![]() ![]() These reservoirs are potentially large enough to raise atmospheric methane concentrations if released during the melting of glacial ice and permafrost. Gas hydrates are solids, usually methane gas, frozen in a cage with water, and extremely susceptible to pressure and temperature changes in the ocean. By the time the ice disappeared completely, some thousands of years later, methane emissions had stabilized." says Dessandier.Īrctic methane reservoirs consist of gas hydrates and free gas. "The isotopic record showed that as the ice sheet melted and pressure on the seafloor lessened during the Eemian, methane was released in violent spurts, slow seeps, or a combination of both. Also, if methane was released for longer periods of time, the archived shells get an overgrowth of carbonate which in itself also can be tested for isotopes. Isotopes are taken up and stored in the shells of tiny organisms called foraminifera and in that way get archived in the sediments for thousands of years as the tiny creatures die. This means that the composition of certain isotopes is correlated to the environmental changes - such as temperature or amount of methane in the water column or within the sediment. Different isotopes of the same element have different weight and interact with other chemical elements in the environment in specific ways. Isotopes are variations of chemical elements, such as carbon and oxygen, in this case. The study is based on measurements of different isotopes found in sediment cores collected from the Arctic Ocean. Seeing thousands of years of methane release in tiny shells We have found that the similarities between the events of both Holocene and Eemian deglaciation advocate for a common driver for the episodic release of geological methane - the retreat of ice sheets." says researcher Pierre-Antoine Dessandier, who conducted this study as a postdoctoral fellow at CAGE Centre for Arctic Gas Hydrate Environment and Climate at UiT The Arctic University of Norway. "In our study, we expand the geological history of past Arctic methane release to the next to last interglacial, the so-called Eemian period. A most recent study in Geology looks even further into the past, some 125,000 years ago, and contributes to the conclusion: Melting of the Arctic ice sheets drives the release of the potent greenhouse gas methane from the ocean floor. Several studies also show that the most recent deglaciation, Holocene (approximately 21ka-15ka ago) of the Barents Sea has had a huge impact on the release of methane into the water. These giants have been consistently waxing and waning, exerting, and lifting pressure from the ocean floor. An ice age has constant glaciations and deglaciations, with ice sheets pulsating with the rhythm of changing climate. reservoir), ice phenology, and the distribution of productivity‐related predictor variables such as total phosphorus, DOC, and chlorophyll a. Additionally, more accurate upscaling efforts require improved global information about waterbody surface area, waterbody type (lake vs. First, we need more methane emission measurements in small reservoirs, large lakes, and both natural and artificial ponds. Finally, we identify several knowledge gaps that limit upscaling efforts. ![]() ![]() We also found that productivity strongly predicted methane ebullition, whereas ecosystem morphometry and waterbody type were more important predictors of diffusive methane flux. reservoirs), and that ecosystem morphometric variables (e.g., surface area and maximum depth) were more important predictors in lakes whereas metrics of autochthonous production (e.g., chlorophyll a ) were more important in reservoirs. We found that the best predictors of methane emission differed by waterbody type (lakes vs. Here we use a new database of total, diffusive, and ebullitive areal methane emissions from 313 lakes and reservoirs (ranging in surface area from 6 m 2 to 5,400 km 2 ) to identify the best predictors of methane emission. Thus, determining the main drivers of methane flux across diverse waterbody types will inform more accurate upscaling approaches. Uncertainty stems partially from whether the sites currently sampled represent the global population as well as incomplete knowledge of which environmental variables predict methane flux. Freshwater lakes and reservoirs contribute substantially to atmospheric methane concentrations, but the magnitude of this contribution is poorly constrained. Methane is an important greenhouse gas with growing atmospheric concentrations. ![]()
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