Human and the Earth

1. Human and the Earth ASTR 1420 Lecture 26 Section 10.5

2. Global Warming

3. Doesn’t everyone already know about Global Warming? GALLUP anual poll global warming is generally exaggerated? 43

4. GALLUP poll When the effects of global warming will begin to happen?

5. GALLUP poll The main cause of global warming?

6. 394.45 now!

7. Consequences

8. Rising sea level 130 2010

9. Past history of CO2 and Global Average Temperature

10. Venus and Earth Venus Earth 1.0 Astronomical Unit (AU) 1.0 Rearth Rocky planet Geological activity Thick atmosphere 57°F • 0.7 Astronomical Unit • 0.95 Rearth • Rocky planet • Geological activity • Thick atmosphere • 900°F 200,000 more CO2 in atmo

11. Why so much more CO2 in the Venusian atmosphere? Total content of Carbon (CO2) in Venus and Earth are same. If Venus and Earth were formed similarly, shouldn’t they have nearly the same atmospheric CO2 content? CO2 in the Earth : atmosphere 1, ocean 60, rocks 170,000 CO2 in the Venus: atmosphere ~200,000, ocean 0, rocks 0

12. Venus was like a tropical paradise (~80°F) before Dry effect Temp was high enough initially so that there was no water condensation • no CO2 dissolution • accumulated outgassed CO2 • warmer temp • more evaporation of water • H2O broken by solar UV • higher CO2 and hotter temp Wet effect More net evaporation than precipitation • ocean gradually vanished • higher T caused rocks to release stored carbon • more H2O in the atmosphere causing even stronger greenhouse • H2O broken by solar UV • dry, barren, hot planet • Either through “Dry” or “Wet” runaway greenhouse effect, Venus lost all her water and CO2 had to be remained in the atmosphere

13. The CO2 cycle acts as a thermostat For the warm Earth, carbonate minerals forms in the oceans at a more rapid rate, and takes away more CO2 Regulation of Earth’s Climate What global warming? We don’t need to worry about it since the CO2 cycle will take care of it!! The cycle is about 400,000 years, and this is a very delicate process

14. Can Earth follow the same footsteps of Venus? YES! • “Wet” runaway greenhouse effect on Earth would require that the majority of the oceans around the world would evaporate more water than precipitate  critical temperature is about 80F • By 2100, average global temperature can rise ~70F which is dangerously close to the critical point. • The only thing that has prevented Earth from being another Venus was the CO2 cycle which is a slow, yet very delicate process. • If this process were ever to start, there is not way to stop it

15. Localized Runaway Greenhouse effect • Pacific ocean to the NE of Australia exhibited a runaway effect (May 2002) • This location was warm enough year round to continually evaporate more water vapor than precipitated back to it. • Luckily, this is only a localized effect and surrounding ocean compensate for it. But, this may be an example tells us that we are uncomfortably close to the entire planetary runaway effect. Should we take a risk with the tipping point?

16. Dr. Martin Luther King, Jr. "Unlike the plagues of the dark ages or contemporary diseases we do not yet understand, the modern plague of overpopulation is soluble by means we have discovered and with resources we possess. What is lacking is not sufficient knowledge of the solution, but universal consciousness of the gravity of the problem and the education of the billions who are its victims.” Acceptance Speech: Margaret Sanger Award in Human Rights, 1966 As scientists and citizens, we have responsibilities to remind the public.