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BIOL 3999: Issues in Biological Science

GLOBAL CHANGE BIOLOGY. BIOL 3999: Issues in Biological Science. Dr. Tyler Evans Email: tyler.evans@csueastbay.edu Phone: 510-885-3475 Office Hours: M,W 10:30-12:00 or by appointment Website: http ://evanslabcsueb.weebly.com /. PREVIOUS LECTURE. How human systems influence Earth systems.

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BIOL 3999: Issues in Biological Science

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  1. GLOBAL CHANGE BIOLOGY BIOL 3999: Issues in Biological Science Dr. Tyler Evans Email: tyler.evans@csueastbay.edu Phone: 510-885-3475 Office Hours: M,W 10:30-12:00 or by appointment Website: http://evanslabcsueb.weebly.com/

  2. PREVIOUS LECTURE • How human systems influence Earth systems EARTH SYSTEMS HUMAN SYSTEMS • socio-economic development • production and consumption • resource use Global Change Biology • ecosystems • climate • geochemical cycles

  3. HOW ARE HUMANS INFLUENCING EARTH SYSTEMS? ALTERING CLIMATE CLIMATE: refers to the behavior of the atmosphere over a longer period of time, and usually for a large area. WEATHER: refers to the conditions of the atmosphere over a short period of time, such as hours or days, and typically for a local area

  4. HOW IS CLIMATE ALTERED? The power of a process to alter the climate is estimated by its RADIATIVE FORCING, the change in the Earth's energy balance due to that process. RADIATIVE FORCES may be: NEGATIVE e.g. volcanic eruptions POSITIVE e.g. increases in solar output Balance between positive and negative radiative forcing determines climate

  5. RADIATIVE FORCING CAN BE CAUSED BY HUMAN ACTIVITIES • carbon dioxide emitted from the burning of fossil fuel is presently the largest single climate forcing agent, accounting for more than half of the total positive forcing since 1750.

  6. Carbon dioxide is naturally present in the atmosphere as part of the Earth's carbon cycle (the natural circulation of carbon among the atmosphere, oceans, soil, plants, and animals). • Prior to the industrial revolution, the carbon cycle was approximately in balance. • SINKS (removes CO2) • photosynthesis • oceans • SOURCES (add CO2) • respiration CO2 CO2

  7. Since that time humans have become a source of CO2 by releasing the carbon stored in fossil fuels • Currently, inputs of CO2 outpace the ability of the carbon cycle to remove it from the atmosphere • SOURCES (add CO2) • respiration • fossil fuels • SINKS (removes CO2) • photosynthesis • oceans CO2 CO2

  8. A USEFUL ANALOGY

  9. CO2 IS ACCUMULATING IN THE ATMOSPHERE 393 ppm in 2013 315 ppm in 1958

  10. CO2 IS ACCUMULATING IN THE ATMOSPHERE KEELING CURVE • named fore Charles David Keeling who collected data • based on atmospheric data collected at Mauna Loa, HI • record starts in 1958 and still continues today • longest continuous record of atmospheric CO2

  11. SEASONALITY IN KEELING CURVE respiration photosynthesis • reflects seasonal differences in photosynthesis (SINK) • deciduous plants shed leaves in winter and respiration outpaces photosynthesis • in summer, photosynthesis outpaces respiration

  12. DOESN’T FULLY EXPLAIN SEASONALITY • when it is winter in Northern hemisphere (i.e. respiration), it is summer in Southern Hemisphere (i.e. photosynthesis). • so shouldn’t these differences cancel each other out? equator • major difference in percent land cover between Northern and Southern hemispheres • most land in Southern hemisphere is in tropics where very little seasonal variation • this difference is greatest at temperate latitudes, where deciduous forests dominate • photosynthesis in the Northern hemisphere growing season is greater than the amount of CO2 respired during winter in the southern hemisphere

  13. HOW DOES CO2 AFFECT CLIMATE? CO2 is a GREENHOUSE GAS and contributes to the GREENHOUSE EFFECT • the Sun emits energy that travels to Earth. Because the Sun is very hot, the energy is emitted in high-energy, short wavelengths that penetrate the Earth's atmosphere.

  14. HOW DOES CO2 AFFECT CLIMATE? CO2 is a GREENHOUSE GAS and contributes to the GREENHOUSE EFFECT • about 30% of the Sun's energy is reflected directly back into space by the atmosphere, clouds, and surface of the Earth. The rest of the Sun's energy is absorbed into the Earth's system.

  15. HOW DOES CO2 AFFECT CLIMATE? CO2 is a GREENHOUSE GAS and contributes to the GREENHOUSE EFFECT • Because the Earth is cooler than the Sun, the energy is emitted in the form of infrared radiation, at wavelengths longer than the incoming solar energy.

  16. HOW DOES CO2 AFFECT CLIMATE? CO2 is a GREENHOUSE GAS and contributes to the GREENHOUSE EFFECT • greenhouse gases in the atmosphere absorb much of the long-wave energy emitted from the Earth's surface, preventing it from immediately escaping from the Earth's system. The greenhouse gases then re-emit this energy, warming the Earth's surface and atmosphere.

  17. HOW DOES CO2 AFFECT CLIMATE? CO2 is a GREENHOUSE GAS and contributes to the GREENHOUSE EFFECT • the increase in the concentration of CO2 has amplified the natural greenhouse effect by trapping more of the energy emitted by the Earth. This change causes Earth's surface temperature to increase among other changes. • greenhouse gases have a POSITIVE RADIATIVE FORCEbecause they absorb energy radiating from Earth’s surface, rather than allowing it to be directly transmitted into space.

