1. Feb. 17, 1993
Climate Change
Feb. 21, 2000
Photo of glacial retreat on Mount Kilimanjaro (Feb to Feb. 2000) from Wikipedia;
Map of Africa from

2. Weather Patterns are Dynamic
e.g., monthly variation
Weather – the state of the atmosphere at a given time and place
Temperature
Image from Wikipedia (see “Climate”)

3. Weather Patterns are Dynamic
e.g., monthly variation
Weather – the state of the atmosphere at a given time and place
Precipitation
Image from Wikipedia (see “Climate”) 3

4. Earth’s Climate is also Dynamic
Climate Change (or Variation) Characterizes Earth’s History
Climate – meteorological conditions that characteristically prevail in a region
For this lecture our focus will be Earth’s average temperature.
Image from Wikipedia (see “Geologic temperature record”) 4

5. Earth’s Climate is also Dynamic
Climate Change (or Variation) Characterizes Earth’s History
Climate Change – a shift of average weather across a region
For this lecture our focus will be Earth’s average temperature.
Image from Wikipedia (see “Geologic temperature record”) 5

6. Earth’s Climate is also Dynamic
Climate Change (or Variation) Characterizes Earth’s History
E.g., Eocene temperature was 4 – 6 °C warmer than today
The Eocene was ushered in with a dramatic spike in temperature (about 2 degree C over 100,000) yr., probably associated with methane inputs into the atmosphere from the deep ocean; the Eocene ended with a rapid cooling (probably associated with a bolide impact).
PETM on figure = Paleocene-Eocene Thermal Maximum ~54 million yr ago.
Atmospheric [CO2] ~1125 ppm!
Source: Lowenstein & Demicco (2006) Science.
Image from Wikipedia (see “Geologic temperature record”) 6

7. Earth’s Climate is also Dynamic
Climate Change (or Variation) Characterizes Earth’s History
E.g., Eocene temperature was 4 – 6 °C warmer than today
Notice the crocodilian and redwood trees in the artist’s interpretation of life on Ellesmere during the Eocene (based on good fossil evidence).
Eocene on Ellesmere Island, far north Canada
Modern day on Ellesmere Island, far north Canada
Images from 7

8. Earth’s Climate is also Dynamic
Climate Change (or Variation) Characterizes Earth’s History
E.g., Eocene seas were m higher than today
Notice that Florida was completely submerged!
Note that in James Hansen’s “Storms of my Grandchildren” sea level on a modern ice-free Earth would be ~75 m higher than it is currently (e.g., see pg. 250). I do not know why Eocene seas were higher than they would be in the modern day on an ice-free planet.
Image from 8

9. Earth’s Climate is also Dynamic
Climate Change (or Variation) Characterizes Earth’s History
E.g., Milankovitch Cycles – Earth’s changing orbit influences
temperature with ~41,000 & ~100,000 yr periodicities
Image from Wikipedia (see “Geologic temperature record”) 9

10. Earth’s Climate is also Dynamic
Climate Change (or Variation) Characterizes Earth’s History
E.g., Pleistocene glacial and inter-glacial periods
Image from Wikipedia (see “Geologic temperature record”) 10

11. Natural Climate “Forcing”
(Physical processes that influence Earth’s avg. temp.)
E.g., Pleistocene glacial and inter-glacial periods
Image from Wikipedia (see “Geologic temperature record”) 11

12. Natural Climate “Forcing”
Orbital
Owing to other planets in our solar system, Earth’s orbit varies over long time scales;
e.g., eccentricity varies from to 0.058
Hypothetical circular orbit, no eccentricity
Hypothetical orbit with 0.5 eccentricity
Image from Wikipedia (see “Milankovitch cycles”)

13. Natural Climate “Forcing”
Orbital
Earth’s axial tilt (obliquity) varies from 22.1° to 24.5°
Image from Wikipedia (see “Milankovitch cycles”)

14. Natural Climate “Forcing”
Orbital
Orbital forcing causes variation in solar heating of the planet
(orbit influences radiative forcing, i.e., solar input)
Image from Wikipedia (see “Milankovitch cycles”)

