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Ocean warming

  • Category
  • Published
    17th Jan, 2019

As per a research published in journal ‘Science”, oceans are heating up 40 percent faster on average than Intergovernmental Panel on Climate Change (IPCC) estimated five years ago.



  • As per a research published in journal ‘Science”, oceans are heating up 40 percent faster on average than Intergovernmental Panel on Climate Change (IPCC) estimated five years ago.
  • The researchers also concluded that ocean temperatures have broken records for several straight years. 2018 is going to be the warmest year on record for the Earth’s oceans, before that 2017 and 2016 were declared as the warmest year.


  • The Synthesis Report (SYR) of the Fifth Assessment Report (AR5), issued in 2014 by the IPCCC, presented five different estimates of ocean heat, but they all showed less warming than the levels projected by computer climate models — suggesting that either the ocean heat measurements or the climate models were inaccurate.
  • Since the early 2000s, scientists have measured ocean heat using a network of drifting floats called Argo, which measure the temperature and saltiness of the upper 6,500 feet of the ocean and upload the data via satellites.
  • In the new analysis, researchers assessed three recent studies that better accounted for the older instrument biases. The results converged at an estimate of ocean warming that was higher than that of the 2014 United Nations report and more in line with the climate models.
  • Historically, understanding ocean temperatures has been difficult. The I.P.C.C. also issued a report in 2018 that described a climate crisis as soon as 2040.


What is ocean warming?

The ocean absorbs most of the excess heat from greenhouse gas emissions, leading to rising ocean temperatures. The Fifth Assessment Report revealed that the ocean had absorbed more than 93% of the excess heat from greenhouse gas emissions since the 1970s. This is causing ocean temperatures to rise.

As the oceans heat up, sea levels rise because warmer water takes up more space than colder water. As per this report, most of the sea level rise observed to date is because of this warming effect, not melting ice caps. The warming alone would cause sea levels to rise by about a foot by 2100, and the ice caps would contribute more. That could exacerbate damages from severe coastal flooding and storm surge.

How it affects:

Ocean warming leads to deoxygenation – a reduction in the amount of oxygen dissolved in the ocean – and sea-level rise – resulting from the thermal expansion of sea water and continental ice melting. The rising temperatures, coupled with ocean acidification (the decrease in pH of the ocean due to its uptake of CO2), affect marine species and ecosystems and, consequently, the fundamental benefits humans derive from the ocean.



On marine species and ecosystems

Marine fishes, seabirds and marine mammals all face very high risks from increasing temperatures, including high levels of mortalities, loss of breeding grounds and mass movements as species search for favourable environmental conditions.

Reefs around the world have suffered from mass bleaching events for three consecutive years. The bleaching of the Great Barrier Reef in 2016 and 2017, for instance, killed around 50% of its corals. 

Corals cannot survive the frequency of current bleaching events from global temperature rise. If temperatures continue to rise, bleaching events will increase in intensity and frequency. The first global scientific assessment of climate change impacts on World Heritage coral reefs, published in 2017 by UNESCO, predicts that the coral reefs in all 29 reef-containing World Heritage sites would cease to exist as functioning coral reef ecosystems by the end of this century if humans continue to emit greenhouse gases under a business-as-usual scenario.

On humans

  • Threat to food security and livelihood: A 2012 report by the Food and Agriculture Organization estimates that marine and freshwater capture fisheries and aquaculture provide 4.3 billion people with about 15% of their animal protein. Fisheries and aquaculture are also a source of income for millions of people worldwide. By altering distributions of fish stocks and increasing the vulnerability of fish species to diseases, ocean warming is a serious risk to food security and people’s livelihoods globally.
  • Spread of disease: Warming ocean temperatures are linked to the increase and spread of diseases in marine species. Humans risk direct transmission of these diseases when consuming marine species, or from infections of wounds exposed in marine environments.

On coastal areas

Rising temperatures also affect vegetation and reef-building species such as corals and mangroves, which protect coastlines from erosion and sea-level rise. Rising sea levels and erosion will particularly affect low-lying island countries in the Pacific Ocean, destroying housing and infrastructure and forcing people to relocate. Kiribati, The Maldives, The Seychelles, The Torres Strait Islands, Tegua, The Soloman Islands, Micronesia, Palau, The Marshall Islands, The Carteret Islands, Tuvalu and Bangladesh are among the worst sufferer of ocean warming.

Around 10 per cent of the world’s population lives in coastal areas that are less than 10 meters above sea level. And about 40 per cent of the world’s population lives within 100 km of the coast.

On climate

The rise in sea surface temperatures is causing more severe hurricanes and the intensification of El Niño events bringing droughts and floods. Powerful storms like Hurricane Harvey (2017) and Hurricane Florence (2018) will become more common, and coastlines around the world will flood more frequently.


Limiting greenhouse gas emissions

Paris Agreement on climate change sets mitigation targets and holds the increase in the global average temperature to well below 2°C above pre-industrial levels. This will help prevent the massive and irreversible impacts of growing temperatures on ocean ecosystems and their services.

Protecting marine and coastal ecosystems

Well-managed protected areas can help conserve and protect ecologically and biologically significant marine habitats. This will regulate human activities in these habitats and prevent environmental degradation.

Restoring marine and coastal ecosystems

Elements of ecosystems that have already experienced damage can be restored. This can include building artificial structures such as rock pools that act as surrogate habitats for organisms, or boosting the resilience of species to warmer temperatures through assisted breeding techniques.

Improving human adaptation

Governments can introduce policies to keep fisheries production within sustainable limits, for example by setting precautionary catch limits and eliminating subsidies to prevent overfishing. Coastal setback zones which prohibit all or certain types of development along the shoreline can minimise the damage from coastal flooding and erosion. New monitoring tools can be developed to forecast and control marine disease outbreaks.

Strengthening scientific research

Governments can increase investments in scientific research to measure and monitor ocean warming and its effects. This will provide more precise data on the scale, nature and impacts of ocean warming, making it possible to design and implement adequate and appropriate mitigation and adaptation strategies.


India has a vast coastline of 7,525 km, almost all of which are to some extent affected by coastal erosion. About 26 percent of the mainland coastline in India face serious erosion problems. Infrastructure projects such as jetties, ports, big road projects, dredged navigational channels, and the destruction of vegetation on the shoreline have all played a role in making the population living the coastal areas and depending on coastal resources highly vulnerable.

The impacts of climate change and sea level rise pose serious threats to coastal regions. The sea level along the Indian coast has been rising at the rate of 1.3mm/year. The 2004 tsunami and severe cyclones created a sudden awareness about coastal protection among policy makers.  

Steps taken by the GOI to preserve coastal ecosystems:

  • India has adopted the National Action Plan on Climate Change (NAPCC) in 2008 which has both to mitigation and adaptation measures. It has eight National Missions which form the core of the NAPCC.
  • India has also signed the Paris Climate Agreement in 2015.
  • Indian Remote Sensing Satellite (IRS) series of satellites are effectively used to monitor coastal habitats, landforms, shoreline, water quality, etc.
  • Areas between high and low tide lines (HTL, LTL) and 500 m from HTL are declared as the Coastal Regulation Zone and construction and industrial activities in this area is prohibited or restricted.

Learning Aid

Practice question:

Analyze the findings of IPCC regarding climate change and examine the doubts and anomalies raised by other experts in the same.


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