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An Introduction to Climate Change - Grand Junction
- 1. An Introduction to Climate Change Gerald C. Nelson Professor Emeritus, University of Illinois, Urbana-Champaign Presentation at Mesa County Library, August 4, 2014
- 2. What is climate change? • Climate – average weather over an extended period, say 30 years • Climate change – changes in those averages • What weather variables? Some examples • Temperature – daily average, minimum, maximum • Rainfall • Heating degree days • Etc.
- 3. Recent Climate Change in Grand Junction (1899 – 2013)
- 5. Summary of Climate Change in Grand Junction since 1899 • It’s been getting hotter in the summer • Maximum August temp increasing from 88°F to 90°F on average • More days in August over 90°F (17°F in 1899 to 21°F in 2013) • It’s been getting less cold at night in the winter • December minimums have been increasing • Summer rains have been declining • August rainfall down (1.16 inches in 1899 to 0.8 inches in 2013) • Note: All values are averages with lots of variation
- 6. Global Average Temperature Change, 1850-2012 Source: IPCC. http://www.climatechange2013.org/images/figures/WGI_AR5_ FigSPM-1.jpg
- 7. Temperature Change Has Not Been Uniform
- 8. What causes warming/cooling? • Start with sunlight falling on the earth • Add greenhouse gasses to the atmosphere to get warming • Add clouds that reflect sunlight to get cooling • Add dust particles that can either reflect or absorb sunlight to get warming or cooling
- 9. What are the most important greenhouse gasses? Gas Sources Global warming potential relative to carbon dioxide Water vapor Evaporation from water bodies GWP of water vapor is not calculated because there is no way to directly influence its concentration (see Scheevel presentation) Carbon dioxide Volcanoes, burning of organic material and fossil fuels 1 Methane Rice paddies, ruminant digestion, natural gas leaks 34 (over 100 years) Nitrous oxide Fertilizer use, decomposition of manure, industrial processes, transportation 298 (over 100 years)
- 10. CO2 at Mauna Loa Observatory has been rising steadily … http://www.esrl.noaa.gov/gmd/ccgg/trends/ The first time in at least 1 million years.
- 11. Other greenhouse gas emissions have also been rising Page 11 From ‘agri-culture’
- 12. Scenarios of Annual CO2 Emissions to 2100 and modeled effects on temperature Note: range of temperature increases by 2100
- 13. How well do the climate models do?
Editor's Notes
- Source: Calculations based on data downloaded from http://www.ncdc.noaa.gov/cdo-web/. Equation of linear regression is 882.12 + 0.2233x, where x is the year number, with 1990= 0. This means that if 1900 had been an average year, the average August evening high would have had been 88.2F. Every year, the average August evening high increases by 0.02233F so that by 2013, the average August evening high would have increased by 2.5.
- Observed averaged combine land and ocean surface temperature anomaly, 1850-2012. Source: IPCC. http://www.climatechange2013.org/images/figures/WGI_AR5_FigSPM-1.jpg Figure SPM.1 | (a) Observed global mean combined land and ocean surface temperature anomalies, from 1850 to 2012 from three data sets. Top panel: annual mean values. Bottom panel: decadal mean values including the estimate of uncertainty for one dataset (black). Anomalies are relative to the mean of 1961−1990. (b) Map of the observed surface temperature change from 1901 to 2012 derived from temperature trends determined by linear regression from one dataset (orange line in panel a). Trends have been calculated where data availability permits a robust estimate (i.e., only for grid boxes with greater than 70% complete records and more than 20% data availability in the first and last 10% of the time period). Other areas are white. Grid boxes where the trend is significant at the 10% level are indicated by a + sign. For a listing of the datasets and further technical details see the Technical Summary Supplementary Material. {Figures 2.19–2.21; Figure TS.2}
- Figure SPM.1 | (a) Observed global mean combined land and ocean surface temperature anomalies, from 1850 to 2012 from three data sets. Top panel: annual mean values. Bottom panel: decadal mean values including the estimate of uncertainty for one dataset (black). Anomalies are relative to the mean of 1961−1990. (b) Map of the observed surface temperature change from 1901 to 2012 derived from temperature trends determined by linear regression from one dataset (orange line in panel a). Trends have been calculated where data availability permits a robust estimate (i.e., only for grid boxes with greater than 70% complete records and more than 20% data availability in the first and last 10% of the time period). Other areas are white. Grid boxes where the trend is significant at the 10% level are indicated by a + sign. For a listing of the datasets and further technical details see the Technical Summary Supplementary Material. {Figures 2.19–2.21; Figure TS.2}
- Reached 400 ppm, the first time in 8 million years.
- Butler, James H., and Stephen A. Montzka. The NOAA Annual Greenhouse Gas Index. Boulder: National Oceanic & Atmospheric Administration Earth System Research Laboratory, updated 2014. http://www.esrl.noaa.gov/gmd/aggi/aggi.html.
- Sources: Le Quéré, Peters, Canadell 2013; Le Quéré et al. 2013; Boden et al. 2010; Tirpak and Vellinga 1990; Legget et al. 1992; Nakicenovic and Swart 2000; and D. P. van Vuuren et al. 2011.