CHEM H90 Lecture Notes - Lecture 25: Keeling Curve, Industrial Revolution, Radiative Forcing
Science of Climate Change
• basics
o since industrial revolution, humanity has been burning fossil fuels, releasing CO2
into air
o concentration of CO2 hit 400 pm on May 9, 2013, highest in 2 million years
o CO2 traps heat in earth’s surface, increasing temp
o even small increases in average temp have very large uncertain effects
o average global temp has risen about 10C over the last century
o multiple effects/evidence that this is occurring
• advanced topics
o are we sure global warming is happening and caused by humans?
o is it too late?
o effects on polar bears, coastal communities, Europe, etc.
o 95% atmospheric scientists believe this; public does not realize this, and misled
by media
• sources
o Jim Hensen, website at Columbia
o Al Gore’s Inconvenient Truth (with a grant of salt)
o IPCC assessment reports, especially fifth one, 2013 especially. Physical Science
report
o interview with Cicerone on NPR
o 2007 Nobel Peace Prize to Gore and IPCC
o deniers: e.g. climatedepot.com
• energy balance
o Earth gets 320 W/m2 from sun
o due to albedo, 31% reflected, leaving 69% to warm earth
o should give Earth mean temp of -19 0C
o actually, mean temp is about +150C
o difference caused by greenhouse effect
o real problem is increase in GH effect
o albedo – efficiency at reflecting visible light
▪ fresh snow extremely reflective – 0.8-0.9
▪ ocean not very reflective – 0.07-0.1
• greenhouse effects
o sunlight (much of it UV) strikes Earth
o reflected light from surface is infra-red, and reradiates out into space
o some of that is absorbed by gas molecules and re-emitted, back to Earth
• carbon cycle
o carbon very abundant on Earth
▪ lots in ground, soil, trees, surface of water, atmosphere, etc.
o atmosphere has 750 Gt of carbon
o imbalance of carbon
▪ 90 Gt from ocean but 92 Gt going back to ocean
• CO2
o Keeling curve
▪ measure CO2 concentration in parts per million
find more resources at oneclass.com
find more resources at oneclass.com
