mid-winter cooling trend is observed over
the period of Arctic amplification. Rather,
we argued that an increasing trend in
polar vortex disruptions related to Arctic
amplification could resolve discrepancies
between the observations and models.
Our analysis showed that across cen-
tral North America, the winter warming
trend is damped relative to the warming
trend across the rest of the Northern
Hemisphere and winter temperature
anomalies are consistently colder than
those predicted by global climate models.
Both discrepancies can be explained by
an increase in stretched polar vortices, for
which the impact of the stretched polar
vortex of February 2021 on weather can
serve as a paradigm. If the number of
stretched polar vortex days is increasing,
it follows that the overall warming trend
in the colder months across the United
States will be dampened.
In addition to our observational analy-
sis, we perturbed a global climate model
with observed fall Arctic trends includ-
ing increasing snow cover across Asia
and less Arctic sea ice. The simulated
response to these trends was both an
increase in stretched polar vortex events
and relatively colder surface temperatures
across the United States that were region-
ally statistically significant.
Blackport et al. argue that in analyzing
the mid-latitude cold extremes caused
by polar vortices, we ignored studies
showing that Arctic warming can also
contribute to a decrease in both cold
extremes and overall temperature vari-
ability. However, previous studies, includ-
ing those cited by Blackport et al., did not
consider the influence of stretched polar
vortices. In addition, the overwhelming
number of studies on Arctic amplification
are consistent with the conclusion that
Arctic amplification can contribute to
the occurrence of severe winter weather
across the Northern Hemisphere mid-
latitudes ( 1 ).
Judah Cohen1,2*, Laurie Agel^3 , Mathew Barlow^3 ,
Chaim I. Garfinkel^4 , Ian White^4(^1) Atmospheric and Environmental Research, Inc.,
Lexington, MA 02421, USA.^2 Department of Civil
and Environmental Engineering, Massachusetts
Institute of Technology, Cambridge, MA
02139, USA.^3 Department of Environmental,
Earth, and Atmospheric Sciences, University
of Massachusetts Lowell, Lowell, MA 01854,
USA.^4 Institute of Earth Sciences, The Hebrew
University of Jerusalem, Edmond J. Safra Campus,
Jerusalem, Israel.
*Corresponding author. Email: [email protected]
REFERENCES AND NOTES
- J. Cohen et al., Nat. Clim. Change 10 , 20 (2020).
- C. I. Garfinkel, S-W. Son, K. Song, V. Aquila, L. D. Oman,
Geophys. Res. Lett. 44, 374 (2017).
10.1126/science.abn8954science.org SCIENCEOUTSIDE THE TOWEREmpowering Afro-Indigenous girls
At 5:15 am on a clear morning in Cali, Colombia, Karen, a bright, curious, and
passionate Indigenous 13-year-old girl from a humble suburban neighborhood,
stepped onto our university-bound bus. She was excited for a second day of science
activities, during which she would conclude experiments she began a week before. We
had selected Karen and 12 other girls of Indigenous and African heritage to participate
in our outreach program, a science, technology, engineering, and mathematics (STEM)
experience grounded in ancestral knowledge.
Karen and the other girls, all of whom expressed interest in transforming their com-
munity by pursuing careers in science, were eager to build on their own knowledge and
see how their traditions intersect with science. They could all explain how small-scale
coffee and cocoa production involved wrapping beans in banana leaves to ferment, and
they had many questions about commercial coffee and cocoa
industrial processes. They also learned how biochemistry can
alter the flavor and texture of the drinks.
A week before, the girls had pressed their fingers into a petri
dish. Now, they analyzed the microbes that had grown by look-
ing through a microscope. Their traditions emphasize caring
for the environment, a strategy that has been emphasized as a
way to prevent pandemics. After months of isolation during the
COVID-19 pandemic, they were fascinated to learn about the
role of bacteria in health and disease.
Women are underrepresented in STEM, a fact that we both observed and studied
during our scientific training. We developed the Biochemical Engineering Community
Assistance Project to empower women in biochemistry fields. The program pro-
vides each participant with a science kit, including scientific gear and experimental
materials. Feedback from the students indicated that owning scientific materials and
conducting studies helped them to identify as scientists. We hope that by introducing
scientific concepts that are relevant to the girls’ life experiences, we can inspire them
to pursue scientific opportunities.
Carolina Orozco Donneys,^1 * Jose Dario Perea^2(^1) Departamento Ingeniería Bioquímica, Universidad Icesi, Cali, Colombia.
(^2) Department of Chemistry, University of Toronto, Toronto, ON, Canada.
*Corresponding author. Email: [email protected]
10.1126/science.abo4155
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730 18 FEBRUARY 2022 • VOL 375 ISSUE 6582