The so-called hiatus in global annual average temperature between 2002 – 2014, once controversial to some but now well-established in the peer-reviewed literature, ended in 2014 with the start of a series of record-breaking El Nino events that spiked global temperatures with a subsequent fallback.
Now a new study into the effect of man-made aerosol pollution adds to likely reasons for the end of the hiatus and may point to lower estimates for future global warming. [bold, links added]
An international research team writing in the journal Atmospheric Chemistry and Physics uses satellite data to show that concentrations of aerosol particles have decreased significantly since 2000.
This is good news as cleaner air benefits health, but it also reduces particles, which have a cooling effect on the terrestrial climate.
According to the Intergovernmental Panel on Climate Change (IPCC), by 2019 the global temperature had risen by 1.1 degrees Celsius compared to preindustrial levels due to increasing greenhouse gasses from burning fossil fuels.
At the same time, the combustion of fossil fuels emits aerosols that cool our climate by reflecting sunlight and increasing the reflectivity of clouds.
Professor Johannes Quaas, a meteorologist at Leipzig University, and colleagues from Europe, China, and the US have published robust observational evidence of significant reduction of aerosol pollution and improved global air quality.
“We analyzed data from NASA’s Terra and Aqua satellites. They have been providing comprehensive satellite observations of the Earth since the year 2000, measuring incoming and outgoing radiation, but also clouds and aerosol pollution. The latter has decreased significantly across North America, Europe, and East Asia since 2000,” Professor Quaas said.
Although Dr. Quaas and his colleagues say this new study stresses the urgent need for rapid and strong reductions in greenhouse gas emissions, the reduction of the compensating effect of cooling aerosols can also be seen in another way.
The researchers estimate that the weakening of aerosol-induced temperature change between 2000 – 2019 is similar to that estimated by the IPCC’s AR6.
Most of this weakening occurred post-2010 coincident with the end of the so-called global warming hiatus period.
It suggests that perhaps up to 60% of the global temperature increase since then is [from] the reduction of global aerosols.
When taken together with a couple of super-strong El Nino events which temporarily drove up the global temperature (see graph below), the new findings suggest that the global warming hiatus — clearly evident prior to 2014 — may not have ended yet.
If NASA’s satellite data are confirmed, it would suggest that much of the very moderate changes in global temperature this century may have been driven primarily by cleaner air and naturally-occurring El Ninos.
The new observational data has strong implications for predictions of future global warming due to greenhouse-gas forcing, suggesting it might be significantly lower than most models suggest.
Read more at NZW
There was no reduction of SO2 emissions from 1975 to 1980. Yet the global cooling trend from 1940 to 1975 reversed to a global warming trend in 1975 with no correlation to SO2 emissions
The decline in SO2 emissions from 1980 to 2000 was small (-16%) and could not account for the large increase of the global average temperature in that period (over +0.59 degrees C. per UAH data)
Any decline of SO2 emissions from 2015 to 2022 has no correlation with the UAH global average temperature, which had a flat trend in that period.
That is a lot of evidence showing SO2 emissions are a minor climate change variable.
The Mt. Pinatubo eruption of 1991 emitted huge volumes of sulfur dioxide. Global temperatures dropped for more than a year. I remember because my crops were starved of sunshine and weren’t mature enough for the early frost in September 1992.
We have Mt Shasta in our area and its still a active Volcano
I’ve been conducting a study here at my place on the southern tablelands of NSW Australia.
Pre 2019 – winter snow levels were always patchy. Never high. Trended to mainly low. Winters were short. First snow late July and season end is supposed to be end August while August often has warm days (25C+) towards the end of that month. September often produced temps (in Sydney) in the mid 30C’s Mid 20C’s here. EG: Early Sept, Sydney Olympics 2000, temps in the mid 30C’s were experienced.
Summer – Hottest months were February – March while December – January also contributed, but not as consistently or as warm as the later two months. Many days above 32C+ and occasionally low 40’s. Also very dry with potential for bushfires. Temps Dec to end Jan averaged high 20C’s to low 30C’s.
Post 2019. Winter now starts circa mid May with snowfalls on the mountains. These snowfalls are not just one storm, as was the case pre 2019. Snow is coming in more often with dumps around 30cm common. Temps for this region have been approximately the same, but because there’s no slight warming between storms events, it is cooler overall.
Rainfall is much more consistent. The ground has been saturated for 12 months. Each time it rains, there is immediate run-off.
Warmer temps are starting mid September but southern lows still occur and the cold returns with more snow. Temps are on the rise but much slower vs pre 2019.
Summer – Is cooler. Only have a few days in the 30C+ range. Nightime temps are noticeably lower – low to mid teens. Rain is present on a semi regular basis, which rarely happened pre 2019. (Summers always very dry) This contributes to cooling temps while humidity is (as expected) higher.
Summed up: My little study / observation can be better understood by businesses such as earth moving, farming, fruit production all of which don’t like rain. Machines bog. Crops don’t grow as well – if tractors can get out and fruit trees are damaged by mold disease.
My observations have been happening while the latest Grand Solar Minimum has been under way and, during both seasons post 2019, we have had a lot more cloud cover.
They want CO2 to be classified a s Pollutant when in fact its needed by Plants and therefore is needed for all life on Earth those liberal Eco-Freak Pinheads need to start thinking without their remotes and CNN
I have believed all along that cleaner air (less soot and sulfur dioxide) would allow more sunlight to reach Earth, warming surface temperatures. Aerosols act as the nucleii for the water droplets that form clouds. More clouds, more shade, more rain, less drought.
When all air traffic was grounded immediately after 9-11, satellite temperature readings responded upwards, significantly. I believe that Brian Catt had those numbers at one time.
Of course the warmists won’t agree with anything that challenges their carbon dioxide blame game.
All while life essential CO2 levels continue its entirely beneficial increase. All while politicians of every stripe and “journalists” continue to entirely ignore the science of the environment – biology. While they purport to love and respect the science, they fail to understand even the basics of CO2 biology. That life on earth – “the environment” is made of little carbon sacks of water called cells. The benefit of more recycled CO2 in an atmosphere well below optimum levels for the environment. All while “journalists ignore the failure of CO2 driven climate models which WITHOUT EXCEPTION exaggerate projected warming when compared to weather balloon and satellite actual temperature data. Our 12° C normal natural range of temperature continues to cycle as it has for the past three million year ongoing Pleistocene/Quaternary Ice Age. And 0.04% CO2 is barely enough to sustain life. Such low levels of CO2 do not drive the climate. As far too many fear-mongering “journalists” and grade school teachers preach in their cult of climate change. Kamala Harris recently stated CO2 is “pollution” simply because the recycled ingredient of life on earth comes from using fossil fuels. She has no idea that she, and every other living being on our planet, is literally made of the stuff. Fossil fuels are THE ONLY GREEN ENERGY. Because they recycle the starvation level lows of one of the two most important ingredients of the environment – CO2. Life on earth is carbon based. Biology has known this for nearly a century. Too bad this simple fundamental fact fails to be taught to our indoctrinated generation. Such will be the legacy of the regressive progressive left. Conservatives, although equally ignorant of the science, are at least more cautious than the left’s eagerness to abandon 85% of the energy that has made us the best fed, longest living, most prosperous human beings that have ever existed. In favour of redundant energy that doesn’t work when the sun doesn’t shine and the wind doesn’t blow. Driving 40 year highs of inflation and bringing energy poverty death back to some of the richest countries in the world.