Climate models give too small temperature increase if decreased air pollution is not included

Maanantai 13.5.2024 klo 12.04 - Mikko Nikinmaa

Air pollution has decreased significantly during the past fifty years in Europe. I remember how in my youth the air in all the densely populated areas was often smoggy, and the sun was always seen through the haze. Air pollution has decreased largely as a result of decreasing number of small particles being emitted in the air. This is mainly due to collecting them in the chimneys and exhaust fumes. Since air pollution is causing millions of deaths per year globally, one would expect that this is unequivocally a good thing.

However, clearer sky also lets solar radiation to pass through more efficiently than during the dirty olden days. Sunshine in summer is associated with heat spells. And the length and severity of those has increased markedly throughout the last decades. In Europe the temperatures have increased much, about one degree, more than the used climate models predict. So, climate change appears to be worse than expected. This appears to be mainly due to the fact that the climate models used to predict climate change have not included decreasing air pollution and consequent increase in solar radiation.

So, combatting air pollution makes climate change worse? Not really, what is seen is the effect of inadequate inputs for mathematical modelling. This means that temperature increases are more drastic for the predicted fossil fuel usage and consequent carbon dioxide load. In other words, we have underestimated the severity of climate change because of inadequate models. However, to a large part, the improvements of air quality can be associated with the decrease in fossil fuel burning, although there have been measures dissociating the two (like catalytic converters). Thus, in the long run, decreased air pollution is the result of discontinued use of fossil fuels, and no disparity between predicted and measured temperatures occurs.