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"Warming of global abyssal and deep Southern Ocean waters between the 1990s and 2000s: Contributions to global heat and sea level rise budgets by Sarah G. Purkey &

Journal of Climate,


Warming of global abyssal and deep Southern Ocean waters between the 1990s and 2000s: Contributions to global heat and sea level rise budgets

Sarah G. Purkey¹,² and Gregory C. Johnson²,¹,*


¹School of Oceanography, University of Washington, Seattle, WA 98195, U.S.A.
²NOAA/Pacific Marine Environmental Laboratory, Seattle, WA 98115, U.S.A.


Abstract


We quantify abyssal global and deep Southern Ocean temperature trends between 
the 1990s and 2000s to assess the role of recent warming of these regions in global heat 
and sea level budgets. We compute warming rates with uncertainties along 28 full-depth, 
high-quality, hydrographic sections that have been occupied two or more times between 
1980 and 2010. We divide the global ocean into 32 basins defined by the topography and 
climatological ocean bottom temperatures and estimate temperature trends in the 24 
sampled basins. The three southernmost basins show a strong statistically significant 
abyssal warming trend, with that warming signal weakening to the north in the central 
Pacific, western Atlantic, and eastern Indian Oceans. Eastern Atlantic and western Indian 
Ocean basins show statistically insignificant abyssal cooling trends. Excepting the Arctic 
Ocean and Nordic seas, the rate of abyssal (below 4000 m) global ocean heat content 
change in the 1990s and 2000s is equivalent to a heat flux of 0.027 (±0.009) W m–2 
applied over the entire surface of the Earth. Deep (1000–4000 m) warming south of the 
Sub-Antarctic Front of the Antarctic Circumpolar Current adds 0.068 (±0.062) W m–2. 
The abyssal warming produces a 0.053 (±0.017) mm yr–1 increase in global average sea 
level and the deep warming south of the Sub-Antarctic Front adds another 0.093 (±0.081) 
mm yr–1. Thus warming in these regions, ventilated primarily by Antarctic Bottom 
Water, accounts for a statistically significant fraction of the present global energy and sea 
level budgets.




*Correspondence e-mail:  gregory.c.johnson@noaa.gov

Link to full paper (pdf file):  http://www.pmel.noaa.gov/people/gjohnson/Recent_AABW_Warming_v3.pdf