Chapter 21: Global Climate Change (Condensed)

1. Chapter 21: Global Climate Change (Condensed)

2. Foreword • The issue of global climate change may be one of the most important issues facing humanity in its history • This issue has the potential to affect the economies, safety and health of the entire world’s population • Hopefully you’ll understand after this review why the science of this topic is so difficult to understand and why it generates so much political controversy

3. The Earth Systems Science approach recognizes four natural subsystems: atmosphere, hydrosphere, geosphere and biosphere. Most researchers now recognize a fifth, non-natural subsystem: the anthroposphere. The Earth’s climate system consists of complex interactions between many components!

4. Global Climate Change • We’ll focus on some basics of the climate system such as atmospheric chemistry and the greenhouse effect

5. Greenhouse Effect – gradual warming of the Earth’s lower atmosphere and surface when certain gases (e.g., H2O, CO2 and CH4 ) absorb heat radiated from the Earth’s surface and then reradiate portions of it About 30% of incoming solar energy reflected back to space Sun Greenhouse gases absorb radiated heat and reradiate some of it to the lower atmosphere radiated heat Earth materials and atmosphere absorb about 70% of incoming light energy; some portion of this energy is emitted to the atmosphere as radiated heat

6. Earth’s Atmospheric Composition (Dry Air)

7. Greenhouse Effect • Would the average person view the greenhouse effect as beneficial or detrimental? • Most people erroneously think that the greenhouse effect is detrimental; the greenhouse effect is a natural phenomenon that helps modify the Earth’s climate and produce livable biological niches

8. Greenhouse Effect • Atmospheric scientists suggest the Earth’s average surface temperature would be about 60 - 70 degrees F colder without a greenhouse effect; under these conditions most of the Earth’s surface would host Arctic conditions - the flora and fauna of Earth would be drastically reduced in number and diversity

9. Global Warming Evidence • There is firm evidence that the greenhouse effect is being enhanced and that we are entering a global warming period • This evidence includes: • 29 of the highest world average annual temperatures ever recorded (since 1880) recorded from 1976-2013; with the exception of 1998, the nine hottest years have occurred since 2001 (2013 was the fourth hottest global year on record, 2005 and 2010 the hottest); • about a 50% reduction in European Alps glacier ice in the last 100 years; Source: National Geographic, Sept. 2012

10. Global Warming Evidence an average rise in world sea levels of about 1 foot during the last century; a decline of about 42% in Arctic sea ice volume in the last 30 years; and the quick melting of portions of the Greenland and Antarctic ice sheets and Antarctic ice shelves (1995, 2002 and 2008 – in March 2002 a portion of the Larsen ice shelf the size of Rhode Island (1250 mi2 ) collapsed into the Antarctic Ocean) (see slides) Change in Arctic Sea Ice Minimum 1979-2007

11. Global Warming Evidence

13. Global Warming • The accumulating evidence suggests global warming is occurring but whether natural or human forces (or both) were causing climate change was vigorously debated • However, the debate in the scientific community has mostly ceased

14. Global Climate Change • The 2013 IPCC (Intergovernmental Panel on Climate Change) report contends that human actions are significantly driving climate change (95% confidence level)

15. Global Warming

16. Global Climate Research • In simple models, the more greenhouse gases in the atmosphere the more radiated heat from the surface gets trapped and the higher the atmospheric and surface temperatures • What are some natural sources of greenhouse gases?

17. Greenhouse Gas Sources • What are some other natural sources of greenhouse gases? Are these sources easy to accurately quantify on a worldwide basis? • Is this a simple or complex research topic?

