El Niño, La Niña, and volcanoes

El Niño means 'the child' and it was named by South Americans who were affected by its effect on local weather after the Christ child, because it usually happens over Christmas.  During an El Niño heat absorbed by the upper layers of the sea is released into the atmosphere.  La Niña is the opposite phenomenon.  During La Niña, the sea absorbs more of the earth's heating up, so air temperatures drop.  Now, overlaid on this cycle, which causes fluctuations round the rising trend caused by global warming is the effect of random volcanic eruptions.  Volcanoes release massive quantities of aerosols into the atmosphere which temporarily cools the earth because they increase the earth's reflectivity or albedo.

The chart below shows how in El Niño years (red), the temperature is above the trend, in La Niña years (blue) it is below, and in years when there is a big volcanic eruption (grey), it is below trend.  Yellow shows years when there were neither volcanic eruptions nor ENSO (El Niño/La Niña) fluctuations.  Note that the chart does not include 2016, which will also be an El Niño year, and is even hotter than 2015.  2017 may or may not be a La Niña year.  If it is, there will be a temporary cooling before the longer term trend reasserts itself.  But note how in the "normal" years after the last La Niña (2010) global temps have risen each year--even though they weren't El Niño years.  It's a scary trend.

It is absolutely vital that we switch as rapidly as possible to renewables in electricity generation and to electric powered vehicles.

(source)