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The ocean acidification occurs when the CO2 of the atmosphere is absorbed by the seawater. More acidic water with a lower pH. About a third of the CO2 released by the burning of coal, oil and gas dissolves in the oceans. Since the beginning of the industrial era, the ocean has absorbed about 525 billion tons of CO2, or about 22 million tons per day.
Researchers have reconstructed the acidity levels of the oceans and atmospheric CO2 over the past 22 million years. the chemistry of fossil shells of tiny marine creatures that once lived near the surface of the ocean. They were able to set their new pH and CO2 records against the backdrop of the range of future carbon emission scenarios recognized by the Intergovernmental Panel on Climate Change (IPCC).
The current pH is probably lower than ever in the last two million years, and as part of a "status quo" scenario where CO2 is emitted at the same rate as in the past. today, atmospheric CO2 would be close to 930 parts per million in the year 2100, compared to about 400 parts per year
Similarly, the pH of the oceans would be less than 7.8 in 2100 compared to at a pH of about 8.1 today. This is significant because the pH scale is logarithmic, which means a drop of 0.1 pH unit represents a 25% increase in acidity.
These levels of atmospheric CO2 and ocean acidity have not been around for some time, when global temperatures were warmer by about 3 ° C than today. because of the natural geological cycle of the Earth.
More and more scientists are discovering evidence of negative impacts. For example, fish are losing their sense of smell because of increasingly acidic oceans, according to a new study from the University of Exeter in the United States. Fish use their sense of smell to find food, secure habitats, avoid predators, identify themselves and find suitable spawning grounds. A reduction in their ability to feel can therefore compromise these essential functions for their survival. The study provides evidence that economically important species, such as bar, will be affected by high CO2 levels, leaving fish vulnerable because they affect their ability to detect odors.
A study conducted by the Australian Institute of Marine and Antarctic Studies has highlighted the challenges facing scientists, governments and communities as ocean acidification continues. These researchers have discovered that in recent centuries, the pH of the ocean surface has dropped 10 times faster than the past 300 million years. The economic cost for coral reefs, wild fisheries and aquaculture is expected to reach more than $ 300 billion a year.
In some parts of the world, such as Chile and the west coast of the United States, some fisheries are already adapting to ocean acidification. partnerships between scientists, industry and government. Other global impacts will likely require similar international collaboration and action, say the researchers. An important question for scientists and policy makers is whether humans should attempt to mitigate ocean acidification by changing the chemistry of the oceans, or whether communities simply need to adapt.
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