Could COVID-19 be the unwitting savior of the earth? asks S.Ananthanarayanan.

What we have been through these last three months will leave an impression on young minds.

Scientists have been speaking of global warming and human destruction of the environment for several decades. In response, there have been international parleys and resolutions to cut emissions, campaigns, seminars, education programmes. Nobody, however, seems to have been convinced, as there is little change in lifestyles. And targets are not being met.

COVID-19, which has created the current crisis, is the chance evolution of a virulent pathogen, and it has no relationship with environmental damage – for there have been outbreaks before we heard of global warming. The crisis, however, is bringing general people face-to-face with natural phenomena, which need to be controlled individually, and with objective, scientific measures. Objects like the virus, molecular biology, RNA and DNA, are concepts of frontier sciences that have developed in recent decades. In a few quick weeks, common people have become familiar with these terms. Against an invisible enemy, we understand the need to use personal protection and the value of sanitisers. And hygiene is being practiced from a scientific perspective. This may be a turning point towards internalising what we learn in science. When Corona is behind us, people may lend a more attentive ear to things said about the environment.

Speaking of the environment, the journal, Nature, has carried a report, by a group from institutes in Australia, with others from the US, Denmark, Sweden, Spain, Estonia, Belgium and Germany, that negates a belief that mature forests would soak in more CO₂₂

While carbon dioxide is the main greenhouse gas that causes global warming, it is also the ‘raw material’ for photosynthesis by plants. The C02 reducing function of the earth’s green cover would hence get stronger when the CO₂₂₂

Mature trees were also found to show increased CO₂₂₂

The study revealed that a good proportion of the carbon absorbed by mature trees ended up by being transferred to the earth below, consumed by soil microbes and respired back into the atmosphere. The results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under increased CO₂

Current civil construction is dominated by use of concrete and concrete reinforced by steel bars. As the manufacture both of cement, for concrete, and steel, are carbon intensive, civil construction has a large carbon footprint. The use of wood in place of concrete, so that buildings contain and preserve the carbon sequestered by forests, rather than pollute the atmosphere by energy intensive processes, is hence of interest. The finding that mature forests are not the great carbon sinks they were imagined to be during rising atmospheric CO₂

Using waste

The study at RMIT, Melbourne, is relevant to the manufacture of cement and steel. Concrete consists of finer particles of sand and larger particles of crushed stone, bound together by cement. The material can bear very high crushing loads and has been a traditional construction material. The use of steel rods to reinforce concrete adds to concrete the capacity to bear bending loads and reinforced concrete dominates civil construction.

Manufacture of both cement and steel consumes energy, and their use has a heavy carbon footprint. In the manufacture of steel, ores of iron are reduced to the metal by the use of high temperature, and carbon, to draw away the oxygen from oxides of iron. What is left is a rocky material, the slag, which has use for road building and as the aggregate, or the coarse material in concrete. Another use of blast furnace slag is to absorb chemicals from wastewater, before the water is allowed to mix with streams or to soak into the ground.

Municipal wastewater contains significant quantities of phosphorus, which would affect the plant and animal life in water bodies. Blast furnace slag is found to be effective in removing most of the phosphorus contaminant. This is apart from the granules of slag filtering out iron and manganese, that wastewater contains. Now, the study shows that apart from cleaning waste water, blast furnace slag also undergoes changes, in the process, that improve its performance as aggregate in concrete. Concrete with blast furnace slag is 17% stronger than with ordinary aggregate and again 8% stronger when the slag has been treated with wastewater, the study shows. This creates a circular economy, with a by-product of manufacture of steel, which is used to strengthen concrete, finding another use, which again, improves its value in concrete.

The use of concrete could be reduced, with two-fold benefit to the environment, by the use of wood in civil construction. Next, the use of reinforced concrete itself can be made more environment friendly when blast furnace slag helps purify wastewater before release into the environment. And then, the very process leading to less use of concrete.

The world has taken many steps to reduce the load on the atmosphere - generating electricity without burning fossil fuels, improving industrial processes, limiting the use of plastics and fertilisers and the use of biotechnology. The impact, however, has not been felt, as lifestyles encourage waste, power consumption and travel. The short periods of shutdown that COVID-19 has imposed on the world has shown that it is possible to live without much that we considered indispensable. Could living grow sensible when things normalize? Could COVID-19 be the unwitting savior of the earth?

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