III. BIOGEOCHEMICAL CYCLES Overview The Water Cycle The Carbon Cycle 1. OVERVIEW

RESERVOIRS: Most atmospheric carbon has been transferred to the hydrosphere (dissolved CO2) and lithosphere (limestone and fossil deposits). Dead and dissolved organic matter are other large reservoirs The atmosphere and biosphere have some, too. reservoirs in gigatons and exchanges in GT/year

FLUXES: Flux between hydro and atmo is still a major exchange reservoirs in gigatons and exchanges in GT/year

FLUXES: Photosynthesis balances respiration Volcanism balances by sedimentation and deposition Net transfer to atmosphere is by burning of fossil fuels (7 GT) and reduction of photosynthesis by forests from deforestation (1 GT) reservoirs in gigatons and exchanges in GT/year

- last 160,000 years (ice cores) 401 280

- Since 1000: up 43% (all since 1760 – Industrial Revolution)

- Since 1955: 318 to 402.24 (Sept 5, 2016) – 26%

- Ocean absorption and acidification

III. BIOGEOCHEMICAL CYCLES Overview The Water Cycle The Carbon Cycle 1. OVERVIEW 2. Change in CO2 3. Consequences – Global warming

2. Since 1860 – increase of 0.8oC – ten hottest years all since 1998 2015 – hottest by the greatest margin; 2016 on pace to be hotter 15 of 17 hottest years on record ALL SINCE 2000

Most heat is absorbed by ocean

III. BIOGEOCHEMICAL CYCLES Overview The Water Cycle The Carbon Cycle 1. OVERVIEW 2. Change in CO2 3. Consequences – Global warming 4. Correlates

Reductions in Polar Ice (area covered) 1979 Nasa.gov 2012

Summer 2012 – Record low summer sea ice

Reductions in polar ice Reductions in glacial ice B-15 is the size of Connecticutt (2000)

Reductions in polar ice Reductions in glacial ice

Reductions in polar ice Reductions in glacial ice Sea level rise

- Increases in Sea Level

Reductions in polar ice Reductions in glacial ice Sea level rise Melting of Permafrost 14% of the world’s organic carbon is stored in permafrost. As the poles warm (and they are warming faster than anywhere else), this carbon may be mobilized as decomposing bacteria gear up…. This is a type of threshold response (not a gradual response), and would involve positive feedback loops…

- More big storms:

Reductions in polar ice Reductions in glacial ice Sea level rise Melting of Permafrost Stronger Storms Effects on the Biosphere - Changes in Plant Growth: Qualitative Effects: Laurance et al. (March 2004, Nature): - Pristine rainforests have changed composition in last 20 years, with an increase in fast-growing species and a decrease in slow growing species… probably as a result of increased CO2 availability.

Reductions in polar ice Reductions in glacial ice Sea level rise Melting of Permafrost Stronger Storms Effects on the Biosphere Changes in Reef Communities: “Almost 15% of the world's reefs are already beyond repair thanks to global warming. Another 30% may be lost over the next 30 years.” – (Nature, February 2004) - Reefs are home to 25% of all marine species - Reefs are nursery areas for the larvae and fry of commercially important fish and crustacean species - Reefs are important storm breaks for tropical coasts

Reductions in polar ice Reductions in glacial ice Sea level rise Melting of Permafrost Stronger Storms Effects on the Biosphere - Changes in Species Diversity 15-37% of terrestrial species may go extinct in the next 50 years, largely because of global warming. (Thomas et al. 2004)

Reductions in polar ice Reductions in glacial ice Sea level rise Melting of Permafrost Stronger Storms Effects on the Biosphere Increases in Human Diseases: UN Environmental Programme Report, Feb 21, 2005: - Environmental change may be the cause of the resurgence of some infectious diseases. - The fatal Nipah virus, normally found in Asian fruit bats, is believed to have crossed over to humans as the bats lost their habitats through forest fires in Sumatra and the clearance of land for palm plantations.

III. BIOGEOCHEMICAL CYCLES Overview The Water Cycle The Carbon Cycle 1. OVERVIEW 2. Change in CO2 3. Consequences – Global warming 4. Correlates 5. Perspectives IPCC 2015 Report: “It is extremely likely that human influence on climate caused more than half of the observed increase in global average surface temperature from 1951 to 2010. There is high confidence that this has warmed the ocean, melted snow and ice, raised global mean sea level and changed some climate extremes in the second half of the 20th century.”