Causes of Climate Change and Its Effects

The general conditions of an area which are usually there or the weather conditions for a longer period in a particular area are referred to as the climate of that region.

The climate varies according to the locations. It is changing now over the years due to some human activities and also naturally. In some places, it may lead to the extinction of certain species.

Table of Contents

Change in Climate
Effects of Climate Change
Climate in Recent Past
Astronomical Causes
Volcanism
Greenhouse Effect
6.1  Concentration of GHGs
6.2  Effects of GHGs
Global Warming
Steps Taken to Reduce

The average weather of a place for many years is called climate. Climate takes millions of years to change whereas weather can change in a couple of hours. Our planet has seen multiple climatic variations since its birth.

Change in Climate

The climate of our surroundings in which we live has been present for almost the last 10,000 years with minor fluctuations.
Glacial and Interglacial periods are there. High altitudes and high latitudes show features and advances of glaciers.
The occurrence of warm and cold periods can also be seen from the examples of sediment deposits in glacial lakes.
The rings found in the trees also reveal clues about wet and dry periods.
All this evidence suggests that change has occurred for many years and it is a natural and continuous process.
India has also a history of alternate dry and wet periods. Some archeological findings show that the desert of Rajasthan has a wet and cool climate around 8,000 B.C. This region was also a center of Harappan civilization from 2,000 to 1700 B.C.From the viewpoint of the geological past, it has been seen that through the Cambrian, Ordovician and Silurian periods, the earth was warm about 500-300 million years ago.
Glacial and interglacial periods occurred during the Pleistocene epoch. The last and major glacial period was about 18000 years ago.
The interglacial period at present started about 10,000 years ago.

Some Effects of Climate Change

The rise in global temperature
The rise in sea level
Shrinking of ice sheets
Warming of oceans
Declining of ice at Arctic Sea
The retreat of the glaciers
Decreasing snow cover
Acidification of Ocean
Extreme and disastrous natural events

Climate in Recent Past

The Climate in the Recent Past

Variability is like a feature of the climate which occurs all the time.
Extreme weather events were witnessed by the nineties decade of the last century.
During the 1990s, the world recorded the warmest temperature of the century and some of the worst floods.
An example of such variability is from 1967-1977, when the worst devastating drought occurred in the Sahel region, the south of the Sahara desert.
A severe drought has also been seen in the southwestern Great Plains of the United States during the 1930s. It is described as a dust bowl.

Records of crop yield or crop failures, floods, and migration of people also tell about the changes occurring in the climate and its effect in the past years.
Europe has witnessed significant episodes of warm, wet, cold, and dry periods during the tenth and eleventh periods when the Vikings settled in Greenland.
From 1550 to about 1850, there was a “Little Ice Age” in Europe.
But during 1885-1940, an upward trend was shown in the world temperature.
The rate of increase in temperature slowed down after 1940.

Astronomical Causes

Causes of Climate Change: Astronomical Causes

There are many causes of climate change. It can be divided into multiple heads-

Astronomical causes can be referred to as changes in solar output which is associated with sunspot activities.
Sunspots are dark patches on the sun that can increase and decrease cyclically.
Due to the increase in the number of sunspots, the weather is cooler and wetter and there occurs great storminess. If there is a decrease in the number of sunspots, it is associated with the warm and drier conditions on Earth. But these statements are only according to the meteorologists, it is not statically significant yet.
Milankovitch oscillations is also an astronomical theory, which describes the characteristics of the cycles of variations occurring in the earth’s orbital around the sun. The wobbling of the earth and changes in the earth’s axial tilt is also described in it.
All these effects of Milankovitch oscillations theory alter the insolation from the sun received by the earth, which results in the change of the climate.

Causes of Climate Change: Volcanism

Climate change can also be done by Volcanism. A lot of aerosols are thrown out in the atmosphere during the volcanic eruptions.
These aerosols remain in the atmosphere for a considerable time which then reduces the sun’s radiation reaching the Earth’s surface.
An example of this type of climate change is Pinatoba and El Cion volcanic eruptions, due to which the average temperature of Earth fell to some extent for some years.

Greenhouse Effect

Causes of Climate Change: Greenhouse Effect

The most important anthropogenic effect on climate change is the increasing concentration of greenhouse gas in the atmosphere which is likely to cause global warming.
Due to the presence of greenhouse gases like carbon dioxide, Chlorofluorocarbons, etc the atmosphere behaves like a greenhouse, that’s why they are called greenhouse gases.
Some of the solar radiation that reaches the earth is trapped due to the greenhouse gases present on the earth, thus the heating due to this reason is called the Greenhouse Effect.
A greenhouse is a place used in cold areas for preserving heat. It is made up of glass, and it allows the radiation coming from the sun and prevents the longwave radiation of the incoming sun rays, which causes the temperature inside the glasshouse to be warmer than outside.
Another example of the greenhouse effect is that we feel warmer inside a bus or a car where windows and doors are closed.
The gases which absorb the longwave radiation of the sun are known as greenhouse gases.

The Concentration of Greenhouse Gases (GHGs)

Some of the primary concerns of Greenhouse gases are Carbon Dioxides (CO2), Chlorofluorocarbons (CFCs), Methane (CH4), Nitrous Oxide (N2O), and Ozone (O3).
Other gases like Nitric Oxide (NO) and carbon monoxide (CO) easily react with greenhouse gases and affect their concentration in the atmosphere.
Carbon Dioxide is the gas present in abundance in the atmosphere.

Effects of Greenhouse Gases

The factors that describe the effectiveness of a greenhouse gas molecule are –

(i) Magnitude of the increase in its concentration,

(ii) Lifetime of its presence in the atmosphere,

(iii) Wavelength of radiation that a gas absorbs.

The highly effective gas of the GHGs present in the atmosphere is Chlorofluorocarbons (CFCs).
Ozone which when present in the stratosphere absorbs violet radiation is very effective in absorbing the terrestrial radiation when present in the lower troposphere.
Another point worth noting is that the more time the greenhouse gas molecule remains in the atmosphere, the longer it will take for the earth’s atmosphere to recover from the climatic changes.

Carbon Dioxide is the greenhouse gas that is present in the largest concentration in the atmosphere. It comes mainly from the combustion of fossil fuels (oil, gas, and coal). Forests and oceans act like sinks of carbon dioxide. Forests absorb carbon dioxide and use it for their growth.
So, deforestation due to changes in land use can cause greater harm and increase the concentration of CO2 in the atmosphere.
The time required to consume the carbon dioxide by the sinks is about 20-50 years. But it is rising at about 0.5 per cent annually.
Chlorofluorocarbons (CFCs) are nothing but the results of human activities.

Ozone that occurs in the stratosphere is formed by ultraviolet rays. Ultraviolet rays convert oxygen into ozone. The CFCs drifted into the stratosphere thus destroying the atmosphere. Large depletion has been seen in Antarctica over the years. The ‘ozone hole’ is a term given to the depletion of ozone concentration.

Global Warming

The Greenhouse effect is a collective term said to the processes that warm the atmosphere and lead to Global Warming.
Global Warming is caused by GHGs which entraps the heat on the earth.
Due to Global Warming, the earth is turning into a Greenhouse.

Steps Taken

Steps Taken to Reduce Greenhouse Emissions

Important initiatives are taken to control the Greenhouse Emissions into the atmosphere.In 1997, the Kyoto Protocol was an important one considering greenhouse emissions. This protocol came into effect in 2005. It bounds different countries to reduce their emissions of greenhouse gases in the atmosphere.