Download Manmade Greenhouse Gases and Global Warming

Greenhouse gases, climate change and
biodiversity
Ecosystem Species Richness
Species losses from different biomes
What is the Greenhouse Effect ?
• Solar radiation consists of a range of light at different wavelengths (spectrum):
• ultraviolet – largely absorbed by ozone (O3) in the stratosphere (high altitude)
• visible – sunlight easiest to reach the ground.
• infrared (heat) - absorbed and trapped by water vapor and certain gases, e.g. CO2
• Visible light is absorbed by the soil, oceans and plants  emitted as infrared (heat)
• A percentage of this IR radiation is trapped from escaping back into space by greenhouse gases.
• If greenhouse gases increase in concentration  more IR is trapped  rise in global
temperatures
Manmade Greenhouse Gases and Global Warming
Greenhouse gas
abundance
Greenhouse effect
contribution
• Water vapor (and clouds)
• Carbon dioxide
• Methane
• Nitrous oxide
• Ozone
• Chlorofuorcarbons (CFCs)
72 % natural, temperature dependent
9-26 %
4-9 %
low
(with sulfur dioxide (SO2)  acid rain)
3-7 %
low
(contribute to ozone depletion)
Gas
Preindustrial
Levels
Current
Levels
Increase since
1750
Global warming
potential (GWP)
(over 100 yrs)
Greenhouse
Radiative Forcing
(W/m2)
Carbon Dioxide
280 ppm
387 ppm
104 ppm
1
1.46
Methane
700 ppb
1,745 ppb
1,045 ppb
25
0.48
Nitrous oxide
270 ppb
314 ppb
44 ppb
298
0.15
CFC-12
0
533 ppt
533 ppt
>2000
0.17
Need to consider not just the man-made changes in the gases, but also their relative abundance
and their intrinsic effectiveness at trapping IR heat (greenhouse effect).
Global Warming Projections
Temperature Change Projections
"Image created by Robert A. Rohde / Global Warming Art"
The Global Carbon Cycle
Net gain + 5.5
No net change
Net loss -2
Units: Gt and Gt/yr
1 Gt = 1,000,000,000 tons
Increased CO2 Emissions Scenarios
Kyoto Protocol
• The Kyoto protocol is an international treaty related
to the United Nations Framework Convention on
Climate Change (UNFCCC or FCCC)
• Aim is to achieve stabilization of greenhouse gas
concentrations in the atmosphere at a level that would
prevent dangerous anthropogenic (man-made)
interference with the climate system.”
• The Kyoto Protocol establishes legally binding
commitments for the reduction of four greenhouse
gases: carbon dioxide, methane, nitrous oxide, sulphur
hexafluoride), and two groups of gases
(hydrofluorocarbons and perfluorocarbons)
• By2008, 183 countries have ratified the protocol,
which was initially adopted for use on 11 December
1997 in Kyoto, Japan and which entered into force on
16 February 2005. US has not ratified.
CO2 emissions are projected to continue to increase
substantially from current levels in the near future
• Under Kyoto, industrialized countries agreed to
reduce their collective GHG emissions by 5.2%
compared to the year 1990.
Clean Air Act
• First written in 1970, the Clean Air Act is the law that defines EPA's responsibilities for protecting
and improving the nation's air quality and the stratospheric ozone layer. The last major change in
the law, the Clean Air Act Amendments of 1990, was enacted by Congress in 1990. Legislation
passed since then has made several minor changes. Most current is 2004.
• Clean Air Act is focused on:
• reducing outdoor, or ambient, concentrations of air pollutants that cause smog, haze, acid
rain, and other problems,
• reducing emissions of toxic air pollutants
that are known to, or are suspected of, causing
.
cancer or other serious health effects,
• and phasing out production and use of chemicals that destroy stratospheric ozone
• Specifically deals with regulations to clean up/reduce:
• Emissions from cars, trucks, buses and heavy equipment
• Interstate and international pollution problems
• Improving air quality in National Parks
• Reducing acid rain
• Reducing toxic air pollutants (smog, ozone)
• permits and enforcement action
• Public participation
Where is biomass being produced ?
i.e. net fixation of carbon dixoide from atmosphere into living organisms
Rainforests:
Carbon sink, neutral or source ?
The net effect on carbon sequestration in mature
rainforests depends on several factors:
Solar radiation (cloud cover)
Soil dryness
During wet season, Guiana and Amazon rainforest is
a net source: respiratory losses (plant/animal
respiration and microbial decomposition >
photosynthesis)
During dry season, photosynthesis is at a peak >
respiration  net sink.
Currently a net sink of 1-1.5 tons/hectare/yr
Likely due to better growth rates from modest
temperature increase over past 150 years (+0.8 oC in
Guiana) favoring photosynthesis
Mature rainforests are close
to carbon neutral
The Global Thermohaline Ocean Circulation
The Atlantic Conveyor
The Atlantic Conveyor
• Warm (less dense) seawater from the Gulf of Mexico is moved northeasterly across Atlantic by prevailing winds 
Gulfstream.
