Examine the fundamental causes of the “Dead Zones” that are appearing more frequently in marine environments.
La Niña refers to the large-scale cooling of ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall. The current La Niña episode started in September 2020 and has continued forRead more
La Niña refers to the large-scale cooling of ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall. The current La Niña episode started in September 2020 and has continued for a third consecutive year and has thus been classified as a ‘triple dip’ La Niña. According to the World Meteorological Organization (WMO), the first “triple-dip” La Niña of the 21st century will continue to affect different parts of the world as given below:
- Impact on atmospheric pressure: La Niña is characterized by lower-than-normal air pressure over the western Pacific. These low-pressure zones contribute to increased rainfall.
- Rainfall associated with the summer monsoon in Southeast Asia tends to be greater than normal, especially in northwest India and Bangladesh. This generally benefits the Indian economy, which depends on the monsoon for agriculture and industry.
- However, strong La Niña events are associated with catastrophic floods in northern Australia.
- Drought conditions: La Niña is also characterized by higher-than-normal pressure over the central and eastern Pacific. This results in decreased cloud production and rainfall in that region.
- Drier-than-normal conditions are observed along the west coast of tropical South America, the Gulf Coast of the United States, and the pampas region of southern South America.
- Temporary cooling impact on global temperatures: During La Niña years, the colder surfaces allow the oceans to absorb more heat from the atmosphere. Consequently, the air temperatures tend to go down, producing a cooling effect, but this is not enough to reverse or neutralize the impacts of global warming.
- Impact on fishing industry: La Niña usually has a positive impact on the fishing industry of western South America. Upwelling brings cold, nutrient-rich waters to the surface. Nutrients include plankton eaten by fish and crustaceans. Higher-level predators, including high-value fish species such as sea bass, prey on the crustaceans.
In light of these impacts, concerns are raised about the unfolding humanitarian catastrophe for millions of people in different parts of the world especially in the Horn of Africa, which is witnessing one of the longest and the most severe droughts. It is necessary to provide tailored information to the humanitarian sector and to support sensitive sectors like agriculture, food security, health, and disaster risk reduction.
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However, the Intergovernmental Panel on Climate Change (IPCC) in its recent report highlighted that AMOC is losing its stability and is very likely to decline over the 21st century due to the following reasons:
Marine organisms need oxygen to survive and if there is deficiency of oxygen demand it causes that area as a dead zone which also lead to a nutrient pollution in Marine water ecosystem. 1. climate change: temperature increases and water becomes warm and lighter and lose the ability to hold oxygen anRead more
Marine organisms need oxygen to survive and if there is deficiency of oxygen demand it causes that area as a dead zone which also lead to a nutrient pollution in Marine water ecosystem.
See less1. climate change: temperature increases and water becomes warm and lighter and lose the ability to hold oxygen and restrict the distribution of oxygen into the water.
2. Eutrophication: It creates hypoxic condition in water due to algae bloom.
3. Nutrient pollution: surplus of nutrients from agricultural run off, usage of fertilizers ,sewage through this enters into the water body and consume oxygen which leads to less oxygen supply.
4. Pollution: Other than nutrient pollution heavy metals, chemicals, oil skills, industrial waste, domestic waste, can also pollute marine ecosystem and creates dead zone areas.
example , Mexico experiences one of the largest dead zone globally due to nutrient rich to run out from the Mississippi River basi
Dead zones in Marine ecosystem requires efforts to reduce pollution eutrophication climate change and need to improve water quality through proper waste water management good environmental policies and mindful agricultural practices.