Greenhouse gas emissions resulting from the burning of fossil fuels have been driving climate warming since the start of the industrial revolution. Greenhouse gases such as carbon dioxide, methane, nitrous oxide, and fluorinated gases trap heat from the sun within the Earth's atmosphere, resulting in an increase in atmospheric temperatures. According to the European Commission, by 2020, atmospheric carbon dioxide levels had risen to 48% above its pre-industrial level (before 1750), and strongly correlate with rising atmospheric temperatures. But it's not just the atmosphere that is warming. The oceans are absorbing most of this heat, and as a result ocean temperatures have been steadily rising too. Rising ocean temperatures can have several negative impacts, and can lead to changes in ocean currents and higher levels of moisture in the atmosphere, both of which can alter global climate patterns.
Record Ocean Warming
July 2023 marked a significant occurrence as ocean temperatures soared to unprecedented temperature levels, establishing a new record with no indications of a cooling trend in sight.
Based on recent data from the European Union's Copernicus Climate Change Service — whose ocean data archives extends back to 1979 — the average global ocean surface temperature surged to 20.96 degrees Celsius (69.7 Fahrenheit) by the end of July, surpassing the previous record of 20.95 degrees Celsius recorded in March 2016. Scientists expect ocean temperatures to rise further still with the onset of El Niño, a natural climate pattern in the Pacific Ocean that contributes to ocean warming and affects weather worldwide, compounding the effect of human-induced global warming.
Ocean Warming Impacts
This year, unprecedented marine heatwaves resulting in elevated ocean temperatures are taking their toll across a broad geographical area from Florida Keys to the North Atlantic, where temperature increases of up to 5 degrees Celsius (9 degrees Fahrenheit) were recorded in the waters between Ireland and the United Kingdom. Extremely high ocean temperatures can trigger widespread coral bleaching, mass die-offs of other marine organisms, and accelerated sea level rise. These impacts can have dire consequences on marine and coastal ecosystems and the species, including humans, that live there.
The Earth's oceans, which make up 70% of its surface, have the remarkable capacity to absorb immense quantities of heat energy. According to the UN Climate Change, the world's oceans have borne the primary brunt of the effects of human-induced global warming for an extended period. As the Earth's largest carbon sink, the ocean absorbs the surplus heat and energy emanating from the escalating greenhouse gas emissions trapped within the Earth's systems. More than 90% of the surplus heat resulting from climate warming has been assimilated by the oceans and is located within the warmer oceans, distributed in surface waters and at greater depths.
As the heat and energy stored within the ocean increases, it sets off a chain reaction of effects such as ice melting, rising sea levels, ocean acidification, harmful algal blooms, and episodes of marine heatwaves that add more fuel to the proverbial fire. These impacts can negatively affect marine biodiversity and the well-being of coastal communities and others living in low-lying areas, as well as communities that depend on marine and coastal systems for their food or livelihoods.
While the oceans effectively act as a heat sink, this does come at a price. Rising ocean temperatures also carries significant consequences for the climate. The world's oceans play a critical role in mitigating the effects of climate warming by absorbing carbon dioxide responsible for driving global warming. However, as water temperatures increase, this absorption process becomes less efficient, resulting in less carbon being taken up by the oceans and more remaining in the atmosphere, thereby driving global warming further.
Warmer oceans drive more powerful storms such as hurricanes and tropical cyclones, which are fueled by warm, moist air near the surface of the ocean. As seawater becomes warmer, the air above the surface becomes warmer and moister, releasing more energy which gives rise to more powerful storms.
How Can we Slow Ocean Warming and Prevent a Climate Crisis?
As industries around the world continue to burn fossil fuels and emit greenhouse gases into the atmosphere, scientists fear that the rising ocean temperatures we are currently witnessing may signify the beginning of a concerning trend in ocean warming. If this trend continues, we will continue to see an increase in extreme weather events such as heat waves (terrestrial and marine), droughts, floods, extreme winds, and wildfires. The only way to reverse this trend and prevent a climate crisis is to reduce our dependence on fossil fuels by opting for cleaner forms of energy.
Sources:
https://www.cnbc.com/2023/08/16/record-ocean-temperatures-why-they-happen-how-they-hurt.html
https://edition.cnn.com/2023/08/04/world/ocean-heat-temperature-record-climate/index.html
https://www.un.org/en/climatechange/science/climate-issues/ocean-impacts
https://climate.ec.europa.eu/climate-change/causes-climate-change_en