• Gulfstream moderates climate for Europe. Warmth and mixing with nutrient rich waters promotes oceanic
phytoplankton growth  high bioproductivity in North Atlantic.
• In North Atlantic, surface water is continually cooled by evaporation making it saltier (denser).
• Water sinks below thermo-halocline to establish a salty cold deep water current heading south.
• Atlantic conveyor is sensitive to atmospheric temperature differences (wind strength) and changes in North Atlantic
salinity.
• Prior global climate changes, e.g. large scale glacial melting at end of last ice age, are believed to have stopped this
circulation  too much inflow of freshwater capped the ocean with a low density surface layer  insufficient
evaporation to make water sink
• Led to drastic climate changes (termperature swings in Europe – 6 oC)  large scale changes in species
• Global warming may alter or reduce strength of the Gulfstream due to reduced temperature differences across latitudes
and glacial ice melting in Greenland, Arctic basin.
• A slowing of the conveyor currents would diminish the entire marine food chain. A 20% loss of phytoplankton
productivity would have major repercussions all the way up to the human food supply.
• Phytoplankton also critical component for depositing biomass/carbonate skeletons when carried into the deep ocean
layer and ocean sediment. Accounts for 50 % of net biomass carbon fixation.
• This process is a key component of keeping the global carbon cycle in balance. A shut down of this process could exert a
positive feedback effect on global warming.
Plankton calcium carbonate skeleton
Changes in North Atlantic Planckton Profiles
Arctic Sea Ice Retreat from Global Warming
• North Pole likely to be free of summer sea ice within 20-30 years
• Lack of ice  reduced solar reflection  positive feedback effect on global warming
Methane and Global Warming
• Methane (CH4) –also known as natural gas or marsh gas
• Product of natural and manmade processes including:
• Decay of vegetation in swamps (methanogenic bacteria)
• Growing rice in paddies
• Burning forests
• Raising cattle (fermentation in their rumens produces methane gas)
• Mining fossil fuels: coal, oil and natural gas deposits – about 2/3 of total increase
• Large submarine and permafrost deposits of methane clathrates (burning ice)
• Melting of arctic sea ice and permafrost  instability in methane deposits and production
• Methane clathrates are highly unstable  small temperature changes  large rapid release of methane. Such
catastrophic releases from marine sediments proposed to have caused Permian-Triassic extinction.
• Permafrost acts as a sink (1700 Gt of carbon stored). Permafrost melting  decomposition of accumulated
organic matter in tundra + clathrates  worst case: 50 Gt release of methane gas (>12-fold). Increased rates
already measurable.
• Both processes have strong positive feedback properties for global warming.
Permafrost In the Northern Hemisphere
Methane blowout, Santa Barbara
“In 2008 the United States Department of
Energy National Laboratory system identified
potential clathrate destabilization in the Arctic
as one the most serious scenarios for abrupt
climate change, which have been singled out
for priority research. The U.S. Climate Change
Science Program released a report in late
December 2008 estimating the gravity of the
risk of clathrate destabilization, alongside
three other credible abrupt climate change
scenarios.”
Fossil Fuel Extraction: ANWR and the Alaska Oil/Natural Gas Pipelines
• Oil pipeline from North Slope/Prudhoe Bay to Valdez cuts across territory
of 3 herds of caribou
• Extensions to Arctic National Wildlife Refuge (ANWRO) planned
• Pipeline sections are either elevated or buried (but since oil is ~120 F 
soil thawing of permafrost)
• Also concerns about rapid access for maintenance/repair from accidents
and earthquakes
• Concerns about alteration in caribou migration pattern, disturbance of
calving grounds
• Caribous are reluctant to cross roads, pipelines or other man-made
obstructions but improves with acclimatization
Bio65 Spring 2009, P.J. Bryant & F.Grün, copyright reserved
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Bio65 Spring 2009, P.J. Bryant & F.Grün,
copyright reserved
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Arctic Melting and Polar Bear Habitat
Threatened Polar Bear Populations
Polar Bear Conservation Politics
• Polar Bear populations: current estimates between 20-30,000
• Predicted >30 % reduction within 3 generations (45 years) due to:
• Global warming habitat loss
• Toxic contaminants
• Stress from shipping and other human encroachment
•Main problem is loss of sea-ice cover  hunting for seals more difficult  starvation  lower reproductive success.
• In 1980, Western Hudson Bay females were: 290 kg (640 lb)
• In 2004, females were 230 kg (510 lb) in 2004.
• Between 1987 and 2004, the population declined by 22%
• Also signs of cannibalism and interbreeding with brown bears (grizzlies)
• May 2008, listed as threatened under Endangered Species Act, but Interior Department noted that the listing could
not be used to regulate greenhouse gas emissions, saying, "That would be a wholly inappropriate use of the
Endangered Species Act. ESA is not the right tool to set U. S. climate policy.”
• Also activated clause to allowed continued oil and gas exploration and development in critical habitat.