18. Climate Reconstruction Research • Ice sheet core samples (see figure) and other materials are being ingeniously investigated for their ability to retain indications of prior atmospheric chemistry and temperature • Scientists are attempting to detail ancient atmosphere greenhouse gas levels to see if they’ve ever fluctuated as much naturally as they’ve done in the last 55 years

19. Global Warming • Although reconstruction of ancient atmospheric chemistries and climates suggest that air CO2 levels haven’t been higher than currently in the last 650,000 years, some data suggest CO2 levels have naturally fluctuated much more than within the last 160 years (millions of years ago). (see figure)

20. Industrial Revolution

21. Global Climate Research • In addition, we are still learning about other sources of greenhouse gases and can’t be sure that we’ve quantified their releases accurately (see figure)

22. Global Climate Research

23. Possible Global Climate Change Outcomes • If atmospheric greenhouse gas concentrations continue to rise and enhance the greenhouse effect, what are some of the proposed consequences of global warming? • Remember: although the topic discussed is often called “global warming” the entire globe won’t be affected similarly, subsequently many researchers and politicians now employ the phrase, “global climate change”

24. Possible Global Climate Change Outcomes • Consequences could include: 1) significant rises in sea levels as increased glacial ice melting occurs; the rising waters could permanently displace millions of people (see figures); National Geographic: August, 2007

25. Possible Global Climate Change Outcomes

26. Possible Global Climate Change Outcomes • Note the adjacent example of the threat of rising seas • 2) Reduction of tillable land as sea levels rise;

27. Possible Global Climate Change Outcomes • 3) Changes in world weather patterns and a higher frequency of severe weather events (e.g., hurricanes, severe thunderstorms, blizzards, extended heat waves, droughts); North Atlantic Tropical Storm Frequency National Geographic: August, 2007

28. Possible Global Climate Change Outcomes Source: National Geographic, Sept. 2012

29. 1980 - 1995: 46 US weather disasters with at least $1 billion in damages 1996 - 2011: 87 US weather disasters with at least $1 billion in damages Source: US National Climatic Data Center 2012 Superstorm Sandy

30. Possible Global Climate Change Outcomes • 4) A greater percentage of land becomes arid and less productive; the glacial source of some major rivers (e.g., the Ganges) may be reduced or eliminated long term (a few hundred years)

31. Possible Global Climate Change Outcomes CNN.com 3/31/06 • 5) The biodiversity of coastal ecosystems declines due to an inability to adapt quickly to rising, warming and acidifying seas (e.g., reefs); Bleached coral

32. Possible Global Climate Change Outcomes 1/26/2012 6) Diseases spread by flies, mosquitoes, ticks become more prevalent as the warmer climates produce longer and more intense infection periods (think about the rapid spread of West Nile Virus across the U.S.); and

33. 7) The deep-water return flow of the Gulf Stream current is reduced/eliminated leading to much colder conditions in the North Atlantic (see figure) Warm, less salty surface current Gulf Stream: 50-90 miles wide; maximum discharge: 540 billion tons/hour Cold, salty deep current

34. Possible Global Climate Change Outcomes • Most climate scientists think there is enough evidence of these effects occurring to strongly support that global climate change is occurring at a rate that requires worldwide action • Complicating factors: How would climate change influence the Jet Stream or weather patterns generated during El Nino and La Nina events?

35. Possible Global Climate Change Outcomes • Please remember that the seven categories of global climate change outcomes we discussed are projections, not a guaranteed reality - the projections are based on incomplete data and an incomplete mathematical understanding of the Earth’s dynamic processes • The first global warming computer models treated the Earth as a rocky ball devoid of life - simpler to model mathematically!

