Changing Climate: Natural Causes

What are these dark spots called?

• Sundots

• Sunspots

Which of the following causes a global increase in temperatures?

• Variations in solar output

• Volcanic eruptions

Answer explanation

Volcanic eruptions cause global cooling, not warming.

During periods of intense solar activity, the number of sunspots increases, resulting in ________ solar radiation.

Answer explanation

This is because the areas surrounding the sunspots radiate more energy, which compensates for the lower temperatures of the sunspot areas.

Describe the example for the factor: variations in solar output.

Answer explanation

The number of sunspots rises and falls with an approximate 11 year cycle which corresponds to earth's cycle of high and low global temperatures. For example, in there was a peak in sunspots in 2000, which matched a rise in global temperatures.

When a volcano erupts, large volumes of carbon dioxide, water vapour, sulfur dioxide, dust and ash are released into the atmosphere. Which of the above will reflect solar energy into space?

• ash

• dust

• carbon dioxide

• sulfur particles

Answer explanation

Ash, dust and sulfur particles (sulfur reacts with water) remain in the atmosphere and even spread around Earth. They reflect solar energy into space and result in a cooling influence on regional and global temperatures.

Describe the example for the factor: volcanic eruptions.

Answer explanation

For example, during the 1991 eruption of Mt Pinatubo, Philippines, 17 million tonnes of sulfur dioxide were released into the atmosphere, causing temperatures to be lowered by about 0.6 $\degree$ C