Climate Change Flashcards
Global warming/climate change
increased warming of global temperatures
human-enhanced greenhouse effect
human activities since IR led to increase of CO2 which has led to increasing global temperatures, 47% increase of CO2 in atmosphere, increase in methane + nitrous oxide, use of CFCs
Intergovernmental Panel on Climate Change (IPCC)
anthropogenic factors almost entirely responsible for climate change
concluded that since 1951-2010 more than half of increase in global temperature caused by humans
Dendrochronology
study of dating past events using tree rings
useful for establishing dates of catastrophic events + identify periods of drought + lower/higher temperatures
Oxygen Isotope Analysis
ratio of 18O & 16O in water + calcium –> tells what environment it was formed in
ice + glaciers have more 16O which is returned to oceans when it melts
Ice Cores
Can analysis ratio of 18O to 16O.
Act as thermometer for ocean (more 16O evaporate when ocean temps low) so ratio of 18O : 16O gives insight into temp
provides info on composition of atmosphere –> air bubbles get trapped into ice which u can measure CO2
Dome C
location in Antarctica w. thickest ice cap –> get information on atmosphere back 800K years, shows that present concentration of CO2 now is highest it has ever been
Pollen Analysis
Radiocarbon dating of pollen in lake bottoms/bogs –> give relative amount of 14C + 12C –> indicates how long ago plant/animal alive
prevalence of which type of plant (ones which thrive in cold vs ones which thrive in warmth) –> indication of environment there
remnant glacial landforms
proof of climate change
glaciers leave marks on landscape
- Striates bedrock = shows height of past glaciers
mounds of unsorted rock called moraines at edges of glaciers –> used to determine original extent of ice + glacial retreat over last century
Spleleothems
calcium carbonate –> leaves “growth rings” in stalagmites + stalactices –> combined with isotopes of carbon/oxygen give info on precip + temperatures when spleothem formed
Causes of climate change
1) atmospheric aerosols
2) fluctuations in solar output
3) variations in earth-sun relations
4) greenhouse gas concentrations
atmospheric aerosols
large quantities of particulates ejected into atmospheric can alter global temperatures
ex: volcanic ash can go in atmosphere + block solar radiation for long time
sulfates = lead to cooling bc they scatter incoming solar radiation
black carbon emissions = absorb solar radiation leading to warming
Fluctuations in solar output
periods of reduced solar sun flairs –> lead to unusually cold weather on earth
connection between sunspot cycles + climate may be strong statistically BUT many scientists unconvinced
Greenhouse Gas Concentrations
Greenhouse gases (Water Vapor, CO2, CH4) cause warming
Strong link btwn increase in CO2 + fossil fuel use
now atmosphere has less 14C compared to IR –> shows that the additional CO2 came from “old” carbon sources –> coal, petroleum
Variations in Earth-Sun Relations
Eccentricity of orbit = changes between eliptical + circular –> leads to variations in insolation
Obliquity of rotational axis = varies from 22.1 - 24.5, when inclination is higher = seasonal variation btwn high + low latitudes is greater
Precessions: Earth’s axis wobbles so it does slightly point in diff directions over 25000 year period. ALTERS TIMING OF SEASONS
Milankovitch: times when significantly less insolation hits earth –> leading to smaller contrasts between winter + summer
Positive Feedback mechanism
Global climate cooling –> ice expanding –> more cooling –> more ice
Global warming –> ice shrinking –> more warming –> less ice
What is complicated about water vapor positive feedback loops
Warmer temp –> more water evaporates –> more water vapor –> more heating bc it’s greenhouse gas
BUT watervapor also produces clouds –> reflect incoming radiation
depends on which types of clouds that are formed bc diff clouds have diff albedos
Observed Climate Change Air Temp
Air temp = increase by more than 1 C
Observed Climate Change Ocean
Ocean = certain upper 700 meters ocean warmed + that 90% of extra energy stored in ocean –> leading to increased ocean acidity + melting sea ice –> increase ocean levels
Observed Climate Change Polar Region
Polar Regions = ice sheets heated more than average, that Antarctica/Greenland lost mass, sea ice declined by 3-4% a decade
Observed Climate Change Weather Patterns
Weather patterns = extreme weather patterns more common
Observed Climate Change Biosphere
shifts in geographical ranges, migration patterns for many animal species
negative crop yields from climate change
Future Climate Change Temperature
Projected:
increase in .3-.7 C by 2035
certain hot temperatures become more frequent
Future Climate Change Ocean Projections
ocean continue to warm + sea levels will continue to rise by 2 mm for 95% of ocean area