15. Natural Climate “Forcing”
Radiative
Image from Wikipedia (see Global Warming)

16. Natural Climate “Forcing”
Radiative
Earth’s avg. temp. = 14 °C (57 °F)
Without the atmosphere’s greenhouse effect it would be about
-18 °C
(-0.4 °F)
Common greenhouse gases in the Earth's atmosphere include water vapor, carbon dioxide, methane, nitrous oxide, ozone, chlorofluorocarbons.
Image from:

17. Anthropogenic Causes of Climate Change
At regional scales, deforestation leads to drying (and heating),
owing primarily to reduced evapotranspiration and water-holding capacity of soil
This isn’t very surprising, since clouds that form from transpired water are absent over wide, treeless rivers & their immediate floodplains in the Amazon Basin
From:
While you may think of a rainforest as being perpetually wet and rainy, the world’s largest rainforest, the Amazon, actually has a dry season when the clouds clear and sunlight drenches the trees. It is during this period, the time without rain, that the forest grows the most. For much of the Amazon Rainforest, the dry season occurs in June, July, and August. During this period, the thick blanket of clouds brought in by large-scale patterns in the atmosphere disappear, and smaller-scale processes that influence the weather become apparent. This image, captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on August 19, 2009, reveals how the forest and the atmosphere interacted to create a uniform layer of “popcorn” clouds one afternoon.
The clouds formed from water vapor released from trees and other plants throughout the day. Plants convert light, carbon dioxide, and water into sugar and oxygen through photosynthesis. The excess oxygen, a waste product of photosynthesis, exits the leaves through tiny pores. As the plants exhale oxygen, water vapor also escapes, a process called transpiration. During the dry season, the rainforest gets more sunlight. The plants thrive, putting out extra leaves and increasing photosynthesis. The photosynthesizing plants release water vapor into the atmosphere. Water vapor is more buoyant than dry air, so it rises and eventually condenses into clouds like the popcorn clouds shown in this image.
These clouds are almost certainly a result of transpiration. The clouds are distributed evenly across the forest, but no clouds formed over the Amazon River and its floodplain, where there is no tall canopy of trees. While water may evaporate from the Amazon River itself, the air near the ground is too warm for clouds to form. Trees, on the other hand, release water vapor at higher levels of the atmosphere, so the water vapor more quickly reaches an altitude where the air is cool enough for clouds to form. When water vapor condenses, it releases heat into the atmosphere. The heat makes the air even more buoyant, and it rises. The higher it rises, the more the air expands and cools, which allows more water vapor to condense. Eventually, thunderstorms can form. The more concentrated clusters of clouds in the image are likely thunderstorms.
In the Amazon, transpiration may play a significant role in transitioning between the rainy and the dry seasons. Westward-blowing trade winds carry moisture from the Atlantic Ocean over South America year round. Once over the continent, regional winds channel the moist air north or south. When winds blow north, Atlantic moisture goes with it, and the part of the rainforest south of the equator experiences a dry season. When winds shift to the south, the seasons reverse. Tropical climatologist Rong Fu, of Georgia Institute of Technology, believes that the shift in wind direction toward the southern Amazon may be triggered by late dry-season thunderstorms originating from transpiring plants. The widespread thunderstorms carry heat high into the atmosphere. The heated air rises, and air from the north replaces it. This movement of air creates the winds that channel monsoon moisture back to the southern part of the Amazon Rainforest.
To read more about the connection between the rainforest and the atmosphere, see The Amazon’s Seasonal Secret on the Earth Observatory.
References
Photosynthesis. On-line Biology Book, Estrella Mountain Community College. Accessed August 21, 2009.
Graham, S., Parkinson, C., Chahine, M. The Water Cycle. NASA’'s Earth Observatory. Accessed August 21, 2009.
Lindey, R. (2007, May 22). The Amazon’s Seasonal Secret. NASA’s Earth Observatory. Accessed August 21, 2009.
U.S. Geological Survey. (2009, May 13). The Water Cycle: Transpiration. Accessed August 21, 2009.
NASA image courtesy Jeff Schmaltz, MODIS Rapid Response at NASA GSFC. Caption by Holli Riebeek.
Instrument:  Aqua - MODIS
Image from:

