chapter 19 Flashcards
to study for the ch17-19 test (dec 4)
factors in climate shifts
- volcanic emissions
- changes in solar input
- continents moving on shifting plates
- meteor strikes
glacial/interglacial periods
alternating cycles of freezing & thawing
factors that provide information about past atmospheric conditions
- antarctic ice cores
- sediment cores, analysed for pollen & fossil
- direct temperature records going back to 1861
- air samples from different locations, analysed for chemical composition & changes
greenhouse effect
certain gases in the atmosphere absorb heat; warms the lower troposphere and surface
- earth’s temperature will rise at least 2deg C by 2050
major ghgs in the lower atmosphere
- water vapour
- carbon dioxide (co2)
- methane (ch4)
- nitrous oxide (n2o)
- chlorofluorocarbons (cfcs)
this country releases more ghgs/person than any other country
usa rahhhhh!H!H!!
sources of major air pollutants & ghgs
- burning of fossil fuels
- deforestation, slash & burn
intergovernmental panel on climate change
ipcc
- formed in 1988
- evaluates possible future climate changes
- findings include: 20th century was the hottest century in the past 1000yrs, 10 warmest years since 1861 occurred since 1990, arctic temperatures have risen 2x as fast as those in the rest of the world, melting permafrost in alaska & russia releases more ghgs into the troposphere, world’s sea level rise by 10-20cm
global warming
refers to temperature increases in the troposphere, causing climate change
global climate change
broader term refers to changes in any aspect of earth’s climate
water vapour
- water vapour comes from evaporation, not directly from human activity
- the amount of water vapour the atmosphere can hold is entirely a function of temperature; as temperature rises, more evaporation occurs, more water vapour is in the atmosphere
- emission of ghgs -> warmer temperatures -> more water vapour -> warmer temperatures; positive feedback loop
role of distribution of clouds in global warming
clouds may (1) increase warming by absorbing & releasing more heat into the troposphere or (2) have a cooling effect by reflecting more sunlight back into space
pollution (particles & aerosol) dimming sunlight
- soot particles in the atmosphere reflect some sunlight back into space
- airborne particles result in more water vapour, leading to ticker, darker clouds
two major sources of methane gas (being released)
- bogs/wetlands
- methane hydrates trapped under arctic permafrost
arctic ice
- higher temperatures -> less ice -> less sunlight being reflected back into space -> higher temperatures; positive feedback loop