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CAUSES OF CLIMATE CHANGE

 What changed  Earth's Climate  Before Industrialization ? 

 Dr. Abhinandan Bhardwaj PhD

Climate Change is nothing new to Earth. Geologic data from past climates proves that Earth had experienced many periods of climate changes which resulted in several Ice ages  and warm periods.  Earth's Climate change prior to industrialization was largely due to the following factors: 
 

Changes in the Earth's orbit around the Sun: Mulitin Milankovitch was the first serbian Mathematician ( 1879-1958) who observed and wrote first theory proving that Earth has experienced various periods of Ice Age during its past. Nasa's latest research on the subject matter had proved his theory. According to his theory changes in Earth's orbit and its tilt were the most important factors which lead the Earth to Ice Age in the past.

Changes in the sun's intensity: Our Sun is a   dying star. Sun  continuously experiences  internal changes, these changes quite often affect the intensity of the sunlight that falls on Earth. The increase or decrease in Sun light intensity can cause warming or cooling effect on Earth. According to latest research from NASA the Sun's light experienced  slight weaker intensity between (1400-1700). This reduction in sun's intensity was the probable reason which resulted in cooling of Europe and North America, that period between 1400 and 1700 is also know as "little Ice Age" .

Volcanic Activity: As earth has experienced much more volcanic activity in the past as it experiences now, volcanism has always played a major role in shaping Earth's climate.  Volcanic activity releases large amounts of aerosols and CO2 into the atmosphere, both of which   can impact the earth's climate. Earth has experienced changes in its climate in the past due to intense volcanic activity in various parts of Earth.

Effects of Aerosols: Volcanic activity releases vast amounts of  aerosols in the atmosphere. Aerosols blocks the sunlight and blocked sun light can cause that region of earth to cool down. But as aerosols do not stay for long in the atmosphere so they only causes  short term cooling. According to USGS, the eruption of the Tambora Volcano in Indonesia in 1815 lowered global temperatures by as much as 5F.
 

Effects of Carbon dioxide emissions: Carbon dioxide is a major Greenhouse gas. Volcanoes emit CO2 which raises the temperature due to greenhouse effect. Historical geologic evidence suggests that CO2 levels and temperatures were considerably higher than present in the past.  CO2  released from ancient volcanic activity had definitive role in raising the Earth's Temperature, but recent studies has shown that present human activities emits 130 times more CO2 than volcanic activity in the past and is a major contributing factor towards present trend of Global Warming.


Greenhouse gas concentrations: Changes in greenhouse gas concentrations on Earth can cause the heating or cooling of the Earth's surface. When global temperatures become warmer, carbon dioxide is released from the oceans. When changes in the Earth's orbit trigger a warm (or interglacial) period, increasing concentrations of carbon dioxide may amplify the warming by enhancing the greenhouse effect. When temperatures become cooler, CO2 enters the ocean and contributes to additional cooling. According to IPCC report, during the last 650,000 years, CO2 levels had impacted various glacial cycles, as CO2 levels were high during warm interglacial periods, and CO2 levels were low during cool glacial periods.

Periods of Glaciations or Ice Ages in Earth's History:

Ice Age is a long-term drop in global temperatures and results in extension of continental ice sheets. According to Earth Scientists , during Earth's  4.5 billion year history, Earth  has experienced about five major ice ages.

The first one is called  the Huronian glaciation which occured around 2.3 to 2 billion years age. The second period of glaciation is called  Sturtian/Marinoan glaciation which happened around 710 to 640 million years back, The third glaciation is called  Andean-Saharan glaciation  which took place about 460 to 430 million years back, the Karoo glaciation happened around 350 to 260 millions years back and the most recent Ice Age, which is still going on  started about 40  million years back.   Generally ice ages lasts about  45,000 and 100,000 years and during these periods continental sheets expands and most of the earth gets covered by ice.

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