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 Greenhouse effectabundance contribution

• Water vapor (and clouds) 72 % natural, temperature dependent

• Carbon dioxide 9-26 %• Methane 4-9 %• Nitrous oxide low (with sulfur dioxide (SO2) acid rain)• Ozone 3-7 %• Chlorofuorcarbons (CFCs) 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).

"Image created by Robert A. Rohde / Global Warming Art"

Global Warming Projections

Temperature Change Projections

No net change

Net gain + 5.5

Net loss -2

The Global Carbon Cycle

Units: Gt and Gt/yr

1 Gt = 1,000,000,000 tons

Increased CO2 Emissions Scenarios

CO2 emissions are projected to continue to increase substantially from current levels in the near future

• 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.

• Under Kyoto, industrialized countries agreed to reduce their collective GHG emissions by 5.2% compared to the year 1990.

Kyoto Protocol

• 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

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Clean Air Act

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

• 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.

The Atlantic Conveyor

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 (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 and Global Warming

• 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

“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.”

Methane blowout, Santa Barbara

22Bio65 Spring 2009, P.J. Bryant & F.Grün, copyright reserved

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 23

Arctic Melting and Polar Bear Habitat

Threatened Polar Bear Populations

• 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.

Polar Bear Conservation Politics

Chlorofluorocarbons and Ozone Depletion

The Antarctic Ozone Hole

• 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 of skin cancer

• Potent sterilizing action (anti-microbial)

Ecosystem pH ChangesPart 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 ChangesOcean pH

Average surface ocean pH

Time pH pH change SourcePre-industrial (1700s) 8.179 0.000 analysed fieldRecent past (1990s) 8.104 -0.075 field2050 (2×CO2 = 560 ppm) 7.949 -0.230 model2100 (IS92) 7.824 -0.355 model

• 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

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

The golden toad (Bufo periglenes) was a small toad that was once abundant in a small restricted region of high-altitude 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 ?

Indicator Species of Global Warming

• 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

Grayson, Donald K. (2005). "A brief history of Great Basin pikas". Journal of Biogeography 32 (12): 2103–2111

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

•Pika, small chinchilla-like rodents found in cool alpine habitats• Range is being restricted vertically due to global warming.• Threatened with extinction in US

range retreat

PikaProc 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

North American Species Indicators