CLIMATE CHANGE- OPINION


Arunayan Sharma serves a heady cocktail of appalling facts that expose our political nonchalance as far as global warming goes

ARE you feeling a little hotter today than yesterday? The coming days might turn out to be all the more unbearable. Are you getting a little hot under the collar already? Climatic patterns have changed drastically over the years, which fact is testified by sudden, unpredictable rainfall round the year.

North Bengal is comparatively cooler than south Bengal because it is very close to the Himalayas and has a larger forest cover and watery areas. But all these advantages hardly mitigate the gruelling effects of summer. Climate change is a taking a severe toll and the planet is getting warmer every passing day. Global warming is a phenomenon the ill effects of which we haven’t yet realised fully.

The term “global warming” is a specific example of climate change, which can also refer to global cooling. The United Nations Framework Convention on Climate Change uses the term “climate change” for change caused by human activities, and “climate variability” for other types of changes. Global warming is the increase in the average temperature of the earth’s near-surface air and oceans in recent decades and its projected continuation.

The global average air temperature near the earth’s surface raised by 0.74 ± 0.18°Celcius (1.33 ± 0.32 °F) during the last 100 years. Globally averaged temperatures since the mid-twentieth century are very likely due to increase in anthropogenic greenhouse gas concentrations via the greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect in pre-industrial times. Earth’s climate changes in response to external forcing, including variations in its orbit around the sun (orbital forcing), volcanic eruptions and atmospheric greenhouse gas concentrations. A common hypothesis proposes that warming may be the result of variations in solar activity. The thermal inertia of the earth’s oceans and the slow responses of other indirect effects mean that the earth’s current climate is not in equilibrium with the forcing imposed.

Sea temperatures increase more slowly than land both because of the larger effective heat capacity of the oceans and also because water bodies lose heat by evaporation more readily than land. The average global surface temperature will likely rise a further 1.1 to 6.4°Celcius (2.0 to 11.5 °F) during the twenty-first century. The year 2005 was the second warmest year behind 1998. Increasing global temperatures will cause the sea level to rise, and is expected to increase the intensity of extreme weather events as well as change the amount and pattern of precipitation. Other effects of global warming include changes in agricultural yields, trade routes, glacier retreat, species extinctions, increase in the range of disease vectors, changes in mountain snowpack and adverse health effects resulting from warmer temperatures. Increasing deaths, displacements and economic losses projected due to extreme weather may be exacerbated by growing population densities in affected areas, although temperate regions are projected to experience some benefits, such as fewer deaths due to cold exposure. Developing countries dependent upon agriculture will be particularly harmed by global warming.

The greenhouse effect is the process by which absorption and emission of infrared radiation by atmospheric gases warm a planet’s lower atmosphere and surface. Naturally occurring greenhouse gases have a mean warming effect of about 33°Celcius (59°F), without which earth would be uninhabitable. The major greenhouse gases are water vapour, carbon dioxide (CO2), methane (CH4) and ozone. Some other naturally occurring gases contribute very small fractions to the greenhouse effect; one of these, nitrous oxide (N2O) is increasing in concentration owing to human activity such as agriculture. Future CO2 levels are expected to rise due to ongoing burning of fossil fuels and land-use change.

Warming by the addition of long-lived greenhouse gases such as CO2 will cause more water to be evaporated into the atmosphere. Since water vapour itself acts as a greenhouse gas, the atmosphere warms further; this warming causes more water vapour to be evaporated and so on until a new dynamic equilibrium concentration of water vapour is reached with a much larger greenhouse effect than that due to CO2 alone. Although this feedback process causes an increase in the absolute moisture content of the air, the relative humidity stays nearly constant or even decreases slightly because the air is warmer.

