Coral and shellfish remove calcium and CO2 from water to make their calcium carbonate shells.
Do clams have thicker or thinner shells lately?
I guess there are people who would know that, I happen to not be one of them.
I know that the clam-farm guys are worried about thinner shells. But that may just be from listening to the alarmist news and not related to actual observed thicknesses.
The basic carbon cycle of life is: (1) the conversion of atmospheric carbon dioxide to carbohydrates by photosynthesis in plants; (2) the consumption and oxidation of these carbohydrates by animals and microorganisms to produce carbon dioxide and other products; and (3) the return of carbon dioxide to the atmosphere. On a global level, the total carbon cycle is more complex, and involves carbon stored in fossil fuels, soils, oceans, and rocks.
We can organize all the carbon on earth into five main pools, listed in order of the size of the pool:
1. Lithosphere (Earth’s crust). This consists of fossil fuels and sedimentary rock deposits, such as limestone, dolomite, and chalk. This is far and away the largest carbon pool on earth. The amount of carbon in the lithosphere: 66 to 100 million gigatons (a gigaton is one million metric tons). Of this amount, only 4,000 gigatons consists of fossil fuels.
2. Oceans. Ocean waters contain dissolved carbon dioxide, and calcium carbonate shells in marine organisms. Amount of carbon: 38,000 to 40,000 gigatons.
3. Soil organic matter. Amount of carbon: 1,500 to 1,600 gigatons.
4. Atmosphere. This consists primarily of carbon dioxide, carbon monoxide, and methane. The amount of carbon in the atmosphere has increased from 578 gigatons in 1700 to about 766 gigatons in 1999, and continues to increase at the rate of about 6.1 gigatons per year.
5. Biosphere. This consists of all living and dead organisms not yet converted into soil organic matter. Amount of carbon: 540 to 610 gigatons.