No matter how near or far you live from the coast, you'll be
affected by it: ocean warming may become one of the biggest threats to
ecosystems and food security.
Ocean warming,
driven by increasing carbon emissions and rising temperatures, may
become one of the biggest challenges facing humanity and threatening the
Earth’s life systems, affecting even those living far from oceanic
coasts. Already impacting people, fish stocks and crop yields, it may lead to more extreme weather events and increased risk from water-borne diseases including cholera. Fuelling global warming,
it would put the livelihood of agrarian and fishing communities in the
Indian and Pacific Ocean regions at stake, cautions the International
Union for Conservation of Nature (IUCN) in a report.
Affecting crop yields
“There is likely to be an increase in mean global ocean temperature of 1-4 degrees Celsius by 2100,”
reads the IUCN report. “The greatest ocean warming overall is occurring
in the Southern Hemisphere and is contributing to the subsurface
melting of Antarctic ice shelves”.
In addition, subsurface heat in the
Pacific and Indian Oceans at a depth of 100 to 500 metres has profound
implications for the Earth’s future warming. In a strong El Niño year this subsurface heat is suddenly transferred to the surface layer and released into the atmosphere. If frequent and continued for a number of years, it further contributes to global warming.
With oceans warming over the course of this century, El Niño events are expected to double in frequency and become more intense according to projections, therefore affecting Pacific and Indian Ocean monsoon systems. This
will badly impact crop yields and, “may affect most Asian countries
including India where agriculture is primarily monsoon rain-fed,” says
Doctor Rahas Bihari Panda of the Department of Environment Science at
India’s North Odisha University.
Such a situation in the food-producing Asian continent may lead to severe food insecurity and hunger across the globe.
Reducing fish mass
Already influencing ecosystems from polar
to tropical regions, ocean warming is driving entire groups of marine
species such as plankton, jellyfish, turtles and seabirds up to 10 degrees of latitude north and south of the Equator to move towards the poles. It has also led to the expansion of low oxygen areas because warmer water holds less dissolved oxygen.
Under the combined influence of rising sea temperatures and less dissolved oxygen, maximum fish size across all seas is predicted to decline by 10 per cent, says Karin Limburg, Professor at State University of New York’s College of Environmental Science and Forestry. Such
a reduction in fish mass may strongly impact fisheries, exacerbating
the already stressed situation in those parts of the world that depend
on them for protein, Limburg adds.
Declining fish production
The oceanic phenomenon has already reduced the abundance of fish species in East Africa and the Western Indian Ocean by killing parts of the coral reefs they depend on. On top of the
fact that tuna catch rates in the Indian Ocean have declined by 50-90
per cent over the past five decades, reduced phytoplankton may become an
additional stress factor leading to a decline in the region’s
fisheries, say scientists at the Indian Institute of Tropical
Meteorology on the basis of a study of the area.
Harvests from marine fisheries in
Southeast Asia are expected to fall by a rate between 10 and 30 per cent
by 2050, compared to the period between 1970 and 2000, according to the
IUCN report. This would affect the livelihood of developing countries’ fishing communities, also making it difficult to meet the global demand deriving especially from areas such as Japan, the USA and Europe.
Making fish inedible
Warmer water also leads to harmful algae blooms that cause neurological diseases such as ciguatera in humans. As
fish consume toxic marine algae in the sea they produce toxins in
their tissues and become carriers of the poison. So, of the fish caught
for human consumption, part of it may not be safe.
In a recent outbreak, over 100 people in India fell sick from a ciguatera infection. With
an annual 50,000 cases around the world, nearly 400 million living in
the Caribbean basin, Pacific Ocean and Indian Ocean regions are
potentially at risk, according to The Louis Malardé Institute.
Need for urgent action
Ocean warming therefore poses one of the
biggest threats to food security and the nutritional ambitions set in
the United Nations’ Sustainable Development Goals (SDGs), a set of global goals defining the international agenda moving towards 2030: in particular Goal 2 aims to end hunger, achieve food security and improved nutrition, and promote sustainable agriculture.
Hence, it has become essential that urgent attention is turned towards ocean warming in order to save ecosystems, marine resources and fisheries. Only strong
measures, including cutting greenhouse gas emissions rapidly and
substantially, can contribute to checking the trend threatening all life
on Earth.
The report was published on January 17, 2017, at the LifeGate.
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