• Climate change refers to the variation in the Earth’s global climate or in regional climates over time. Though it is a natural phenomena which could occur due to natural variations within the earth’s atmosphere (like glaciations, ocean variability, etc.) or natural events (like volcanism, plate tectonics, solar variation, orbital variations, etc.) however, anthropogenic factors have increased its pace at an unprecedented level.

  • Some of the evidences of climatic change provided by IPCC are as below (IPCC & www.un.org and www.cdmindia.com):

  • Rising Temperature and increased warming: The most dramatic change has been in the temperature, with measurement records suggesting that warming by 0.3-0.6 °C has already taken place since the 1860s. Eleven of the last twelve years rank among the warmest years in global surface temperature since 1850. The rate of warming averaged over the last 50 years is nearly twice that for the last 100 years.

  • Carbon build up in the atmosphere: Carbon dioxide is the dominant contributor to current climate change  due to fossil fuel burning. The rest is due to land-use change, especially deforestation, and, to a lesser extent, cement production (Source: IPCC). It is estimated that the atmospheric concentration of Carbon dioxide has increased from a pre-industrial value of 278 parts per million (ppm) to 379 ppm in 2005.

  • Glaciers are melting: Mountain glaciers and snow cover have declined in both hemispheres, and have contributed to sea level rise by 0.77 millimeters a year on an average from 1993 to 2003. Further, snow cover is decreasing in most regions, particularly in spring. The maximum extent of frozen ground in the winter/spring season has decreased by about 7 per cent in the Northern Hemisphere since 1900.

  • Arctic is warming: Average Arctic temperatures increased at almost twice the global average rate in the past 100 years. Satellite data since 1978 shows that the average Arctic sea ice extent has shrunk by 2.7 per cent per decade.

  • More water, but not everywhere: More precipitation has been observed in the eastern parts of the globe whereas southern side has experienced more drying and  intense droughts.

  • The effects of global warming are difficult to quantify because of the complicated relationships between air temperature, precipitation quantity and pattern, vegetative cover and soil moisture. However, it is likely to harm humanity in the following ways:

  • Over the next hundred years, the earth's surface temperature is projected to increase by 1.4 to 5.8 °C. As a result, large quantities of water locked in the polar ice caps and glaciers will be released as a consequence of warming. This, together with an increase in the thermal expansion of the oceans, will make the global mean sea level rise by 9 cm to 88 cm.

  • A rise in sea level could inundate and erode coastal areas, increase flooding and salt-water intrusion; this will affect coastal agriculture, fisheries and aquaculture, freshwater resources, human settlements and tourism.

  • Further, higher summer temperatures will increase the demand for energy for space cooling. The frequency and duration of heat waves is expected to increase, which, combined with greater humidity and urban air pollution, will cause a greater number of heat related illness and deaths.

  • The availability of water in the rivers of India, Australia, Southern Africa, South America, Europe and the Middle East is expected to decrease. Salt-water intrusion from rising sea levels will further reduce the quality and quantity of freshwater supplies.

  • By the 2080, substantial dieback of tropical forests and grasslands is predicted to occur, particularly in parts of South America and Africa. Environmental damage such as overgrazed rangeland, deforested mountain sides, and denuded agricultural soils means that nature will be more vulnerable to changes in climate.

  • Most of the world's endangered species,  around 25 per cent of mammals and 12 per cent of birds may become extinct over the next few decades as warmer conditions alter the forests, wetlands, and rangelands they depend on.

  • A general reduction is expected in potential crop yields in most tropical and sub-tropical regions. Mid-continental areas, such as, the United States' "grain belt" and vast areas of Asia are likely to dry. Such changes could cause disruptions in food supply.

  • World's vast human population, much of it poor, is vulnerable to climate stress as millions live in dangerous places or floodplains  or exposed hillsides.

  • Further, higher temperatures are expected to expand the range of some dangerous "vector-borne" diseases, such as malaria, which already kills one million people annually, most of them children.

National Action Plan on Climate Change-2008