by Ian Bradford
It’s all to do with Aerosols. In the atmosphere, aerosols in general block the sun’s radiation from reaching the Earth. Aerosols are actually small particles or droplets that float in the air. They come in many forms, both natural and industrial and include sea salt, mineral dust, ash, sulphates, nitrates and black carbon (soot). So we are talking about wildfire smoke, volcanic gases, and many human activities.
Soot has a warming effect but this is well overshadowed by the cooling effect of the other aerosols. In fact no one has taken much note of the cooling effect of aerosols, but scientists lately have found that their cooling effect may be greater than realised.
When the sky is clear, (no clouds), aerosols can reflect incoming sunlight back to outer space – the direct effect. This blocks part of the energy that would have reached the surface, thus having a cooling effect on the climate. Aerosol particles can provide nucleating sites for the formation of cloud droplets. In other words, they can seed clouds. The resultant brightening of clouds makes them more potent at shielding the Earth’s surface from sunlight. More aerosols can make clouds last longer by suppressing rainfall.
Norwegian climate scientist Bjorn Samset, together with an international team of scientists, have quantified the cooling effect saying that the Earth would be 0.5 to 1.1 deg C warmer if most of the aerosols disappeared. Samset says in fact if China makes progress in reducing what is called pollution there, planners should be prepared for the cleaner air to cause a jump in temperatures.
Samset also says that rising temperatures will likely lead to and increase precipitation as more water evaporates from oceans, lakes and rivers. (Is this already happening as we see high rainfall and flooding in many parts of the world?).
What connects all aerosols is that they are all of a size that is relevant for interaction with sunlight. The cooling effect becomes stronger as the particles grow. Samset and the scientists believe that the volume of human caused aerosols is so great that they have counteracted any global warming to a certain extent.
Volcanoes make natural cooling aerosols. Explosive volcanic eruptions can inject gases all the way into the stratosphere, which is the layer that begins at about 10,000 metres. Volcanoes emit sulphur dioxide gas which combines with water in the atmosphere to form tiny particles which can circle the globe and stay in the air for a few years. Mount Pinotubo’s enormous eruption in 1991 is a recent example. Sulphates from the eruption cooled the atmosphere by 0.4 to 0.5 deg C and made 1992 and 1993 the coolest years in the past 35 years. Not much Sulphur dioxide was emitted by the Tongan volcano in Feb 2022. It did, however, emit a huge volume of sea water which may also have an influence on the rainfall over the past year or so. Ironically, this sea water in the atmosphere would cause a small amount of warming.
Unlike volcanic aerosols, human caused aerosols do not travel very high in the atmosphere, so only last for between 3 and 5 days. But “air pollution” aerosols are being produced continuously, so these particles are a constant presence.
The Covid-19 pandemic showed what can happen if humans reduced their aerosol “pollution”. Fossil-fuelled air travel, driving, electricity use, and industrial activity all decreased sharply in the spring of 2020. This led to clearer air which led to a slight warming up to 0.2 to 0.5 Deg C in some places.
Several scientists HRCR Nair et al, have stated that if there is a 100% switchover to zero emission renewables from fossil fuels, the net radiative heating of the earth would increase. During the Covid shutdown the increase in earth’s surface heat was of the order of 15-20 Watts per square metre. This kind of surface brightening has major implications for regional climate, especially the monsoonal circulation and precipitation over East Asia and all tropical regions.
Any drying trend seen round the earth has come as a result of increased aerosol emissions. So when you remove aerosols you heat up the earth’s surface, increase evaporation, and get more rainfall. There will also be a greater likelihood of extreme events. There are regions that are susceptible to extreme rainfall already, there are landslides and mudslides and many people killed each year. Is the removal of aerosols causing the escalation of these events?
Strategies focussing on the phase out of fossil fuels all lead to the quick removal of the short-lived aerosols, while the longer lived major “greenhouse” gases decrease much more slowly, likely resulting in undesired net warming of the climate during a decade long transition period.
Some may argue that these latest findings are an argument for geo-engineering. This is not a good idea as unexpected things happen when geo-engineering is involved. One example was someone who said they could save the polar icecap (not that it needed saving), by emitting sulphur aerosols over the North Pole, and they found large impacts of that on the South Asia monsoon season because it changed the whole circulation of the atmosphere. At some stage you would need to terminate the geo-engineering and if that happens all the problems are going to come back more or less immediately.
One thing is obvious to me. Over the time the earth has been in existence, it seems to have found an equilibrium, for each situation which has arisen. The UN/IPCC and Greenies want to upset this equilibrium. There is no climate crisis so we should just abandon all these futile climate mitigation targets, like a push to net zero, and get on with our lives.
Ian Bradford, a science graduate, is a former teacher, lawyer, farmer and keen sportsman, who is writing a book about the fraud of anthropogenic climate change.
Originally punlished on Breaking Views.