It was the Intergovernmental Panel on Climate Change (IPCC), a UN-sponsored working group of some 2,400 scientists from around the world, that first drew attention to human role in climate change in a major way. In its report on anthropogenic (human-caused) impact on global climate (1995), it highlighted that world climate had indeed changed significantly over the last two centuries and there is clearly a human influence on global climate. If the present trends continue, the global mean surface air temperatures will rise from 1 °C to 3.5 °C by AD 2100. This is a huge rise considering that the difference between current temperatures and the last ice age is only about 5 °C.
Evidence of Global Warming In the 140-year period ending AD 2000, there has been global mean warming of 0.45 ± 0.15 °C. In India, mean temperature in the nineteenth century is estimated to have risen by about 0.2 to 0.6 °C (in the last 40 years, by about 0.2 to 0.3 °C). The mean temperature of the Earth rose about 0.4 °C (1 °F) in the twentieth century.
The twentieth century was the warmest century of the second millennium AD. The global average surface temperature has risen over that in the twentieth century by about 0.6 PC. Most of the warming occurred during 1910 to 1945, and during 1976-2000. The 1990s were probably the warmest decade and 1998, the warmest year in the instrumental record since the year 1961. New analyses indicate that the rise in temperature in the twentieth century is probably the largest of any century during the past millennium.
On average, between the years 1950 and 1993, night-time daily minimum air temperatures over land increased by about 0.2 °C per decade. This is about two times the rate of increase in daytime daily maximum air temperatures (0.1 °C per decade). The rise in sea surface air temperature has been about half that of the mean land surface temperature of the air over the same period.
Temperatures have been increasing during the past four to five decades in the lowest eight kilometres of the atmosphere (about 0.1 °C per decade). The lowest eight kilometres of the atmosphere and the surface are influenced differently by factors like stratospheric ozone depletion, atmospheric aerosols and the El Nino phenomenon.
The Earth’s glaciers are melting at a fast rate and there has been a decrease in snow cover and ice extent. Satellite data indicates that there has been a decrease of about 10 per cent in the snow cover since the late 1960s. There is likely to have been a reduction of about two weeks in the annual duration of lake and river ice cover in the mid-and high-latitudes of the northern hemisphere over the twentieth century.
The mountain glaciers in non-polar regions have retreated in the century. There is likely to have been about 40 per cent decline in Arctic sea-ice thickness during late summer to early autumn in recent decades but a considerably slower decline in winter sea-ice thickness.
With reference to specific areas, the following form significant evidence of global warming:
i. The edge of the West Antarctic ice sheet is shrinking at 400 feet every year.
ii. Much of Antarctica’s Larsen B and Wilkes ice shelves disintegrated in 1998-99.
iii. Glacial ice has shrunk nearly 25 per cent over the last 40 years in the Tien Shan Mountains, China.
iv. Half of all glacial ice melted away in the Russian Caucasus mountains in the past four decades.
v. Glacial retreat increased sevenfold in the Andes mountains of Peru from 1978 to 1995.
vi. In the Bering Sea, area of sea-ice has shrunk five per cent in the past 40 years; in the Arctic Ocean, the sea-ice area has reduced by about 14,000 square miles since 1978.
vii. The largest glacier on Mt. Kenya has almost disappeared. Glaciers in the Alps mountains shrank by about 50 per cent in the last century.
The sea levels are rising as a result of melting of glaciers. Tide gauge data reveal that global average sea level increased between 0.1 and 0.2 metres during the twentieth century. Global ocean heat content has increased since the 1950s.
It is likely that precipitation has risen by 0.5 to 1 per cent per decade in the twentieth century over most mid-and high-latitudes of the northern hemisphere continents. Rainfall is likely to have increased by 0.2 to 0.3 per cent per decade over the tropical (10 °N to 10 °S) land areas. Rainfall is likely to have decreased over a large part of the northern hemisphere sub-tropical (10 °N to 30 °S) land areas during the last century by about 0.3 per cent every decade.
