASA Earth Observatory images created by Jesse Allen, using Land Surface Data from the MODIS Science Team. Caption by Michael Carlowicz.

Posted on by Tassia Owen Posted in News and Events
CERES data over Pacific Ocean

While the upper part of the world’s oceans continue to absorb heat from global warming, ocean depths have not warmed measurably in the last decade. This image shows heat radiating from the Pacific Ocean as imaged by the NASA’s Clouds and the Earth’s Radiant Energy System instrument on the Terra satellite. (Blue regions indicate thick cloud cover.)

The cold waters of Earth’s deep ocean have not warmed measurably since 2005, according to a new NASA study, leaving unsolved the mystery of why global warming appears to have slowed in recent years.

Scientists at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, analyzed satellite and direct ocean temperature data from 2005 to 2013 and found the ocean abyss below 1.24 miles (1,995 meters) has not warmed measurably. Study coauthor Josh Willis of JPL said these findings do not throw suspicion on climate change itself.

“The sea level is still rising,” Willis noted. “We’re just trying to understand the nitty-gritty details.”

In the 21st century, greenhouse gases have continued to accumulate in the atmosphere, just as they did in the 20th century, but global average surface air temperatures have stopped rising in tandem with the gases. The temperature of the top half of the world’s oceans — above the 1.24-mile mark — is still climbing, but not fast enough to account for the stalled air temperatures.

Many processes on land, air and sea have been invoked to explain what is happening to the “missing” heat. One of the most prominent ideas is that the bottom half of the ocean is taking up the slack, but supporting evidence is slim. This latest study is the first to test the idea using satellite observations, as well as direct temperature measurements of the upper ocean. Scientists have been taking the temperature of the top half of the ocean directly since 2005, using a network of 3,000 floating temperature probes called the Argo array.

“The deep parts of the ocean are harder to measure,” said JPL’s William Llovel, lead author of the study published Sunday in the journal Nature Climate Change. “The combination of satellite and direct temperature data gives us a glimpse of how much sea level rise is due to deep warming. The answer is — not much.”

The study took advantage of the fact that water expands as it gets warmer. The sea level is rising because of this expansion and the water added by glacier and ice sheet melt.

To arrive at their conclusion, the JPL scientists did a straightforward subtraction calculation, using data for 2005-2013 from the Argo buoys, NASA’s Jason-1 and Jason-2 satellites, and the agency’s Gravity Recovery and Climate Experiment (GRACE) satellites. From the total amount of sea level rise, they subtracted the amount of rise from the expansion in the upper ocean, and the amount of rise that came from added meltwater. The remainder represented the amount of sea level rise caused by warming in the deep ocean.

The remainder was essentially zero. Deep ocean warming contributed virtually nothing to sea level rise during this period.

Coauthor Felix Landerer of JPL noted that during the same period warming in the top half of the ocean continued unabated, an unequivocal sign that our planet is heating up. Some recent studies reporting deep-ocean warming were, in fact, referring to the warming in the upper half of the ocean but below the topmost layer, which ends about 0.4 mile (700 meters) down.

Landerer also is a coauthor of another paper in the same journal issue on 1970-2005 ocean warming in the Southern Hemisphere. Before Argo floats were deployed, temperature measurements in the Southern Ocean were spotty, at best. Using satellite measurements and climate simulations of sea level changes around the world, the new study found the global ocean absorbed far more heat in those 35 years than previously thought — a whopping 24 to 58 percent more than early estimates.

Both papers result from the work of the newly formed NASA Sea Level Change Team, an interdisciplinary group tasked with using NASA satellite data to improve the accuracy and scale of current and future estimates of sea level change. The Southern Hemisphere paper was led by three scientists at Lawrence Livermore National Laboratory in Livermore, California.

NASA monitors Earth’s vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

For more information about NASA’s Earth science activities in 2014, visit:

http://www.nasa.gov/earthrightnow

For more information on ocean surface topography from space, visit:

http://sealevel.jpl.nasa.gov

More information on NASA’s GRACE satellites is available at:

http://grace.jpl.nasa.gov

For more information on the Argo array, visit:

http://www.argo.ucsd.edu/index.html

Posted on by Tassia Owen Posted in News and Events
GreatLakes_tmo_2014269

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC. Caption by Mike Carlowicz.

A few days after autumn showed up on the calendar in the Northern Hemisphere, it showed up on the landscape of North America. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured these views of fall colors around the Great Lakes (September 26) and New England (September 27, 2014). The brown and orange shades are most pronounced in the Upper Peninsula of Michigan, northern Wisconsin, upstate New York, New Hampshire, Vermont, Maine, and southern Quebec and Ontario. You can also see faint traces of phytoplankton blooms in the lakes and offshore in the North Atlantic.

The changing of leaf color in temperate forests involves several causes and reactions, but the dominant factors are sunlight and heat. Since temperatures tend to drop sooner and sunlight fades faster at higher latitudes, the progression of fall color changes tends to move from north to south across North America from mid-September through mid-November. Read more

See an animation of the changing colors on this article from the Huffington Post.

Posted on by Tassia Owen Posted in News and Events

namericalsta_tmo_2014215

If you live in the northern hemisphere, the past few weeks have been strange. In places where it should be seasonably hot—the eastern and southern United States and western Europe—it’s just been warm. In places where weather is usually mild in the summer—northern Europe, the Pacific coast of North America—it has been ridiculously hot. Read more

NASA Earth Observatory images by Jesse Allen, using data from the Land Processes Distributed Active Archive Center (LPDAAC). Caption by Michael Carlowicz, with image interpretation from Bill Patzert (NASA JPL), Jason Samenow (The Washington Post) and Linus Magnusson (European Centre for Medium-Range Weather Forecasting).

Posted on by Tassia Owen Posted in News and Events

california_ast_2011095

In its weekly report issued on July 31, the U.S. Drought Monitor reported that 82 percent of the state of California was in an extreme drought and 58 percent was in exceptional drought—up from 79 and 36 percent just two weeks ago. The drying of farmlands and suburbs is mirrored by the shrinking of the state’s reservoirs.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA’s Terra spacecraft captured these false-color views of central California on April 5, 2011 (top), and May 15, 2014. ASTER collects data in infrared, red, and green wavelengths of light, which are then combined to make false-color images where vegetation appears red; buildings and roads are white and gray; water is dark blue; and dry, barren land is tan. Read more

NASA Earth Observatory image by Jesse Allen, using data from NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Caption by Michael Carlowicz.