By Ranil Senanayake –
Addressing Climate Change – Part II
The second question raised by Sri Lanka’s position at the COP on Climate Change in Paris was on the danger to agricultural productivity by the rising temperatures. This was not a simplistic knee jerk reaction like ‘is is better to hold the temperature under 1 degree or 2 degrees,?’ but address the alarming real danger of food insecurity that will be brought to most tropical nations by the phenomenon of ambient temperature rise.
Why is a heat wave so dangerous? Apart from the heat stress in human and animals, it could exceed the threshold for enzymatic activity. All of agriculture depends on the good growth of plants, all plants rely on their chlorophyll to grow and produce. Chlorophyll is a molecule that functions to an optimum at about 37degrees, above that their performance falls. In heat waves often exceeding 38 degrees plant productivity will be impacted and yields drop (fig1). This year much of Australia dealt with a brutal spring heat wave that reduced farmers’ yields.
The danger to agricultural production is further exasperated by the reliance on chemical farming with so-called ‘high yield ‘ crops of the so called ‘Green Revolution’ . These crops have been bred by reducing their maintenance biomass (leaves and roots) for crop biomass (seeds or fruit). This reduction of their natural defenses being made possible by the use of chemical fertilizers and toxins. But in a high temperature situation when chlorophyll is functioning sub-optimally such reductions may bring serious crop losses.
Chemical fertilizers are produced using large amounts of energy, usually fossil energy. The creation of this fossil energy results in the discharge of huge volumes of Carbon Dioxide into the atmosphere. This, in addition to the fossil carbon footprint of agro toxins and fossil fuel use adds greatly to global warming which in turn creates the dangerous heat waves around the planet and finally affects the farmer through increased heat stress on the crop.
What are the ways out? One would be to look for plants that have a wide heat stress tolerance; another will be to design future agroecosystems that can use the heat reducing mechanisms of ecosystems to respond to temperature raises.
However one urgent national needed to deal with climate change is to begin mapping out high risk areas in the future and warm farmers in those areas of the steps they should take to adapt to the oncoming changes. Probability maps need to be constructed for temperature, rainfall intensity, wind intensity and salt-water intrusion. Sri Lanka like many other tropical nations does not have the wherewithal to conduct research on and monitor these risks. Capacity to do so could be an outcome to our second question.
*To be continued