10. Natural Cause of Climate change

Refer to this website -http://www.climatechangechallenge.org/Resource%20Centre/Climate-Change/3-what_causes_climate_change.htm.

How does volcanic eruption and solar variations affect the climate?

Identify and describe natural causes of climate change.

What are some natural causes of climate change?

A. Variations in solar output

An increase in magnetic activity results in an increase in solar radiation. The magnetic activity of the sun has a cycle that lasts about 11 years.

An increase in solar radiation is due to an increase in sunspots.

Areas surrounding the sunspots radiate more energy to make up for the cooler sunspot areas. With higher solar radiation, earth’s temperatures will increase.

There was a peak in the number of sunspots in 2000 coincided with high solar activity and global temperatures increased during this period.

B. Volcanic eruptions

When a volcano erupts, large volumes of carbon dioxide, water vapour, sulphur dioxide, dust and ash are released into the atmosphere. Sulphur dioxide reacts with water to form sulphur-based particles in the atmosphere. Together with dust and ash, these particles reflect solar energy back into the space, resulting in global dimming.

Global dimming is the gradual reduction in the amount of sunlight reaching the earth’s surface. Temporarily cools the earth for months or years.

For example, Mount Pinatubo in the Philippines erupted in 1991, released 17 million tonnes of sulphur dioxide into the atmosphere. This lowered temperatures in the northern hemisphere by as much as 0.6°C for as long as two years. Temporary global cooling effect will cease once the volcanic dust and ash settle.

Look at the video below which shows the 5 deadliest volcanoes in history.

Look at how volcanic eruption can cause global cooling resulting in threatening living conditions for the people -

Krakatoa, Indonesia erupted in 1883 and global temperature dropped by average of 2.1 degree Fahrenheit and temperatures returned to normal only in 5 years' time. 36,000 people died.

Mt Tambora, Indonesia erupted in 1915 and 10 times more powerful than Krakatoa's. Some countries in the northern hemisphere experienced snow in June and cause famine as the crops cannot grow. 90,000 people died.

Huaynaputina, Peru erupted in 1600. 2 million people died. Russia experienced the coldest winter in 600 years and 1/3 of its population perished.

Laki, Iceland erupted 1783.- eruption lasted 8 months with millions of death. The haze poisoned 1/4 of Iceland's population and thousand more across Europe. The temperature was coldest on record for North America.