A recent study has found that global climate changes affect the carbon emissions from organic matter breakdown in streams and rivers. But the emission rate is not as adversely affected by temperature changes as has been predicted by metabolic theory.
The study indicates that a 1-degree to 4-degree Celsius rise in water temperature increases the average breakdown rate by 5 percent to 21 percent and not 10 percent to 45 percent.
Though streams and rivers make up only 3 percent of the Earth’s land surface, they play a major role in contributing to the carbon cycle. Microbes and invertebrates in the water consume organic matter such as leaves. Some of this matter contributes to the growth of the organisms, some small-pieced litter flows downstream and some is emitted into the atmosphere in the form of carbon dioxide through respiration. Carbon dioxide is a greenhouse gas. It contributes to global warming and ocean acidification.
As water in these water bodies become warmer, the process of litter decay speeds up. This in turn means more carbon emission and thus, global warming. Hence, this is a cycle. But the study states that litter decay is not quite as fast as expected based on metabolic theory.
The temperature of water around the globe is rising at an annual rate of about 0.01 degrees to 0.1 degrees Celsius due to changes in climate and land use.