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Ocean Change

Climate Crisis – AN OCEAN CRISIS

Michael AW

OUR OCEAN IS ALSO THE WORLD’S LARGEST STORE OF CARBON, where an estimated 83 percent of the global carbon is circulated.

TO ADDRESS THE CURRENT CLIMATE CRISIS we must address the ocean crisis in the same breath. The ocean is sick, and if left untreated, long-term survival of the human species on this planet is at risk. Life on Earth cannot be sustained without the ocean–there are no exceptions. The implications of a failing ocean are catastrophic to everything, including us. Let us examine how the ocean and climate change directly affects our human world.

There is a close relationship between our planet’s climate and the ocean as they are constantly in contact, influencing one another. The impacts of El Niño and La Niña are caused by a combination of two factors: warm water failing to mix with cold water because a lack of strong trade winds to move them. The increased occurrence of extreme weather events over the past few decades is no coincidence. When land temperature increases, so does the ocean’s, setting off chain reactions within the most varying marine ecosystems. Polar ice is melting at an alarmingly fast rate. Ice that has been frozen for millions of years is now slipping rapidly into the ocean, causing the sea level to rise.

With mangroves ripped up and sand dunes dredged to get that perfect view, beachfront houses become the perfect candidate for landslides. The rising sea levels also mean the disappearance of the beautiful, colourful corals that snorkellers seek. Sediment and runoff from unsustainable coastal development suffocate corals, while hot ocean temperatures cause them to bleach and eventually perish. The microscopic algae (zooxanthellae) that live within the coral tissues need stable water and light parameters to grow and thrive, and will die without them, killing the coral animal as they go.

But the real punch in the proverbial stomach is the loss of organisms from the ocean, a decline that has negative effects on the entire global population and economy. The loss of life from the sea is a two-fold debacle. We remove nearly entire functional groups from food chains through unsustainable fishing practices, while at the same time impeding the possibility of recovery. We are “fishing down the food web” as marine biologist Daniel Pauly says, referring to the recurring pattern of declining mean trophic level of fisheries landings. And yet, business as usual continues without much thought of the consequences to species and the ecosystems within which they interact.

Everything on our planet is connected. The ocean holds control over all of us, whether we want to accept or not. It tempers our weather, provides food, influences the world’s economy, living conditions, and more. It holds us delicately on the landmasses that rose from its depths and makes up 99 percent of Earth’s living space. Not being inhabitants of the ocean does not justify our ignorance of its importance for our survival.

THE CURRENT CLIMATE CRISIS IS DIRECTLY LINKED TO OUR OCEAN IN CRISIS. Now is the time to repair natural resources that have sustained us for the entirety of human existence, and with a sense of hope, redemption will prevail.

As climate change tightens its grip, its effects are being felt across the planet. Some significant shifts are already underway, and the disruption cause by warming water temperature to our seas looks set to worsen. The following is a breakdown of some of the primary changes in our ocean as Earth warms.

About 90 percent of the excess heat trapped by atmospheric greenhouse gases is soaked up by the world’s oceans. Because oceans are so big, the temperature change to the seawater can seem small – the sea surface layer has warmed by just over 0.5C in the last century. That, however, is enough to cause significant disruption, and the warming is accelerating.

Things expand as they warm, becoming less dense and taking up more space. The oceans are no different. Indeed, between 1993-2010, thermal expansion is thought to have raised sea levels by an average of 1.1 millimetres a year, while the total observed rise in sea level for the same period was an average of 3.2 millimetres annually.

Warmer water also influences the atmosphere above it. Increased sea surface temperatures are associated with more powerful hurricanes and tropical cyclones, potentially increasing the number of the severe category 4 or 5 storms that strike islands and coastal areas. Warmer waters also hold less carbon dioxide, which means more will stay in the atmosphere to accelerate global warming.

