EARTH S ATMOSPHERE, PAST AND PRESENT

Transcription

1 EARTH S ATMOSPHERE, PAST AND PRESENT 1. Introduction 2. Evolution of Earth s atmosphere 3. Present-day composition 4. Atmospheric density and pressure 5. Atmospheric structure 6. Air pollution

2 Earth s atmosphere: a thin envelope of gases. Source: Christopherson, 2009, p. 63.

3 Earth s atmosphere: a thin envelope of gases. Source: Weber State University HARBOR balloon flight, August 2009.

4 EVOLUTION OF EARTH S ATMOSPHERE (Source: After Christopherson, 1997) Age (bn. yrs BP) Composition Features 4.6 to 4.0 H 2 O, HCN, NH 3, CH 4, S, Cl, others 4.0 to 3.3 At 4.0: H 2 O, CO 2, N 2, S, hydrocarbons, little/no free O to 0.6 At 3.0: CO 2, H 2 O, N 2, <1% O to present Today: 78% N 2, 21% O 2, 0.9% Ar, 0.036% CO 2, trace gases Primary atmosphere, lost to space Outgassing; anaerobic. At 3.6: chemosynthetic bacteria Outgassing At 3.3: first photosynthesis in cyanobacteria Gradual development of atmosphere; abundance of LIFE

5 The GAIA hypothesis, formulated by Jim Lovelock in the 1970s and early 80s Basic concepts: The Earth is alive, that is, functions as one enormous organism Consequently, the Earth s biosphere helps regulate conditions to keep conditions suitable for itself

6 The Faint Young Sun Paradox Formation of Earth and the solar system Present day

7 The faint young sun paradox. Source: Frakes, et al., Solar luminosity relative to present CO 2 relative to present Temp. (K) Billion years BP 1 140

8 Evolution of Earth s atmosphere over billions of years shows that composition is DYNAMIC, not static, i.e. it can and does change over time.

9 Components of the Lower Atmosphere (% dry air) Oxygen Nitrogen Others Oxygen 21 Nitrogen 78 Others 1 Argon 0.93 CO Others 0.04

10 HYDROSPHERE BIOSPHERE ATMOSPHERE LITHOSPHERE

11 The ecosystem concept: biotic and abiotic components. Source: Christopherson, 2012, p Nutrients Producers Consumers Decomposers

12 Carbon dioxide cycle. Source: Christopherson, 2012, p. 566.

13 On time-scales less than billions of years, atmospheric composition changes less dramatically, but still changes, especially concentrations of gases such as carbon dioxide and methane. These changes are natural over relatively longer time-scales (100,000 year cycles), but recent evidence suggests humans have affected the composition of Earth s atmosphere since the industrial revolution (roughly 1850).

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15 Atmospheric carbon dioxide concentrations over the last 1000 years. Source: IPCC, 1996.

16 Carbon dioxide concentration (ppm) Couldn t this all be part of a natural cycle? Atmospheric CO 2 recorded in the Vostok ice core, Antarctica, and measured at Mauna Loa, Hawaii. Years before present Source: data from WDC Paleoclimatology and NOAA Mauna Loa CO 2 records.

17 Recent carbon dioxide increases in the context of the last 1000 years. Source: Christopherson, 2012, p. 285; Arctic Climate Impact Assessment, 2004.

18 Atmospheric carbon dioxide concentration recorded at Mauna Loa, Hawaii. See Christopherson, 2012, p. 64. Atmospheric carbon dioxide (ppm) Year Data source: NOAA Earth Systems Research Laboratory,

19 Trends in atmospheric carbon dioxide concentration over the last 800,000 years. Source: NOAA Earth Systems Research Laboratory,

20 Atmospheric methane concentrations. Source: IPCC, 1996.

21 Global average temperature change over the last 140 years. Source: IPCC, 2001.

22 Global average temperature change over the last 140 years. Source: The heat is on, The Economist, 2011.

23 Global average temperature change over the last 1000 years. Source: IPCC, 2001.

24 Recent carbon dioxide increases in the context of the last 1000 years. Source: Christopherson, 2012, p. 285; Arctic Climate Impact Assessment, 2004.

25 Source: Christopherson, 2012, p. 62.

26 Height in kilometres Height in miles Source: Christopherson, 2012, p.62. Atmospheric pressure in millibars

27 Source: Christopherson, 2012, p61. Height in kilometres Height in miles Thermosphere Mesosphere Stratosphere Troposphere Temperature

28 Normal lapse rate. Source: Christopherson, 2012, p. 66.

29 The atmosphere as a protective filter. Source: Christopherson, 2012, p. 66.

30 Mesosphere Stratosphere Space shuttle Endeavour viewed from the International Space Station. Source: Eos volume 92 number 50, p. 471, 13 December 2011 Troposphere

31 Smog in the Wasatch Front/Salt Lake City area. Source: Salt Lake Tribune, 2002.

32 Smog in the Wasatch Front/Salt Lake City area, during and after an inversion. Source: Salt Lake Tribune, 2007.

33 Utah air quality grades 2007 for ozone (24-hr). Source: American Lung Association. County Cache Weber Davis Salt Lake Utah Grade C F F F F

34 Utah air quality grades 2007 for particulates (24-hr). Source: American Lung Association. County Cache Weber Davis Salt Lake Utah Grade F F F F F

35 Formation of photochemical smog. Source: Christopherson, 2012, p. 74.

36 Air pollution and mixing in the atmosphere: the effects of inversions. Source: Christopherson, 2012, p. 72.

37 Air pollution and mixing in the atmosphere: the effects of inversions. Source: Christopherson, 2012, p. 72.

38 Atmospheric concentration of CFC-11. Source: IPCC, 1996.

39 Source; Christopherson, 2009, p. 71.

40 Source; Christopherson, 2012, p. 69.

41 Antarctic ozone hole as measured by NASA TOMS instrument.

42 Antarctic ozone hole, September Source; Christopherson, 2012, p. 68.