18. Anthropogenic Causes of Climate Change
At regional scales, deforestation leads to drying (and heating),
owing primarily to reduced evapotranspiration and water-holding capacity of soil
E.g., cities in the Brazilian Amazon are warmer and drier than
those areas were before they became urban centers
E.g., much of Greece is warmer and drier today
because of deforestation in earlier millennia
Note that unlike global changes, regional changes provide opportunities to make assessments with good sample sizes (whereas since we only have one Earth, pinpointing underlying causes of global changes is more difficult).
These examples are not global, but they demonstrate that
humans can alter regional climate patterns

19. Anthropogenic Causes of Climate Change
International Panel on Climate Change (IPCC)
est by the United Nations
Taking all the accumulated evidence into account, anthropogenic increases in greenhouse gases are the principal causes of modern global warming; i.e., we are experiencing an anthropogenically enhanced greenhouse effect
Image from Wikipedia (see “Greenhouse gas”) 19

20. Anthropogenic Causes of Climate Change
Al Gore
(b. 1948)
45th U. S. Vice President
Shared Nobel Peace Prize (2007) with IPCC
Academy Award (2007) for the documentary film: An Inconvenient Truth
Photo from:

21. Anthropogenic Causes of Climate Change
The Keeling Curve
Image from NOAA

22. Anthropogenic Causes of Climate Change
On this figure, temperatures and CO2 concentrations were estimated from ice cores through examination of isotopes (temp.) and CO2 concentration.
Remember what we said about the Eocene (climate in northern Canada; sea level)?
Notice the close match between greenhouse gas concentration in the atmosphere and Earth’s average temperate!
IPCC predictions are for [CO2] by 2100:
500 to 1000 ppm;
with concomitant global temperatures 1.1 to 6.4 °C higher
Image from 22

23. Montreal Protocol (1987) – re CO
Treaty to enact resolutions from the United Nations’ Vienna Convention on the Protection of the Ozone Layer (1985) to “protect the ozone layer by taking precautionary measures to control equitably total global emissions of substances that deplete it [e.g., CFCs], with the
ultimate objective of their elimination”
It is clear that unlike the Montreal Protocol (w.r.t. ozone depletion), the Kyoto Protocol (w.r.t. atmospheric greenhouse gas increases) has had relatively little effect (see pp , Jeffrey D. Sachs, 2008, Common Wealth: Economics for a Crowded Planet)!
It was easier to convince corporate industry to end use of CFCs etc. than it has been to reduce the use of fossil fuels!
September 2006
Image from Wikipedia (see “Ozone depletion”) – NASA image of largest Antarctic ozone hole ever recorded 23

24. Kyoto Protocol (1997) – re CO2
Legally binding treaty through 2012 (when ratified by states) intended to enact resolutions from the United Nations’ Framework Convention on Climate Change (1992) to achieve “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system”
Green = signed & ratified
Red = signed, but not ratified
Grey = non-signatory
It is clear that unlike the Montreal Protocol (w.r.t. ozone depletion), the Kyoto Protocol (w.r.t. atmospheric greenhouse gas increases) has had relatively little effect (see pp , Jeffrey D. Sachs, 2008, Common Wealth: Economics for a Crowded Planet)!
It was easier to convince corporate industry to end use of CFCs etc. than it has been to reduce the use of fossil fuels!
McKibben (2008) Environmental Writing Since Thoreau. Pg. xxvi.
Re CO2 in comparison to CO –
“This is an altogether higher orbit, involving much heavier lifting.”
McKibben (2008)
Image from Wikipedia (see “Kyoto Protocol”) 24

25. Declining Glacial Thickness
Image from Wikipedia (see “Global Warming”)

26. Glacial retreat (loss) on
Feb. 17, 1993
Glacial retreat (loss) on
Mt. Kilimanjaro
Feb. 21, 2000
Photo of glacial retreat on Mount Kilimanjaro (Feb to Feb. 2000) from Wikipedia;
Map of Africa from

27. Glacial retreat (loss)
in the Alps
Oct. 2, 2010 – Looking down the glacial valley below Lämmerenhütte…
Photo by K. Harms – looking down the glacial valley below Lämmerenhütte; Switzerland, October 2010