36. Variables Affecting the Degree of Climate Change • There are other variables (factors) which may affect the degree of climate change. • 1) A few scientists have proposed that as air CO2 levels rise, plant productivity will rise since CO2 is necessary for photosynthesis; the more CO2 absorbed by plants the less likely a severe global warming event

37. Variables Affecting the Degree of Climate Change • Experiments with plants in CO2-enriched lab atmospheres and outside forest plots have produced variable results - hardwood trees respond positively and absorb more CO2 for a few years; most grasses and ferns show declines in productivity • Therefore could the distribution, and type, of plant species (and animals) across the globe be altered? (see figure)

38. Variables Affecting the Degree of Climate Change • A nutrient (iron) seeding project in a portion of the southern Pacific ocean in 1993 successfully increased the population of CO2-absorbing phytoplankton, however the positive results were short-lived • Do you advocate “geoengineering” on a large scale? (see slide) • A Californian company, Climos, wants to commercialize iron fertilization and an India/Germany iron fertilization experiment was completed in 2009

39. Geoengineering • Note the India/Germany iron fertilization experiment was not very successful Earth Magazine, June 2009

40. Source: Earth Magazine; December 2008

41. Geoengineering • Pay attention to this topic!

42. Variables Affecting the Degree of Climate Change • In addition, fairly recent (2004) data from the TERRA satellite suggests plant productivity has increased 5-10% on average worldwide during the last twenty years • How would this hypothesis be affected by continued deforestation and land development?

43. Update EarthSky // Earth, Science WireRelease Date: May 31, 2013 • 145 Increasing CO2 in air is making deserts greener Scientists call this a “carbon dioxide fertilization effect.” It has caused a gradual greening of arid regions on Earth from 1982 to 2010. Scientists have long suspected that a flourishing of green foliage around the globe, observed since the early 1980s in satellite data, springs at least in part from the increasing concentration of carbon dioxide in Earth’s atmosphere. Now, a study of arid regions around the globe finds that a carbon dioxide fertilization effect has, indeed, caused a gradual greening from 1982 to 2010. View Larger | New research links gradual greening of arid areas like Australia’s outback to increasing concentrations of atmospheric carbon dioxide. Photo by Bruce Doran Focusing on the southwestern corner of North America, Australia’s outback, the Middle East, and some parts of Africa, Randall Donohue of the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Canberra, Australia and his colleagues developed and applied a mathematical model to predict the extent of the carbon-dioxide (CO2) fertilization effect. They then tested this prediction by studying satellite imagery and teasing out the influence of carbon dioxide on greening from other factors such as precipitation, air temperature, the amount of light, and land-use changes. The team’s model predicted that foliage would increase by some 5 to 10 percent given the 14 percent increase in atmospheric CO2 concentration during the study period. The satellite data agreed, showing an 11 percent increase in foliage after adjusting the data for precipitation, yielding “strong support for our hypothesis,” the team reports.

44. Variables Affecting the Degree of Climate Change • 2) Some scientists have proposed the world’s oceans could absorb enough air CO2 to offset a significant global warming event; investigations are being conducted to test this hypothesis

45. Variables Affecting the Degree of Climate Change • Preliminary results (2003) suggest the oceans absorb more carbon than they emit – about 2 billion tons annually • Potential problems: • a) warm waters absorb less carbon dioxide; if the oceans continue to warm this carbon dioxide “sink” will decrease (see article); • b) increased carbon dioxide absorption by the ocean will decrease the pH (make more acidic) of the ocean’s waters and threaten to dissolve the exoskeletons of reef corals and certain shellfish (see slide) CNN.com; 5/18/2007

46. 5/28/08 Implications for world oceans?

47. Oceans’ acidic shift may be fastest in 300 million years

48. Variables Affecting the Degree of Climate Change • 3) Multiple hypotheses exist involving clouds: warming will result in more atmospheric water vapor; some climatologists suggest this will result in more high-elevation clouds • A 4% increase in high-elevation clouds could cause enough sunlight to be reflected (off cloud ice crystals) back to space to offset a significant global warming event (see figure) Source: National Geographic, Sept. 2012

49. reflected sunlight ice crystals high-altitude clouds

50. Variables Affecting the Degree of Climate Change • 4) Other modelers suggest that if any additional clouds form at low altitudes (these lack many ice crystals) that they would spur a significant global warming event since water vapor is an effective greenhouse gas (see figure) • These are only a few of the future climate models - this field of study is very complex!