This is how climate change is reshaping the entire planet

We know the climate is changing. But the phrase “climate change” gets repeated so often it can be hard to remember what it really describes. It’s not just that the planet is getting hotter. Everything is changing. To better understand our future, Massive asked two climate scientists to describe what the world is facing. This is part two. Part one is here.

Fossil fuels are organic material – they’re made up of the remains of living things that, over hundreds of thousands of years, have broken down into oil and coal. When that fuel is burned, the carbon becomes carbon dioxide, which enters the atmosphere.

Carbon dioxide acidifies the ocean

Sudden influxes in freshwater aren’t the only things affecting the chemistry of the ocean. The sudden increase of carbon dioxide in the atmosphere is having serious effects on the chemistry of seawater. Because the ocean and the atmosphere are in constant contact, about a third of the excess carbon dioxide that humans have emitted into the atmosphere has been absorbed by the ocean. This is a big deal for global climate because the absorption of that carbon dioxide has meant that it isn’t around to trap solar radiation and increase Earth’s temperature. 

But that relief from rising temperatures comes at a price. 

When carbon dioxide dissolves into water, it makes the water more acidic. So, as the ocean absorbs more carbon dioxide, its pH is decreasing. This change is devastating for ocean ecosystems. 

Scientists estimate that the ocean’s pH has declined by 0.1. This might not seem like a lot, but pH is measured on a logarithmic scale. That means that pH 7 is ten times more acidic than pH 8. And unfortunately, a lot of oceanic life relies on seawater being slightly basic to survive. An acidifying ocean spells disaster for marine and human systemsWe can avert this and other effects of climate change by decreasing global carbon dioxide emissionsMassive Science | Keira Monuki | Nov 30

Many shell-building creatures, like corals and oysters, make their shells out of calcium carbonate. In seawater that is slightly acidic, they can’t gather enough carbonate ions to make their shells. In the more acidic seawater of the future, their shells will start to dissolve, and they will die.

Coral reefs are the rainforests of the ocean. They are incredibly biodiverse places, with about 25 percent of all known oceanic species relying on coral reefs. And they’re in trouble. A combination of warming water and ocean acidification means that 99 percent of shallow-water corals are threatened with extinction, with troubling implications for the animals that live there. If we do nothing about climate change, by 2100, our existing coral reefs might simply be gone

Ocean acidification has economic as well as environmental effects. Already, current levels of ocean acidification are making it impossible for oyster larvae in the Pacific Northwest to form their shells, and as oceans acidify, this could become a global problem. Some experts project that the total loss to the shellfish industry from ocean acidification could be over $1 billion by 2100. And salmon fishing – an $18 billion industry – is also at risk from ocean acidification. Salmon eat pteropods, a type of marine snail that also makes their shells out of calcium carbonate. As the ocean acidifies, pteropods will have a harder time surviving, affecting everything that eats them. 

Elisa Bonnin, Massive Science, 8 December 2020. Full article.

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