The worst disasters can enable the most fascinating observations. A by-product of the prolonged, hideous Covid pandemic and its concomitant worldwide lockdowns was how it enabled scientists to observe human beings’ impact on nature – specifically, how much better plants can absorb carbon dioxide when humans are inactive.
Photosynthesis
As New Scientist reported, from 2018 to 2021, scientists observed satellite measurements of plants across Europe focusing on the amount of light they reflected – specifically the green element from the pigment chlorophyll that plants produce in photosynthesis. This is the process in which plants soak up sunlight and carbon dioxide, and create energy and oxygen.
Initially it was observed that plants were photosynthesising more effectively at weekends: people are resting, transport usage and industrial activity are reduced, less dust is thrown up, lowering the concentration of aerosol particles in the air, and more sunlight is let in – which plants took in and boosted the accompanying uptake of CO2.
It was in 2020, the year of worldwide coronavirus lockdowns, that aerosol particle concentrations plummeted – and photosynthesis rates vaulted, and stayed higher, all week, every week.
Measurements for that year suggest plants could take up an extra 41 million tons of CO2.
The case for working from home just got better – not only does doing so reduce energy usage and the output of nitrous dioxide as well as carbon dioxide (creating ULEZ by default!), it enables plants to soak up more of the CO2 already out there. How quickly nature can recover itself if left to do it …
Over 20 years before, 9/11 enabled another observation. i.e. a 1° C spike in temperatures as all the grounded airliners and consequent absence of vapour trails allowed in more sunlight (if you think 1° C isn’t a lot, we’re battling to keep the rise in global temperatures to 1.5° C above pre-industrial levels).
As the 2005 BBC Horizon documentary ‘Global Dimming’ presented, human activities were keeping the world cooler by way of pollution-sourced particulates reflecting sunlight and providing less radiation for increased greenhouse gas concentration to retain the heat.
Wouldn’t this be a wonderful irony, that the temperature rises caused by rising greenhouse gas output are tempered by other kinds of filth sent airborne by our wealth generating activities? We should proceed as normal!
Nothing’s for free
Unfortunately, nothing’s for free. The increased particulate concentration was merely disguising the impact of already existent concentrations of greenhouse gases. And there are always surprising, deadly consequences.
As Horizon explored, the sub-Saharan area of the Sahel is normally parched save for an annual monsoon – on which all life there depends – brought by equatorial rains brought north by seasonally increased temperatures over the north’s oceans. But by the 1970s and early 1980s these monsoons weren’t happening, as the north’s oceans, thanks to global dimming wrought by US and European industries, were cooler. The ensuing crop failures and collapse in the sustainability of nomadic farming contributed heavily to the 1984 famine in Ethiopia.
It’s fascinating to see the extent to which this two-decade-old documentary’s predictions are playing out (also watch the truly chilling 1983 Horizon ‘Killer in the Village’, made on the cusp of the AIDS epidemic when understanding of the disease was still very nascent).
Completing the perfect storm in Ethiopia in 1984 was a bitter civil war and a murderous, authoritarian government. Unfortunately, in successive years the entire sub-Saharan belt extending to West Africa has become increasingly unstable, with a slew of (Russia-backed) coups seen these last few years. In 2022 and 2023 we’ve also seen worldwide wildfires that will have produced staggering amounts of particulate, while those plants we need to absorb CO2 instead go up in flames and release a load more. Adding to the dust clouds are wars (see Ukraine, Gaza), as do the upheavals of millions displaced by conflict and oppression (Ukraine, Sudan, Gaza, Abkhazia, to name a few). Maybe we can watch a documentary in a few years to see how it all played out. If there is an Earth.
