My understanding of green house gases is that, these are the gases formed in nature. But when their proportion in the atmosphere raises, they prevent the deflection of suns heat from the earth surface back into space. So the suns light gets trapped and rises the temperature.
Now there are many such
types of gases like water vapor, carbon dioxide, n2o etc. But in general all of them would be kept in limits by nature if not disturbed by man. So the fungi which releases these gases also would not be so harmful to the earth surface than we humans contribute to artificially.
