"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