Climate change

Anyone walking the face of earth can vouch the changing trends of our climate. Hottest years in the history have been experienced during the past decade. Rain pattern is changing. Erratic heavy rains and resulting floods are occurring more frequently causing massive devastations. All atmospheric indicators are pointing to these disturbing patterns unfailingly. Recorded temperatures during the past century bear ample witness (Fig 1).

Fig 1

These changes and their future trends are of deep concerns to humanity. If the ambient temperatures change what consequences will these have on life, plants and animals, on the planet? Man himself, his crops and livestock will take a certain beating from unfavorable temperatures. These developments threatening humanity and its march forward coupled with fast expanding population represent the tipping of balance of food needs-availability equation. So a concern is dawning on humanity to understand and counter these climate related effects.

Economic progress and population pressure are heavily straining our food base. More and better food is required to feed rising and prospering humanity. Rising heat due to climate change, on the other hand, is threatening food production systems. Besides, direct adverse effect, it would have multi-fold indirect effects also. Glaciers, the vast storehouses of water feeding rivers, are melting (Fig 2) reducing water availability; favorable crop growing areas would squeeze, insect and disease activities would rise posing health hazards and making food production difficult.

Human activities are at the base of all these disturbing trends. Man is devouring natural resources. It is estimated that the current rate of resource use is 1.4 planet equivalent which, naturally, over long time is unsustainable and, in fact implosive. Industry, transport, agriculture are all using natural resources at an accelerated pace and, at the same time, churning out toxic wastes injurious to environment.

Fig 2. Receding Himalayan glaciers

Fossil fuel consumption alone is adding billions of tons of CO₂ annually (Fig 3). Other toxic gases – nitrogen and sulfur oxides, chlorofluorocarbons (CFCs) -  from powerhouses, smelters, chemical and fertilizers industries are accumulating in atmosphere.  Natural gas, diary industry and anaerobic rice cultivation are contributing methane to the environment. All these gases have affected the makeup of gaseous envelop around the earth planet. This atmospheric cover around the earth is a protective screen that obstructs harmful solar radiation reaching the ground. For example, ozone layer in the upper atmosphere screens out much of the harmful UV radiation from sun. Its depletion would increasethe incidence of UV on earth with harmful consequences for humans and other living beings. Natural atmospheric composition was responsible for maintaining a healthy balance of incoming and outgoing radiation which, in turn, maintained a favorable environment for life. Any change in composition would jeopardize this atmospheric ability rendering earth planet inhospitable. This is happening due today. Fuel use in home heating, cooking, transports, and power generation is adding billions of ton of carbon to the air (Fig 3). Its CO₂ contents have risen from 280ppm preindustrial level to over 390 ppm presently. Similarly, nitrogen and sulfur oxides, methane and man-made gases (CFCs) have increased significantly. These gases have affected the radiation exchange capacity of the atmosphere. Most of the incoming solar radiation is in short waves which can pass through the atmosphere. Once on the earth it heats the earth surface and heat is radiated back as infrared in long waves. The infrared is absorbed by these gases and radiated back to the earth surface raising its temperature.  Average earth temperature is 15°C it has already risen by 0.74°C due to  of these gases. These gases, for this reason, are called green-house gases (GHGs) since their net effect is similar to what we experience in green-houses.

Fig. 3 Global carbon emissions

The rising temperatures are injurious to crop and animals. It is estimated that every single degree increase in temperature in Celsius would reduce wheat yields by 7 and rice yield by about 10 percent. So temperature changes, at a time when food demand is increasing  could spell disaster for human survival.

The world is alive to these threats and the two international agricultural organizations - CIMMYT and IRRI - are putting together packages that can sustain agricultural production in unfolding future scenario while reducing fuel consumption and so arresting harmful effects of agriculture on the environment.