Oceans are the life support system of our planet and humankind. The seas flow over nearly three-quarters of the Earth and hold 97% of the planet’s water. Sea plants, like Posidonia, produce 70% of the oxygen we breathe, that’s every second breath we take. The oceans are home to incredible biodiversity and some of the most massive creatures on earth. Producing more than half of the oxygen in the atmosphere , they also absorb the most carbon from it. No matter where you live in the world, from the mountains to the desert, oceans directly affect your life and the lives of everyone you know.
Basically, overfishing means taking too many fish out of the seas before new fish can reproduce to replace those caught. Worldwide, 90% of large predatory fish stocks are gone due to overfishing. The United Nations predicts that if current trends continue, global fish stocks may be extinct by the year 2048.
The depletion of fish stocks means a risk of losing a valuable food source that many people depend on for economic and dietary reasons. Nearly two-thirds of the world’s population relies on fish for 40% of their protein, and about 13 million people depend on fishing for all or most of their incomes.
While individuals cannot solve this global problem of overfishing without international policymakers’ help, it’s still critical to make change where we can. Our power lies in our consumption choices. Each time you use a dollar, you are voting. With each dollar spent or withheld, you support an industry or help bring one to an end.
Today, the oceans and marine life are facing the threat of permanent alteration from a number of sources of pollution, and plastic is among the most significant. Plastic accounts for 60-80% of marine garbage, and in high-density areas, reaches up to 95%.
The reality is that every piece of plastic that has ever been made still exists in one form or another. Even when burned, it breaks down into microscopic, toxic particles. Made from oil, plastic is not a material that our planet can digest.
Plastic permeates our modern lifestyles but there are simple ways for individuals and communities to reduce their plastic footprint by choosing to use reusable alternatives to common consumer goods like shopping bags, coffee cups, water bottles, utensils, straws, and more.
93% of the excess heat generated by human activities via the greenhouse effect is absorbed by the ocean, thus mitigating the increase in temperature of the atmosphere. This heat absorption causes a slight warming of the ocean which can be detected as deeply as seven hundred meters below sea level. It has now reached the deep sea in the polar regions and is spreading to all ocean basins. Considering the volume of the ocean, this represents a significant amount of heat!
Increasing ocean temperatures affect marine species and ecosystems, causing coral bleaching and the loss of breeding grounds for marine fishes and mammals. Ice melt and sea-level rise are two additional crucial consequences of warming seawater.
Rising ocean temperatures also affect the benefits humans derive from the ocean – threatening food security, increasing the prevalence of diseases, and causing more extreme weather events and the loss of coastal protection.
For more than 200 years, or since the industrial revolution, the concentration of carbon dioxide (CO2) in the atmosphere has increased due to the burning of fossil fuels and land use change. The ocean absorbs about 30% of the CO2 that is released in the atmosphere, and as levels of atmospheric CO2 increase, so do the levels in the ocean.
When CO2 is absorbed by seawater, a series of chemical reactions occur resulting in the increased concentration of hydrogen ions. This increase causes the seawater to become more acidic and causes carbonate ions to be relatively less abundant.
An acidified ocean make building and maintaining shells and other calcium carbonate structures difficult for calcifying organisms such as oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. These changes in ocean chemistry can affect the behavior of non-calcifying organisms as well such as their ability to detect predators.
There is no area of the ocean that sin't suffering from human-made habitat destruction, but coastal areas are disproportionately affected. As the global population grows, coastal land use and development increases.
With development come far-reaching impacts on coastal ecosystems and the species dependent on them. Coastal areas are home to over 90% of all marine species, but we are losing these habitats at an alarming rate.
Coastal habitats serve as critical habitats for marine life and the destruction of these inflict repercussions to dependent species.
Coastal development linked to human settlements, industry, aquaculture, or infrastructure can cause severe impacts on nearshore ecosystems. The impacts of coastal development are both direct (e.g., in the form of landfilling, dredging, coral and sand mining for construction) and indirect, such as from increased run-off and erosion of sediment and pollutants.
The growing impact of human activities is causing a rapid loss of animal and plant biodiversity. Currently, the rate of animal extinction is 1,000 to 10,000 times higher than the natural extinction rate. According to a UN report on the state of the global environment, 25% of the world’s mammals face extinction by the year 2032.
In the oceans, the rate of biodiversity destruction is cataclysmic. There is a wide range of causes of marine species extinction and endangerment, such as habitat loss, acidification, atmospheric change, and pollution. The most dominant and influential threat, however, is overfishing. Overfishing is reported to be the greatest threat to marine biodiversity in all regions. When the population of a species is reduced, the genetic variation is reduced along with it. This compromises the species’ ability to adapt to new environmental stresses and changes.