1. Global Warming What is it? What’s causing it? Lake Powell, Colorado River

3. CO2: one of the main heat- trapping gases. Its concentration in the atmosphere, past 250 yrs. Past 10,000 yrs

4. It’s getting warmer Hottest years: 2014 2010 2005 1998 Hottest decade: 2001-2010 IPCC NASA

5. Glacier nat park, Montanna-1 Glacier Nat Park, Montana: melting 1850: 150 named glaciers. 2007: 26. 2030: 0 expected

6. Alaska: melting

7. Austria: melting

8. HIMALAYAS: MELTING. Mt. Everes (left), 1921 and 2007

9. Arctic: melting. 1979 and 2003 Expected to be ice- free in summer by 2030. Reflectivity feedback could have serious consequences for Greenland.

10. Greenland surface melt extent. Complete melting: 24 ft sea-level rise.

11. The West Antarctic ice sheet is melting Would raise sea levels 16 feet Would take a few centuries May be already unstoppable

12. To see what this means, let’s turn to the past. 800,000 years of climate history. The “Pleistocene”: 2.5 Mya – today. CO2 was ~180 to 300 ppm. present interglacial Temperature (red) CO2 (blue)

13. Temperature (red) CO2 (blue) Today’s CO2 concentration: above 400 ppm!

14. To see what 400 ppm means … … we must go back before the ice ages (2.5 Mya to today):

15. Pliocene era, 5 Mya - 2.5 Mya. Poles much warmer, tropics slightly warmer. Temperatures were 6 deg F warmer. Sea levels 70 feet higher. The last time CO2 concentration was ~ 400 ppm:

16. Will the CO2 spike be the icon of a new geological age? Many geologists have already named it: The Anthropocene

17. Is this what you want for your grandchildren? It’s a moral issue.

18. THANK YOU! ART HOBSON ahobson@uark.edu Website: physics.uark.edu/hobson We’re all in this together! Thank you