sciencemag.org SCIENCEPHOTO: NASA/SDOSea ice hits near-record low
POLAR SCIENCE | Arctic sea ice dropped
below 4 million square kilometers for
only the second time in modern history,
reaching its seasonal bottom at 3.74 mil-
lion square kilometers on 15 September,
the National Snow and Ice Data Center
announced this week. Because of a warm-
ing climate, the minimum ice cover has
shrunk over the past few decades by an
area equal to the size of Alaska, Texas,
and Montana—combined. Although the
ice extent in 2012 was even lower than
this year, scientists have shown the
melt is now being driven not only by
the warmer atmosphere, but also by the
upward advance of a deep layer of
warm Atlantic water, previously held
beneath the cold surface layer (Science,
28 August, p. 1043).CDC backtracks on testing
POLICY | The U.S. Centers for Disease
Control and Prevention (CDC) last week
reversed highly criticized guidance
suggesting people who were exposed to
someone with COVID-19 don’t need a
test if they don’t have symptoms. Public
health experts denounced the 24 August
guidance as the result of political interfer-
ence, noting that those who don’t feel sick
can still spread the virus. The new lan-
guage, published on 18 September, says
anyone who has had close contact with
an infected person should get tested. The
update came 2 days after the departure of
two political appointees from CDC’s par-
ent agency, the Department of Health and
Human Services (HHS)—top spokesperson
Michael Caputo and science adviser Paul
Alexander. Both tried to silence CDC
officials who spoke out about the serious-
ness of the pandemic, according to emails
uncovered by The New York Times. HHS
announced this week that Alexander
had been permanently let go and Caputo
would take a 60-day medical leave.U.S. vaccine distrust grows
COVID-19 | Public confidence in a corona-
virus vaccine has plunged in the United
States over the past 4 months amidNEWS“
We will be forever thankful for the 12 crews ...
risking their lives defending our scientific treasure.
”
Sam Hale, chairman of the Mount Wilson Institute Board of Trustees, in a statement after
the Mount Wilson Observatory was declared safe from California’s Bobcat fire.ASTRONOMYA new solar cycle dawns
IN BRIEF
Edited by Kelly ServickT
he Sun’s waxing and waning activity, manifested in sunspot
numbers and blasts of radiation and particles, has officially
entered the next of its roughly 11-year cycles, NASA and the
National Oceanic and Atmospheric Administration (NOAA)
announced last week. Solar activity passed a minimum in
December 2019, meaning Solar Cycle 25 has been underway
for nearly 1 year. Observatories on the ground and in space study
the Suns outpourings meticulously, to both understand its work-
ings and give warnings if one of those blasts is heading our way. A
direct hit could disrupt power grids and communications, knock
out satellites, and threaten astronauts, especially on the Moon,
outside Earths protective magnetic field, where astronauts may
venture as early as 2024. Preparations have begun for the pro-
jected maximum activity in 2025: NASA will study solar radiation
levels at the Moon with its Gateway lunar orbiting station, while
NOAA plans to place its Space Weather Follow-On satellite up-
stream from Earth to give early warning of incoming blasts.1548 25 SEPTEMBER 2020 • VOL 369 ISSUE 6511
The Sun
during its 2014
solar maximum (left)
and 2019 minimum.