Greenhouse gases such as carbon dioxide (C0₂) , methane (CH₄) and nitrous oxide (N₂0) trap heat in the atmosphere. Lakes can play an important role in regulating these gases at global scales. Total carbon uptake by lakes is of the same magnitude as that of oceans or forests, despite lakes occupying <1% of the Earth's area. In lakes, GHGs are mostly produced in the bottom sediment as products of organic matter decomposition. Geothermal activities - of importance to some Rotorua lakes - may also contribute substantial amounts of C0₂ and CH₄.