I'm not an avid reader of Geophysical Research Letters (GRL) but I followed a link to 'Drift of Earth's Pole Confirms Groundwater Depletion as a Significant Contributor to Global Sea Level Rise 1993-2010' and found it fascinating. (It helps that this is a journal that requires a plain language summary).
In the years 1993-2010 it is estimated that globally we pumped 2,150 gigatonnes of groundwater to irrigate crops. 2005-2015 satellite altimetry data shows global mean sea level (GMSL) rising at 3.5 mm/yr; 1.3 mm/yr comes from ocean density changes (a result I think of the oceans heating up) and 2.2 mm/yr comes from Ocean Mass Increase (OMI). The GRACE satellite provides estimates of the contribution to OMI from melting ice sheets, glaciers, and terrestrial water storage (TWS): dams and the like. Increasing TWS has mitigated GMSL through much of the 20th century. Moving all this water around changes the planet's mass distribution and its rotation. For the period 1993-2010 groundwater storage changes are estimated to have moved the pole about 4.36 cm/yr - about 75 cm in total - and to be a major cause of the change in GMSL. There is good agreement between predicted and observed polar motion.
This all sounds rather dry (sorry the pun just crept in there) but to me it is amazing that human activity has moved enough water to increase mean sea level and to move the rotational pole: more evidence that we are living in the Anthropocene now.
The original letter can be found at 2023GL103509. GRACE measures gravity anomalies to show how mass is distributed around the planet and how it varies over time. That's also pretty amazing in my opinion.
This 2010 paper 2010GL044571, also from GRL, estimates global groundwater depletion (not extraction, note) at 283 cubic km per year in the year 2000 - that's 2.83e11 cubic metres. A year is 3.154e7 seconds which makes the depletion rate about 9,000 tonnes/second (assuming that a cubic metre of water weighs about a tonne). The same paper says that groundwater is being extracted at about 2.5 times the depletion rate (so aquifers are filling up again, but not as fast as they're being emptied).
Post. Category discussion topic tag water. It is a summary of a note originally written for Barnet u3a Science & Technology group in 2023.