Emissions of greehhouse gasses

1. Emissions of greehhouse gasses

2. Climate forcing factors = Factors causing climate to change

4. Temperature • Direct temperature measurements span 140 years • Global temperature has increased about 1 deg C

5. Some solar radiation is reflected by atmosphere Sun More radiation is absorbed by Earth and warms it Atmosphere Infrared radiation (heat) is released from the Earth Earth Some infrared radiation is absorbed by greenhouse gases warming Earth and lower atmosphere Greenhouse gases

6. Greenhouse gases Greenhouse warming potential (GWP) -- takes into account the ability of a gas to absorb infrared radiation, and the lifetime of the gas in the atmosphere Gas [conc] GWP carbon dioxide (CO2) 360 ppm 1 methane (CH4) 1745 ppb 23 nitrous oxide (N2O) 314 ppb 296 CFC-11 268 ppt 4600 CFC-13 4 ppt 14000 water (H2O)

7. A diversion to the stratosphere… CFC’s: These gases affect the ozone layer in the stratosphere (GOOD OZONE) BUT this is not related to their effect as a greenhouse gas in the troposphere (BAD OZONE)

8. Good ozone Bad ozone A diversion to the stratosphere… Stratosphere 10 to 45 km Troposphere 0 to 10 km Earth

9. Ozone • Good ozone shields the earth from UV radiation

11. Ozone • Good ozone shields the earth from UV radiation • Bad ozone = smog; affects animal and plant health

13. Ozone • Good ozone shields the earth from UV radiation • Bad ozone = smog; affects animal and plant health Neither are climate forcing factors!

14. Back to greenhouse gasses and climate forcing…

15. Greenhouse gases Carbon dioxide is the largest single contributor to climate forcing Carbon dioxide contributes about half of total climate forcing from greenhouse gases

16. Measurements of past atmosphere come from bubbles trapped in ice cores

17. Past temperature recorded in oxygen isotopes; 4-12 deg C variation between ice ages

18. These records show a correlation between greenhouse gas concentrations and temperature

19. Greenhouse gases and temperature Current temperature increase a sharp change from past 1000 years Climate might otherwise be cooling,but this is speculation

20. Greenhouse gases

21. Greenhouse gas sources Methane Tg/yr Animals 80 Termites 40 Rice Paddies 110 Wetlands 115 Fuels 180 Total 525 Yellow text = anthropogenic source

22. Greenhouse gas sources Nitrous Oxide Tg/yr Biomass burning 2 Land use (agriculture) 1.4 Denitrification (soil) 5.7 Denitrification (ocean) 2 Total 11.1 Yellow text = anthropogenic source

23. Greenhouse gas sources Carbon Dioxide Pg/yr Fossil Fuel 6.3 Land clearing 1.7 Ecosystem respiration 120 Ocean efflux 105 Yellow text = anthropogenic source

24. Eff + Edf = atm + ocean + other The global carbon balance(in Pg C year-1): Fossil fuels + deforest. =  atmosphere +  oceans +  ??? 5.5 + 1.6 = 3.3 + 2.0 + 1.8 1 Pg = 1015 grams From: IPCC 1995

25. Predicting climate

26. Climate predictions • General circulation models (GCM) are used to predict future climate • Driven by physical processes that involve transfers of energy and water • Used with different greenhouse gas ‘scenarios’ to predict climate in a future atmosphere

27. GCM predictions • Models are tested against climate records from the past • Model predictions are compared with other similar GCM predictions • GCM temperature predictions are typically quite accurate

30. GCM predictions • Global climate predicted to warm 1.5 - 6 deg C by 2050 if CO2 increases at current rate. • High latitudes & and land surfaces warm most. • Washington DC now has 30 days over 90 deg F. Will have 85 days over 90 deg F.

31. Gainesville is not predicted to change very much.Why?

32. GCM predictions • GCM precipitation predictions are more variable and considered less accurate

34. GCM predictions • Changes in precipitation are more variable globally • Wet tropics may become wetter Arid zones may become drier

35. GCM predictions Wamer temperatures = more energy More energy = larger storms

37. How will climate warming affect life in FL?

38. Sea level change in FL