Detecting Change in the Atlantic Meridional Overturning Circulation
Baehr, J., Keller, K. and Marotzke, J. 2008. Detecting potential changes in the meridional overturning circulation at 26°N in the Atlantic. Climatic Change 91: 11-27.
The three researchers report that continuous observations with a simulated array that mimics the continuous monitoring system deployed in the framework of the UK Rapid Climate Change program for approximately 60 years "yields a statistically significant (p < 0.05) detection with 95% reliability assuming a random observation error of 1 Sv," while "observing continuously with an observation error of 3 Sv yields a detection time of about 90 years (with 95% reliability)," and "repeated hydrographic transects every 5 years/20 years result in a detection time of about 90 years/120 years, with 95% reliability and an assumed observation error of 3 Sv."
Since Baehr et al. (2007) have already used real-world hydrographic transect data to demonstrate "there was no MOC trend over the past 50 years," we will probably have a tad more time to prepare for any undesirable consequences of a drastic decline in the Atlantic MOC than did the unfortunate folks in the non-award-winning film The Day After Tomorrow.
Baehr, J., Haak, H., Alderson, S., Cunningham, S.A., Jungclaus, J.H. and Marotzke, J. 2007. Timely detection of changes in the meridional overturning circulation at 26°N in the Atlantic. Journal of Climate 20: 5827-5841.