Do volcanoes contribute to climate change and global warming?

Interestingly, volcanoes can have both a cooling and warming effect on the planet’s climate.

When volcanoes erupt, they emit a mixture of gases and particles into the air. Some of these, such as ash and sulphur dioxide, have a cooling effect, because they (or the substances they result in) reflect sunlight away from the earth. Others, such as CO2, cause global warming by adding to the greenhouse effect.

The cooling influence is particularly marked in the case of large eruptions able to blast sun-blocking particles all the way up to the stratosphere – such as Mount Pinatubo in 1991, which caused a significant dip in global temperatures in the following two years.

As for greenhouse gases, underwater and land-based volcanoes are estimated to release, in total, around 100–300 million tonnes of CO2 each year, according to some studies. That’s a large quantity, but only around 1% of the amount that humans release from burning fossil fuel alone.

In general, the cooling influence of a volcano will dominate for the period immediately after the eruption but the warming impact will last much longer. For instance, a very large volcano in 2011 may significantly reduce temperatures in 2012 but slightly warm them in 2100.

All aspects considered, it can be said that the contribution to the present day atmospheric CO2 loading from volcanic emissions is relatively insignificant.