Climatic Changes

 

Introduction to Climate Change

What is climate change? 

Greenhouse gases (including carbon dioxide and methane) trap heat in the earth’s atmosphere. Without them, too much heat would escape and earth’s surface would freeze. However, increasing the concentration of greenhouse gases in the atmosphere causes earth’s surface to heat more and the climate to change. 

The Intergovernmental Panel on Climate Change (IPCC) was set up in 1988 and is the international body for assessing the science related to climate change. 

The following are key facts from the Intergovernmental Panel on Climate Change’s 

• Anthropogenic greenhouse gas emissions have increased since the pre-industrial era due to population growth and economic growth;
• Atmospheric concentrations of carbon dioxide, methane and nitrous oxide are now higher than the last 800,000 years (they have increased from a preindustrial level of about 275 ppm of carbon dioxide to about 400 ppm of carbon dioxide);
• Global land and ocean surface temperature rose 0.85°C between 1880 and 2012;
• Global mean sea level rose by 0.19m between 1901 and 2010;
• Continued emission of greenhouse gases will cause further warming and changes in the climate system with increasing impacts for people and ecosystems; and 
• Limiting climate change will require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks. 

Causes of climate change

The causes of climate change can be divided into two categories - Natural and man made

Natural causes

There are a number of natural factors responsible for climate change. Some of the important factors are continental drift, volcanoes, ocean currents and the earth's tilt.

• Continental drift

The continents we see today were formed when the landmass began gradually drifting apart, millions of years back. This drift changed the position of water bodies of the landmass and the flow of ocean currents and winds. These changes affect the climate. This drift of the continents continues even today.

• Volcanoes

When a volcano erupts it throws out large volumes of sulphur dioxide (SO2), water vapour, dust, and ash into the atmosphere. Although the volcanic activity may last only a few days, yet the large volumes of gases and ash can influence climatic patterns for years. The gases and dust particles partially block the incoming rays of the sun, leading to cooling.

• The earth's tilt

The earth is tilted at an angle of 23.5° to the perpendicular plane of its orbital path. Changes in the tilt of the earth affect the severity of the seasons. More tilt means warmer summers and colder winters; less tilt means cooler summers and milder winters.

• Ocean currents

The oceans are a major component of the climate system. They cover about 71% of the Earth. The oceans absorb the sun's radiation about twice as much as the atmosphere

Human causes

• Greenhouse effect

The earth receives energy from the sun, which warms the earth’s surface. As this energy passes through the atmosphere, a certain percentage (about 30) gets scattered. Some part of this energy is reflected back into the atmosphere from the land and ocean surface. Certain gases in the atmosphere form a sort of blanket around the earth and absorb some of this energy. These gases like carbon dioxide, methane, and nitrous oxide, along with water vapour, comprise less than one per cent of the atmosphere. They are called 'greenhouse gases'. Just as the glass of the greenhouse prevents the radiation of excess energy, this ‘gas blanket’ absorbs some of the energy emitted by the earth and maintains keeps temperature levels. Hence it is named ‘greenhouse effect’.

• Agriculture

The increasing population has resulted in increased demand for food. This results in pressure on natural resources. Climate change will affect agricultural yield directly because of alterations in temperature and rainfall, and indirectly through changes in soil quality, pests, and diseases. It is said that the yield of cereals is expected to decline in India. Extreme weather conditions such as high temperature, heavy rainfall, floods, droughts, etc. will also affect crop production.

• Weather

A warmer climate will change rainfall patterns, lead to increased droughts and floods, cause melting of glaciers and polar ice sheets, and result in increased sea- level rise. An increase in the number of cyclones and hurricanes over the last few years has been attributed to changes in temperature.

• Sea level rise

One of the outcome of climate change is the rising sea level. The heating of oceans, and melting of glaciers and polar ice sheets, is predicted to raise the average sea level by about half a metre over the next century. Sea-level rise could have a number of physical impacts on coastal areas, including loss of land due to inundation and erosion, increased flooding, and salt-water intrusion. These could adversely affect coastal agriculture, drinking water resources, fisheries, human settlements, and health.

Preventive measures

Reduction in the use of non-renewable sources of energy (fossil fuels)

Increased use of renewable sources like solar, wind energy etc.

Save trees and grow more trees

Avoid indiscriminate use of non degradable materials like plastics