Environmental Systems

Assessment statements 6.1.1-6.1.7

The issue of Global warming

6.1.1 Describe the role of greenhouse gasses• Carbon Dioxide is a major Greenhouse Gas• Other gasses: methane, nitrous oxide, tropospheric

ozone, CFCs, and water vapor. • Under natural conditions these gasses absorb heat

and keep the earth’s temp at a range that can support life.

• The Greenhouse effect is normal & necessary condition for life on earth. If it were not for these gasses, earth’s temperature would be 35°C or 63°F colder than it is now.

Greenhouse Effect: a natural process that traps heat near the Earth’s surface.

• short wave radiation in

• long waveradiation out

• re-radiationdownward by“greenhousegases” in atmosphere

6.1.2- Ways in which humans add to greenhouse gasses

• 1. Burning Fossil Fuels• 2. Deforestation• 3. Rice and Cattle Farming

One fifth of global Methane emissions (by humans) b/c of wetland rice paddies (the largest of man-made methane sources).

Human Inputs• carbon dioxide (CO2)

– 67% from top 10 countries

• China = 21.5% of total

• US = 20.2% of total

• China’s per capita = 4.62

• US’s per capita = 18.99

• Largest per capita?

– 56.24…..Qatar….Why?

• chlorofluorocarbons

a) CO2

b) CFCs

Fig. 19–2 c & d

Human Human inputsinputs

(continued)(continued)

•methane (CH4)

•nitrous oxide (N2O)

c) CH4

d) N2O

Has the concentration of atmospheric carbon dioxide

changed?

Mauna Loa, Hawaii

Has the concentration of atmospheric carbon dioxide

changed?

Cape Grim, Tasmania

Global Warming?

Are the two linked?

Fig. 19–4

Climate Climate During Past During Past

160,000 Years160,000 Years• End of last ice age

about 10,000 ago

• Now in warm

interglacial period

• During the last ice age,

the earth was on

average only 3-5oC

colder than today.

Fig. 19–5

What is the Scientific Consensus?What is the Scientific Consensus?• Mean global temperature

rose about 0.6º C (1º F) in past 100 years

• Increase is real, not explained by natural variation in solar radiation

• Warming greater at poles than equator

• Likely future scenario: doubling of CO2 (from 280 ppm to 560 ppm) before 2100 leading to an additional 2ºC

6.1.3 Qualitative effects on mean global temperature increase.

1. Melt polar icecaps & glaciers causing rise in sea levels. Coastal cities could be wiped out.

2. This will cause relocation or disappearance of temperate & desert biomes because of weather changes = ?

3. Crop losses and alterations in crop growing seasons due to increased flooding and weather.

4. Local - Chesapeake bay fisherman will suffer reduced oyster harvest due to increased salinity. Increased temperature increases bacterial infections of oysters.

Consequences of increased G. Gasses

Consequences of a global temperature rise on artic

ecosystemsIncreased

Decomposition

of detritus in

PermafrostThis releases

methane into the

atmosphere!

Feedback loop?

Global Warming?

• 1920: Photograph by unknown photographer in the collection of the National Snow and Ice Data Center/World Data Center for Glaciology. Public domain by virtue of age. [1]

• August 8th, 2005: Photograph by Bruce F. Molnia of the USGS, in the collection of the National Snow and Ice Data Center/World Data Center for Glaciology. Public domain as a work of the US government. [2]

• Glacier Bay National Park, Alaska

Consequences of a global temperature rise on arctic

ecosystems

Expansion of habitats available for

temperate species

Glacier Bay National Park, Alaska

Consequences of a global temperature rise on arctic

ecosystems

Loss of ice habitat

Consequences of a global temperature rise on arctic

ecosystems

• Changes in producers and prey that other trophic levels rely on

• Increased success of pest, including pathogens

Consequences of a global temperature rise on freshwater

supply

• Increased Evaporation• Increased Precipitation in dry areas and possible

Decrease Precipitation in normally wet areas– This can change river flows

– Monsoons and Hurricanes could increase in intensity

– Thermal expansion of Oceans as Polar ice caps and glaciers melt

• This can cause the mixing of salt and fresh water supplies!

• How will this affect our freshwater supplies?

Feedback?

• What are some positive feedbacks in Global Warming?

• What are some negative feedbacks in Global Warming?

• Time lags?

6.1.5 - Ways to reduce G. gassesLocally

1. Walk, ride bike, carpool, mass transit2. Replace standard light bulbs with fluorescents and worn

out appliances with energy efficient models3. Wrap your water heater - insulate house4. Ask utility co. for a home energy audit to pinpoint

energy wasters5. Stopping slash and burn agricultural methods6. Use alternative energies7. Buy hybrid or electric cars8. Use types of rice that can be grown under much drier

conditions.

Globally…Regulate1. “Kyoto Protocol” – First met in 1997 in Kyoto Japan 160

nations agreed to cutback emissions of CO2, NO2 & CH4 6% below 1990 levels. (No penalties discussed) (multiple amendments have been made…US has not signed)

• An international agreement linked to the United Nations Framework Convention on Climate Change

• The Protocol places a heavier burden on developed nations under the principle of "common but differentiated responsibilities."

• IPCC (Intergovernmental Panel on Climate Change) advises the decisions at the convention

– IPCC set up by UN; 830 scientists, authors, and editors from 85 countries– They assess the Physical Science Basis, Impacts, Adaptations and Vulnerability, and Mitigation

of Climate Change– Write a summary report – last one called the Fifth Assessment Report (AR5) was finalized in

October 2014

2. Emission Trading – Allow industries/countries that violate quotas to purchase the “extra emissions” from other industries/countries that beat their assigned reductions. Also new forest offset emission. (US Proposed this)

3. Government mandated change from coal to oil to natural gas to alternative energy sources.

4. Carbon Tax

Restore…reactive

• Restoration of forests

• Irrigation of once temperate lands

• Desalinization of ocean water

• Build water levies for flooded coastal areas

What can we do?