Climate ChangeClimate Change

Climate Change BackgroundClimate Change Background

The earth has been in a warming trend for the past few centuries

Mainly due to the increase in greenhouse gas emissions

CO2, CH4, N2O, H2O

Atmosphere will be warmer because the earth can retain more heat (larger greenhouse effect)

The Greenhouse EffectThe Greenhouse Effect

Greenhouse gases: definition:Greenhouse gases: definition:____________________________________________________________________________________________________________________________________________

Greenhouse gases act to __________ the Greenhouse gases act to __________ the atmosphereatmosphere

The most abundant greenhouse gas is ________The most abundant greenhouse gas is ________

Greenhouse gases are transparent to incoming Greenhouse gases are transparent to incoming solar radiation (short wave) radiation, but absorb solar radiation (short wave) radiation, but absorb outgoing long-wave radiationoutgoing long-wave radiation..

warmwarm

water vaporwater vapor

The Enhanced, or Runaway The Enhanced, or Runaway Greenhouse EffectGreenhouse Effect

Burning of fossil fuels cause an increase in Burning of fossil fuels cause an increase in greenhouse gas concentrationsgreenhouse gas concentrations Fossil fuels are coal, petroleum, natural gasFossil fuels are coal, petroleum, natural gas

Clearing of forests also Clearing of forests also increases carbon dioxide concentrations, because increases carbon dioxide concentrations, because

plants remove COplants remove CO22 from the air from the air

Enhanced greenhouse gases are expected Enhanced greenhouse gases are expected to lead to a warmer climate.to lead to a warmer climate.

Greenhouse warming effectivenessGreenhouse warming effectiveness

Different gases vary in their ability to act as a greenhouse Different gases vary in their ability to act as a greenhouse warmer.warmer.

GasGas Concentration (ppm)Concentration (ppm) GreenhouseGreenhouse

warmingwarming((WW/m/m-2-2))Water VaporWater Vapor 30003000 ~100~100Carbon DioxideCarbon Dioxide 353353 ~50~50MethaneMethane 1.721.72 1.71.7Nitrous oxideNitrous oxide 0.310.31 1.31.3OzoneOzone 0.01-0.10.01-0.1 1.31.3CFC11CFC11 0.000280.00028 0.060.06CFC12CFC12 0.004840.00484 0.120.12

Strength of warmingStrength of warming

Current CO2: ~380 ppm

Carbon Dioxide Trend from 1950 - 2010Carbon Dioxide Trend from 1950 - 2010

Future projections of COFuture projections of CO22

ConcentrationsConcentrations

What happens in the future depends on how What happens in the future depends on how much more COmuch more CO22 we release into the we release into the

atmopshereatmopshere Even the low-emission scenarios result in Even the low-emission scenarios result in

greatly increased COgreatly increased CO22 concentrations by the concentrations by the

year 2100year 2100 Max concentration (of scenarios shown): 970 ppmMax concentration (of scenarios shown): 970 ppm Min concentration (of scenarios shown): 550 ppmMin concentration (of scenarios shown): 550 ppm (Compare with current value: 380 ppm)(Compare with current value: 380 ppm)

Future Predictions: TemperatureFuture Predictions: Temperature

Notes on Temperature Notes on Temperature ProjectionsProjections

Projected Warming: 2000 – 2100 ranges from Projected Warming: 2000 – 2100 ranges from ~1.4~1.4°C to ~5.8°C. (°C to ~5.8°C. (~2.5~2.5°F to ~10.5°F)°F to ~10.5°F) not all places will warm at the same ratenot all places will warm at the same rate

Curves represent warming produced for Curves represent warming produced for seven independent scenariosseven independent scenarios

Each bar on right represent range of warming Each bar on right represent range of warming produced by models of differing sensitivies for produced by models of differing sensitivies for a specific scenario.a specific scenario.

Land areas are projected to warm more than the Land areas are projected to warm more than the oceans with the greatest warming at high latitudesoceans with the greatest warming at high latitudes

Annual mean temperature change, 2071 to 2100 relative to 1990: Global Average in 2085 = 3.1oC

(5.5oF)

Some areas are projected to become wetter, others Some areas are projected to become wetter, others drier with an overall increase projecteddrier with an overall increase projected

Annual mean precipitation change: 2071 to 2100 Relative to 1990

Sea LevelSea Level

Main climate changesMain climate changes

Higher temperatures – Higher temperatures – especially on landespecially on land

Polar RegionsPolar Regions

Hydrological cycle more intenseHydrological cycle more intense Storms have more “fuel,” so they can be more powerful, Storms have more “fuel,” so they can be more powerful,

bringing more intense rainfalls bringing more intense rainfalls

Sea levels riseSea levels rise Oceans expand with extra heatOceans expand with extra heat

Melting of polar iceMelting of polar ice

Changes in weather eventsChanges in weather events

As Poles warm quickly relative to the As Poles warm quickly relative to the tropics…tropics… The jet stream will weaken and move northThe jet stream will weaken and move north

The storm track will move north with itThe storm track will move north with it Latitude bands 30-40 degrees should get drierLatitude bands 30-40 degrees should get drier Rain events begin to replace snow eventsRain events begin to replace snow events reduction in the # of strong tornadoes in U.S.reduction in the # of strong tornadoes in U.S. Tornado Alley migrates northTornado Alley migrates north Atlantic hurricanes will more easily form and grow to Atlantic hurricanes will more easily form and grow to

even greater strength even greater strength

Predictions For the Bay AreaPredictions For the Bay Area

Decreased winter precipiation as jet Decreased winter precipiation as jet stream moves northstream moves north

Increased summer precipiation as water Increased summer precipiation as water is warmer/more subtropical moistureis warmer/more subtropical moisture

Weaker sea breeze due to warmer ocean Weaker sea breeze due to warmer ocean temperatures results in hotter summerstemperatures results in hotter summers

Less snowpack in Sierra Nevada, leading Less snowpack in Sierra Nevada, leading to water shortagesto water shortages