A study suggests that the central-western Greenland Ice Sheet (GIS) is approaching a critical transition and will undergo significantly enhanced melting in the near future.
Image credit: Pixabay/mariohagen.
Edited by Anny Cazenave, Centre National d'Etudes Spatiales, Toulouse, France, and approved January 4, 2016 (received for review August 27, 2015)
Significance
We present the first, to our knowledge, estimate of global sea-level (GSL) change over the last ∼3,000 years that is based upon statistical synthesis of a global database of regional sea-level reconstructions. GSL varied by ∼±8 cm over the pre-Industrial Common Era, with a notable decline over 1000–1400 CE coinciding with ∼0.2 °C of global cooling. The 20th century rise was extremely likely faster than during any of the 27 previous centuries. Semiempirical modeling indicates that, without global warming, GSL in the 20th century very likely would have risen by between −3 cm and +7 cm, rather than the ∼14 cm observed. Semiempirical 21st century projections largely reconcile differences between Intergovernmental Panel on Climate Change projections and semiempirical models.
Abstract
We assess the relationship between temperature and global sea-level (GSL) variability over the Common Era through a statistical metaanalysis of proxy relative sea-level reconstructions and tide-gauge data. GSL rose at 0.1 ± 0.1 mm/y (2σ) over 0–700 CE. A GSL fall of 0.2 ± 0.2 mm/y over 1000–1400 CE is associated with ∼0.2 °C global mean cooling. A significant GSL acceleration began in the 19th century and yielded a 20th century rise that is extremely likely (probability
Footnotes
- ↵1To whom correspondence should be addressed. Email: robert.kopp{at}rutgers.edu.
Author contributions: R.E.K. designed research; R.E.K., A.C.K., K.B., B.P.H., J.P.D., and W.R.G. performed research; R.E.K., K.B., C.C.H., J.X.M., E.D.M., and S.R. contributed new analytic tools; R.E.K. and K.B. analyzed data; R.E.K., A.C.K., K.B., B.P.H., J.P.D., W.R.G., C.C.H., J.X.M., E.D.M., and S.R. wrote the paper; A.C.K., B.P.H., and W.R.G. compiled the database of proxy reconstructions; C.C.H., J.X.M., and E.D.M. contributed to the design of the statistical model; and K.B. and S.R. developed and implemented the semiempirical projections.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1517056113/-/DCSupplemental.
Freely available online through the PNAS open access option.
Common Era global sea-level variability
Article Classifications
- Physical Sciences
- Sustainability Science
Sign up for Article Alerts
Jump to section
You May Also be Interested in
A study explores how white bar formation in clownfish may be tied to differential recruitment in and adjustment to different sea anemone species.
Image credit: Pauline Salis.
Genetic analyses reveal that the Sudanese Kordofan melon is the closest relative and may be a precursor of domesticated watermelons.
Image credit: Shan Wu.
Intact ecosystems have a big role in sequestering carbon. Hence, safeguarding the biosphere from further degradation is an existential challenge for humanity.
Image credit: Shutterstock/Kritskiy-ua.
People are increasingly dividing themselves into social and political factions. Models can hint at how it happens—and maybe offer ways to mitigate it.
Image credit: Dave Cutler (artist).