12 Scientific American, March 2020 Illustration by Dion MBD
SCIENCE AGENDA
OPINION AND ANALYSIS FROM
SCIENTIFIC AMERICAN’S BOARD OF EDITORS
The rollout of 5G wireless technology will make mobile com
munications dramatically faster and more efficient. But 5G could
also lead to dangerous setbacks for weather forecasting. That is
the worry voiced by national and international science agencies
and independent experts. The Federal Communications Com
mission (fcc), however, which regulates U.S. wireless networks,
doesn’t seem concerned—and that’s a big problem.
5G promises better performance than earlier generations of
wireless telecommunications. Some of 5G’s frequency bands, how
ever, are perilously close to those used by weather instruments on
Earthorbiting satellites. The 5G transmissions at 24 gigahertz can
overlap with the 23.8GHz signal naturally emitted by atmospher
ic water vapor and monitored by these instruments. Visible in day
or night, through clear or cloudy skies, the 23.8GHz signal is a
reliable indicator of humidity that is used to sharpen weather
forecasts—including the strengths, locations and paths of
storms—on scales from hours to days. Unless, that is, the data are
disrupted by some source of interference—such as the signals
emitted by new 5G base stations and devices.
That interference is measured in units called decibel watts,
and several agencies have called for relatively strict limits on how
much of this electronic noise is permissible—the more negative
the number, the stricter. The European Com mission, for example,
set a maximum threshold of –42 decibel watts. But during an
inaugural auction last year for U.S. rights to use the 24GHz
transmission band, the fcc set a much looser noise limit of
–20 decibel watts—well in excess of ceilings based on studies from
nasa, the National Oceanic and Atmospheric Administration
(noaa), and the U.S. Navy. After the auction, noaa acting admin
istrator Neil Jacobs told Congress that the fcc’s lax noise limits
would result in as much as a 77 percent drop in satellite water
vapor data. This, Jacobs said, could lead to a two to threeday lag
in predicting the movements of hurricanes, effectively throwing
the nation’s satellitebased forecasting capabilities back to 1980
levels. Moreover, Jacobs testified, 5G interference could force
noaa to abandon plans for new weather satellites.
Yet late last fall delegates of the International Telecommuni
cation Union Radiocommunication Sector (ITUR), the organiza
tion managing global radiospectrum use, agreed to in troductory
5G noise limits of between –29 and –33 decibel watts. Taking
effect this year, the ITUR limits are more stringent than the
fcc’s but are still likely to be a problem for meteorologists.
Responding to congressional concerns before last spring’s
auction, commission chair Ajit Pai defended the decisions on 5G
noise limits, calling criticisms “exaggerated and unverified last
minute assertions.” Yet it is the fcc, not its critics, that is failing
to validate its claims: as of this writing, the commission has
yet to produce any study supporting its recommended 5G noise
limits. Meanwhile the agency is planning auctions of other
5Gfrequency bands that overlap with satellite monitoring of pre
cipitation, clouds and sea ice.
These actions are part of a broader, more disturbing pattern
of imperious behavior by the fcc. The agency has already opened
up previously protected regions of the radio spectrum for new
uses while rapidly moving forward with approvals for globe
girdling constellations of satellites offering broadband Internet.
Both types of activity could degrade a wide array of astronomical
observations from groundbased telescopes, and a massive influx
of new satellites also poses significant risks of creating more
“space junk,” which already threatens existing orbital assets,
including the International Space Station.
Fortunately, the fcc is not unaccountable. In a rare instance
of congressional bipartisanship, in December 2019 the top Dem
ocrat and Republican on the House Science Committee jointly
asked the Government Accountability Office to investigate why,
exactly, the fcc’s 5G recommendations differ so strongly from
those of other federal agencies. This is a good start. Congress
should use its considerable powers, budgetary and otherwise, to
increase pressure on the fcc to “show its work” and to engage
more meaningfully with dissenting government agencies, scien
tific institutions and other stakeholders to develop sustainable
solutions for 5G—and for accurate weather forecasting.JOIN THE CONVERSATION ONLINE
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from 5G Tech
Storm forecasts could lose reliability
under new U.S. wireless standards
By the Editors
© 2020 Scientific American