Section 3 Remote sensing of global change Greenhouse gasses Global Change Instructor: Dr. Cheng-Chien LiuCheng-Chien Liu Department of Earth Sciences National Cheng Kung University Office: Building of Earth Sciences, room Voice: ext Office hours: Monday 14:00 – 17:00, Wednesday 9:00 – 12:00 URL: Last updated: 25 April 2005

Introduction  Definition of greenhouse gasses The gasses that prevent heat energy given off by the sun from leaving our atmosphere back into space  Greenhouse effect See next section

Introduction (cont.)  A list of greenhouse gasses Carbon dioxide CO 2 Methane CH 4 Chlorofluorocarbon CFC Ozone O 3 Water vapor H 2 O Nitrous oxide N 2 O Soot …

Mechanism of Greenhouse effect  Black body radiation  Selective absorption of energy by greenhouse gasses Long wavelength radiation  preferred Daytime  absorption (long : short = 89:50) Nighttime  release long radiation  Consequences Make the Earth warmer Reduce the diurnal variation of temperature

Fig. 1 The electromagnetic spectrum after and before penetrating the atmosphere. Source: Fig

Emission of Greenhouse Gases  Slowdown International cooperation   CFC use  (Phase-out) (Montreal Protocol )  Slower growth of CH 4  A steady rate of CO 2 emissions  Significance of CH 4 The warming effect  CH 4 :CO 2 = 1:2 CH4  tropospheric O 3   Tropospheric O 3 is a principal ingredient in "smog," which is harmful to human health and reduces agricultural productivity

Emission of Greenhouse Gases (cont.)  A cheaper and faster way  reduce CH 4  Reduction of CH 4 emissions and soot could yield a major near term success story in the battle against global warming, thus providing time to work on technologies to reduce future CO 2 emissions. A short video about CH 4 and climate change MethPackage_QTbigprogress.mov MethPackage_QTbigprogress.mov  Long-term goal  reduce CO2 Limiting CO2 will still be needed to slow global warming over the next 50 years.  If the same fossil fuel consumption rate with CH4 and pollution halted for the next 50 years  C   If “business-as-usual”  C   the specter of imminent disaster

Fig. 2 Fig. 2 changes in 12 climate "forcings" or factors that have contributed to climate change since 1850 Source:

Fig. 3 Fig. 3 Growth rate of climate forcings by greenhouse gases Source:

Questions  Ozone is one of the greenhouse gases. Does the depletion of ozone cause the global warming directly?