A brief overview of climate change and aquatic environments with emphasis on the Caspian Sea

Climate change means any distinct change in patterns expected for climate which occurs in a long term and a particular region or the entire global climate. Increasing greenhouse gases in the atmosphere will keep the sun warm and increase the Earth's temperature. Therefore, recognizing greenhouse gas sources plays an important role in controlling adverse climate change conditions. Aquatic environments are important sources of greenhouse gas emissions, such as carbon dioxide, methane and nitrous oxide. The global warming increases the emission of methane gas from sea bottom to the atmosphere. Another event in aquatic environments related to climate change, is the attaching/adhering of biofouling species on the body of boats and ships which is followed by the high frictional resistance, due to generated roughness, which leads to an increase of weight and subsequent potential speed reduction and it may also entail a need for heavier and less energetically efficient machinery. The increase in fuel consumption can be up to 40% and produce more carbon dioxide. In rice fields (rice combined with fish), fish perturbation of the soil entails water turbidity due to resuspension of sediment granules and a higher level of methane gas emission. Thus, the purpose of this research is to briefly review the role of aquatic environments and their components, in increasing and reducing some greenhouse gases, as well as sources of these gases water ecosystems with emphases on climate change effects on the Caspian Sea based on various researches.