How climate change occurs?

Climate change is a word we often hear nowadays. Climate change is basically a change in the climate system of the planet which we observe in things like temperature, weather, etc. But why this change is happening? What is the reason behind it? Are we human behind this? We will know all the reasons behind climate change further in this blog.

What is climate change?

Climate change refers to change in the weather and it’s pattern. These takes place due to change in climate system of earth. The climate system is basically consisted of 5 components. These 5 components are atmosphere(air), hydrosphere(water), biosphere(living things), cryptosphere(ice and permafrost), Lithosphere(earth’s upper layer).

The energy of each component flows constantly from one component to another. This decides the weather and it's pattern. The average of the weather is known as climate. The energy for this process is mostly received from sun.

All the component receives this energy and also gives-off the energy to outer space. So the balance between the energy received and given away decides how the weather and temperature will change. The balance between this is known as earth’s energy budget.

Earth’s energy budget will have certain change in weather which leads to change in the climate. The change in Earth's energy budget can cause due to internal variable and external forcing. This can be natural or anthropogenic(due to human activities) which leads to change in climate for typical period of some decades known as climate change.

Natural reasons for climate change

Ocean-atmosphere variables:

The ocean-atmosphere variable is a variation in climate for certain specific time cause due to flow of energy between two components of the climate system affecting the earth’s energy budget affecting the global surface temperature.

El Niño–Southern Oscillation:

El Nino Southern oscillation is basically an irregular periodic variation. This variation takes place in sea surface temperature and wind over the tropical eastern pacific Ocean which affects tropical and subtropical climate.

It consists of El Nino which is a warm phase and La Nina which is the cool phase. This can make a really significant change in climate. These phases last several months and occurs in few years.

Pacific decadal Oscillation:

The pacific decadal oscillation is a climate variable where the mid latitude of the pacific basin is the centre of it. As like El Nino, it is also warm and cool surface oscillation. This can affect the climate for years or even decades.

Atlantic Multidecadal Oscillation:

The Atlantic multidecadal oscillation is Atlantic ocean’s climate cycle affecting the sea surface temperature. These takes place because of rainfall pattern, hurricane activity and even fish population.


As we all know the earth gets most of its energy from the sun. But sunlight reaching the earth's surface varies on the motion of the earth. The various changes in earth’s position is known as “Milankovitch Cycles”. There is also change in sun’s sunlight annual. Although the change is very little but the impact of it on the earth is significant.


Volcanoes can be the major reason for the climate change. Volcanoes went erupted(Known as volcanic eruption) releases sulphur Dioxide, dust, ash, and greenhouse gasses which can contribute to climate change.

When a volcano erupts it releases dust and ash in the atmosphere. This dust consists of small particles and large particles which can even reach stratosphere(the second layer of earth’s atmosphere) resulting shading of the sunlight. As the because of shading of the sunlight this will result in temporary cooling of the earth.

The release of sulphur is even more effective in cooling of the earth. Same as ash, sulphur also goes up to stratosphere and mixes with water and becoming sulphuric acid aerosols.The sulphuric acid makes a haze of tiny droplets in the stratosphere that reflects incoming solar radiation, causing cooling of the Earth’s surface. This can stay up to three years in stratosphere and can cause significant cooling worldwide as it moves by wind all over the world.

Volcanic eruption even contributes to global warming as it also releases greenhouse gasses like water vapour and carbon dioxide. Thus when there is any volcanic eruption there is always significant increase in greenhouse gas emission.

Human activities:

As we have seen before, there are many natural reasons behind climate change. But human activities also contributing the climate change. And the biggest reason for human impact on climate change is excessive greenhouse gas emission.

Excessive greenhouse gas emissions are changing the earth’s energy budget which can lead to warming or cooling of the climate system. It has been seen that since from industrial era the climate of the earth is getting warmer and the emission of the greenhouse started increasing after this era started.

The greenhouse gases consist of mainly Carbon Dioxide(CO2), Methane(CH4), Nitrous Oxide(N2O), halocarbons.

Carbon dioxide is increases due to use of fossil fuels for transportation and various purposes. Even deforestation also contribute in CO2 and even decrease the uptake of it by plants.

Methane is also released by natural gas distribution, agriculture and even in landfill.Fertilisers and fossil fuel burning releases nitrogen oxide. Halocarbon like CFC is also produced through refrigerating agent.

Ozone is a greenhouse gas which is produced by chemical reaction of carbon monoxide, hydrocarbon,nitrogen oxide and even gets destroyed by halocarbons.

Water vapour are mostly released naturally but human activities still can influence it as due other greenhouse gas emissions, the earth is getting warmer are releases more water vapour.

The issue created by this is known as radiative forcing. Radiative forcing is a measure of how the energy balance of the Earth-atmosphere system is influenced when factors that affect climate are altered. This results in absorption of outgoing thermal radiation which due to increase in ozone which warms the planet.

Aerosol released result in absorption of solar radiation causing positive and negative forcing but mostly negative forcing which changes the cloud properties.

So since the industrial era the climate change is contributed by human activity resulting warming planet and drastically changing weather. Although, this is not supposed to be good sign for earth.

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