Climate change Indicators: Greenhouse Gases

Climate Feedback – Greenhouse Gases and Global Temperatures  

Introduction:  

Climate is the weather condition of an area for a long period of time. There is a difference between climate and weather. The condition of atmosphere at a particular time is called weather. Weather conditions can change from day to day whereas climate is the pattern that lasts for a longer time.  

The rainfall, sunshine, wind, humidity, and temperature are the factors that describe the climate at a location. Changes in the weather may occur suddenly and noticeably whereas changes in the climate take a long time and are therefore less noticeable. There are changes in the Earth’s climate and all living things are adapted naturally to this change. 

But the last 15 – 20 years climate change has been taking place very rapidly and for some plant and animal species it has been very hard to adapt to changed climate. It is said that human activities are responsible for the speed at which this change has taken place. 

Studies have shown that human activity may cause climate change but there are natural factors that are also responsible for the climate change. 

Factors affecting climate change 

Climate change is due to the natural and man-made changes. Natural changes are continental drift, Earth’s orbit and the tilt of its axis, movement of tectonic plates, impact of asteroids, the sun’s cycle, volcanic eruptions, and man-made changes are human activities.  

Natural causes of climate change: 

Continental drift 

Today the continents we see were formed when the landmass began slowly moving apart, millions of years back. This movement changed the position of water bodies of the landmass and the flow of ocean currents and winds. These changes affect the climate. Even today this drift of the continents continues. 

Volcanoes: 

Volcanic eruptions throw out large volumes of sulphur dioxide (SO2), water vapor, dust, and ash into the atmosphere. Though volcanic activity lasts only for a few days, but the large volumes of gases and ash can impact climatic patterns for years. The gases and dust particles partially block the incoming sun rays that lead to cooling. 

The Earth’s tilt 

The Earth is tilted at an angle of 23.5° to the perpendicular plane of its orbital path. The severity of the seasons is caused by the changes in the tilt of the Earth. If the tilt is more, it means warmer summers and cold winters, whereas less tilt means cooler summers and mild winters. 

Ocean currents 

The major component of the climate system is oceans. About 71% of the Earth is covered by oceans.  

Man-made causes of climate change 

Human activity: 

Human activities such as the burning of fossil fuels have increased the concentration of greenhouse gases in the Earth’s atmosphere that causes the warming of the planet. Without human intervention, the natural system would push our planet toward a cooling period. 

Global warming trend was observed since the middle of 20th century due to the human expansion of the “greenhouse effect”. It results when the atmosphere absorbs heat radiating from the Earth toward space. 

Human activity has led to the increase in greenhouse gases in the atmosphere. One of the causes is the industrial revolution. It leads to holding more heat and this causes an increase in the surface temperatures. Atmospheric aerosols cause climate change by spreading and absorbing infrared and solar radiation. Aerosol can also cause a change in the microphysical and chemical properties of clouds. Deforestation has increased the amount of sunlight reflected from the ground back into space. 

Greenhouse Effect: 

We know that Earth receives energy from the sun that warms the surface of the Earth. When this energy goes through the atmosphere, some percentage of energy gets scattered, and some portion of energy gets reflected to the atmosphere from the ground and the surface of the ocean. Some gases in the atmosphere form a blanket around the Earth and absorb a certain amount of this energy. The gases like CO₂, CH₄, N₂O and water vapor consists of less than 1% of the atmosphere. These gases are called greenhouse gases. Greenhouse gas means an atmospheric gaseous substance that can adequately absorb infrared radiation. Greenhouse gases got its name from the typical greenhouse used during plant cultivation. Greenhouses can control temperature because of the transparent glasses that help in the entry of sunlight. This sunlight then warms the air present inside the greenhouse but does and allows the warm air to get out. 

The greenhouse effect was first identified by a French scientist, Jean-Baptiste Fourier. He noticed the similarity in the activity in the atmosphere and in a greenhouse. The blanket of greenhouse gases has been there since the creation of the Earth. But because of increased human activities, large amount of greenhouse gases is released into the atmosphere that leads to the increased thickness of the blanket and it upsets the ‘natural greenhouse effect.’ 

Let us see gases that contribute to the greenhouse effect: 

Water vapor: 

Water vapor is the most abundant greenhouse gas, but it acts as feedback to the climate. Water vapor increases as the Earth’s atmosphere warms, and may form clouds and precipitation, making these important feedback mechanisms to the greenhouse effect. 

Carbon dioxide (CO₂): 

Carbon dioxide is present in less amount but is a very important component of the atmosphere. Carbon dioxide released through natural activities such as respiration, volcano eruptions, through human activities like deforestation, changes in land use, and burning fossil fuels. Atmospheric CO₂ has increased by 48% since the industrial revolution started. This has a strong effect on climate change. The amount of CO₂ in the atmosphere indirectly affects the concentration of ozone in the stratosphere. 

