Tropical oceans, like most natural biomes, have been unable to escape the impacts of climate change.
Located around the equatorial band, tropical oceans have regulated global temperatures for millennia. They redistribute heat from the sun to the polar regions and create precipitation that brings rainfall to inland areas. But the recent and rapid rise in global average temperatures has brought unexpected changes to our tropical oceans.
The excess heat that’s being generated by trapped greenhouse gases is getting absorbed by tropical oceans, with detrimental effects for marine life and people living in coastal regions. Warmer ocean waters are melting sea ice and glaciers at unprecedented rates, leading to sea-level rise and coastal flooding. Higher temperatures are also destroying coral reefs and disrupting marine food chains.
In this article, we explore how climate change is affecting the tropical oceans and what we can do to protect them from climate change.
- Tropical oceans make up just 0.01 percent of the Earth’s oceans but contain almost all of the world’s coral reefs and mangrove forests.
- Climate change is warming the tropical oceans and causing them to absorb high levels of carbon dioxide, causing seawater to become more acidic.
- Ocean acidification, warmer ocean temperatures, and altered ocean currents are destroying marine habitats, melting sea ice, and precipitating stronger storm seasons.
What are the world’s tropical oceans?
Tropical oceans are oceans that exist in the equatorial region of our planet, between the Tropic of Cancer and the Tropic of Capricorn. Temperatures in these waters usually stay above 20°C and remain constant throughout the year. Well-known tropical oceans include the Indian Ocean, the central Pacific Ocean, the central Atlantic, and most parts of the Caribbean Sea.
Tropical oceans maintain warm surface temperatures because they receive much of the Sun’s heat throughout the year. This heat drives the global circulation of ocean currents as well as tropical weather patterns like hurricane seasons. It also causes seawater to evaporate constantly, forming warm, moist air that condenses into rain clouds. As a result, tropical oceans see more frequent, heavy rains than temperate oceans.
Although tropical oceans make up just 0.01 percent of the Earth’s ocean volume, they are a source of half of the world’s fish stock. They’re also home to 95% of the world’s mangrove forests and most of the planet’s coral reefs, which require the warm waters of tropical oceans to survive.
What role do tropical oceans play in the Earth’s climate?
Warm tropical oceans act as regulators of the Earth’s climate. They absorb heat from the sun and exchange large quantities of water, gases, and particles with the atmosphere.
These oceanographic processes that occur in the equatorial oceans help redistribute heat to the polar regions, keeping global temperatures stable and our planet habitable.
Recent research by scientists from Plymouth University’s Marine Institute and the National Center for Scientific Research (CNRS) has found evidence that suggests that tropical oceans may even “act like a heart” that pulses warm water currents towards the North and South poles.
But as global average temperatures rise, many of the pulses seem to coincide with the melting of polar sea-ice and ice shelves in Antarctica, Greenland, and the Arctic. These anomalous pulses have the potential to increase the intensity of El Niño events, which may in turn lead to more extreme cyclones, heat waves, and droughts.
Oceanographers predict that the heat-regulating ability of tropical oceans will make them vital in the fight against climate change. Unprecedented changes in warm and cold ocean current patterns are already starting to make an impact on the climates of coastal regions.
How is climate change affecting the tropical oceans?
Anthropogenic climate change, or climate change caused by human activity, is altering tropical ocean temperatures and currents with serious consequences for climate patterns around the world.
Rising ocean temperatures, the changing chemistry of seawater, and altered currents are three of the most visible impacts of climate change on tropical oceans.
Rising ocean temperatures
Tropical oceans have long been known to absorb heat from both the sun and the atmosphere. But the recent increase in trapped greenhouse gases, which has raised global average temperatures, has also caused a rise in upper ocean heat content.
The excess heat, unable to escape our atmosphere, is being absorbed by tropical oceans at distressing rates. Available data indicates that between 1971 and 2010, more than 90 percent of the warming that happened on our planet occurred in the ocean.
The extra heat is contributing to the rapid melting of submerged ice in Antarctica and the shrinking of wintertime Arctic sea ice. It is also increasing the rate of ocean evaporation, leading to more rainstorms that flood coastal regions.