There has been a two per cent increase in cloud cover over mid-to-high-latitude land areas during the twentieth century.
The earth’s climate depends upon the solar radiation factor. The energy absorbed from the sun has to be balanced by outgoing long-wave thermal radiation from the Earth and the atmosphere. Part of this outgoing energy is absorbed and re-emitted by radioactive atmospheric gases which are called greenhouse gases. When this absorption and re-emission takes place, the net emission of energy into space is reduced. So the atmosphere and the surface air will warm on earth till the outgoing energy equals the incoming energy. This is called the greenhouse effect.
The main natural greenhouse gases are water vapour, the largest contributor to the greenhouse effect, carbon dioxide (CO2), methane, nitrous oxide and ozone. These are naturally found in the atmosphere. The largest sources of methane in the atmosphere are natural wetlands, rice paddies and livestock. Nitrous oxide is released by the oceans and soil.
Causes of Global Warming:
Global warming in recent times has resulted in heating up of the atmosphere not as a result of the natural greenhouse effect but as a result of increase in the greenhouse gases—CO2, methane, nitrous oxide and ozone—in the atmosphere as a result of human activities. What happens is that due to increase in greenhouse gases, the infrared radiation that is absorbed from space as well as part of the outgoing energy that is absorbed and re-emitted by the gases, increase.
So the atmosphere and the surface warm up much more than they should. The outgoing energy and the incoming should equal but the balance is affected. The main greenhouse gases differ in their intensity of heat trapping (‘radioactive forcing’) and in their ability to affect the radiative balance of the Earth.
Globally, the most important industrial activity that has led to a great increase in CO2 emissions is burning of liquids. Carbon dioxide released from the combustion of petroleum fuels in transportation and power generation has been excessive. Then comes burning of solids like coal, mainly for generation of power. A large amount of CO2 is emitted by many industries, even cement. In the manufacture of cement, half a tonne of CO2 is estimated to be released when one tonne of cement is produced.
Methane is released in the course of natural gas production (drilling, venting and transmission), biomass burning, termites, landfills and coal mining.
Nitrous oxide is released by biomass burning and the use of fertilisers also have a role in emitting this gas. There are substantial differences between countries regarding the source of emissions. In the industrial nations, emissions are very large due to burning of liquid fuels. In these countries, personal transport is much more developed and greater use is made of oil in heating and in power. On the other hand, the burning of coal is the biggest source of emission—of CO2 release—in developing countries. In India and China, more than 80 per cent of the CO2 that is emitted comes from burning of coal.
Increase in ozone in the troposphere below 10 km is a concern. Ozone in the troposphere that acts here is different from ozone in the higher stratosphere, where ozone absorbs ultraviolet radiation. In the troposphere, ozone does not absorb radiation but acts as a greenhouse gas.
Emission of nitrous oxides by aircraft engines has increased ozone in the troposphere and has contributed to global warming. Ozone here is some 30 times as effective at absorbing the Earth’s radiation as is CO2.
CFCs While the natural greenhouse gases are showing an increase over the decades, there is also the concern of emission of purely man-made greenhouse gases which include many ozone- depleting substances like the CFCs or chlorofluoro carbons.
These are much more potent than the same quantity of carbon dioxide or methane. Additional CFC atoms added to the atmosphere are 10,000 times more effective at absorbing infrared radiation than are additional molecules of CO2. The CFCs already account for a quarter per cent of the greenhouse forcing. A quadrupling of the CFCs is likely to result in an increase in temperature in from 0.5 °C to 1.0 °C.
The CFCs deplete the ozone layer in the atmosphere which is vital for absorbing ultraviolet (UV) radiation from the sun and protecting the Earth from harmful radiation affect. Increased UV radiation would adversely affect plant and animal life on Earth as well as affect climate as it would increase the Earth’s surface temperature and aid in global warming.
