Our oceans are getting increasingly warmer and more acidic – and negatively affecting the delicate balance of marine ecosystems. Damage to coral reefs and reduced diversity of marine species are just a few examples of the negative effects of climate change. It’s a vicious cycle that feeds on itself, because our planet's oceans play a crucial role in counteracting the effects of global warming – and, consequently, in protecting biodiversity. Water temperatures are rising In 2022, average ocean temperatures rose for the seventh year in a row. A new record was reached in late March of this year, when the global average ocean surface temperature rose above 21°C. This figure, experts say, reflects a trend of continuous acceleration that has been going on for several decades: in just a few years the rate of temperature growth has increased by 24%. The rising temperature of the oceans is a huge problem for the species living in them, because it affects the food chain and fragile balances among marine populations. For example, when there are unfavorable environmental conditions, some organisms migrate to cooler areas – and some fish species face extinction altogether. Heat waves also have a negative effect, because the scorching heat on the earth's surface causes the surface temperatures of coastal waters to soar, even within just a few days. Rising sea temperatures are also negatively impacting coral reefs: reef bleaching is a phenomenon caused by the death of certain algae and other living organisms that are responsible for coral pigmentation. As they become less and less colorful, coral reefs become less attractive as a habitat for fish, and thus, eventually, die. The damage to marine animals and coastal ecosystems A study conducted by the School of Biological Sciences at the University of Adelaide together with the Globe Institute at the University of Copenhagen has shown that warmer waters threaten marine life in more than 70% of the planet's most biodiverse areas. In fact, most marine life forms, such as plankton and fish, live close to the surface, where the increase in temperatures is greatest. Suffice it to say that it only takes a rise of a few tenths of a degree to have a major impact on these organisms. Further complicating the situation are the increase in extreme weather events and, most importantly, rising sea levels. Since 1993, sea levels have risen about 10 centimeters, due mainly to melting glaciers; this is a real threat to coastal communities and coastal ecosystems. Besides the risk of flooding and the possible negative consequences for human activities due to coastal erosion, it is the fish and organisms living in these habitats that suffer the most. Oceans and their role in climate change Our seas and oceans are essential to maintaining the balance of living ecosystems. In addition to absorbing a quarter of all carbon dioxide released into the atmosphere, they emit more than half of the oxygen we breathe, which is why they are often referred to as the "aquatic lungs of the earth." When the temperature of the oceans rises, less carbon dioxide is absorbed. As a result, this greenhouse gas will be more present in the atmosphere, giving rise to a self-perpetuating cycle. We shouldn’t forget that the oceans are also an important source of food and not coincidentally are the place where life originated, as well as being at the base of the food chain due to the presence of plankton. An important international agreement for the future of the seas The importance of aquatic environments was further highlighted when a historic milestone was reached recently after more than 15 years of debate among member states of the United Nations (UN). The legally binding agreement adopted by the UN protects the high seas, the maritime area that lies outside the exclusive economic zones of the various countries. The high seas make up about two-thirds of the world’s oceans, so this is a shared effort that can make a difference in protecting fisheries, natural marine habitats and aquatic biodiversity.
