Natural changes: Volcanic Activity

Question 1

overview

Answer 1

This is a short term change. A volcanic eruption such as Mount Merapi in Indonesia, returns carbon trapped in rocks deep in the Earth’s crust for millions of years back into the atmosphere.

In the Palaeozoic era (542-251 million years ago) volcanoes were much more active than they are today. A vast amount of CO2 was emitted into the atmosphere.

Question 2

present day

Answer 2

the volume emitted is 130-380 million tonnes of CO2 per year which is much less than the 30 billion tonnes emitted by human activity. There is however, potential for a very large eruption which could disrupt the carbon cycle significantly e.g. if the super volcano Yellowstone erupted.

Also, as plates move at destructive plate boundaries they collide and the oceanic crust sinks. The crust melts under heat and pressure. When volcanoes erupt they vent the gas to the atmosphere as CO2 and cover the land with fresh silicate rock, to begin the cycle again.

Question 3

negative feedback

Answer 3

volcanic eruptions can also have a negative feedback. Sulphur dioxide emitted from volcanoes, which, when converted to sulphuric acid in the atmosphere, forms droplets which reflect radiation from the Sun back into space (albedo) cooling the Earth’s lower atmosphere.