The CFCs which are extremely harmful include CFC-11, CFC-12, CFC- 113 and CFC-114 which are used in aerosols and refrigeration, for making foams and in solvents. 1, 1,1, Trichloroethylene (TCA), methyl chloroform, carbon tetrachloride, HALON-1211 and HALON- 1301 are other ODS substances used in solvents and for fighting fire.
Thermal pollution has been a factor contributing to global warming. It results from increased human use of energy and from discharge of waste heat into the atmosphere or ocean. Though not yet very significant on a global scale, this heat source may become appreciable as the twenty- first century advances. If energy production is concentrated in large nuclear power parks, thermal pollution would become a crucial source of global warming.
Effects of Climate Change:
Climate changes can severely affect human societies, agriculture and the natural ecosystems. Terrestrial and aquatic ecosystems, which provide many goods and services on which we rely, would be severely affected. Organisms and human infrastructure will not be able to adapt quickly and sufficiently to changed climatic effects.
An ominous outcome of higher temperatures would be release of stores of methane hydrate now under permafrost in the Arctic. Combined with oxidation of high-latitude peat lands, release of the carbon stores would add greatly to the CO2 content in the atmosphere. Thus the effects of warming themselves would cause more warming.
Many wild plant and animal species found today can be forced out of their present area of growth/habitat as climate warms. Many of them could adapt to the new conditions by migrating and other means but some would also die out. Climate change would impact on agricultural and forestry management in the sense that earlier spring planting of crops may be required and there would be alterations in forests due to fires and pests.
Rising sea levels and heavy storm damage would severely affect coastlines. Sea levels are increasing at about 2 mm per year. Thermal expansion alone can multiply that rate five times. A one-metre rise in sea level over the twenty-first century would mean submergence of some low-lying island nations and displacement of a large number of people—some 70 million people each in China and Bangladesh alone. The melting of glaciers and Antarctic ice-sheets, which hold the greatest volume of fresh water on Earth, would make necessary massive dikes to prevent flooding in the megacities of the world.
Infectious diseases would become more common as global temperatures rise. Insect vectors would expand their ranges and become more active in areas they inhabit. Malaria, for instance, could spread from an area of 40 per cent to 60 per cent of the planet and it could arrive in new places like Nairobi in Kenya and Harare in Zimbabwe. Exposure to infections and diseases would be a result of heat, increase in UV radiation as well as pollutants like chlorinated hydrocarbons. The same elements associated with warming that add to the vitality of a disease may reduce human immunity to it by weakening our natural defences.
The Intergovernmental Panel on Climate Change (IPCC), in its 2007 report, has identified the regional impact of climate change in the time to come.
In Africa, by 2020, there will be increased water stress affecting 75 to 250 million people. By the same time, yields from rain-fed agriculture would come down by up to as much as 50 per cent. Low agricultural production would severely affect food security and increase malnutrition among people. Arid and semi-arid land would increase by 5-8 per cent by 2080. The cost of adaptation to flooding of low-lying areas would be a minimum of 5-10 per cent of GDP (Gross Domestic Product).
In Asia, freshwater availability will decrease by the 2050s. Increased flooding of seas and rivers; compounding of pressures on natural resources and the environment associated with rapid urbanisation, industrialisation and economic development; and endemic morbidity and mortality due to diarrhoeal desease will rise in East, South and South-east parts of Asia.
In Europe, climate change will magnify regional differences in natural resources and assets. Mountainous areas will face glacier retreat, have less snow cover and winter tourism, and many species may become extinct (up to 60 per cent due to high emissions by 2080). In the southern part of Europe, high temperatures and drought will further worsen conditions, as will reduced water availability, hydropower potential and crop productivity. Wildfires will occur with greater frequency and heat waves will be on the rise.
In North America, there will be decrease in snowpack, more winter flooding, and reduced summer water flows. Moderate climate change will increase aggregate yields of rain-fed agriculture by 5-20 per cent climate change effects will interact with development and pollution for many coastal communities.