Methane (CH₄): 

Methane gas is produced both by natural sources and human activities, such as the decomposition of wastes in landfills, agriculture, rice cultivation, ruminant digestion and manure management associated with domestic livestock. On a molecular basis, methane is a more active greenhouse gas than carbon dioxide but is much less abundant in the atmosphere. 

Nitrous oxide (N₂O):  

Nitrous oxide is a powerful greenhouse gas. It is produced by soil cultivation practices, especially using commercial and organic fertilizers, combustion of fossil fuels, production of nitric acid, and burning of biomass. 

Chlorofluorocarbons (CFCs):  

It is a synthetic compound and is mainly used in industrial production in several applications. It absorbs infrared radiation and indirectly affects the concentration of ozone in the stratosphere. Hence it is largely regulated in production and release to the atmosphere by international agreement because of its ability to contribute to the destruction of the ozone layer.  

Ozone(O₃): 

Ozone is produced by the chemical reaction that involves oxygen. Ozone helps in the absorption of infrared and ultraviolet radiation. 

Sulphur dioxide (SO₂): 

It is released into the atmosphere by volcanic eruptions, burning coal and biomass. It forms aerosols that scatter solar radiation. 

Human contribution to greenhouse gases: 

Carbon dioxide is released by burning fuels such as coal, oil, natural gas and, by destroying forests, the carbon stored in the trees is released as carbon dioxide into the atmosphere. Increasing agricultural activities, changes in land-use patterns, and other sources lead to rising levels of methane (CH₄) and nitrous oxide (N₂O). Industrial processes also release artificial and new greenhouse gases such as CFCs (chlorofluorocarbons), whereas automobile exhaust leads to the generation of ozone. The subsequent greater greenhouse effect is more commonly called as global warming or climate change.  

Effect of Climate Change: 

It is very difficult to predict the consequences of changing the natural atmospheric greenhouse, but some effects that can be noticed are as follows: 

Change in weather 

On an average, Earth will become warmer, and some parts may be comfortable with warmer temperatures, whereas others may not. 

Overall warmer conditions may probably lead to more evaporation and precipitation, but individual parts will vary like some regions may become wet and other regions may remain dry. 

Rise in Sea Level 

A strong greenhouse effect will warm the ocean and partly melt glaciers and ice sheets, that will lead to the increasing sea level. Ocean water will also expand if it warms, resulting in the rise of sea level. 

Effect on food production 

The demand for food is increasing due to the increase in the population. This increases the pressure on natural resources. The effect of climate change will affect agricultural yield directly due to changes in temperature and rainfall, and indirectly through changes in soil quality, pests, and diseases. Severe weather conditions like high temperature, heavy rainfall, floods, droughts, etc., will also affect crop production. 

Effect on Biological Cycles 

Due to higher temperatures, biological cycles will be affected. The most affected biological cycle is water cycle because the atmosphere becomes somewhat warmer than it was previously, due to this, the amount of evaporation is also expected to rise, and higher amount of precipitation will be experienced. On the other hand, global warming also causes the loss of coastal areas and other habitats that result in the decrease of organism population and diversity. 

Effect on health: 

The effect of global warming may directly affect human health by increasing cases of heat-related mortality, dehydration, spread of infectious diseases, malnutrition, and damage to public health infrastructure. 

Forests and wildlife 

Change in climate directly affects the plants and animals in the natural environment. Plants and animals are very sensitive to climate change. If the rate of climate change continues to increase, various species of plants and animals could become extinct. 

Rising temperature, ocean acidification, and lack of oxygen cause damage to marine ecosystems such as fish and coral reefs. 

Preventive measures: 

• Reduce the use of non-renewable energy sources (fossil fuels). 
• Increase the use of renewable sources such as solar, wind energy, etc. 
• Avoid cutting trees and grow more trees. 
• Avoid random use of non-degradable materials such as plastics. 

Summary

• Climate is the weather conditions of an era for a long period of time.
• The condition of atmosphere at a particular time is called weather.
• Climate change is due to natural and man- made changes.
• Natural changes are continental drift, Earth’s orbit and tilt of its axis, movement of tectonic plates, impact of asteroids, the sun’s cycle, volcanic eruptions , and man-made changes are human activities.
• The greenhouse effect was first identified by a french scientist, Jean-Baptiste Fourier.
• A greenhouse gas means an atmospheric gaseous substance that can adequately absorb infrared radiation.
• Change in weather, rise in sea level, effect on health, effect on wildlife and forests , effect on biological cycles, effect on food production is some of the effects of climate.