Seen from below, clouds emit infrared radiation back to the surface and so exert a warming effect; seen from above, they reflect sunlight and emit infrared radiation to space and so exert a cooling effect. The atmosphere’s temperature decreases with height in the troposphere. Most of the

radiation emitted from the upper atmosphere escapes to space while most of the radiation emitted from the lower atmosphere is re-absorbed by the surface or the atmosphere. Thus, the strength of the greenhouse effect depends on the atmosphere’s rate of temperature decrease with height: if the rate of temperature decrease is greater the greenhouse effect will be greater, and if the rate of temperature decrease is smaller then the greenhouse effect will be weaker. When global temperatures increase, ice near the poles melts at an increasing rate. As ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice and thus absorb more solar radiation. A different hypothesis is that variations in solar output, possibly amplified by cloud seeding via galactic cosmic rays, may have contributed to recent warming. It suggests that the magnetic activity of the sun is a crucial factor deflecting cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate. One predicted effect of an increase in solar activity would be a warming of most of the stratosphere, whereas greenhouse gas theory predicts cooling there.

These security effects include increased competition for resources between countries, mass migration from the worst affected areas, challenges to the cohesion of major states threatened by the rise in sea levels and, as a consequence of these factors, an increased risk of armed conflict, including even nuclear conflicts. Others have suggested a quota on worldwide fossil fuel production, citing a direct link between fossil fuel production and CO2 emissions. There has also been business action on climate change, including efforts at increased energy efficiency and limited moves towards use of alternative fuels. One important innovation has been the development of greenhouse gas emissions trading through which companies, in conjunction with government, agree to cap their emissions or to purchase credits from those below their allowances. Awareness of the scientific findings surrounding global warming has resulted in political and economic debate. Poor regions appear at greatest risk from the suggested effects of global warming, while their actual emissions have been small compared to the developed world. In the Western world, the idea of human influence on climate has gained wider acceptance in Europe than in the USA.

A variety of issues are often raised in relation to global warming. One is ocean acidification. Increased atmospheric CO2 increases the amount of CO2 dissolved in the oceans. CO2 dissolved in the oceans reacts with water to form carbonic acid, resulting in acidification. That organisms and ecosystems are adapted to a narrow range of acidic condition raises extinction concerns, directly driven by increased atmospheric CO2 that could disrupt food webs and impact human societies that depend on marine ecosystem services. Global dimming — the gradual reduction in the amount of global direct irradiance at the earth’s surface — may have partially mitigated global warming in the late twentieth century. Ozone depletion, the steady decline in the total amount of ozone in the earth’s stratosphere, is frequently cited in relation to global warming. It is important to note that the warming will be greater at higher latitudes and over land than over oceans. Initial warming may occur in the northern hemisphere. In relation to temperature changes, predictions regarding the rise in sea level show it will rise at the rate of 5cm/ decade. At this rate by 2100 the sea level will rise by 15-90 cm, probably sinking low laying areas like islands of the Pacific and the Indian Ocean — a major environmental threat for Bangladesh and Sunderbans.

Along with the rise in sea level and temperature changes, predictions also indicate that the frequency of major tropical storms will increase. Elevated sea surface temperature can cause corals to lose their symbiotic algae essential for the nutrition and colour of corals. When the algae die, corals appear white and are referred to as “bleached”. Water temperatures of as little as one degree Celsius above normal summer maxima, lasting for at least two to three days, can be used as a predictor of coral bleaching events. Birds now indicate that global warming has set in motion a powerful chain of effects in ecosystems worldwide. In the future unchecked warming could put large numbers of species at risk, with estimates of extinction rates as high depending on the region, climate scenario and potential for birds to shift to new habitats.

Climate change is inevitable but the pace of change is avoidable. In India, the most vulnerable are the islands. Andaman, Nicobar and Lakshadweep are beautiful and pristine and their coral reefs — the best in India — are treasures that should be preserved at any cost. Coral reefs are one of the most productive ecosystems on earth, providing many critical services to fisheries, shorelines protection, tourism and medicine and are also believed to be among the most sensitive ecosystems to anthropogenic and natural stress.

North Bengal will also face the effect of global warming and climate change. The main attraction here is tea and tourism. With rising temperatures tourism will decline. Darjeeling will be the worst hit. Another important factor is that floods will occur more frequently. Floods and riverbank erosion in Malda is mainly caused by the ever-swelling Ganges. Global warming will also cause the Gangotri glacier to melt which, in turn, will contribute to huge water flow in the Ganges river system and lead to perennial floods and river bank erosion. Increase of sweet water in the river system will also affect the ecology of the Sunderbans.

The writer is director, Centre for Ecological Engineering, Malda

source; Shri Barun Roy