Just like on land, rising temperatures in the oceans generate damaging heatwaves. They occur when unusual weather conditions or water currents cause above-average water temperatures for at least five consecutive days. But they can last for months or even years. A marine heatwave called “The Blob” hung around the northern Pacific from 2013-2015 and killed a million seabirds on the west coast of the United States.

As carbon dioxide dissolves in seawater, it reacts to form carbonic acid, a fairly weak acid, but enough to alter the pH of seawater, which is naturally alkaline. Since the industrial revolution, dissolved carbon dioxide is estimated to have lowered the average pH of the top layer of the oceans by 0.1 pH units, from about 8.2 to 8.1 (7 is neutral).

While that does not sound like much, it is important to know that pH is measured on a logarithmic scale, which means a decrease in pH by 0.1 represents a nearly 30 percent increase in acidity. This has some significant knock-on effects for seawater chemistry and the ecosystems that rely on it.

The increase in acidity is particularly bad news for shellfish and other forms of sea life that use the mineral calcium carbonate to form their shells and exoskeletons. Water that is more acidic holds less calcium carbonate, so less is available calcifying organisms such as oysters, clams, sea urchins, shallow water corals, deep sea corals and calcareous plankton. What is worse, the change in chemistry causes existing carbonate structures to dissolve.

Corals are particularly vulnerable. Experiments on a small patch of Australia’s Great Barrier Reef show that artificially reducing the seawater carbon dioxide content to pre-industrial levels boosted coral calcification by 7 percent. And when the scientists raised the amount of carbon dioxide, decreasing ocean pH to the level expected by the end of this century, calcification dropped by a third.

As global warming continues, it is inevitable that massive ice sheets in Greenland and Antarctica will collapse and melt entirely, eventually pouring enough water into the oceans to raise global sea levels by several metres. The UN’s climate body now projects that, under a low-emissions scenario, average sea level will rise between 61 centimetres and 1.1 metres by the end of the century.

By 2050, rising seas could push peak high tides above land currently home to at least 500 million people, mostly in Asia. Coastal ecosystems will be affected, too. Beach and dune environments face more severe and frequent flooding and erosion, while sensitive freshwater habitats including mudflats and marshes needed for bird and turtle species to breed, will be swamped with seawater.

Sea ice, which forms when seawater freezes each polar winter, is also melting and thinning more and more each summer. Melting of this ice doesn’t significantly contribute to sea levels, but it does pose big problems for animals that rely on it for their habitat.

Ocean currents are vulnerable to the effects of climate change. At present, those currents act as massive global conveyor belts: as winds push through the atmosphere from the warm equator to the colder poles, they drag surface water with them. Cooled by the chilly polar air, this water becomes denser, and so sinks to the deep ocean, where it is pushed back towards the equator (becoming warmer, less dense and rising as it goes) by the next batch of denser water coming from above. Round and round the cycles go, transporting and mixing nutrients as they swirl along.

Melting ice interferes with this system. Huge amounts of fresh water pouring in at the poles lower the density of the seawater, making it slower to sink. Without the same driving downward force, the whole global cycle can weaken. In 2018, scientists suggested that the major current in the Atlantic Ocean had slowed by about 15 percent, and some studies predict that could drop to more than 30 percent by 2100. Based on what has happened in the past, scientists say slower ocean currents can bring significant changes in the Earth’s atmosphere, and so to the weather.

Ocean creatures rely on oxygen dissolved in seawater, but climate change is gradually draining oxygen from the seas: about 1-2 percent is thought to have been lost from 1960 to 2010, and that could rise to 4 percent by 2100.

Warmer water holds less oxygen, while disruption to ocean currents limits the amount of oxygen transported from the surface to the depths. A growing problem occurs when the fertiliser and other nutrients added to agricultural soils drain into rivers and eventually get dumped into coastal waters. Boosted by the unexpected supply of food, algae can grow and proliferate rapidly to form massive floating blooms that are frequently problematic due to their toxicity. When the algae die and sink, the microbes that work to decompose the blooms in the depths soak up oxygen from the surrounding water resulting in dead zones. In severe cases, dissolved oxygen levels can fall so low that parts of the deep ocean become barren. A 2011 global survey found at least 415 of these dead zones, up from 49 in the 1960s.

