Presentation on theme: "Have out B.4/B.7 worksheet Objective: Describe the relationship between global dimming and global warming. Catalyst: Why does global dimming occur only."— Presentation transcript:
Have out B.4/B.7 worksheet Objective: Describe the relationship between global dimming and global warming. Catalyst: Why does global dimming occur only during the daylight hours, while global warming occurs both during day and night? Homework: Read lab B.6 Specific Heat Capacity, page 346. – Answer: What is the goal of the lab? What concept/idea will we use to accomplish this goal? – Create a flow chart for the procedure of the lab. Do not simply copy steps from the book. – Create a data table that you will use to record data during the lab.
B.4 Thermal Properties – Reflectivity: Light colors reflect more light than dark colors and stay cooler – Specific Heat Capacity: Materials with higher SHC store more thermal energy and are slower to heat up and slower to cool down (water!)
Assignment Do B.5 and B.8 on the same page. You may work in groups of 2 and use the same paper.
Climate Change (a.k.a. Global Warming)
Key Indicators & Evidence Carbon Dioxide Concentration Global Surface Temperature Artic Sea Ice Land Ice Sea Level Glacial Melting Rates Growing Seasons Major Precipitation Events
Other Evidence of Climate Change Increases in Glacial Melting Rates
Other Evidence of Climate Change Growing Seasons Lengthening A recent study of European spring and autumn plant phases indicates that on average, spring events advanced by about six days and autumn events were delayed by about five days over the period from 1959 to 1993 (Menzel and Fabian, 1999). The long-term consequences of these changes are uncertain. The changing climate may impair the extent to which an animal’s life cycle is synchronized with its food supply. Birds, for example, can adjust to warmer temperatures by flying to more northern areas in any given year, but the vegetation upon which they (or their prey) rely may take decades or longer to adjust (see Root, 1997).
Other Evidence of Climate Change
Keep in Mind: Evidence is sometimes anecdotal We don’t have controlled experiments Difficult to determine causal connection does increased [GHGs] Hurricane Y
4 major reasons Variations in Earth’s orbit Solar variation Non-human changes in GHG concentrations Position of continents versus oceans Why would climates change in past?
Feedbacks in Climate Change Negative feedbacks—results in LESS global warming Global warming (GW) expansion of algae populations in ocean greater uptake of CO 2 Higher [CO 2 ] more plant growth greater uptake of CO 2 GW more evaporation more clouds less solar input Positive feedbacks—results in MORE global warming GW more evaporation more water vapor more IR reradiation GW reduction of snowpack less light reflection GW more energy use higher GHG emissions (more air conditioning but less heating?)
Sources of information on climate change 1.Evaluation of geologic record What does the distant past tell us? 2.Monitoring of present record What does recent data tell us? 3.Mathematical models Can we model the atmosphere and make predictions? What do these models tell us about the future?
The Geologic Record & Climate Change We use proxies (time capsules): sediment cores in oceans – certain unicellular species live in waters with specific temperatures – <250 million years (age of oceans) glacial ice CO 2 bubbles trapped in ice <500,000 years
tree rings – thickness of rings ( dendrochronology ); thick = high T, water avail. – < 1,200 years pollen records – plants live in certain T. regimes – ~10-20 Kyrs The Geologic Record & Climate Change More proxies: Sunflower Ragweed
What do proxies tell us? 1.Last 2.5 million years, T’s have varied 4-10°C 2.Last 160 Kyrs, [CO 2 ] = ppm (currently ~380 ppm) 3.Last million+ years, peak T was 1-2°C warmer than today. The Earth has had these temperatures before, but never this much CO 2.
Low level change is as equally likely as a high level change. PREDICTED FUTURE TEMPERATURE CHANGE
There is a danger in taking “risk,” given that: we are near the peak Earth T. of the past 2 Myr ecosystems are already stressed in other ways: pollution (pesticides/synthetic chemicals), depleted fisheries & deforestation, dams/roads, invasive species locations most vulnerable to changes are currently in the worst position to respond/adapt (e.g., continent of Africa & Oceania) Additional reasons to be concerned about climate change: These thoughts lead to: “Where there are threats of serious or irreversible environmental damage, lack of full scientific certainty shall not be used as a reason for postponing cost effective measures to prevent environmental degradation.”
“Better safe than sorry.” “A ounce of prevention is worth a pound of cure.” “Where there are threats of serious or irreversible environmental damage, lack of full scientific certainty shall not be used as a reason for postponing cost effective measures to prevent environmental degradation.”
Review Data CO 2 Surf. Temp. Sea Ice Land Ice Sea Level Extreme weather Glaciers melting Growing seasons lengthened Historical Climate Change Variations in Earth’s orbit Solar variation Non-human changes in GHG concentrations Position of continents versus oceans Feedback Systems Negative Positive Consequences Increase sea levels More severe weather Elongated growing season Gathering Info Current measurements Historical proxies Mathematical models
Essay (Due 5/31 or 6/1) Intro, conclusion and as follows – What are the possible causes of global dimming? – What is the evidence that global dimming occurs? – What tools and techniques are used to study global dimming? – How is global dimming causing scientists to re-evaluate current climate models? – What can be done to reduce global dimming? Should these steps be taken without also addressing global warming? Why or why not? Should be typed and printed out and well-written! No more than 3 pages double-spaced. Write clearly and to the point!
Lab Report: Formal excluding Intro and Procedure (Due 6/4 or 6/5) You do not need to do Intro, Procedure You do need to do Data, analysis, and conclusion including book questions Must be typed