La Nina Winding Up to Follow El Nino
February 12, 2016
Above, one of the first interviews I did at the American Geophysical Union Fall Meeting in 2011 was with Josh Willis, of NASA Jet Propulsion lab. At the time, we were just coming out of a large La Nina event, following the el Nino of 2010.
The event had some significant and very interesting effects on rainfall and sea level rise – which may be instructive for us looking forward. Storm tracks shifted enough to dump enormous rainfall onto land areas, so much so that sea levels actually dropped by a measurable amount, — one of those moments briefly celebrated by deniers as “proof” that global warming was over. You can see that deviation in the satellite sea level graph below.
Even as the El Nino weather phenomenon continues to impact global temperatures and crops, its counterpart La Nina is increasingly expected to emerge in the coming months for the first time in four years.
The return of La Nina, Spanish for “the girl” and characterized by unusually cold ocean temperatures, is possible later this year, the U.S. government forecaster said Thursday. It joined other forecasters in projecting La Nina could follow on the heels of one of the strongest El Ninos on record.
Weather models indicate La Nina conditions, which tend to occur unpredictably every two to seven years, may emerge in the Northern Hemisphere fall, while El Nino – which means “the little boy” in Spanish – is expected to dissipate during the late spring or early summer, the National Weather Service’s Climate Prediction Center (CPC) said in its monthly forecast.
The phenomenon can be less damaging than El Nino, but severe La Ninas are linked to floods, droughts and hurricanes.
Below, a new study sheds more light on the water storage phenomenon – which is ongoing even in non-la nina years.
Vast volumes of water falling as rain and snow have stayed on land in recent years, slowing the rise of the seas, new research has revealed.
Water is constantly evaporating from oceans and moving to land, where it’s stored fleetingly in lakes, snowpacks, soil and tree canopies, before flowing back again.
Seas have been rising about 3.2 millimeters (one-eighth of an inch) yearly since the early 1990s. The rate is projected to pick up pace as more water melts from glaciers and ice sheets, and as warming oceans continue to expand.
Because of the high amounts of water being trapped on land, the rate fell to 2.4 millimeters from 2002 to 2014, slowing sea level rise by a quarter, according to the findings from the study.
During the 12-year period studied, Reager said enough water to fill Lake Huron — which between Michigan and Ontario is one of the world’s biggest lakes — was drawn out of the oceans and stored on land.
One of the lesser-known causes of sea level rise is the pumping of groundwater out of aquifers for irrigation and other uses, which eventually ends up in the oceans. The researchers discovered that twice as much water was trapped on land from 2002 to 2014 than was pumped out of aquifers.
Some of the additional water stored on land would have been trapped in new reservoirs, such as China’s Three Gorges Dam. But the analysis showed the effect of new and expanded reservoirs was minor.
Instead, the changes appear to have been caused by the whims of long-term weather patterns.
Bottom line, if you thought weather might even out with the end of El Nino, just a reminder the last one was a doozy.