_________________ is the average meteorological

conditions—temperature, precipitation, wind, etc.—that

prevail in a region.

Climate ____________

may refer to any change in climate over time whether due to natural variability or human activity.

Three major sources of natural variability affect climate:

1. Changes in Earth's orbit,

2. Changes in ocean currents due to shifting continents or large-scale melting of continental ice, and

3. Changes in the composition of the global atmosphere—especially water vapor and "greenhouse" gases such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)—due to volcanic or other tectonic activities.

“_______________________"

The term refers to the ability of these gases to absorb energy radiated from Earth to space and to thus warm the atmosphere.

http://members.optushome.com.au/wingchan1/ian/globwarm/what.htm

Human activity may also influence the composition of

the global atmosphere. • Major sources include

• combustion of fossil fuel,

• _______________________, • production of some agricultural

commodities such as rice and livestock.

Intergovernmental Panel on Climate Change (IPCC),

1. organizes, summarizes, and reports the work of several hundred scientists.

2. does not make policy decisions.

3. is not in charge of global climate control regulations.

http://www.ers.usda.gov/Briefing/GlobalClimate/Questions/agclimmp.htm

Declines in crop production would likely be offset somewhat by increases in livestock production.

Increase in atmospheric carbon dioxide (CO2) indicates that its direct growth-promoting effects on crops would likely

boost world and U.S. agricultural production.

• The major greenhouse gases (GHG's) associated with U.S. crop and livestock production are • carbon dioxide (CO2),

• methane (CH4),

• nitrous oxide (N2O).

• Agriculture contributes greatly to both methane and nitrous oxide emissions.

Agriculture accounts for• about a third of national methane emissions—mostly from the

digestive process in ruminant animals and manure management

• nearly three-quarters of nitrous oxide emissions, mainly from the use of nitrogen ____________________.

• Rice cultivation and crop residue burning also contribute to GHG emissions.

• Farm production emits carbon dioxide mostly through • the use of _______________________________ in farm operations,• the manufacture and distribution of nitrogen fertilizers and other farm

chemicals, and • the generation of electricity used on farms.

http://yosemite.epa.gov/oar/globalwarming.nsf/UniqueKeyLookup/RAMR5WNMKC/$File/04agriculture.pdf

Per capita GHG emissions by country

2000http://upload.wikimedia.org/wikipedia/commons/e/ea/GHG_per_capita_2000.svg

Greenhouse Gas Emissions per Capita - 2003

http://globalis.gvu.unu.edu/indicator.cfm?IndicatorID=199

Agriculture is not the only source of greenhouse gas emissions.

The international community is addressing the challenges posed by global climate change through

the United Nations Framework Convention on Climate Change (UNFCCC).

• The Convention seeks to stabilize atmospheric concentrations of greenhouse gases (GHG's) at safe levels. Covered gases include • carbon dioxide (CO2), • methane (CH4), • nitrous oxide (N2O), • hydrofluorocarbons, • perfluorocarbons, • sulfur hexafluoride.

The _________________________to the UNFCCC

• Signed by over 80 counties in November 1998

• Formalizes this commitment by setting specific emissions reduction targets for developed countries, Eastern Europe, and the former Soviet Union

• Across countries, the reductions in national GHG emissions average about 5 percent below 1990 levels over the first commitment period (2008-2012).