Warming up to climate change: Why do global sea surface temperatures matter?
- March 19, 2024
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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Warming up to climate change: Why do global sea surface temperatures matter?
Subject: Environment
Section: Climate change
Context:
- The average global sea surface temperature (SST) for February 2024 stood at 21.06 degree Celsius, the highest ever in a dataset that goes back to 1979.
More on news:
- The previous record of 20.98 degree Celsius was set in August 2023.
- Almost 90 per cent of the extra heat trapped by greenhouse gasses has been absorbed by the oceans, making them steadily warmer over the decades.
- Between 1982 and 2016, such heat waves have doubled in frequency and have become longer and more intense, according to a 2021 study by the UN’s Intergovernmental Panel on Climate Change (IPCC).
- In 2023, the concentration of GHG reached the highest levels ever recorded in the atmosphere, according to C3S.
Graphical Representation of the sea surface temperatures:
- Since March 2023, the average daily SST has been off the charts.
- While the orange line shows 2023’s temperatures, other gray lines track temperatures of previous years.
- The solid back line represents where we are so far in 2024 and it is way above any other previous year, including 2023.
Why are the oceans getting warmer?
- Carbon dioxide, methane, ozone, and nitrous oxide are some of the notable GHGs, which essentially trap heat in the atmosphere and contribute to global warming.
- As a result, the average global temperature has risen at least 1.2 degree Celsius above pre-industrial times.
- Almost 90 per cent of the extra heat trapped by GHGs has been absorbed by the oceans, making them steadily warmer over the decades.
- Apart from global warming, there are other factors which have led to a spike in ocean temperatures.
- For instance, El Niño — a weather pattern that refers to an abnormal warming of surface waters in the equatorial Pacific Ocean — has contributed to both ocean warming and rising global surface temperatures.
- There is also less dust blowing off the Sahara Desert recently due to weaker-than-average winds.
- The dust forms a “giant umbrella that shades” the Atlantic water and reduces ocean temperatures.
- But now, the umbrella has partially folded and more of the Sun is beating down on the ocean.
Why are rising sea surface temperatures a cause of worry?
- Higher ocean temperatures can have irreversible consequences for marine ecosystems.
- Warmer oceans lead to an increase in ocean stratification — the natural separation of an ocean’s water into horizontal layers by density, with warmer, lighter, less salty, and nutrient-poor water layering on top of heavier, colder, saltier, nutrient-rich water.
- The rise in temperatures, however, has made it harder for water layers to mix with each other. Due to this, oceans are able to absorb less carbon dioxide from the atmosphere and the oxygen absorbed isn’t able to mix properly with cooler ocean waters below, threatening the survival of marine life.
- Nutrients are also not able to travel up to the surface of the oceans from below.
- This could threaten the population of phytoplankton , single-celled plants that thrive on the ocean surface and are the base of several marine food webs.
- Phytoplankton are eaten by zooplankton, which are consumed by other marine animals such as crabs, fish, and sea stars.
- If The phytoplankton population plummets, there could be a collapse of marine ecosystems.
- Warmer oceans cause marine heat waves (MHWs), which occur when the surface temperature of a particular region of the sea rises to 3 or 4 degree Celsius above the average temperature for at least five days.
- MHWs are devastating for marine ecosystems as they contribute to coral bleaching, which reduces the reproductivity of corals and makes them more vulnerable to life-threatening diseases. They also impact the migration pattern of aquatic animals.
- Higher ocean temperatures may also result in more frequent and more intense storms like hurricanes and cyclones.
- Warmer temperatures lead to a higher rate of evaporation as well as the transfer of heat from the oceans to the air.
- When storms travel across hot oceans, they gather more water vapor and heat.
- This results in more powerful winds, heavier rainfall, and more flooding when storms reach the land — meaning heightened devastation for humans.