With impressive specificity, RNAi can potentially block nucleotide sequences that are only found in a target pest and not in friendly insects or humans.
Image credit: Science Source/USDA/Nature Source.
New Research In
Physical Sciences
Featured Portals
Articles by Topic
Biological Sciences
Featured Portals
Articles by Topic
Edited by Gerald R. North, Texas A&M University, College Station, TX 77843, and accepted by the Editorial Board January 6, 2014 (received for review September 30, 2013)
See related content:
Significance
The Arctic sea ice retreat has been one of the most dramatic climate changes in recent decades. Nearly 50 y ago it was predicted that a darkening of the Arctic associated with disappearing ice would be a consequence of global warming. Using satellite measurements, this analysis directly quantifies how much the Arctic as viewed from space has darkened in response to the recent sea ice retreat. We find that this decline has caused 6.4 ± 0.9 W/m2 of radiative heating since 1979, considerably larger than expectations from models and recent less direct estimates. Averaged globally, this albedo change is equivalent to 25% of the direct forcing from CO2 during the past 30 y.
Abstract
The decline of Arctic sea ice has been documented in over 30 y of satellite passive microwave observations. The resulting darkening of the Arctic and its amplification of global warming was hypothesized almost 50 y ago but has yet to be verified with direct observations. This study uses satellite radiation budget measurements along with satellite microwave sea ice data to document the Arctic-wide decrease in planetary albedo and its amplifying effect on the warming. The analysis reveals a striking relationship between planetary albedo and sea ice cover, quantities inferred from two independent satellite instruments. We find that the Arctic planetary albedo has decreased from 0.52 to 0.48 between 1979 and 2011, corresponding to an additional 6.4 ± 0.9 W/m2 of solar energy input into the Arctic Ocean region since 1979. Averaged over the globe, this albedo decrease corresponds to a forcing that is 25% as large as that due to the change in CO2 during this period, considerably larger than expectations from models and other less direct recent estimates. Changes in cloudiness appear to play a negligible role in observed Arctic darkening, thus reducing the possibility of Arctic cloud albedo feedbacks mitigating future Arctic warming.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: eisenman{at}ucsd.edu.
Author contributions: K.P., I.E., and V.R. designed research; K.P. and I.E. performed research; K.P., I.E., and V.R. analyzed data; and K.P., I.E., and V.R. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. G.R.N. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1318201111/-/DCSupplemental.
Albedo decrease due to Arctic sea ice loss
Sign up for Article Alerts
Jump to section
You May Also be Interested in
It's an intriguing new hypothesis that has started to garner attention as researchers continue to debate the merits of multiple models.
Image credit: NASA/GSFC.
Changing environmental conditions and genetic adaptations may explain how penguins radiated and expanded their geographic ranges to encompass diverse environments.
Image credit: Aurora Fernández Durán (photographer).
In the United States, mortality rates and life expectancy were worse for Blacks during nonpandemic years than for Whites during the COVID-19 pandemic, a study finds.
Image credit: Pixabay/PIRO4D.
Genetic insights could help shore up populations of a rare dog species thought to be nearly extinct in the wild.
Image credit: Anang Dianto (photographer).