NASA

  • Carbon Dioxide
    413 parts per million
    Carbon dioxide levels in the air are at their highest in 650,000 years
  • Global Temperature
    1.9°F since 1880
    Nineteen of the 20 warmest years on record have occurred since 2001
  • Arctic Ice Minimum
    12.85 percent per decade
    In 2012, Arctic summer sea ice shrank to the lowest extent on record
  • Ice Sheets
    428 Gigatonnes per year
    Satellite data show that Earth’s polar ice sheets are losing mass
  • Sea Level
    3.3 millimeters per year
    Global average sea level has risen nearly 7″ (178 mm) over the past 100 years
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3 Responses to NASA

  1. shinichi says:

    Global Climate Change

    Climate Change: Vital Signs of the Planet

    NASA

    https://climate.nasa.gov/

  2. shinichi says:

    GRACE, GRACE-FO Satellite Data Track Ice Loss at the Poles

    https://climate.nasa.gov/news/2959/grace-grace-fo-satellite-data-track-ice-loss-at-the-poles/


    Greenland’s Steenstrup Glacier, with the midmorning sun glinting off the Denmark Strait in the background. The image was taken during a NASA IceBridge airborne survey of the region in 2016. Credit: NASA/Operation IceBridge


    During the exceptionally warm Arctic summer of 2019, Greenland lost 600 billion tons of ice—enough to raise global sea levels by nearly a tenth of an inch (2.2 millimeters) in just two months, a new study shows.

    Led by scientists at NASA’s Jet Propulsion Laboratory and the University of California, Irvine, the study also concludes that Antarctica continues to lose mass, particularly in the Amundsen Sea Embayment and the Antarctic Peninsula on the western part of the continent; however, those losses have been partially offset by gains from increased snowfall in the northeast.

    “We knew this past summer had been particularly warm in Greenland, melting every corner of the ice sheet,” said lead author Isabella Velicogna, senior project scientist at JPL and a professor at UCI. “But the numbers really are enormous.”

    For context, last summer’s losses are more than double Greenland’s 2002-2019 yearly average.

    “In Antarctica, the mass loss in the west proceeds unabated, which will lead to an even further increase in sea level rise,” Velicogna said. “But we also observe a mass gain in the Atlantic sector of East Antarctica caused by an uptick in snowfall, which helps mitigate the enormous increase in mass loss that we have seen in the last two decades on other parts of the continent.”

    She and her colleagues came to these conclusions in the process of establishing data continuity between the recently decommissioned Gravity Recovery and Climate Experiment (GRACE) satellite mission and its successor, GRACE Follow-On.

    As mission partnerships between NASA and the German Aerospace Center, and NASA and the German Research Centre for Geosciences, respectively, the GRACE and GRACE-FO satellites were designed to measure changes to Earth’s gravitational pull that result from changes in mass, including water. As water moves around the planet—flowing ocean currents, melting ice, falling rain and so on—it changes the gravitational pull ever so slightly. Scientists use the precise measurements of these variations to monitor Earth’s water reserves, including polar ice, global sea levels and groundwater availability.

    The first GRACE mission was launched in 2002 and decommissioned in October 2017. GRACE-FO, based on similar technology and designed to continue the data record of its predecessor, launched in May 2018. Because of this brief gap, the study team used independent data to test and confirm that the GRACE and GRACE-FO data over Greenland and Antarctica were consistent. Velicogna was pleased with the results.

    “It is great to see how well the data line up in Greenland and Antarctica, even at the regional level,” she said. “It is a tribute to the great effort by the project, engineering and science teams to make the mission successful.”

    The study, titled “Continuity of Ice Sheet Mass Loss in Greenland and Antarctica From the GRACE and GRACE Follow-On Missions,” was published March 18 in Geophysical Research Letters. In addition to scientists from JPL and UCI, the GRACE and GRACE-FO data continuity project involved researchers from University of Grenoble in France, University of Utrecht in the Netherlands, and the Polar Ice Center at the University of Washington in Seattle.

