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

3. CO2: one of the main heat-trapping gases
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 NASA IPCC Hottest years: 2014 2010 2005 1998
Hottest decade:
IPCC

5. Glacier nat park, Montanna-1
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 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. Today’s CO2 concentration: above 400 ppm!
CO2 (blue)
Temperature (red)

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

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

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