Global Change

1. CHAPTER 19 Global Change

2. Is this evidence of global warming?

3. Climate Change Debate? • “The major scientific agencies of the United States — including the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) — agree that climate change is occurring and that humans are contributing to it.” - EPA

4. Questions Still Up For Debate • Scientists are still researching a number of important questions: • Exactly how much will Earth warm? • How quickly will it warm? • What will the consequences of the warming be in specific regions of the world?

5. Global Change • Global change: any chemical, biological, or physical property change of the planet (ex: cold temperatures causing ice ages) • Global climate change: changes in the climate of the Earth • Global warming: one aspect of climate change, the warming of the oceans, landmasses, and atmosphere of the Earth

7. Greenhouse Effect • When radiation from the sun hits the atmosphere, 1/3 is reflected back • Some UV radiation is absorbed by the ozone layer • Some strikes the Earth and is converted into low-energy infrared radiation • Infrared radiation then goes back toward the atmosphere, where it’s absorbed by greenhouse gases that radiate most of it back to the Earth

9. Greenhouse Gases • Water vapor (H2O) • Carbon dioxide (CO2) • Methane (CH4) • Nitrous oxide (N2O) • Chlorofluorocarbons (CFCs) • Ozone (O3)

10. Global Warming Potential • Certain GHGs are more effective at warming the Earth than others • 2 most important factors: • How well the gas absorbs energy • How long the gas stays in the atmosphere • Global Warming Potential (GWP) is a measure of the total energy that a gas absorbs over a particular period of time (usually 100 years), compared to CO2

12. U.S. Greenhouse Gas Emissions in 2010

14. Natural Sources of Greenhouse Gases • Carbon dioxide from volcanic eruptions • Methane from decomposition • Nitrous oxide from denitrification • Water vapor

15. Anthropogenic Sources of Greenhouse Gases • Burning of fossil fuels • Agricultural practices • Deforestation • Landfills • Industrial production (ex: CFCs)

18. U.S. Carbon Dioxide Emissions, By Source

19. Particulate Matter • Aerosols are a subset of air pollution that refers to the tiny particles suspended in our atmosphere • Particles can be both solid and liquid • Light-colored aerosol particles can reflect incoming solar energy • Dark particles can absorb solar energy

20. Greenhouse Effect • http://www.youtube.com/watch?v=ZzCA60WnoMk&list=PLi_1unC2AWvBgO2QcF9pfnWlyg4MemHAw

21. Radiative Forcing • Energy is constantly flowing into the atmosphere and being absorbed by Earth • Some energy is always radiating back out into space (infrared light) • If: • Energy flowing out > energy flowing in = cooling • Energy flowing out < energy flowing in = warming • Energy flowing out = energy flowing in = no change

22. Radiative Forcing Energy is constantly flowing into the atmosphere and being absorbed by Earth Some energy is always radiating back out into space (infrared light) If: Energy flowing out > energy flowing in = cooling Energy flowing out < energy flowing in = warming Energy flowing out = energy flowing in = no change

23. Radiative Forcing Energy is constantly flowing into the atmosphere and being absorbed by Earth Some energy is always radiating back out into space (infrared light) If: Energy flowing out > energy flowing in = cooling Energy flowing out < energy flowing in = warming Energy flowing out = energy flowing in = no change

24. Radiative Forcing • Radiative forcing is a direct measure of the impact that human activities are having on changing the planet’s climate • Measured in watts per square meter (W/m2) of surface

26. IPCC • The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change • Established in 1988 by two United Nations organizations: the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) • Its mission 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 and other experts contribute (on a voluntary basis) to writing and reviewing reports, which are reviewed by representatives from all the governments

27. Increasing CO2 Concentrations • David Keeling began measuring CO2 in 1958

28. Comparing Emissions • Which country emits the most CO2? • Which country emits the most CO2 per capita?

29. Comparing Emissions

30. CO2 Emissions Per Capita • http://www.google.com/publicdata/explore?ds=d5bncppjof8f9_&met_y=en_atm_co2e_pc&idim=country:CHN&dl=en&hl=en&q=china%20co2%20emissions

31. What do you think? • Should developing countries be held to the same CO2 emissions standards as developed countries? • Things to consider: • How did developed countries become so wealthy? • Which countries are to blame for climate change? • Will strict CO2 standards inhibit growth in developing countries? • Will developing countries be able to afford costly new technology?

32. Global Temperature Change • Since 1880, temperatures have increased 0.8°C

34. Global Temperature Change • http://www.youtube.com/watch?v=SF5FxpedVlw&list=PLi_1unC2AWvBgO2QcF9pfnWlyg4MemHAw

35. Temperatures & Greenhouse Gas Concentrations in Past 400,000 Years • No one was around thousands of years ago to measure temperatures, so we must use indirect measurements • Changes in species composition • Chemical analysis of ice

36. Ice Cores • Ice cores contain an abundance of climate information – more so than any other natural recorder of climate like tree rings or sediment layers • Although their record is short (in geologic terms), it can be highly detailed and extend back hundreds of thousands of years • This record can include: • Temperature • Precipitation • Chemistry and gas composition of the lower atmosphere • Volcanic eruptions • Solar variability

38. Ice Cores • http://www.youtube.com/watch?v=NENZ6TSc1fo&feature=player_embedded

39. CO2 Concentration Throughout History

40. CO2 Heat Trapping • http://www.youtube.com/watch?v=-RTLU4VTZ9o&list=PLi_1unC2AWvBgO2QcF9pfnWlyg4MemHAw

43. Sediment Cores • Rarely disturbed ocean sediment cores can provide records up to 180 million years ago as new layers of sediment bury and preserve those of the past • Fossilized specimens of microscopic foraminifera can provide clues to the climate conditions during their lives • Some species are only found in certain environments, so we can reconstruct the sea level, ocean, and climate conditions of that period based on our knowledge of foraminifera species

44. Oxygen Isotopes • Ocean water during warmer times has a lower 18O / 16O ratio than ocean water during colder times • Foraminifera incorporate that oxygen into their shells (CaCO3), which accumulate on the ocean floor after they die • We can estimate the water temperature by the ratio of  18O / 16O in fossilized shells

45. Climate Models • Scientists use climate data gathered from the past to help predict the future • Current models predict that average global temperatures will increase 1.8⁰ – 4.0⁰ C (3.2⁰ – 7.2⁰ F) by 2100

47. Battery Drive • Bring in your old batteries to HR and put in the canisters this week

48. Feedback Loops • What is a positive feedback loop? • What is a negative feedback loop?

49. Positive Feedback Loop

50. Positive Feedback Loop • We know that an increase in CO2 in the atmosphere causes a greater capacity for warming through the greenhouse effect • Higher temperatures  warmer oceans  oceans release CO2 gas into atmosphere