The Global Mean Surface Temperature (GMST) of the Earth is relentlessly rising due to global warming – or is it? A look at the recent record seems to tell a different story. This graph shows changes in the GMST over the past decade. (The anomaly is the amount by which the GMST has increased over the pre-industrial average temperature.)
The average annual GMST hasn’t increased since 2016 when it peaked at 1.02 degrees C. What’s happening?
It has to do with ENSO, an acronym for the “El Niño Southern Oscillation.” ENSO is a periodic and irregular variation of the sea surface temperature over the tropical eastern Pacific Ocean. It affects the climate of much of the tropics and subtropics and is caused by changes in the prevailing winds over the Pacific Ocean.
When winds are predominantly westerly (blowing east), currents move from the warm central Pacific towards the west coast of South America. This warms the tropics and subtropics and causes the GMST to spike. This is called an “El Niño” (the boy) event. Conversely, easterly winds cause an upwelling of cool water from the depths of the ocean along the west coast of South America which causes a general cooling of the atmosphere. This is called a “La Niña” (the girl) event.
Since the Earth is warming against this oscillating background effect, the GMST does not increase smoothly. For example, the big spike in 2016 was due to an extremely strong El Niño. Then, in 2017 and 2018, El Niño was replaced by a moderately strong La Niña and the GMST went down. In 2020 the GMST returned to 1.02 degrees, but this was without the help of an El Niño. This past year the GMST once again declined because of the effect of a moderately strong La Niña.
The La Niña that occurred in 2021 was comparable in strength to a La Niña that occurred in 1999 and 2000. The following graph measures the impact of the 1999 – 2000 event.
This La Niña reduced the GMST by .22 degrees. If the current La Niña has had the same impact, without it, the GMST for 2021 would have been 1.06 degrees, which would have been the highest annual GMST anomaly ever recorded. Today’s La Niña is already waning, so temperatures will revert to their previous levels and higher, especially when El Niño returns.
In November, 2021 the UN held another conference on climate change. Most of the countries of the world were represented. This was one of many UN conferences that have been held over the years in an effort to secure commitments to reduce greenhouse gas emissions. It appears that this conference (COP 26) was no more effective than its predecessors at achieving commitments to any meaningful reductions in greenhouse gas emissions. These would need to be huge reductions in order to reach the target of reducing emissions by 50% by 2030.
The UN’s International Panel on Climate Change (IPCC) monitors, collects data on, and reports climate change research from all countries. It tells us that, in order to avoid reaching the 1.5-degree threshold, a point at which we will no longer be able to avoid severe climate consequences, we must reduce global greenhouse gas emissions by 50% by 2030. Consider for a moment what you would have to do to reduce your own carbon footprint by 50%, and then imagine what it will require for the whole world to do it. The task is enormous, but it cannot be accomplished until there is a will to do it, and so far, we don’t appear to be there.