Latin America By mid-twenty-first century, temperature rise and decrease in soil water will lead to gradual replacement of tropical forest by savanna in eastern Amazonia. Semi-arid vegetation is likely to be replaced by arid-land vegetation in many areas. Significant biodiversity loss through species extinction; decrease in productivity of important crops and livestock; increase in people at risk of hunger are likely changes in precipitation patterns and disappearance of glaciers will affect water availability for human consumption, agriculture and energy generation.
By 2020, there will be significant loss of biodiversity in ecologically rich sites like the Great Barrier Reef and Queensland Wet Tropics where Australia and New Zealand are concerned. By 2030, water security problems are likely to intensify in southern and eastern Australia and in Northland and some eastern regions of New Zealand.
By 2030 again, production from agriculture and forestry will decline in southern and eastern Australia and eastern New Zealand, Initial benefits, however, are projected in some regions of New Zealand. Rise in sea level and increase in storms and coastal flooding, in combination with coastal development and population growth, will increase risks by 2050.
In Polar Regions, there will be a reduction in thickness and extent of glaciers and ice sheets.
Changes in natural ecosystems will have adverse effects on organisms like some migratory birds, mammals and higher predators. There would be mixed impacts for human communities including adverse impact on infrastructure and traditional indigenous ways of life. As climatic hurdles to species invasions are reduced, specific ecosystems and habitats will be rendered vulnerable.
In Small islands, rise in sea level will exacerbate inundation storm surge, erosion and other coastal hazards. As a result, vital infrastructure, settlements and facilities that support livelihood of island communities will be threatened. Local resources will be affected by deterioration in coastal conditions and water resources will be reduced in small islands, as of the Pacific and the Caribbean. Higher temperatures would mean increased invasion by non-native species of animals, especially in mid- and high-altitude islands.
Response of Humans to the Challenge of Global Warming:
It is not possible to evolve a single strategy or technology to mitigate climate change effects. It is also to be borne in mind that vulnerability to climate change rises due to factors other than simply global warming. These factors include poverty and unequal access to resources, food security, and trends in economic globalisation, conflict and incidence of diseases.
As pointed out by the IPCC 2007 report, governments need to integrate climate policies into wider areas and activities like policies relating to development, regulations and standards, taxes and charges, trade permits, financial incentives, research, demonstration and information instruments.
An effective carbon-price signal could realise sizeable mitigation potential in all sectors. International agreements like the Kyoto Protocol represent a positive global response to climate change. They have stimulated national policies, created an international carbon market and set up new institutional mechanisms to provide the foundation for mitigation efforts in the future.
Climate Change Convention:
The growing recognition of the link between greenhouse gasemissions and human activity led to the setting up of the Intergovernmental Negotiating Committee (INC) by the UN General Assembly in 1990 for drafting a framework convention. The UN Framework Convention on Climate Change (UNFCCC) was adopted by the INC in 1992 and it entered into force in March 1994. The convention aims to stabilise the greenhouse gas concentration in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate change. India became a party to the Convention in November 1993.
The USA produces one-fifth of the extra 22 million, tonnes of C02 added to the atmosphere every year. It is the largest anthropogenic source of this gas, both in total and per capita. China follows in terms of total emissions but is eighth in per capita releases.
International countries pledged to return to 1990 emissions by the year 2000. But there was no progress towards this goal, as made clear at the follow-up meeting at New York in 1997.
An important international conference on global climate change was convened in Kyoto, Japan in December 1997. One hundred and sixty nations agreed on a treaty, the Kyoto Protocol (KP). The industrialised nations pledged to roll back C02, methane and nitrous oxide emissions to an average of 5.2 per cent below 1990 levels by the year 2012. it was agreed that hydro-fluorocarbons, per-fluorocarbons and sulphur hexafluoride will be reduced by 5.2 per cent. Different nations have opted for different limits within the guidelines agreed upon. The European Union nations agreed to an eight per cent average cut-back. The USA and Japan were committed to seven and six per cent cuts respectively. However, no specific mechanisms were evolved to enforce the Protocol.
