Page 81 - Frontier Technologies to Protect the Environment and Tackle Climate Change

Frontier Technologies to Protect the Environment and Tackle Climate Change

Significant sea level rises are of concern, as at least 40 per cent of the world's population lives in cities
that are vulnerable to sea rise, including important economic centres such as New York, Miami, Los
Angeles, Tokyo and Mumbai. With glaciers starting to flow faster and breaking into icebergs that
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are moving into the ocean (a process known as ‘calving’), a continuous increase in the rate of mass
loss can be expected, resulting in an accelerating rate of sea level rise, that will continue to increase
more rapidly every year.

Box 19 details the impact of climate change on ice sheets in Greenland, the world’s largest island,
with a national population of less than 57 000 that is most vulnerable to the effects of the territory’s
accelerating ice melt. 236

Box 19: Use of Space 2.0 technologies to map Greenland’s ice sheet
237, 238, 239

While the acceleration of Greenland’s ice loss has been established using satellite data such
as the above, precise models for accurate future predictions need even more advanced
satellite technologies.

To this end, in 2018, NASA launched a new cutting-edge satellite to map the loss of ice
in Greenland precisely: The Ice, Cloud and land Elevation Satellite-2 (ICESat-2). ICESat-2’s
spacecraft provides power, propulsion, orbit, navigation, data storage and handling, and
features precise knowledge of the satellite’s position in space – which is critical for taking
highly accurate measurements.

ICESat-2 follows a previous five-year mission, the ICESat, which concluded in 2009. The first
ICESat helped demonstrate the way that ice cover has disappeared from coastal parts of both
Greenland and Antarctica, as well as the thinning of sea ice. As its successor, ICESat-2 will
provide additional information by examining how ice cover changes over the course of one
year. It may help explain, for example, why the Tracy and Heilprin Glaciers, which flow side
by side into Inglefield Gulf in northwest Greenland, are melting at radically different rates.
ICESat-2 is a spacecraft with a single major instrument, instead of the usual assortment of
sensors and antennas. It deploys an industrial-size, hyper-precise altimeter: The Advanced
Topographic Laser Altimeter System (ATLAS), which is a single, powerful green laser split
into six beams (three pairs of two) that pass over the landscape in programmed patterns.

Next to the laser is a special telescope that monitors the beams’ reflections, collecting a dozen
photons from each laser pulse 10 000 times per second. With ICESat-2’s altitude readings
being accurate down to the inch, it should be able to tell whether an ice sheet has risen or
fallen to the order of millimeters, and monitor ice sheet elevation and sea ice thickness.
The satellite’s laser reference system controls where the laser is pointing, ensuring that it is
aligned with the telescope. The laser reference system also tells the spacecraft where the
telescope is pointing so that it can adjust if needed. The same space laser can also return
measurements on land topography, vegetation characteristics, and clouds.

Figure 30 illustrates how ICESat-2's instrument takes measurements every 2.5 feet (85 cm)
along its ground path – mapping dips and drop-offs in the ice.

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