  18. CO2 IS NOT THE ONLY GREENHOUSE GAS THAT AFFECTS CLIMATE • several other greenhouse gases produced by human activities: METHANE (CH4) a colorless, odorless non-toxic gas consisting of molecules made up of four hydrogen atoms and one carbon atom. NITROUS OXIDE(N2O) is a colorless, non-flammable gas with a sweetish odor, made up of two nitrogen atoms and one oxygen atom SULFUR HEXAFLUORIDE (SF6) Human made gas containing one sulfur atom and six fluoride atoms • human sources of greenhouse gases far exceed natural sources

  19. METHANE • methane (CH4) is the second most prevalent greenhouse gas emitted in the United States from human activities. • methane is emitted by natural sources such as wetlands, however over 60% of total CH4 emissions come from human activities. INDUSTRY AGRICULTURE LANDFILLS • primary source of methane is natural gas • enteric fermentation • bi-product of decaying organic matter

  20. NITROUS OXIDE • is a colorless, non-flammable gas with a sweetish odor • nitrous oxide is naturally produced in the oceans and in rainforests • globally, about 40% of total N2O emissions come from human activities: CARS NITRIC ACID NYLON FERTILIZER formed in catalytic converters Component of nylon also used in fertilizers improve plant production BURNING ORGANIC MATTER

  21. SULFUR HEXAFLUORIDE • fluorinated gases have no natural sources and only come from human-related activities ALUMINIUM SEMICONDUCTORS • these compounds were produced as an alternative to chlorofluorocarbons (CFCs), which were responsible for depleting the ozone layer • ironically, these compounds are potent greenhouse gases with long atmospheric lifetimes

  22. GREENHOUSE GASES THROUGH TIME CARBON DIOXIDE

  23. GREENHOUSE GASES THROUGH TIME METHANE

  24. GREENHOUSE GASES THROUGH TIME NITROUS OXIDE

  25. GREENHOUSE GASES THROUGH TIME SULFUR HEXAFLUORIDE AND RELATED COMPUNDS

  26. NOT ALL GREENHOUSE GASES ARE CREATED EQUAL…

  27. ATMOPSHERIC CONCENTRATIONS OF ALL THESE GREENHOUSE GASES ARE INCREASING 2008 economic crisis

  28. 2008 Global CO2 Emissions • from fossil fuel combustion and some industrial processes (million metric tons of CO2) • half of emissions are coming from two countries • not corrected for population (i.e. per capita)

  29. WILL THE TREND OF INCREASING GREEENHOUSE GASES CONTINUE?

  30. FUTURE GREENHOUSE GAS EMISSION SCENARIOS • Predictions focus on carbon dioxide: • other greenhouse gases track the pattern of CO2 • CO2 is by far the largest source of greenhouse gases A CO2 PROBLEM WORLD (77%) U.S.A (84%)

  31. FUTURE CO2 EMISSIONS SCENARIOS • goal of developing future emission scenarios is not to predict the future • understand what futures are possible and where major points of uncertainty lie • inform how present-day decisions will influence a range of possible futures FUTURE CLIMATE MODELS • to develop future emission scenarios and how this will impact climate scientists use MODELS: a mathematical representation of the interactions between human activities and key components of the Earth systems. • to construct climate models, scientists divide each of the Earth's components spatially into a set of boxes. Simple models may have only a few boxes. The most complex models may have more than a hundred thousand.

  32. CLIMATE MODELS HAVE TWO COMPONENTS: • 1.) Earth System Models • explore future changes in physical and biogeochemical responses to changing atmospheric composition and radiative forcing • use mathematical equations based on well-understood principles to depict the behavior of Earth processes in each box. • the movement of energy, air, and water are represented as horizontal and vertical exchanges between the boxes. In this way, models represent interactions between different parts of the climate system and the world.

  33. CLIMATE MODELS HAVE TWO COMPONENTS: • 2.) Integrated Assessment Models • driving forces and responses by humans through changes in technology, economies, lifestyle and policy • explore alternative socio-economic conditions that would result in such future atmospheric composition changes • Integrated assessment models contain three main factors: a. POPULATION b. URBANIZATION c. ECONOMIC DEVELOPMENT more urban areas = more CO2 bigger economy = more CO2 more people = more CO2

  34. EFFECT OF POPULATION SIZE ON CO2 EMISSIONS

  35. EFFECT OF ECONOMY ON CO2 EMISSIONS

  36. INTERNATIONAL PANEL ON CLIMATE CHANGE (IPCC) • international body for the assessment of climate change established by the United Nations and World Meterological Organization in 1998 • goal is to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts. • thousands of scientists from all over the world contribute to the work of the IPCC on a voluntary basis and reflect a range of views and expertise

  37. FUTURE CO2 EMISSION SCENARIOS • very rapid economic growth • pursue wealth over environment • changes in economic structures • reductions in energy use • clean and resource-efficient technologies.

  38. LECTURE SUMMARY • climate is altered by changes in radiative forcing • carbon dioxide emitted from the burning of fossil fuel is presently the largest single climate forcing agent • inputs of CO2 outpace the ability of the carbon cycle to remove it from the atmosphere • accumulation of CO2 in atmosphere exhibits a distinct seasonal trend • CO2 and other human emissions act as greenhouse gases and contribute to the greenhouse effect. • greenhouse gas emission are tightly linked with economic development • greenhouse gases emissions are expected to increase over the next century

  39. NEXT LECTURE: CO2 AND TEMPERATURE

  40. MORE INFORMATION GREENHOUSE GASES Environmental Protection Agency http://www.epa.gov/climatechange/ghgemissions/ TRENDS IN CO2 EMISSIONS NOAA Earth System Research Laboratory http://www.esrl.noaa.gov/gmd/ccgg/trends/mlo.html IPCC AND EMISSION SCEANRIOS http://www.ipcc.ch/

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