ALARMING WARMING UP OF OCEANS

 

ALARMING WARMING UP OF OCEANS

 Nikunja Bihari Sahu

 

        According to the findings of a new research, world's oceans are warming up very fast and have attained the highest level in 2019. This is due to the fact that the oceans have absorbed most of the heat released due to the man-made greenhouse gas emissions in recent years. This is expected to further accelerate the process of climate change on our planet bringing more extreme weather conditions, more tropical storms and change in rainfall patterns.  The rate at which the oceans are warming up is itself alarming. This is evident from the fact that the warming during the period 1987 to 2019 is 4.25 times faster compared to the period form 1955 to 1986. The temperature rise of ocean waters in last 25 years has been estimated to be roughly equal to the heat released from 36 lakh Hiroshima type nuclear explosions. According to the reports, the oceans have absorbed an additional amount of 25 x 10²⁰ Joules of heat in the year 2019 compared to the year 2018. This is approximately equal to the total heat released due to all the persons on Earth if each of them uses as many as 100 microwave ovens or hair-driers for one year!

        According to an IPCC report, during the period from 1970 to 2013 (43 years), the oceans have absorbed nearly 90% of the heat released due to greenhouse gases. Although the temperature of ocean waters have been on the rise since last 100 years, the rise has been accelerated phenomenally in recent years due to the unprecedented emission of greenhouse gases due to human activities. With the existing rate of increase of the ocean temperature, a 4 degrees rise in the global ocean temperature is predicted by the year 2100. This will critically affect marine ecosystem of the oceans around the world.

          The unprecedented warming up of oceans is evident from the fact that the Ocean Heat Content (OHC) set a new record in early 2019 since the time OHC records came into existence in 1940. Based on data collected worldwide, the OHC continued to rise outpacing its early rate of warming by a large percentage. In addition, 2019 was the warmest year in the 65 years record of ocean observations, based on the analysis by researchers from the Institute of Atmospheric Physics in Beijing. The five highest years on record for annual Ocean Heat Content (OHC) were 2015 to 2019. OHC, used to quantify the rate of global warming, describes the amount of heat stored in the ocean in the upper levels from the surface to 2000 meters in depth. A high OHC can adversely disrupt the marine ecosystems across the world.

        The  reason for the unusual rise of temperature of ocean waters in 2019    is primarily attributed  to the huge amount  of  Carbon dioxide  absorbed by the oceans released from  recent  forest fires of Australia ( due to which 80 Lakh hectares of forest was burnt)  . The increased absorption of Carbon dioxide also contributed to the higher acidity level of the ocean waters which will have a drastic effect on the marine life.

      Increasing ocean temperatures can have catastrophic effects on marine species and ecosystems worldwide. Most ocean dwellers, from plankton to whales, live in the upper layers of the ocean, primarily in the zone where temperatures are increasing fastest. Many of these marine organisms are sensitive to even slight or short-lived changes in temperature.  Rising temperatures can also cause coral bleaching, the loss of breeding grounds for marine fishes and animals   and contribute to extreme weather events and surging sea levels. Scientists predict that warmer oceans will make storms like hurricanes and tropical cyclones more frequent and more intense in future thus increasing the likelihood of producing enormous volumes of rain. Another impact of warming up of oceans is the thermal expansion of water that contributed to the global sea level rise. Thermal expansion has contributed to about half of all the sea-level rise observed across the world so far which is even more  than contributed by melting of  ice from either Greenland or Antarctica glaciers .

     The Paris Agreement sets out a global framework to avoid dangerous consequences of climate change by limiting global warming to well below 2°C mark compared to pre-industrial levels. Achieving the mitigation targets set by the Paris Agreement is crucial to prevent the massive, irreversible and catastrophic impacts of ocean warming on marine ecosystems of the world.

                                                                                        Education Officer

                                                                         Regional Science Centre, Bhopal 

                                                                                         Phone: 8018708858