Changes to interconnected and complex food webs are hard to predict. Fisheries in some areas might actually get a boost as valuable new species are driven into their nets, but overall, the impact is likely to be overwhelmingly negative. A study last year suggested that warmer waters had reduced the total amount of fish that can be caught in a sustainable way by an average of 4 percent since the 1930s. The worst-affected sea was the Sea of Japan, with a 35 percent reduction in fishery size due to warming sea temperature. The East China Sea saw a drop of 8 percent.

Future drops in fish catches would threaten the food security of a large fraction of the world’s growing population. According to the UN, fish provide more than 3.1 billion people with at least 20 percent of their animal protein. It’s an important source of fatty acids and micronutrients, too. Fish currently supply 17 percent of all the protein consumed in the world, and demand is expected to continue to increase as incomes rise in the developing world.

WE MUST LEAVE AS MUCH CARBON AS POSSIBLE in our natural living systems, REDUCE THE AMOUNT OF CARBON we use in the form of fossil fuels, and support new and evolving technologies that help extract excess carbon from our atmosphere. WE MUST WORK TO ACHIEVE GLOBAL CARBON NEUTRALITY BY 2035.

OUR OCEAN IS OUR LIFE-SUPPORT SYSTEM – it provides everything we need for our survival; from the FOOD WE EAT TO THE OXYGEN WE BREATHE. Our Ocean is now in crisis – we are in trouble.

Already under pressure from overfishing and pollution, marine life ranging from large fish down to cyanobacteria, is also affected by climate change. As waters warm and currents shift, some sea life can simply move, for example towards the cooler water of the poles. These shifts in distribution have knock-on effects for species that feed on them: from people trying to catch tuna, to fish looking for zooplankton.

THESE SIX AREAS OF CHANGE are far too significant to keep ignoring. We are undoubtedly rapidly running out of time to make the sweeping production and lifestyle changes necessary to get carbon emissions under control. Every action counts and we can all choose to make a difference. Outside of the individual choices we make about the way we live our daily lives; systemic global shifts must simultaneously occur if we are to mitigate the effects of our warming world in any meaningful way.

If we reduce the actions we need to take to their simplest components, they would be the following: leave as much carbon as possible in our living systems, reduce the amount of carbon we use in the form of fossil fuels, and support new and evolving technologies that help extract excess carbon from our atmosphere. All three of these carbon control action categories are currently happening, but their implementation must be expanded and accelerated. We must work to achieve global carbon neutrality by 2035.

What would it take to attain this bold target? We would need to work towards protecting all the ecosystems, both on land and underwater, that sequester more carbon than they release. This means the bolstering of both green and blue carbon habitats, including forests, grasslands, marshes, mangroves, kelp forests, and seagrass beds. The animals that inhabit these ecosystems, from whales to fish to rabbits to birds, also function as carbon capture units, and as such, must be protected too. Then there is the business of divesting our culture and business from fossil fuels. The world of our future must be powered with clean, renewable energy. Finally, there is the need to pull excess carbon from our atmosphere to help stabilize our climate. There are both low- and high-tech solutions for this ranging from planting trees to negative emissions technologies that remove CO2 through direct air capture (DAC) systems, and more options are under development all the time.

Solutions are within reach and the battle to save us from ourselves is well underway. We now know that the current climate emergency is directly linked to our ocean in crisis. Now is the time to repair the natural resources that have sustained us for the entirety of human existence, and with a sense of hope, redemption will prevail.

We are undoubtedly running out of time to make the sweeping production and lifestyle changes necessary to get carbon emissions under control. EVERY ACTION COUNTS, AND WE CAN ALL CHOOSE TO MAKE A DIFFERENCE.