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Global climate change

Reasons on why the rate of global warming slowed between 1998 and 2012

By Brett Anderson, AccuWeather senior meteorologist
9/13/2018, 2:26:04 PM

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Rebecca Lindsey from climate.gov recently put together an excellent article about the so-called "global warming pause" that occurred between 1998 and 2012.


Lindsey makes some excellent points.......

--The slowdown in the rate of warming was obviously temporary since global average surface temperatures set a new record high in 2014, 2015 and 2016.

--The rate of surface warming since the late 1980s has been more than two times as fast as the warming averaged over the entire historical record.


Key reasons for this temporary slowdown in warming from 1998-2012

--Thanks to the super El Nino, which had a significant, natural warming influence on the globe, 1998 was the warmest year of the 20th century. Having a record-warm year as the starting point for a trend analysis increases the odds of finding a cooling trend. The rest of the period was more dominated by cooler, ENSO events (La Nina).

--Starting around 2000, the Pacific Decadal Oscillation (PDO) was mostly in its cooler phase.

--Excess heat was being trapped deep in the oceans (not released into the atmosphere) during the early 21st century.

--Solar cycles during the 1998-2012 period were below average. This weaker-than-normal period of solar activity had a small influence on the slowing of surface warming in the early part of this century.

--There was an increase in moderate-sized volcanic eruptions during the early part of the 21st century that likely increased the amount of light-reflecting particles in the stratosphere.

Factoring in these natural factors, re-forecasts of climate models shows that the previous gap between observations and original model predictions is much more narrow during the period (see bottom graph).


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Graphs and images courtesy NOAA.

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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Global climate change