Questions about GW in the Future Scientific Debate Ch 16 Global Warming Part 2 Questions about GW in the Future Scientific Debate

Question 1 How fast have CO2 emissions increased in the past? What is expected in the future 1750 280 ppm 2001 371 ppm (32% inc in 250 yrs) 2100 500 ppm if rate is constant (35% in 100 yrs) 700 ppm if rate increases (90% in 100 yrs)

Question 2 How much will the temperature increase by 2100 relative to 1900? 2000 + 0.5-1.0 oC 2050 +1.0-3.5 oC 2100 2.0-6.0 oC Note that the max 6 oC increase is comparable to the 6 oC decrease in temp that caused the ice age.

Question 3 How much will sea level rise relative to 1900? 2000 4"-10" 2000 4"-10" 2100 20 " @ 50% of the world's population lives on coastline so a 20" rise in the ocean will displace millions of people

Question 4 Why does GW cause sea level to rise? increase of water in the seas due to melting polar ice caps, icebergs increase in volume of water with temperatures above 4 oC (thermal expansion of sea water)

Question 5 How will precipitation be affected? As the global temp increases, more water evaporates and then falls as rain and snow. For each degree oC increase in temp, there is a 2% increase in average global precipitation. As temp increases, there is more energy in the atm and more capacity for violent weather (storms, hurricans, typhoons, etc).

Question 6 How will agriculture by impacted? Areas that are wet (Figure 16.3) will become wetter and be subject to flooding. Areas that are dry will suffer more drought and starvation. More photosynthesis, expanded growing regions, more harmful insects and bacteria, drier soil as moisture evaporates.

Question 7 How will GW impact human health? self-study

Global Warming The Scientific Debate There is scientific certainty about the increase in the earth's temperature (and observations such as those on pp 587-588) the identity and role of greenhouse gases in trapping heat in the earth’s atmosphere the determination that human activities are increasing greenhouse gases

Global Warming The Scientific Debate There is debate about What % of global warming is due to human activities? % due to natural causes? How do changes in human activity change global warming? How are contributors to GW related to each other? How do we quantify GW on agriculture, natural resources, health, climate...

Global Warming The Scientific Debate There is debate about climate predictions based on computer models What are the responsibilities of developed nations? developing nations in reducing GW? What should individuals, communities and countries do to reverse or slow GW? Note that in the U.S., each person is responsible for 6.6 tons (5.4 tons due to burning of fossil fuels) of greenhouse gas emissions and this has increase 3.4% between 1990-1997.