DP Bio Topic 4-4 Climate Change

Topic 4.4 Climate ChangeIB Biology

R. Price

v. 1 2015

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#1: Carbon dioxide and water vapour are the most significant greenhouse gases

Carbon Dioxide• Into atmosphere -> cell respiration,

combustion biomass, fossil fuels• Removed from atmosphere -> dissolve

in oceans, photosynthesisWater Vapour• Into atmosphere -> evaporation from

ocean, transpiration from plants• Removed from atmosphere -> rain &

snow

#2: Other gases including methane and nitrogen oxides have less impact

Greenhouse Effect•Water vapor = 50%•Clouds = 25%, •Carbon dioxide (CO2)= 20%•Methane (CH4) = 5%•Nitrous oxide (N2O) = < 1%

Oxygen & nitrogen NOT greenhouse gases (don’t absorb longer-wave radiation)

By Andrew Lacis [Public domain], via Wikimedia Commons

#3: The impact of a gas depends on its ability to absorb long-wave radiation as well as on its concentration in the atmosphere

Warming impact of greenhouse gas:

1. How readily absorbs long-wave radiation

2. Concentration of the gas in the atmosphere

Methane absorbs more radiation than carbon dioxide, but there’s more carbon dioxide in the atmosphere

#4: The warmed Earth emits longer-wave radiation (heat)

• Surface of the Earth absorbs short-wave radiation from the sun• Earth re-emits energy as longer-

wave radiation

#5: Longer-wave radiation is reabsorbed by greenhouse gases which retains the heat in the atmosphere

• Ozone (O3) in atmosphere absorbs 25-30% short wavelength radiation (UV) before it reaches the Earth• Earth re-emits energy as longer-

wavelength radiation (heat)• 70-80% of re-emitted energy

captured by greenhouse gases

If we didn’t have global warming, Earth’s surface = -18 deg. C

#6: Global temperatures and climate patterns are influenced by concentrations of greenhouse gases

Ice Cores from Antarctic•Remember, correlation does not prove causation•Evidence supporting hypothesis•CO2 is a greenhouse gas•Ice cores have bubbles of trapped gas•Measure CO2 in trapped bubbles• Measure hydrogen isotope ratios in ice for temperature•As CO2 levels rise, so do global temperature

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#7: There is a correlation between rising atmospheric concentrations of carbon dioxide since the start of the industrial revolution two hundred years ago and average global temperatures

• Large fluctuations in CO2 over last 800,000 years. But. . . • CO2 levels have never been this

high (400 ppm)• Unnatural rise since 1950• Combustion of coal, oil, natural

gas• Correlation between rising

atmospheric CO2 levels and global temperature

#8: Recent increases in atmospheric carbon dioxide are largely due to increases in the combustion of fossilized organic matter

•Since 1950, large increases in global combustion of fossil fuels•Coal, oil, natural gas used for power generation & transportation

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Sources

Content Allott, Andrew, and David Mindorff. Biology: Course Companion. 2014 ed. Oxford: Oxford UP, 2014. Print. Oxford IB Diploma Programme.

Walpole, Brenda. Biology for the IB Diploma. 2nd ed. Cambridge: Cambridge UP, 2014. Print.

ImagesUnless otherwise noted, images are obtained from Pixabay (www.pixabay.com) and used under the CC0 Public Domain license.