What was done
The authors utilized century-long records of sea-level and rainfall data to provide support for their hypothesis that an increase in rainfall over India leads to a decrease in salinity along the coast that is ultimately expressed as an increase in sea-level.

What was learned
Sea-level as measured at Mumbai (Bombay) - which is believed to be representative of the entire Indian Ocean - was generally low from 1880 to 1920, whereupon it rose for several decades, peaking in the late 1950s and falling thereafter.  A roughly similar pattern was observed in annual all-India rainfall, suggesting that the authors' hypothesis has merit.  Indeed, they note that "interdecadal changes in sea level mimic those in rainfall over the Indian subcontinent."

What it means
The authors note that their hypothesis "differs from those usually invoked in constructing scenarios of long-term changes in sea level," one of which they explicitly mention is the global warming hypothesis that "invoke[s] the rise in temperature in the upper ocean and the melting of polar ice caps" - both of which phenomena, if operative, would increase the volume of ocean water - to explain the rise in sea level.

So which is it?  Monsoon or global warming?  What is ultimately responsible for the interdecadal variability of the Indian Ocean sea-level over the past 120 years?  People on both sides of the debate would love to proclaim their side the winner; but as the authors remark at the end of their intriguing paper, the data are such that "they do not allow separation of natural, very low-frequency variability of monsoon rainfall and sea level from that caused by other effects, including the warming of the globe due to anthropogenic effects."

Ergo, the debate continues, even though the authors have demonstrated that "interdecadal changes in sea level mimic those in rainfall over the Indian subcontinent," which sounds a lot like the climate alarmists' refusal to acknowledge the implications of the similar fact that interdecadal changes in climate mimic those in solar activity over the past few centuries (see Solar Climatic Effects in our Subject Index).  These relationships are summarily thrust aside, while the "correlations" of temperature and CO2 in the ice core records - which are pathetic (see our Editorial of 1 April 1999 CO2 and Temperature: The Great Geophysical Waltz and our Journal Review The Pathetic Relationship Between Atmospheric CO2 and Earth's Temperature Over the Past Sixty Million Years) - are used as evidence, if one can call it that, for a plan to totally restructure the way humanity lives upon the planet.  Have we all gone mad?