Warming of Oceans

Warming of Oceans

Subject – Environment

Context – The latest Intergovernmental Panel on Climate Change (IPCC) report has warned that ocean warming will continue over the 21st century and is likely to continue until at least the year 2300 even if we minimise carbon emissions.

Concept –

• The amount of ocean warming observed since 1971 will likely at least double by 2100 under a low warming scenario and will increase by 4-8 times under a high warming scenario,” warns the report, adding that human influence is the main driver of the warming.
• This warming can help create both anoxic (waters that have no dissolved oxygen) and hypoxic (low oxygen concentration) zones. The report adds that these oxygen-deficient areas are expected to persist for thousands of years.
• Previous studies have noted that warming oceans can cause stress, decrease the range, increase diseases and even wipe out many commonly eaten fish. Last year, a study noted that future ocean warming and acidification may drag down the commercial Arctic cod fishery by 2100.
• Several species were noted to migrate poleward or to deeper waters to stay in their ideal temperature range.
• A new research published suggested that fish like sardines, pilchards and herring will become smaller in size and not be able to move to better environments.
• Though the team studied Clupeiforms – the order of ray-finned fish which includes anchovies, Atlantic herring, Japanese pilchard, Pacific herring, and South American pilchard – they note that the findings have implications for all fish.
• As temperature increases, the demand for oxygen of many fish species will exceed their capacity to extract oxygen from the environment through their gills. As a result, the aerobic capacity of fish decreases in warming waters, and this reduction may be more important in larger fishes. This tells us that global warming could limit the aerobic capacity of fish, impairing their physiological performance in the future.
• The modern version of Darwin’s idea of evolution by natural selection posits that organisms with genes that favour survival and reproduction will tend to leave more offspring than their peers, causing the genes to increase in frequency over generations.