But most worrying of all, the continued melting of sea ice is causing sea levels to rise at a rate of about one-eight of an inch per year. Without intervention, sea levels by 2050 could threaten the lives of around 150 million people.
Changes in the chemistry of seawater
Tropical oceans don’t only absorb heat from the atmosphere but also exchange chemicals with it. It’s believed that oceans absorb around 30 percent of the carbon dioxide found in the atmosphere – a large portion because there is currently 412 parts per million of carbon dioxide in our atmosphere, almost 1.5 times the amount found at the start of the Industrial Revolution.
When the carbon dissolves in the ocean, it forms carbonic acid which increases the acidity of seawater. Increased acidification interferes with the shell growth of marine life such as corals and crabs and the health of plankton populations. Over time, the decline of these marine creatures disrupts the food chain and alters the biodiversity of ocean ecosystems.
Scientists believe that most of the carbon being absorbed by tropical oceans comes from the burning of fossil fuels, deforestation, and cement production.
Climate change may also alter the direction and speed at which tropical ocean currents travel. Scientists have found that atmospheric circulation, which drives ocean currents, has increased and intensified over the past three decades.
Scientific models demonstrate that the intensity of the currents has increased by about 15 percent per decade. Though the studies are still being reviewed, current observations of westerly winds in the Antarctic Ocean, for example, indicate that they’ve been pushed more to the south, causing a slight strengthening of the Antarctic Circumpolar Current.
The changes in the currents, coupled with warmer ocean temperatures, could affect jet streams, the development of strong storms, and the amount of heat stored in the oceans.
How do changes in the tropical oceans affect human and marine life?
Changes in the tropical oceans can drastically alter human and marine life in coastal regions. A slight increase in ocean temperatures is enough to make certain marine ecosystems uninhabitable while causing sea levels to rise.
In recent decades, ocean acidification has led to hundreds of coral bleaching events. Lower pH levels and warm temperatures force coral reefs to eject their algal partners, which they depend on for oxygen and waste removal. Without oxygen, the corals die out.
The decline in coral reefs further reduces marine biodiversity in coastal areas, particularly fish populations. Some marine species may migrate to other areas with better conditions for feeding and spawning. Fish, octopus, and squid that stay in warmer waters have been found to experience stunted growth and changes in their predatory habits.
An increase in ocean temperatures also causes sea levels to rise as glaciers and sea ice melt at irregular rates. This poses a direct threat to coastal communities, especially those in areas that are below or just above sea level. It’s estimated that 10 percent of the world’s population lives in these areas, all of whom are vulnerable to river floods and coastal flooding.
The island of Kiribati, for example, has already lost two islands to rising sea levels. It and other small island nations may disappear underwater by the end of the century if climate change is not reduced.
Can anything be done to protect tropical oceans from climate change?
While the impacts of climate change on tropical oceans may seem uncontrollable, there are active steps that we can take to protect tropical oceans from further damage.
The root cause of ocean acidification and warmer ocean temperatures in the high carbon dioxide levels in our atmosphere. The burning of fossil fuels for energy, manufacturing, and transportation contributes directly to the warming of our tropical oceans as the excess heat is absorbed.
Switching to renewable energies such as wind, solar, and geothermal can reduce the amount of carbon dioxide that gets emitted into the atmosphere. Cycling or driving an electric vehicle to work can also help cut your carbon footprint.
Another effective climate mitigation measure is to create more marine protected areas (MPAs) that protect coral reefs, mangroves, wetlands, and barrier islands from human exploitation. MPAs can make coastal regions more resilient to floods and habitat loss. They’re also known to help stimulate new carbon sequestration.
Some policymakers go further and suggest that ocean-centered solutions should be at the forefront of the fight against climate change. This means switching ships to zero-carbon propulsion systems, installing offshore renewable energy power plants, and decarbonizing the global shipping fleet.
Others look to enact changes in financial regulations that reduce funding for carbon-intensive activities. They suggest that financial institutions should be required to track and disclose carbon emissions from their lending and investment activities.
Another way to fight climate change with your money
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Both of these services can help you reduce your carbon footprint and decrease the number of greenhouse gases that go into the atmosphere. By limiting your impact on the environment, you can help protect the tropical oceans from climate change.
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