Chapter 19 Global Change

1. Chapter 19 Global Change

2. Global Change • Global change- any chemical, biological or physical property change of the planet. Examples include cold temperatures causing ice ages. • Earth’s climate has varied naturally through time • Global climate change- describes changes in the climate of the Earth (temperature, precipitation, wind, storm frequency, etc.) • Global warming- one aspect of climate change, the warming of the oceans, land masses and atmosphere of the Earth. • Only one aspect of climate change

3. The sun and atmosphere keep Earth warm • Four factors exert the most influence on climate • The sun = without it, Earth would be dark and frozen • Supplies most of Earth’s energy • The atmosphere = without it, Earth’s temperature would be much colder • The oceans = shape climate by storing and transporting heat and moisture • How Earth spins, tilts, and moves through space influence how climate varies over long periods of time

4. The fate of solar radiation • The atmosphere, land, ice, and water absorb 70% of incoming solar radiation

5. Greenhouse gases warm the lower atmosphere • As Earth’s surface absorbs solar radiation, the surface increases in temperature and emits infrared radiation • Greenhouse gases = atmospheric gases that absorb infrared radiation • Water vapor, ozone, carbon dioxide, nitrous oxide, methane, halocarbons [chlorofluorocarbons (CFCs)] • After absorbing radiation, greenhouse gases re-emit infrared energy, losing some energy to space • Greenhouse effect = energy that travels downward, warming the atmosphere and the planet’s surface

6. The greenhouse effect is natural • Greenhouse gases have always been in the atmosphere • We are not worried about the natural greenhouse effect • Anthropogenic intensification is of concern • Global warming potential = the relative ability of one molecule of a greenhouse gas to contribute to warming • Expressed in relation to carbon dioxide (potential = 1) • Methane is 25 times as potent as carbon dioxide

9. Greenhouse Gases in order from most to least • Water vapor • Carbon dioxide • Methane • Nitrous oxide • Ozone

11. Carbon dioxide is of primary concern • It is not the most potent greenhouse gas, but it is extremely abundant • The major contributor to the greenhouse effects • CO2 exerts six times more impact than methane, nitrous oxide, and halocarbons combined • Deposition, partial decay, and compression of organic matter (mostly plants) in wetlands or marine areas led to formation of coal, oil, and natural gas • These deposits remained buried for millions of years

12. Other greenhouse gases add to warming • Methane = fossil fuels, livestock, landfills, crops (rice) • Levels have doubled since 1750 • Nitrous oxide = feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers • Ozone levels have risen 36% due to photochemical smog • Halocarbon gases (CFCs) are declining due to the Montreal Protocol • Water vapor = the most abundant greenhouse gas • Contributes most to the natural greenhouse effect • Concentrations have not changed

13. U.S. emissions of major greenhouse gases

15. Natural Greenhouse Gases • Volcanic eruptions- mainly carbon dioxide • Methane – from decomposition • Nitrous oxide- from denitrification • Water vapor-from evaporation and evapotranspiration

16. Anthropogenic Causes of Greenhouse Gases • Burning of fossil fuels • Agricultural practices • Deforestation • Landfills • Industrial production- CFC’s are an example

19. Increasing CO2 Concentrations • David Keeling began measuring CO 2 in 1958.

20. Emissions from the Developed and Developing World

21. Global Temperatures since 1880 • Since 1880 temperatures have increased 0.8°C (1.4 o F)

23. Temperatures and Greenhouse Gas Concentrations in Past 400,000 Years • No one was around thousands of years ago to measure temperatures so we use other indirect measurements. Some of these are • Changes in species compositions • Chemical analyses of ice

24. Atmospheric CO2 concentrations have increased from 315 ppm to 389 ppm

25. Proxy indicators tell us about the past • Paleoclimate = climate of the geological past • Gives a baseline to compare to today’s climate • Proxy indicators =indirect evidence that serve as substitutes for direct measurements • Shed light on past climate • Ice caps, ice sheets, and glaciers hold clues to Earth’s climate history • Trapped bubbles in ice cores provide a timescale of: • Atmospheric composition, greenhouse gas concentrations, temperature trends • Snowfall, solar activity, and frequency of fires

26. More proxy indicators • Cores in sediment beds preserve pollen grains and other plant remnants • Tree rings indicate age, precipitation, droughts, and fire history • In arid regions, packrats carry seeds and plants to their middens (dens) • Plant parts can be preserved for centuries • Researchers gather data on past ocean conditions from coral reefs • Scientists combine multiple records to get a global perspective

28. Putting It Together • We know that an increase in CO2 in the atmosphere causes a greater capacity for warming through the greenhouse effect. • When the Earth experiences higher temperatures, the oceans warm and cannot contain as much CO2 gas and, as a result, they release CO2 into the atmosphere.

