Why does C02, 0.04% of our atmosphere, affect our

climate?

Paul H. Carr

AF Research Laboratory Emerituswww.MirrorOfNature.org

Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature

This talk was inspired by my conversation with Peter Somssich about trace gases in automotive light bulbs.

Increasing CO2 gas density: 1. raises temperature of earth’s surface. 2. reduces temperature of the stratosphere.

-Outgoing spectral radiance at the top of Earth's atmosphere showing the absorption at specific frequencies and the principle absorber CO2 at 16 microns. -The red curve shows the flux from a classic "blackbody" at 294°K (≈31°C≈69.5°F).  Schmidt, G.A.,  2010 J. Geophys. Res.,115, D20106, doi:10.1029/2010JD014287.

CO2 levels now 110 ppm above the pre-industrial average

1875

• Carbon isotope ratios indicate the CO2 increase since 1850 is from burning ~300 million yr old fossil fuels.

1750-2005: Even if the cloud albedo effect is assumed to have the maximum cooling value, there would still be a net warming of the climate due to human activities. (UN Intergovernmental Panel on Climate Change, IPCC, 2007Report)

Solar Irradiance increased by only 0.2% since 1750.

The shadowing effect of clouds cools by preventing sunlight from warming the earth.

Runaway Greenhouse Effect on VenusScience, 330, 356-359, 15 October 2010

Parameter Mars Earth VenusTs (K) 215 288 730

ơTs exp4 (W/m2) 121 390 16,100

PS (bar) 0.01 1 100

Ultraviolet observations of VENUS’ cloud cover----

Venus surface temp hotter than Mercury’s 693K.Venus atmosphere is 96% CO2, 3% Nitrogen.

Atmospheric CO2: Principal Control Knob Governing Earth’s TemperatureAndrew A. Lacis,* Gavin A. Schmidt, David Rind, Reto A. Ruedy

Science, 330, 356-359, 15 October 2010http://pubs.giss.nasa.gov/docs/2010/2010_Lacis_etal.pdf

Ample physical evidence shows that carbon dioxide (CO2) is the single most important climate-relevant greenhouse gas in Earth’s atmosphere. This is because CO2, like ozone, N2O, CH4, and chlorofluorocarbons, does not condense and precipitate from the atmosphere at current climate temperatures, whereas water vapor can and does. Noncondensing greenhouse gases, which account for 25% of the total terrestrial greenhouse effect, thus serve to provide the stable temperature structure that sustains the current levels of atmospheric water vapor and clouds viafeedback processes that account for the remaining 75% of the greenhouse effect.

Without the radiative forcing supplied by CO2 and the other noncondensing greenhouse gases, the terrestrial greenhouse would collapse, plunging the global climate into an icebound Earth state.

Time evolution of global surface temperature, top-of-atmosphere (TOA) net flux, column water vapor, planetary albedo, sea ice cover, and cloud cover, after zeroing out all the non-condensing greenhouse gases. The model used in the experiment is the GISS 2°×2.5° AR5 version of ModelE with the climatological (Q-flux) ocean energy transport and the 250 m mixed layer depth. The model initial conditions are for a pre-industrial atmosphere. Surface temperature and TOA net flux utilize the left-hand scale.

Cooling from zeroing out all the noncondensing GHGs and aerosols. Below 0 C, water vapor becomes snow & ice

Tem

pera

ture

600 500 400 300 200 100 present Time (thousand years ago)

Science, Vol. 310, p. 1313, Nov. 2005

Historical TemperatureHistorical Temperature

Ice Age

Car

bon

Dio

xide

(pp

m)

600 500 400 300 200 100 present Time (thousand years ago)

300

280

260

240

220

200

180

160

Science, Vol. 310, p. 1313, Nov. 2005

Historical CO2 ConcentrationHistorical CO2 Concentration

Tem

pera

ture

Car

bon

Dio

xide

(pp

m)

600 500 400 300 200 100 present Time (thousand years ago)

300

280

260

240

220

200

180

160

Science, Vol. 310, p. 1313, Nov. 2005

400 -Present Levels of Carbon Dioxide are Higher - 400

CO2 decrease from 300 to 200 ppm, 100,000 years ago, helped drive temperature down 3.5 C into an ice age.

Ice Age

During the steepest warming, the CO2 released (dots) from the sea preceded the global temperature rise (green line) by several centuries. -CO2 RATE OF CHANGE is 1/300 of the PRESENT RISE.-CO2 greenhouse effect drove the 3.5 C increase in average global temperature. -Sea levels rose ~ 100 meters. Flood stories

4 M PEOPLE 7 B

Ice Age

Nature, 484, 49-54 (05 Apr 2012)

CHANGES IN THE EARTH’S TILT & ORBIT TRIGGERD THE ICE AGE WARMING

• C02 CONCENTRATION IN THE INDUSTRIALIZED NORTHERN HEMISPHERE IS GREATER THAN THE SOUTHERN.

• TEMP. INCREASE, SINCE 1880, OF NORTHERN = 1.1 deg. C• TEMP. INCREASE OF SOUTHERN HEMISPHERE = 0.4 deg C

http://www.americanscientist.org/issues/pub/2014/2/watching-earth-change

HUMAN CO2 FOOTPRINT Atmospheric Infrared Sounder (AIRS) Aboard NASA’s Aquilla Satellite.

At present rate of 2.5 ppm rise per year, humans are increasing CO2 at a rate 300 times faster than the recovery from the ice age 18,000 -10,000 years ago.

CO2 CONCENTRATIONS, HIGHEST (33%) IN 800,000 YRS, WILL REACH 1000 PPM IN 240 YEARS.

• Our present level of 400 ppm could reach ~ 1000 ppm by 2100.

• Arctic became ice-free 8 M years ago when CO2 = 300 - 450 ppm.

• Antarctic melted ~ 40 M years ago, CO2 ~ 700 ppm

-Earth was ice-free, sea levels 100s meters higher.

Dinosaur Extinction 65M Yr. BP Figure from Dr. James Hansen, NASA GISS

Continental ice sheets grew when CO2 was low, 300 and 40 million years ago.

Atmospheric CO2 is the Principal Control Knob Governing Earth’s Temperature:

1.Resonant absorption at 16 microns.2. Lifetime of at least 100 years.

Why does C02, 0.04% of our atmosphere, affect our

climate?

Paul H. Carr

AF Research Laboratory Emerituswww.MirrorOfNature.org