The Kyoto Protocol had mandated that 36 rich countries including the USA, Canada, Japan, Australia and the EU reduce their emissions by 5.2 per cent. But the US has not signed the treaty. Australia signed it just before the Bali conclave of 187 countries (December 2007).
The Kyoto Protocol expires in 2012. The Bali Declaration (December 2007) impressed the need for a successor treaty to the protocol which was to be finalised by December 2009 in Denmark. However, the Copenhagen Summit (December 2009) did not achieve this objective.
In order to ensure serious adherence to commitments to reduce global warming, the Kyoto Protocol provides that if rich countries are not able to meet their targets then they will need to buy Certified Emission Reduction (CER) certificates from developing countries. The CER certificates will be earned by the developing countries if they reduce their emission equivalent to one tonne of CO2 by adopting Clean Development Mechanisms (CDMs). The developing countries are not subjected to GHG emission reduction targets because their emissions are low. The rich – countries would buy the CER certificates from poor nations for a price for not meeting their reduction targets.
It is clear that developing nations are being lured by the rich ones into carbon trading. But developing nations themselves want to grow at a fast rate in order to eradicate poverty. So their emissions would also increase to a large extent and they will not be able to earn CERs after some time. So carbon trading cannot be a practical long- term strategy to tackle global warming.
Cutting emissions has been a problem for all countries, especially the industrialised ones. The countries are-opposed to cutting emissions as something that is not feasible: it would impinge enormously on economic development. Some people oppose limits on emissions, saying that the costs of making changes are greater than the benefits. In USA, for instance, industries and labour unions argue that strict greenhouse gas controls could eliminate 10,000 jobs in the country and could cost as much as 830 billion a year. Economies around the world would be plunged into depression. But ecological economists point out that emissions could be cut by 30 per cent without additional costs or job losses. Positive benefits from cutting emissions like clean air, renewable energy and stabilised weather, would more than make up for the costs of controls.
Developing nations do not have strict emission limits as they fear restrictions would hit them severely. The question posed by them is why poorer nations should forego the benefits from energy consumption and other modern technology that rich nations enjoy especially when much of the global warming today can be traced to activities of the industrialised countries.
However, it is necessary to remember that if the developing countries continue to increase fossil fuel consumption at the present rate, the results would be disastrous. China, for instance is set to replace the USA as the world’s leading CO2 emitter in the twenty-first century. In other words, as we all inhabit one world, the activities of some would impact upon all.
The USA has for long lobbied hard to treat emissions as commodities and allow trading, banking and borrowing from fixed carbon quotas as part of the KP. Countries that are able to beat their assigned reductions will be able to sell the excess to other countries that fall short. There can be emission offsets like new forests. The US then can pay a developing country to plant a few million trees without putting emission controls on its power plants.
Phasing Out CFCs and the Montreal Protocol:
Recognising the need to protect the 24- km-thick ozone layer in the stratosphere which absorbs UV radiation which would otherwise, among other things, increase the Earth’s surface temperature, the international community pledged on steps to control and finally ban the production of CFCs, which aid in ozone depletion, and other ozone depleting substances (ODS). The Vienna Declaration and the subsequent Montreal Protocol on Substances that Deplete the Ozone Layer were adopted in 1987 and strengthened in 1990.
The Protocol sets time-tables to phase out CFCs and other ODS and detailed rules governing international trade in ODS and products based on them. Significantly, the developing countries face a problem in this realm as they lack the financial and technological means that developed nations have. They, therefore, have been allowed a ten- year grace– period (upto AD 2010) before full compliance to the Protocol. The provisions of the Protocol came into effect in India from September 17, 1992.
