The Carbon Cycle

Carbon Dioxide and Carbonate system Why is it important? 1. CO 2 regulates temperature of the planet 2. Important for life in the ocean 3. Regulates the pH of water

100 ppm

TEMPERATURE CO 2 1-6°C

CO 2 Temperature 80 ppm Glacial-interglacial CO 2 and temperature change

CO 2 changes in the last 300 yr 80 ppm Industrial Revolution

CO 2 changes in the last 50 yr: the Keeling curve Oceans Biosphere Rock Weathering

How much CO 2 can you sink in the ocean? Process that control CO 2 absorption in the ocean Chemical Biological Physical Carbon Cycle

CO 2 O2O2 pH acidbasic (m)

Dissolved Gases in the Ocean Oxygen profile

Dissolved Gases in the Ocean Oxygen profile low oxygen environment compensation depth Respiration: Animal, plants and microbial decomposition

The Carbonate System from dissolution of Calcium Carbonate from dissolved CO 2 gas sources of inorganic carbon

CO 2 in the ocean ~ 1000m

Total dissolved inorganic carbon this is very small not found in this form Total dissolved inorganic carbon

Total dissolved inorganic carbon formation and decomposition of organic matter (1) from dissolution of Calcium Carbonate (2)

Carbonic Acid Bicarbonate Ion Carbon Dioxide and Carbonate system Carbonate

Distribution of Carbon species in water + -

Iong/LFormula weight g/mol Molar concentration M Normality Cl SO HCO Br H 2 BO F-F Tot: ~0.594

Iong/LFormula weight g/mol Molar concentration M Normality Na Mg Ca K+K Sr Tot: ~ 0.594

What control the absorption of Carbon Dioxide in the ocean? How can we measure it? The carbonate system chemistry in seawater The concept of alkalinity, pH …

Strong base cations (less) strong acid anions Alkalinity: is the net molar concentration, in charge- equivalents, of the cations of strong bases in excess of the anions of strong acids Def: in simple terms represents the degree to which a solution resists a decrease in pH when acid is added

Alkalinity Alkalinity is fundamental for hard corals and coralline algae to properly secrete new skeletal material. When alkalinity levels drop, the carbonate ions needed are not available and the process slows or stops. Alkalinity is measured in one of two units: milliequivalents per liter (meq/l), or parts per million of calcium carbonate (ppm CaCO3). The 'ppm CaCO3' unit reports the concentration of CaCO3 in pure water that would provide the same buffering capacity as the water sample in question. This does not mean the sample contains that much CaCO3. In natural seawater, though, carbonates make up 96% of the alkalinity so equating alkalinity with carbonate hardness isn't too far off.

from GLODAP climatology

Strong base cations What happens to this balance? (less) Strong acid anions

Total dissolved inorganic carbon Calcium Carbonate dissolution and formation (2) +alkalinity -alkalinity Total dissolved inorganic carbon

What happens if I add or remove CO 2 by photosynthesis and respiration?

Carbon Cycle

CO 2 changes in the last 50 yr Oceans Biosphere Rock Weathering

Ocean Acidification: Change in pH between 1751 and 1994 (up another ~10% if until 2009)

TimepHSourceH + relative change Pre-industrial (18 th century) 8.179Data (reconst.) 0% Recent past (1990s) 8.104Field data18.9% Today ~8.069Field data28.8% 2050 (2XCO 2 ) 7.949model69.8% model126.5%

several important articles in 2010 summarized by Scientific American: July 2010: William Howard (ACEC Research Center in Hobart, Tasmania) states that "the current rate of ocean acidification is about a hundred times faster than the most rapid events" in the geologic past. August 2010: Marah J. Hardt and Carl Safina (USF) make the case that in the 15-year period , acidity has increased 6 percent in the upper 100 meters of the Pacific Ocean from Hawaii to Alaska

Today‘s world pCO 2 : ppmV High-CO 2 world pCO 2 : ppmV Emiliania huxleyi Gephyrocapsa oceanica Calcidiscus leptoporus A summary of studies indicate that almost all calcifying species examined to date have shown reduced calcification rates at higher pCO 2 levels, but only a small fraction of the natural species have been tested.

Consensus among the participants was that higher CO 2 levels will generally be detrimental to calcifying organisms and that food web structures and biodiversity will likely change, but it is not clear how this might impact overall productivity and top level predators (e.g. fish). CoccolithophoresForams Corals calcite aragonite

Ocean acidification: What corals are dying to tell us slides from Ken Caldeira

A cautionary tale from 65Ma: the Cretaceous-Tertiary extinction -huge comet blasts Yucatan -releases S into atmosphere -acid rain falls on ocean for 1-2 years -ALL surface calcifiers die for 2 million years!

We are changing CO2 rates faster than the geologic past

The surface ocean changes will lead deep ocean changes