Section 3 Remote sensing of global change

Section 3 Remote sensing of global change Greenhouse gasses Global Change Instructor: Dr. Cheng-Chien Liu Department of Earth Sciences National Cheng Kung University Office: Building of Earth Sciences, room 30206 Voice: +886-6-2757575 ext. 65422 E-mail: ccliu88@mail.ncku.edu.tw Office hours: Monday 14:00 – 17:00, Wednesday 9:00 – 12:00 URL: http://mail.ncku.edu.tw./~ccliu88/ 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 CO2 • Methane CH4 • Chlorofluorocarbon CFC • Ozone O3 • Water vapor H2O • Nitrous oxide N2O • Soot • …

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

Fig. 4.2.1 Fig. 1 The electromagnetic spectrum after and before penetrating the atmosphere. Source: http://www.ccrs.nrcan.gc.ca/ccrs/learn/tutorials/fundam/chapter1/chapter1_4_e.html

Emission of Greenhouse Gases • Slowdown • International cooperation  • CFC use  (Phase-out) (Montreal Protocol ) • Slower growth of CH4 • A steady rate of CO2 emissions • Significance of CH4 • The warming effect  CH4:CO2 = 1:2 • CH4  tropospheric O3 • Tropospheric O3 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 CH4 • Reduction of CH4 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 CO2 emissions. • A short video about CH4 and climate change http://svs.gsfc.nasa.gov/stories/greenhouse_20020103/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  0.70C  • If “business-as-usual”  1.40C  the specter of imminent disaster

Fig. 2 Fig. 2 changes in 12 climate "forcings" or factors that have contributed to climate change since 1850Source: http://svs.gsfc.nasa.gov/stories/greenhouse_20020103/figure1m.gif

Fig. 3 Fig. 3 Growth rate of climate forcings by greenhouse gasesSource: http://svs.gsfc.nasa.gov/stories/greenhouse_20020103/figure2m.gif

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

Section 3 Remote sensing of global change