Oceans Great Dying 2.0: Earth’s climate moderator is warming faster

Subject: Geography

Section: Oceanography

Context: Oceans are heating up as they cross their natural capacity to sink carbon and atmospheric heat induced by GHGs emissions

Role of Ocean:

The oceans modulate the global climate and control the planetary temperature thus the weather events like rains, storms and cyclones, floods and droughts
About 50-80 per cent of the oxygen produced on Earth can be traced back to the sea
The most important role the oceans play is that of a carbon sink. Four-fifths of the global carbon cycle is circulated through them
As the global greenhouse gas (GHG) emissions caused by human activities have been growing exponentially, the oceans have absorbed more than 90 per cent of the global warming created by humans since the 1970s

Impact of Climate Change on Oceans:

Changes in ocean temperatures and currents will lead to alterations in climate patterns around the world
With rising warming, the temperature below the surface also goes up, affecting the species.
More carbon in the atmosphere means also more of the same in the oceans being a sink.
After certain level, this will increase the levels of dissolved carbon. This will further change the chemistry of the seawater by making it more acidic, thus turning the foundation of the vibrant living world in the oceans toxic
Acidic water means many species like coral and shellfish would not be able to build their shells or skeletons leading to a collapse of the population
The most significant warming was in the southern oceans. About 90 per cent of the net global ocean heat gain occurred in the region
The northern hemisphere has more landmasses and hence a higher concentration of aerosols, which are known to prevent heat from getting sucked into the ocean.
Natural variability like ENSO, Pacific Decadal Oscillation and Atlantic multi-decadal oscillation created those fluctuations.

Concept:

What is ENSO?

The El Niño-Southern Oscillation (ENSO) is a recurring climate pattern involving changes in the temperature of waters in the central and eastern tropical Pacific Ocean.
On periods ranging from about three to seven years, the surface waters across a large swath of the tropical Pacific Ocean warm or cool by anywhere from 1°C to 3°C, compared to normal.
This oscillating warming and cooling pattern, referred to as the ENSO cycle, directly affects rainfall distribution in the tropics

Pacific decadal oscillation:

The Pacific Decadal Oscillation (PDO) is often described as a long-lived El Niño-like pattern of Pacific climate variability
Extremes in the PDO pattern are marked by widespread variations in the Pacific Basin and the North American climate.
In parallel with the ENSO phenomenon, the extreme phases of the PDO have been classified as being either warm or cool, as defined by ocean temperature anomalies in the northeast and tropical Pacific Ocean

Atlantic multi-decadal oscillation

The Atlantic Multi-decadal Oscillation (AMO) has been identified as a coherent mode of natural variability occurring in the North Atlantic Ocean with an estimated period of 60-80 years.
It is based upon the average anomalies of sea surface temperatures (SST) in the North Atlantic basin, typically over 0-80N.