• August 2008 State of Alaska (Gov. S. Palin) sued US Interior Secretary to have listing reversed, claiming the listing
was not based on the best scientific and commercial data available, a view rejected by polar bear experts.
Chlorofluorocarbons and Ozone Depletion
• Chlorofluorocarbons (CFCs) are synthetic gases which are
noninflammable, nontoxic, and very stable.
Widely used in industry as:
• refrigerants (e.g., in refrigerators and air conditioners)
• solvents
• propellants in aerosol cans (now banned in most countries)
• in the manufacture of plastic foams.
• Atmospheric decomposition is slow: >60–100 years.
• Very potent greenhouse gases but more important negative effect is
on ozone in upper atmosphere
• Annual ozone destruction (ozone hole in Antarctica and Arctic
• Elevated levels of UVA and UVB irradiation reaching
• High UV exposure results in chromosomal damage and increases risk The Antarctic Ozone Hole
of skin cancer
• Potent sterilizing action (anti-microbial)
Ecosystem pH Changes
Part I: Acid Rain
• Acid rain caused by release of sulfur dioxide and nitrous oxide into atmosphere from:
• Volcanic eruptions
• Burning fossil fuels (especially high sulfur coal)
• Reacts in atmosphere to produce sulfuric and nitric acids
• Can damage ecosystem either by dry deposition (soot) or rainwater
• Normally rainwater is slightly acidic ~ pH 5.5. Acid rain pH<4
•Soil impact:
• Mobilises and leaches away important
nutrients and increases aluminium
concentration (toxic to plant and tree roots)
• Increases plant stress  tree die-off or
decreased disease resistance
•Watershed impact:
• Acidifies ponds, lakes and streams with
poor buffering capacity
• Aquatic organisms are differentially sensitive to low pH  reduced biodiversity
• Disruption of trophic food chains
• Reduced growth and reproduction
• Below pH 5 no fish eggs will hatch
• Elimination of brook trout and lake trout
• Eastern US very sensitive (low buffering capacity): Adirondacks/Catskills (NY), Pine Barrens (NJ),
Appalachians and New England. Some areas 70-90 % streams too acidic.
• 14,000 lakes in Canada are non-productive due to acid rain.
Acid Rainfall in Europe
Tree damage from acid rain
Rainwater pH Measurements in US
Ecosystem pH Changes
Ocean pH
• Increased atmospheric CO2 and global warming have an additional deleterious environmental
effect: change towards lower ocean pH
• Carbon dioxide dissolves in sea water to generate carbonic acid (H2CO3)
• With global warming, warmer oceans also have a lower capacity for CO2 buffering
• Calcifers (coccolithophores, corals, foraminifera, echinoderms, crustaceans and molluscs) have
calcium carbonate shells and skeletons that are sensitive to dissolving with lower pHs
• Combined effects of lower pH and higher temperature is diastrous to coral ecosystems  coral
bleaching  die-offs
Average surface ocean pH
Time
Pre-industrial (1700s)
Recent past (1990s)
2050 (2×CO2 = 560 ppm)
2100 (IS92)
pH
pH change
Source
8.179
0.000
analysed field
8.104
-0.075
field
7.949
-0.230
model
7.824
-0.355
model
Global Coral Bleaching Events
• 1998, 20 % global destruction including 90 %
throughout Bahrain, the Maldives, Sri Lanka, Singapore,
and parts of Tanzania
• Another episode in 2005-2007: roughly 60% of the
coral cover in the Virgin Islands and 53% in Puerto Rico
died
bleached coral reef
Coral Bleaching Events are Associated with Large Scale Weather Cycles
Expected Effects of Atmospheric CO2 Levels on Coral Ecosystems
Indicator Species of Global Warming
The golden toad (Bufo periglenes) was a small toad that
was once abundant in a small restricted region of highaltitude cloud-covered tropical forests, about 30 square
kilometers in area, above the city of Monteverde, Costa
Rica.
• Went extinct by 1989
• Change in local climate ?
• Loss of cloud-forest rainfall due to increased global
warming or deforestation upwind ?
• More likely deforestation caused loss of tree
transpiration and elevated temperatures  raised cloud
forming zone  insufficient fog/rain
North American Species Indicators
range retreat
Gray jay
• Gray jay disappearing from southern range
• Key habitat requirement is cold temperature to store perishable food and tree bark
pliable enough to wedge food items e.g. black spruce, lodgepole pines.
• Rising temperatures are changing boreal species ranges  dependent species also
decreasing
Proc Biol Sci. 2006 November 22; 273(1603): 2809–2813.
Climate change and the demographic demise of a hoarding bird living on the edge. T.A. Waite and D. Strickland
•Pika, small chinchilla-like rodents found in cool alpine habitats
• Range is being restricted vertically due to global warming.
• Threatened with extinction in US
Grayson, Donald K. (2005). "A brief history of Great Basin pikas". Journal of Biogeography 32 (12): 2103–2111
Pika