ENV SCI 15 LECTURE 22

TODAY’S MATERIAL• Carbon Budget• Activity 7

http://vulcan.project.asu.edu/index.php

Launch CO2 flux USA video

Atmospheric CO2, CH4, and N2O concentration history over the industrial era (right) and from year 0 to the year 1750 (left), determined from air enclosed in ice cores and firn air (colour symbols) and from direct atmospheric measurements (blue lines, measurements from the Cape Grim observatory)

http://www.nature.com/nature/journal/v484/n7392/full/nature10915.html

Average global temperature (blue), Antarctic temperature (red), and atmospheric CO2 concentration (yellow dots).

https://www.skepticalscience.com/co2-lags-temperature.htm

http://cliffmass.blogspot.com/2013/10/ocean-acidification-and-northwest.html

The figure above shows the increase in atmospheric CO2 (red line), the increase in CO2 gas of the waters in the middle of the Pacific (dark blue), and the decline of ph from 8.11 to 8.07 since 1988 (24 years, light blue).

http://earthobservatory.nasa.gov/blogs/climateqa/mauna-loa-co2-record/

Launch land connection video

Watching the Earth Breathe: An Animation of Seasonal Vegetation and its effect on

Earth's Global Atmospheric Carbon Dioxidehttp://svs.gsfc.nasa.gov/vis/a000000/a003900/a003947/index.html

Launch Global plant carbon uptake video

How Much Carbon do Plants Take from the Atmosphere?

http://svs.gsfc.nasa.gov/vis/a000000/a003700/a003764/index.html

Launch Africa plant carbon uptake video

How Much Carbon do Plants Take from the Atmosphere?

Simplified schematic of the global carbon cycle. Numbers represent reservoir mass, also called ‘carbon stocks’ in Pg C (1 Pg C = 1,015 g C) and annual carbon exchange fluxes (in Pg C yr–1). • Black numbers and arrows

indicate pre-industrial reservoir mass and exchange fluxes.

• Red arrows and numbers indicate annual ‘anthropogenic’ fluxes averaged over the 2000–2009 time period.

http://earthobservatory.nasa.gov/Features/OceanCarbon/ The concentration of carbon dioxide (CO2) in ocean water (y axis) depends on the amount of CO2 in the atmosphere (shaded curves) and the temperature of the water (x axis). This simplified graph shows that as atmospheric CO2 increases from pre-industrial levels (blue) to double (2X) the pre-industrial amounts (light green), the ocean CO2concentration increases as well. However, as water temperature increases, its ability dissolve CO2decreases. Global warming is expected to reduce the ocean’s ability to absorb CO2, leaving more in the atmosphere…which will lead to even higher temperatures.

http://earthobservatory.nasa.gov/Features/OceanCarbon/

In the short term, the ocean absorbs atmospheric carbon dioxide into the mixed layer, a thin layer of water with nearly uniform temperature, salinity, and dissolved gases. Wind-driven turbulence maintains the mixed layer by stirring the water near the ocean’s surface. Over the long term, carbon dioxide slowly enters the deep ocean at the bottom of the mixed layer as well in in regions near the poles where cold, salty water sinks to the ocean depths.

CO2 dissolves in water to form carbonic acid. (It is worth noting that carbonic acid is what eats out limestone caves from our mountains.) In the oceans, carbonic acid releases hydrogen ions (H+), reducing pH, and bicarbonate ions (HCO3-).

CO2 + H2O => H+ + HCO3- (1)

The additional hydrogen ions released by carbonic acid bind to carbonate ions (CO32-), forming

additional HCO3-.

H+ + CO32- => HCO3

- (2)

This reduces the concentration of CO32-, making it harder for marine creatures to take up

CO32- to form the calcium carbonate needed to build their exoskeletons.

Ca2+ + CO32- => CaCO3

(3)

The two main forms of calcium carbonate used by marine creatures are calcite and aragonite. Decreasing the amount of carbonate ions in the water makes conditions more difficult for both calcite users (phytoplankton, foraminifera and coccolithophore algae), and aragonite users (corals, shellfish, pteropods and heteropods).

http://www.gly.uga.edu/railsback/Fundamentals/FundamentalsCarbs.html

In certain areas near the polar oceans, the colder surface water also gets saltier due to evaporation or sea ice formation. In these regions, the surface water becomes dense enough to sink to the ocean depths. This pumping of surface water into the deep ocean forces the deep water to move horizontally until it can find an area on the world where it can rise back to the surface and close the current loop

The oceans are mostly composed of warm salty water near the surface over cold, less salty water in the ocean depths.

http://svs.gsfc.nasa.gov/vis/a000000/a003600/a003658/

Launch thermohaline conveyor video

Figure 1 shows a simplified diagram of the global carbon cycle. The open arrows indicate typical timeframes for carbon atoms to be transferred through the different reservoirs.

Figure 2 illustrates the decay of a large excess amount of CO2 (5000 Pg C, or about 10 times the cumulative CO2 emitted so far since the beginning of the industrial Era) emitted into the atmosphere, and how it is redistributed among land and the ocean over time. During the first 200 years, the ocean and land take up similar amounts of carbon. On longer time scales, the ocean uptake dominates mainly because of its larger reservoir size (~38,000 Pg C) as compared to land (~4000 Pg C) and atmosphere (589 Pg C prior to the Industrial Era). Because of ocean chemistry the size of the initial input is important: higher emissions imply that a larger fraction of CO2 will remain in the atmosphere. After 2000 years, the atmosphere will still contain between 15% and 40% of those initial CO2 emissions. A further reduction by carbonate sediment dissolution, and reactions with igneous rocks, such as silicate weathering and sediment burial, will take anything from tens to hundreds of thousands of years, or even longer.

http://svs.gsfc.nasa.gov/vis/a000000/a004100/a004110/

Launch RCP 2.6 video

These visualizations represent the mean output of how certain groups of CMIP5 models responded to four different scenarios defined by the IPCC called Representative Concentration Pathways (RCPs). These four RCPs - 2.6, 4.5, 6 and 8.5 - represent a wide range of potential worldwide greenhouse gas emissions and sequestration scenarios for the coming century. The pathways are numbered based on the expected Watts per square meter - essentially a measure of how much heat energy is being trapped by the climate system - each scenario would produce

http://svs.gsfc.nasa.gov/vis/a000000/a004100/a004110/

Launch RCP 8.5 video

The carbon dioxide concentrations in the year 2100 for each RCP are:RCP 2.6: 421 ppmRCP 4.5: 538 ppmRCP 6: 670 ppmRCP 8.5: 936 ppm

Schematic representation of carbon cycle numerical experimental design. Concentration-driven (left) and emissions-driven (right) simulation experiments make use of the same Earth System Models (ESMs), but configured differently. Concentration-driven simulations prescribe atmospheric CO2 as a predefined input to the climate and carbon cycle model components, but their output does not affect the CO2. Emissions-driven simulations prescribe CO2 emissions as the input and atmospheric CO2 is an internally calculated element of the ESM.