29. Feedback complicates our predictions • Tropospheric warming will transfer more water to the air • But the effects are uncertain • A positive feedback loop = more water vapor … more warming … more evaporation … more water vapor … • A negative feedback loop = more water vapor … more clouds … shade and cool Earth OR increase evaporation • Minor modifications of the atmosphere can lead to major effects on climate

30. Current and future trends and impacts • Evidence that climate conditions have changed since industrialization is everywhere • Fishermen in the Maldives, ranchers in Texas, homeowners in Florida, etc. • Scientific evidence that climate has changed is overwhelming and indisputable • Intergovernmental Panel on Climate Change (IPCC) was established in 1988 • Composed of hundreds of international scientists and government officials

31. The IPCC’s fourth assessment report (2007) • The IPCC reports on the synthesis of scientific information concerning climate change • Global consensus of scientific climate research • Summarized thousands of studies • Documented observed trends in surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, etc. • Predicted impacts of current and future climate change on wildlife, ecosystems, and human societies • Discussed strategies to pursue in response to climate change

33. Temperatures continue to increase • Average surface temperatures increased 0.74 °C since 1906 • Most of the increase occurred in the last few decades • Extremely hot days have increased • The 16 warmest years on record have been since 1990

34. The future will be hotter • In the next 20 years, temperatures will rise 0.4 °C • At the end of the 21st century, temperatures will be 1.8–4.0 °C higher than today’s • We will have unusually hot days and heat waves • Polar areas will have the most intense warming • Sea surface temperatures will rise • Hurricanes and tropical storms will increase • In power and duration

35. Temperatures will rise globally Projected increases in surface temperature for 2090–2099 relative to 1980–1999

36. Precipitation is changing, too • Some regions are receiving more precipitation than usual, and others are receiving less • Droughts have become more frequent and severe • Harming agriculture, promoting soil erosion, reducing water supplies, and triggering fires • Heavy rains contribute to flooding • Killing people, destroying homes, and inflicting billions of dollars in damage

37. Projected changes in precipitation Precipitation will increase at high latitudes and decrease at low and middle latitudes

38. Melting snow and ice • Mountaintop glaciers are disappearing • Glaciers on tropical mountaintops have disappeared • The remaining 26 of 150 glaciers in Glacier National Park will be gone by 2020 or 2030 • Reducing summertime water supplies • Melting of Greenland’s Arctic ice sheet is accelerating • Warmer water is melting Antarctic coastal ice shelves • Interior snow is increasing due to more precipitation • Melting ice exposes darker, less-reflective surfaces, which absorb more sunlight, causing more melting

39. Worldwide, glaciers are melting rapidly • Nations are rushing to exploit underwater oil and mineral resources made available by newly opened shipping lanes • Permafrost (permanently frozen ground) is thawing • Destabilizing soil, buildings, etc. and releasing methane

40. Rising sea levels • Runoff from melting glaciers and ice will cause sea levels to rise • As oceans warm, they expand • Leading to beach erosion, coastal floods, and intrusion of salt water into aquifers

41. Coastal areas will flood An earthquake caused the 2004 tsunami (tidal wave) that killed 100 Maldives residents and caused $470 million in damages • Storm surge = temporary, localized rise in sea level • Caused by the high tides and winds of storms • Cities will be flooded • 53% of people in the U.S. live in coastal areas

42. Rising sea levels will devastate coasts • 1 million acres of Louisiana’s wetlands are gone • Rising sea levels eat away vegetation • Dams upriver decrease siltation • Pollution from the Deepwater Horizon • Millions of people will be displaced from coastal areas

44. Coral reefs are threatened • Coral reefs are habitat for food fish • Snorkeling and scuba diving sites for tourism • Warmer waters contribute to coral bleaching • Which kills corals • Increased CO2 is acidifying the ocean • Organisms can’t build their exoskeletons • Oceans have already decreased by 0.1 pH unit • Enough to kill most coral reefs

45. Climate change affects organisms and ecosystems • Organisms are adapted to their environments • They are affected when those environments change • Global warming modifies temperature-dependent phenomena (e.g., timing of migration, breeding) • Animals and plants will move toward the poles or upward in elevation • 20–30% of species will be threatened with extinction • Rare species will be pushed out of preserves • Droughts, fire, and disease will decrease plant growth • Fewer plants means more CO2 in the atmosphere

46. Animals and plants have nowhere to go • GTS- 12 adorable animals affected by climate change. Be able to describe one animal and how its affected. http://mashable.com/2015/12/05/climate-change-animals/#zSNPnaUH2kqt

47. Climate change affects people • Societies are feeling the impacts of climate change • Agriculture: shortened growing seasons, decreased production, crops more susceptible to droughts • Increasing hunger • Forestry: increased fires, invasive species • Insect and disease outbreaks • Health: heat waves and stress can cause death • Respiratory ailments, expansion of tropical diseases • Disease and sanitation problems from flooding • Drowning from storms

48. Climate change affects economics • Costs will outweigh benefits of climate change • It will widen the gap between rich and poor • Those with less wealth and technology will suffer most • External costs of damages will be $10–350/ton of carbon • It will cost 1–5% GDP on average globally • Poor nations will lose more than rich ones • The Stern Review predicts it will cost 5–20% of GDP by 2200 • Investing 1% of GDP now could avoid these costs

50. Impacts will vary regionally • Where we live will determine how we experience the impacts of climate change • Temperature changes have been greatest in the Arctic • Melting ice sheets, thinning ice, increasing storms, etc. • Harder for people and polar bears to hunt • U.S. temperatures will continue rising • Plant communities will shift north and upward • More frequent extreme weather events • The southern U.S. will get drier, the northern wetter • Sea levels will rise and may be worse in the East