The Indian Scene:
In India, consumption for CFCs and other ODS is less than three gram per capita. It was less than 20g between 1995 and 1997 whereas 300 g is permitted under the Montreal Protocol. It qualifies for technical and financial assistance including transfer of technologies through the mechanism of the fund set up under the aegis of the protocol. The nation has, however, started phasing out ODS ahead of the agreed-upon schedule.
Under the Ozone Depleting Substances (Regulation and Control) Rules, 2000 for phasing out of various ODS besides regulating production, trade, import and export of ODS, use of CFCs in manufacturing products beyond January 1, 2003 is prohibited, except in metered dose inhaler and for other medical purposes. Halons are to be used only for very essential purposes from 2001. ODS such as carbon tetrachloride and methyl chloroform and CFC for metered dose inhalers can be used upto January 1, 2010 only.
The rules provide for compulsory registration of ODS-based products, importers, sellers and stockiest.
Indian scientists have indigenised the technology ‘ for the manufacture of hydro-fluorocarbons (HFCs) which can substitute CFCs in various applications. It had been the close preserve of multinational companies for long. But increasingly, the potential of HFCs as powerful greenhouse gases is becoming known. HFC 13a has, for instance, half the warming potential of the common CFCs. So manufacturers of refrigerators are now opting for simple hydrocarbons like pentane and butane to replace CFCs.
Sector wise Adaptation Necessary:
There is a need to chalk out sectorwise adaptation strategies to combat global warming as after all, it is only identification of specific adaptation options and key constraints and opportunities in each sector that can ensure achievement of concrete goals. What follows is a sectorwise strategy programme along with the policy initiatives necessary and an attempt to identify problems: key mitigation technologies and practices are presented. Some important sectors are taken up for discussion.
There is a need for expanded rainwater harvesting, adoption of water storage and conservation techniques, desalination and efficiency in use of water for irrigation. This requires national water policies that include integrated water resources management and water-related hazards management.
The bottlenecks to such options involve financial and human resources constraints with physical barriers. A synergy has to be developed with other sectors.
Adjustment of planting dates and crop variety grown, crop relocation, improved land soil protection have been identified. More relevant R&D policies, institutional reform, land tenure and reform, capacity-building and crop insurance policies are necessary.
There are, here too, technological and financial constraints and those regarding access to new varieties and markets.
The technologies and practices currently commercially available relate to improved crop and grazing land management, soil carbon storage, restoration of cultivated peaty soils and degraded lands, improved rice cultivation techniques and livestock and manure management to reduce CH4 emissions. There are improved nitrogen fertiliser application techniques to reduce N20 emissions.
Some measures that have proven to be environmentally effective are maintaining of soil carbon content and efficient use of fertilisers and irrigation.
Infrastructure Settlement (coastal zones included):
Adaptation options should involve relocation, construction of seawalls and storm surge barriers, dune reinforcement, creation of marshlands/wetlands as buffer against sea level rise and flooding, and protection of existing natural barriers. Standards and regulations must be evolved to integrate climate change considerations into design, update land-use policies, evolve building codes and insurance.
Apart from financial and technological barriers, there are problems in availability of relocation space even as opportunities exist in integrated policies and management and synergies with sustainable development goals.
The adaptation strategy should involve strengthening of overhead transmission and distribution infrastructure, underground cabling for utilities, energy efficiency, use of renewable sources and reduced dependence on single sources of energy. National energy policies, regulations, and fiscal and financial incentives should encourage use of alternative sources.
There is a need to incorporate concerns of climate change in design standards. Key constraints in this sector are in access to viable alternatives, financial and technological barriers and acceptance of new technologies. Currently, technologies and practices available include improved supply and distribution efficiency, fuel switching from coal to gas, nuclear power, renewable heat and power, combined heat and power, early applications of C02 capture and storage (CCS). Policies, measures and instruments shown to be environmentally effective include reduction of fossil fuel subsidies and taxes or carbon charges on fossil fuels.