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Probabilistic hindcasts and projections of the coupled climate, carbon cycle and Atlantic meridional overturning circulation system: a Bayesian fusion of century-scale observations with a simple model

Abstract

How has the Atlantic Meridional Overturning Circulation (AMOC) varied over the past centuries and what is the risk of an anthropogenic AMOC collapse?We report probabilistic projections of the future climate which improve on previous AMOC projection studies by (i) greatly expanding the considered observational constraints and (ii) carefully sampling the tail areas of the parameter probability distribution function (pdf).We use a Bayesian inversion to constrain a simple model of the coupled climate, carbon cycle and AMOC systems using observations to derive multicentury hindcasts and projections. Our hindcasts show considerable skill in representing the observational constraints. We show that robust AMOC risk estimates can require carefully sampling the parameter pdfs. We find a low probability of experiencing an AMOC collapse within the 21st century for a business-as-usual emissions scenario. The probability of experiencing an AMOC collapse within two centuries is 1/10. The probability of crossing a forcing threshold and triggering a future AMOC collapse (by 2300) is approximately 1/30 in the 21st century and over 1/3 in the 22nd. Given the simplicity of the model structure and uncertainty in the forcing assumptions, our analysis should be considered a proof of concept and the quantitative conclusions subject to severe caveats
Authors:
Urban, Nathan M. (Dept. of Geosciences, Penn State Univ., University Park, PA (United States)), e-mail: nurban@psu.edu; Keller, Klaus [1] 
  1. Earth and Environmental Systems Inst., Penn State Univ., University Park, PA (United States)
Publication Date:
Oct 15, 2009
Product Type:
Journal Article
Resource Relation:
Journal Name: Tellus. Series A, Dynamic Meteorology and Oceanography; Journal Volume: 62A; Journal Issue: 5; Other Information: 73 refs., 6 figs., 1 tab.; 10.1111/J.1600-0870.2010.00471.X
Subject:
54 ENVIRONMENTAL SCIENCES; CLIMATIC CHANGE; CLIMATE MODELS; ATMOSPHERIC PRECIPITATIONS; SEASONAL VARIATIONS; FORECASTING; CARBON CYCLE; METEOROLOGY
OSTI ID:
1000553
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
Journal ID: ISSN 0280-6495; TRN: SE1007257
Availability:
Available from DOI: http://dx.doi.org/10.1111/j.1600-0870.2010.00471.x
Submitting Site:
SWD
Size:
page(s) 737-750
Announcement Date:
Dec 30, 2010

Citation Formats

Urban, Nathan M. (Dept. of Geosciences, Penn State Univ., University Park, PA (United States)), e-mail: nurban@psu.edu, and Keller, Klaus. Probabilistic hindcasts and projections of the coupled climate, carbon cycle and Atlantic meridional overturning circulation system: a Bayesian fusion of century-scale observations with a simple model. Sweden: N. p., 2009. Web. doi:10.1111/J.1600-0870.2010.00471.X.
Urban, Nathan M. (Dept. of Geosciences, Penn State Univ., University Park, PA (United States)), e-mail: nurban@psu.edu, & Keller, Klaus. Probabilistic hindcasts and projections of the coupled climate, carbon cycle and Atlantic meridional overturning circulation system: a Bayesian fusion of century-scale observations with a simple model. Sweden. doi:10.1111/J.1600-0870.2010.00471.X.
Urban, Nathan M. (Dept. of Geosciences, Penn State Univ., University Park, PA (United States)), e-mail: nurban@psu.edu, and Keller, Klaus. 2009. "Probabilistic hindcasts and projections of the coupled climate, carbon cycle and Atlantic meridional overturning circulation system: a Bayesian fusion of century-scale observations with a simple model." Sweden. doi:10.1111/J.1600-0870.2010.00471.X. https://www.osti.gov/servlets/purl/10.1111/J.1600-0870.2010.00471.X.
@misc{etde_1000553,
title = {Probabilistic hindcasts and projections of the coupled climate, carbon cycle and Atlantic meridional overturning circulation system: a Bayesian fusion of century-scale observations with a simple model}
author = {Urban, Nathan M. (Dept. of Geosciences, Penn State Univ., University Park, PA (United States)), e-mail: nurban@psu.edu, and Keller, Klaus}
abstractNote = {How has the Atlantic Meridional Overturning Circulation (AMOC) varied over the past centuries and what is the risk of an anthropogenic AMOC collapse?We report probabilistic projections of the future climate which improve on previous AMOC projection studies by (i) greatly expanding the considered observational constraints and (ii) carefully sampling the tail areas of the parameter probability distribution function (pdf).We use a Bayesian inversion to constrain a simple model of the coupled climate, carbon cycle and AMOC systems using observations to derive multicentury hindcasts and projections. Our hindcasts show considerable skill in representing the observational constraints. We show that robust AMOC risk estimates can require carefully sampling the parameter pdfs. We find a low probability of experiencing an AMOC collapse within the 21st century for a business-as-usual emissions scenario. The probability of experiencing an AMOC collapse within two centuries is 1/10. The probability of crossing a forcing threshold and triggering a future AMOC collapse (by 2300) is approximately 1/30 in the 21st century and over 1/3 in the 22nd. Given the simplicity of the model structure and uncertainty in the forcing assumptions, our analysis should be considered a proof of concept and the quantitative conclusions subject to severe caveats}
doi = {10.1111/J.1600-0870.2010.00471.X}
journal = {Tellus. Series A, Dynamic Meteorology and Oceanography}
issue = {5}
volume = {62A}
place = {Sweden}
year = {2009}
month = {Oct}
}