Someone said that volcanic eruptions have no impact on climate change, well I'd be a bit more inquisitive about that.
And quite right, you should be inquisitive.
While CO2 emitted from Volcanoes is low-ish (usually stated as between 1% and 2% of global CO2 emissions), that is most certainly glossing over many other aspects.
Volcanoes don't
emit a lot of CO2 because of their nature, there is no free carbon to burn nor will CO2 stored within a volcano. You are unlikely to have coal, oil, gas or peat sitting in the layer of earth over a volcanic fissure, it will have burnt off long ago. Lava is mostly a kind of sand product (Silicon based), no carbon involved.
However anything that is burnt in the lava flow is probably carbon based and also sea water when heated will release its dissolved CO2.
But next there is a secondary effect caused by the debris emitted from the volcano, the dust reduces sunlight over a large area, this reduces the CO2 absorption by plants on land and plankton at sea. Apart from the local vicinity the amount of light reduction is small but it is amplified by the very large area it covers. There is a slight offset which is caused by the sea cooling with reduced sunlight which reduces the CO2 naturally released by seawater but this is small compared to the loss of CO2 absorption by plankton.
There are probably more effects caused by Sulpher Dioxide and various other gases (especially acids) emitted by volcanos but that is beyond my knowledge, I've only looked at CO2 which is one of many greenhouse gases.
