In Brazil, pro-development a hard blow to nature

The extent of the Amazon rainforests is 1.7 times the total geographical area of India, which is 320 million hectares. With such an enormity, the trees there take in 2 billion tones of CO2 every year and produce 6% of world’s oxygen and 20% of freshwater.

A study by Nature suggests that the economic benefit of leaving the Amazon rainforests in its current state would be 8.2 billion dollar a year.

Deforestation and degradation of these forests would lead to a fall in rainwater and agricultural losses of 422 million dollars and social and economic losses valued in monetary terms would be as much as 3.5 trillion dollars over a period of 30 years.

Brazil’s President Jair Bolsonaro, who took office on January 1, 2019, is all out for development even at the expense of environmental degradation. After his taking over the office, there has been mindless clearing of tree growth for expansion of agriculture and mining etc.

Natives are expanding their agriculture and burning of wood, which have been the source of fire that brought the forests to flames for months together.

Several countries pleaded with Brazil for action to check the destruction of the forests, but the president remained defiant.

He was reminded of the 2015 Paris Accord that the Green House Gas (GHG) emission be checked so that the global temperature rise is restricted to 20 degrees Celsius as compared to pre-industrial temperature, yet he reiterated that development is the priority for his regime.

As 60% of the Amazon forests are in Brazil, world bodies have to engage with the regime sincerely. Scientific researchers have established that these forests are important for the survival of mankind.

Such large-scale forests are biotic pumps, which can bring rains in regions located a few thousand kilometres from the coastline. And without rains, not only will the agriculture sector across the continents suffer, but the economy of Brazil will collapse.

During the past 30 years, there has been a growing concern over human-induced climate change. We have ignored the hydrological role of rainforests and only focused on the emission of greenhouse gases.

Biotic Pump Theory

Two physicists, A M Makarieva and V G Gorshkov, from St Petersburg Nuclear Physics Institute, Russia have studied and have brought out a paper titled ‘Biotic Pump of Atmospheric Moisture as Driver of the Hydrological Cycle On Land’, which was published in Hydrology and Earth System Sciences.

It has been observed that water from the land flows into the oceans under gravity and the loss of water from land is continuously compensated by the atmospheric transport of moisture from the ocean to land. Using data from terrestrial transects, the physicists have found that air fluxes can transport moisture over non-forested areas for a few hundred kilometres.

In contrast, precipitation over extensive natural forests is independent of the distance from ocean for several thousand kilometres.

This explains the existence of an active biotic pump that transports atmospheric moisture inland from the ocean. A physics principle is formulated to explain the phenomenon of biotic pump, according to which the low-level air moves from areas with weak evaporation to areas with intense evaporation.

Due to a high leaf-area index, tropical evergreen forests maintain high evaporation fluxes, which support the ascending air motion over the forest and ‘suck in’ moist air from the ocean, which is the essence of the biotic pump, resulting in enhanced precipitation at any distance from the ocean.

Land with low leaf-index vegetation can lead up to ten-fold reduction in precipitation and run-off. The evidences testify that an intense terrestrial water cycle is unachievable without extensive forests covering the width of the continent.

This theoretical claim of physicists is supported by worldwide observations that the condensation of water vapour at cloud-forming altitude bring about a sharp reduction in local atmospheric pressure, resulting in the implosion of sufficient strength so as to suck air from the surface. Trade winds from Africa to equatorial South America pick up moisture from the Atlantic Ocean, which is carried by the wind and is sucked in over Amazon’s forests. This way, the hydrological cycle drives mass circulation of air, and can be understood to be driven by processes of convection that take place over the 550-million hectare Amazon Basin. The ‘fuel’ for the convection being contingent on the high rate of water vapour pumping from closed-canopy vegetation.

If the forests are to disappear, then moisture would no longer be sucked in, and given the natural fallout rate of rainfall, some 600 kilometres from evaporation to precipitation, the land would dry out and turn into desert.

Deforestation, though, is a matter of concern. Biologists, ecologists and climatologists are adamant with their view that the surface winds will keep blowing in the same pattern, as it was prior to deforestation. And thus rain will still get deposited in the interiors of the continents, especially along equatorial tropics. The Biotic Pump Theory of the two physicists, thus, did not have acceptance among scientists of other streams.

Peter Bunyard, a researcher in University of Sergio Arboleda, Bogota, has interacted with the two physicists and found them standing by their theory. His paper Without Its Rain Forests, Amazon Would Turn To Desert was published in The Ecologists in 2015. Experimental confirmation of Peter Bunyard has also silenced the argument that forests consume water and competes with other downstream water uses such as agriculture, industry, energy and households. This conclusion is half-truth. Even slow degradation of these forests will make alarming changes in climatic conditions.

(The writer is former Principal Chief Conservator of Forests, Karnataka)