28. Glacial retreat (loss)
in the Alps
Oct. 2, 2010 – Looking up the valley below Lämmerenhütte, towards the remnant glacier…
Photo by K. Harms – looking up the glacial valley below Lämmerenhütte; Switzerland, October 2010

29. Glacial retreat (loss)
in the Alps
Oct. 2, 2010 – Lämmerenhütte…
Photo by K. Harms of Lämmerenhütte; Switzerland, October 2010

30. Glacial retreat (loss)
in the Alps
Oct. 2, 2010 – At the remnant glacier above Lämmerenhütte…
Glaciers like this supply the Rhone River with water; without the glaciers…
Photo by K. Harms – the remnant glacier above Lämmerenhütte; Switzerland, October 2010

31. Tatoosh Island, Washington
Decreasing oceanic pH
Dissolving carbon dioxide in sea water increases the H+ ion concentration and lowers pH.
Note that there was a “spike in ocean acidification during the Palaeocene–Eocene thermal maximum (PETM) 55Ma” that was devastating to marine biodiversity (J. B. C. Jackson, 2010, Phil. Trans. Roy. Soc.).
Tatoosh Island, Washington
Photo from Wikipedia; figures from Wootton et al Proceedings of the National Academy of Science

32. Fig. 1. (A) Linkages between the buildup of atmospheric CO2 and the slowing of coral calcification due to ocean acidification.
Kyle downloaded this from Science’s web site (Nov. 2013), especially to show the chemistry of ocean acidification; see also: HoeghGuldberg_etal_2007_Science.pdf
(A) Linkages between the buildup of atmospheric CO2 and the slowing of coral calcification due to ocean acidification. Approximately 25% of the CO2 emitted by humans in the period 2000 to 2006 (9) was taken up by the ocean where it combined with water to produce carbonic acid, which releases a proton that combines with a carbonate ion. This decreases the concentration of carbonate, making it unavailable to marine calcifiers such as corals. (B) Temperature, [CO2]atm, and carbonate-ion concentrations reconstructed for the past 420,000 years. Carbonate concentrations were calculated (54) from CO2atm and temperature deviations from today's conditions with the Vostok Ice Core data set (5), assuming constant salinity (34 parts per trillion), mean sea temperature (25°C), and total alkalinity (2300 mmol kg–1). Further details of these calculations are in the SOM. Acidity of the ocean varies by ± 0.1 pH units over the past 420,000 years (individual values not shown). The thresholds for major changes to coral communities are indicated for thermal stress (+2°C) and carbonate-ion concentrations ([carbonate] = 200 μmol kg–1, approximate aragonite saturation ∼Ωaragonite = 3.3; [CO2]atm = 480 ppm). Coral Reef Scenarios CRS-A, CRS-B, and CRS-C are indicated as A, B, and C, respectively, with analogs from extant reefs depicted in Fig. 5. Red arrows pointing progressively toward the right-hand top square indicate the pathway that is being followed toward [CO2]atm of more than 500 ppm.
O Hoegh-Guldberg et al. Science 2007;318:
Published by AAAS

33. Climate Change Impacts Biota
Altered expression of traits (owing to phenotypic plasticity;
e.g., phenology)
Range shifts (especially upslope and to higher latitudes)
Adaptation (to changing environment)
Extinctions (when range shifts and adaptation fail to keep pace with changing environments) 33

34. Climate Change Impacts Biota
Range map and image of polar bear (Ursus maritimus) from Wikipedia 34

35. Opinions on Climate Change
Do you think human activity is a significant contributing
factor in changing mean global temperature?
Peter T. Doran & Maggie Kendall Zimmerman Examining the scientific consensus on climate change. Eos 90:22-23.
If it does not make sense to you to pay attention to what climate scientists think, consider the extent to which we pay attention to specialists in the area of interest for specialized problems. For example, we tend to listen to medical researchers and practitioners when we contemplate the consequences of smoking tobacco on human health (does it make more sense to listen to the general public’s collective opinion or grocer’s or a nuclear physicists than to the medical profession’s collective opinion when considering whether or not to smoke tobacco?)…
From Doran & Zimmerman (2009) Eos (formerly Transactions of the American Geophysical Union)

36. Opinions on Climate Change
John Oliver re Climate Change “debate”