We had heard of climate changing phenomena. one called El Niño (the hot one) and the second – its reverse – La Niña (the cool one). Together these events make up the El Niño Southern oscillation (ENSO). But we didn’t know their characteristics.
During El Niño, the Pacific Trade Winds are weaker. As it is not displaced by the Trade Winds, the warmer surface water prevents any upwelling of cool water from the depths. As a result the temperature of the air over the Pacific ocean increases. In La Niña the trade winds increase, blowing surface water westward, allowing cold water from the depths to come to the surface, where it cools the air.
We did not appreciate the connection between these events and weather elsewhere in the world. We recommend that you click on this link to Carbon Brief , which explains both phenomena and their effects.
The good news is that the current El Niño, which has contributed to making 2016 the hottest year on record, is on the way out. It will be succeeded by La Niña, which should bring relief to many places seriously impacted by El Niño. Even so, this cooling effect will probably not prevent 2016 from being one of the three hottest years ever.
Next year – with La Niña in charge, the world’s average temperature should drop slightly. But that does not mean that North America can breathe a sigh of relief. La Niña increases the risk of hurricane activity in the Atlantic.
The warming from this El Niño exceeded that of the extraordinary El Niño of 1997-98, years that at the time were the hottest ever. In the following years a strong La Niña had a cooling effect. So the Earth’s average temperature did not rise although the percentage of CO2 in the atmosphere continued to increase. Denialists claimed that this “pause” demonstrated that global warming theories were inaccurate.
Certain climatologists suggest that a future La Niña could well be hotter that the El Niño of 1997-98. If so, this should demonstrate once and for all that claims of a pause were politically inspired and had no basis in science.
Sadly the debate went on for the best part of two decades, blocking positive political action, making it more difficult to meet targets that would cap emissions of CO2 at a safe level.