Maggie's Farm

The piece in the National Post begins:

They drift along in the worlds' oceans at a depth of 2,000 metres -- more than a mile deep -- constantly monitoring the temperature, salinity, pressure and velocity of the upper oceans.

Then, about once every 10 days, a bladder on the outside of these buoys inflates and raises them slowly to the surface gathering data about each strata of seawater they pass through. After an upward journey of nearly six hours, the Argo monitors bob on the waves while an onboard transmitter sends their information to a satellite that in turn retransmits it to several land-based research computers where it may be accessed by anyone who wishes to see it.

These 3,000 yellow sentinels --about the size and shape of a large fence post -- free-float the world's oceans, season in and season out, surfacing between 30 and 40 times a year, disgorging their findings, then submerging again for another fact-finding voyage.

Read the whole thing and find out what they are telling us.