Oceans absorbed heat equivalent to 3.6 billion Hiroshima atom-bomb explosions in last 25 years
Past five years held the record for the highest average ocean temperature ever recorded, with 2019 being the warmest in history.
World's oceans were the warmest ever in the recorded history in 2019, especially between the depth of 2,000 metres. Researchers suggest in a study that the past 10 years have been the warmest on record for global ocean temperatures and the last five years hold the highest record.
The study was conducted by a team of 14 scientists from 11 institutes across the world and was published in “Advances in Atmospheric Sciences” journal.
How much heat is absorbed by oceans?
The ocean temperature is about 0.075 degree Celsius above the average observed during 1981-2010. Scientists suggest that to reach this temperature, oceans might have absorbed heat equivalent to 3.6 billion Hiroshima atom-bomb explosions in past 25 years. The total amount of heat comes to 228,000,000,000,000,000,000,000 (228 Sextillion) Joules.
Cheng Lijing -- the lead author of the paper -- calculated the amount of heat absorbed by oceans and suggested that the atomic bomb dropped on Hiroshima exploded with an energy of about 63,000,000,000,000 Joules.
The reason behind the irrefutable heating:
The lead author said that "there are no reasonable alternatives aside from the human emissions of heat-trapping gases to explain this heating".
"This measured ocean warming is irrefutable and is further proof of global warming," he added.
Researchers examined the warmth trends dating back to the 1950s. They also compared the 1987 to 2019 data recording period to the 1955 to 1986 period. They observed that over the past six decades, the more recent warming was about 450% that of the earlier warming, reflecting a major increase in the rate of global climate change.
John Abraham, the co-author of the paper, said: "The key to answering this question is in the oceans -- that's where the vast majority of the heat ends up. If you want to understand global warming, you have to measure ocean warming."
He suggested that we can use energy more efficiently and diversify our energy resources.
The effects of the heat:
More than 90 per cent of the global warming heat has gone to oceans since 1970. Only 4 per cent of the heat has warmed the atmosphere and the land where humans live.
Lead author Cheng said: "Even with that small fraction affecting the atmosphere and land, the global heating has led to an increase in catastrophic fires in the Amazon, California and Australia in 2019, and we're seeing that continuing in 2020.
“The global ocean warming has caused marine heatwaves in Tasman Sea and other regions," he added.
A heatwave in North Pacific -- first detected in 2013 and also called 'the blob' -- caused major loss to marine life including phytoplankton, zooplankton, fish, around 100 million cod and whales.
According to Rice Kinder Institute for Urban Research, Hurricane Harvey caused a damage of $108 billion and 82 deaths in the Gulf of Mexico in 2017. The following year, a hotspot in the Atlantic Ocean near the Carolinas led to Hurricane Florence. It caused 53 deaths and around $38 to $50 billion economic damage.
"The price we pay is the reduction of ocean-dissolved oxygen, harmed marine lives, strengthening storms, reduced fisheries and ocean-related economies," said Cheng.
“However, the more we reduce greenhouse gasses, the less the ocean will warm. Reduce, reuse and recycle and transferring to a clean energy society is still the major way forward," he added.
Who should be blamed?
Apart from the ocean heat, climate change is also acidifying the oceans. A recent report listed out the top 20 companies responsible for the acidification of the one-fifth of the ocean. The list also included Coal India.
Recently, a 53-year-old journal revealed that coal companies knew about the dangers of global warming but they chose to ignore it. All of this led to where we are now but there are ideas that can change the way forward.