Monitoring Earth’s climate variables with satellite laser altimetry

Figure 3: Changes in sea ice and land ice in the polar regions from ICESat and ICESat-2.Main maps show sea ice thickness for the Arctic and Greenland region (sea ice thickness for January 202064) and the Antarctic region (average for April to November 2019)82 from ICESat-2. The height change rate for the land ice sheet is also shown, based on data from ICESat to ICESat-2 (ref. 49). Inset panels show details of processes made possible with high-resolution ICESat-2 data. a, Melt pond bathymetry and depth on Arctic sea ice in June 2019 from ICESat-2 with near-coincident Sentinel-2 Multi-Spectral Instrument image of surface ponding53. b, Sea ice freeboard in October 2004 from ICESat with near-coincident Envisat ASAR image of sea ice conditions79. The ICESat ground track is shown as a dashed line. In the small inset map of Antarctica, × marks the approximate geographical location of the image and the ICESat profile. Flight direction is from left to right. Pink arrows indicate leads. Solid green line indicates interpolated sea surface height79. c, Sermeq Kujalleq (Jakobshavn Isbræ) recorded by a single ground track of ICESat-2 ATL03 data and analysed with the density-dimension algorithm for ice surfaces216. d, Rift on Ross Ice Shelf as seen in ICESat GLA12 and ICESat-2 ATL06 data49. Part a is adapted from ref. 53, CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Part b is adapted with permission from ref. 79, Wiley. Part c is adapted from ref. 106, Elsevier. Part d is adapted with permission from ref. 49, AAAS.

“Monitoring Earth’s climate variables with satellite laser altimetry” , was recently published in Nature Reviews Earth & Environment by the Center’s Lori Magruder and Amy Neuenschwander on how satellite laser altimetry has provided critical measurements of Earth for multi-disciplinary knowledge of climate impact. Co-authors on the paper include Sinead Farrell and Laura Duncanson of the University of Maryland, Bea Csatho of the University of Buffalo, Sahra Kacimi of the Jet Propulsion Laboratory and Helen Amanda Fricker of the Scripps Institution of Oceanography at UC San Diego.

Abstract: Satellite laser altimetry measures accurate elevations of the Earth’s surface and precise changes with time, monitoring key climate variables. These observations have transformed understanding of the Earth System, revealing changes and dynamics across spheres. In this Review, we highlight the Earth and climate science contributions from three NASA satellite laser altimeter missions: Ice, Cloud and land Elevation Satellite (ICESat; 2003–2009), ICESat-2 (2018 to present) and Global Ecosystem Dynamics Investigation (GEDI; 2018 to present). Over two decades of observations, satellite altimetry revealed cryosphere decline, including a loss of 320 Gt yr?1 in global land ice from Greenland and Antarctica, and a 30% decrease in volume of winter sea ice in the Arctic between 2003 and 2021. Observations have also been key to understanding ecosystems on land, providing data on the hydrosphere (showing that 57% of the Earth’s seasonal terrestrial water storage variability comes from human-managed reservoirs) and biosphere (showing that forest carbon stocks have globally increased owing to growth, despite a loss of the equivalent of ~8 Gt CO2 from land use). In the atmosphere, the data have enabled assessment of the global vertical cloud distribution, aerosol fraction, and dust and smoke transport. There is currently no planned satellite laser altimeter mission to continue from ICESat-2 and GEDI, jeopardizing critical data collection that supports decision-making and environmental management.

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