    JPL managed the GRACE mission and manages the GRACE-FO mission for NASA’s Earth Science Division in the Science Mission Directorate at NASA Headquarters in Washington. Caltech in Pasadena, California, manages JPL for NASA.

    More information on GRACE and GRACE-FO can be found here:

    https://www.nasa.gov/mission_pages/Grace/index.html

    https://gracefo.jpl.nasa.gov/mission/overview/

  3. shinichi says:

    Greenland, Antarctica Melting Six Times Faster Than in the 1990s

    https://climate.nasa.gov/news/2958/greenland-antarctica-melting-six-times-faster-than-in-the-1990s/


    An aerial view of the icebergs near Kulusuk Island, off the southeastern coastline of Greenland, a region that is exhibiting an accelerated rate of ice loss. Credit: NASA Goddard Space Flight Center


    Observations from 11 satellite missions monitoring the Greenland and Antarctic ice sheets have revealed that the regions are losing ice six times faster than they were in the 1990s. If the current melting trend continues, the regions will be on track to match the “worst-case” scenario of the Intergovernmental Panel on Climate Change (IPCC) of an extra 6.7 inches (17 centimeters) of sea level rise by 2100.

    The findings, published online March 12 in the journal Nature from an international team of 89 polar scientists from 50 organizations, are the most comprehensive assessment to date of the changing ice sheets. The Ice Sheet Mass Balance Intercomparison Exercise team combined 26 surveys to calculate changes in the mass of the Greenland and Antarctic ice sheets between 1992 and 2018.

    The assessment was supported by NASA and the European Space Agency. The surveys used measurements from satellites including NASA’s Ice, Cloud, and land Elevation Satellite and the joint NASA-German Aerospace Center Gravity Recovery and Climate Experiment. Andrew Shepherd at the University of Leeds in England and Erik Ivins at NASA’s Jet Propulsion Laboratory in Southern California led the study.

    The team calculated that the two ice sheets together lost 81 billion tons per year in the 1990s, compared with 475 billion tons of ice per year in the 2010s—a sixfold increase. All total, Greenland and Antarctica have lost 6.4 trillion tons of ice since the 1990s.

    The resulting meltwater boosted global sea levels by 0.7 inches (17.8 millimeters). Together, the melting polar ice sheets are responsible for a third of all sea level rise. Of this total sea level rise, 60 percent resulted from Greenland’s ice loss and 40 percent resulted from Antarctica’s.

    “Satellite observations of polar ice are essential for monitoring and predicting how climate change could affect ice losses and sea level rise,” said Ivins. “While computer simulations allow us to make projections from climate change scenarios, the satellite measurements provide prima facie, rather irrefutable, evidence.”

    The IPCC in its Fifth Assessment Report issued in 2014 predicted global sea levels would rise 28 inches (71 centimeters) by 2100. The Ice Sheet Mass Balance Intercomparison Exercise team’s studies show that ice loss from Antarctica and Greenland tracks with the IPCC’s worst-case scenario.

    Combined losses from both ice sheets peaked at 552 billion tons per year in 2010 and averaged 475 billion tons per year for the remainder of the decade. The peak loss coincided with several years of intense surface melting in Greenland, and last summer’s Arctic heat wave means that 2019 will likely set a new record for polar ice sheet loss, but further analysis is needed. IPCC projections indicate the resulting sea level rise could put 400 million people at risk of annual coastal flooding by the end of the century.

    “Every centimeter of sea level rise leads to coastal flooding and coastal erosion, disrupting people’s lives around the planet,” said Shepherd.

    As to what is leading to the ice loss, Antarctica’s outlet glaciers are being melted by the ocean, which causes them to speed up. Whereas this accounts for the majority of Antarctica’s ice loss, it accounts for half of Greenland’s ice loss; the rest is caused by rising air temperatures melting the surface of its ice sheet.

    For more information about the Ice Sheet Mass Balance Intercomparison Exercise, visit:

    http://imbie.org/

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