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Why Climates Change Dr. Mary Snow and Dr. Rich Snow Applied Aviation Sciences Embry-Riddle Aeronautical University Daytona Beach, Florida
Geologic Time Scale Divides Earth’s 4. 6 billion-year History into: Eons, Eras, Periods, and Epochs If a 24 -hour day represents all of history, humans arrived during the last minute
To understand climate change, we need to understand what causes a place on Earth to have a certain climate in the first place What are the large-scale climate controls?
Climate Controls: 1) Latitude 2) Altitude 3) Currents 4) Land Water Differences 5) Continental Drift 6) Astronomical 7) Composition Let’s Take a Brief Look at Each. . .
1) Latitude Earth’s Axis Points North, so During the Year Different Latitudes Receive the Direct Rays of the Sun.
Summer (in the Northern Hemisphere)
Winter (in the Northern Hemisphere)
2) Altitude Atmosphere is Warmed from Below by Earth Higher Altitudes are Colder
3) Currents Large Scale Gyres in the Oceans Continually Redistribute Heat Energy Poleward
Global Winds Also Transport Heat Energy Around Earth
4) Land & Water Differences Water heats and cools far more slowly than does land
5) Continental Drift Earth’s crust is fractured into plates that move in various directions…
6) Also Consider Astronomical Forcing Mechanisms…
Milankovitch Cycles Occur every 100, 000 years---Often it is these cycles that are referred to as CYCLICAL CLIMATE CHANGE However, the IPCC and other climate scientists compare CURRENT TRENDS to this NATURAL RANGE OF VARIABILITY.
Temperatures Over Past 2 Million Years 100, 000 -Year Pattern of Glacial & Interglacial Periods: 90, 000 Years of Cooling & Expanding Ice Sheets 10, 000 Years of Warming & Rising Sea Levels
7) Composition Earth’s climate evolved VERY slowly over its 4. 6 billion year history The relatively recent change, especially in the addition of greenhouse gases (GHGs) FROM BURNING FOSSIL FUELS, has been VERY rapid.
Data from direct observation
What is global warming? Shortwave radiation from Sun passes through the atmosphere and is absorbed by Earth’s surface. Absorption changes the surface and the wavelength. Earth re-radiates longwave radiation that is absorbed by greenhouse gases (GHGs) and warms the atmosphere.
What are the primary GHGs and their sources? Sources GHGs
What evidence do we have of a warming atmosphere? Insight into past climates is based on both proxy data and direct observation. Dendroclimatology Tree rings provide records of previous climates.
Lake bottom sediment cores trap pollen grains Pollen diagrams provide information of past vegetation, and therefore, climate, at a site.
Proxy data are also provided by core samples taken by drilling through… coral beds, river beds, and seafloors.
Variations of Earth’s surface temperature for the past 1, 000 years
Proxy data from ice core drilling: Antarctica’s Vostok Station
Air bubbles trapped in ice are tiny packages or samples of atmospheric composition through time.
National Ice Core Laboratory University of New Hampshire Library of Paleoclimate
Data from direct observation Variations of Earth’s surface temperature for the past 140 years
Earth’s mean surface temperature has increased about 1. 2º F to 1. 5º F since 1900. (NOAA, 2005) NASA reports that most of the warming has occurred over the past 30 years. (NASA, 2005) Greenhouse gases from fossil fuel combustion are responsible for most of the warming of the last 50 years. (EPA, 2006)
In the U. S. , 2006 was the warmest year on record. Globally, 2005 was the warmest year on record. Of the twelve warmest years on record, eleven occurred during the past twelve years (1995 -2006). (IPCC, 2007)
Climate models predict that mean Earth temperature could increase from 2. 5ºF to 10. 4ºF above 1990 levels by 2100. “Global temperatures are dangerously close to the highest ever estimated to have occurred in the past one million years” (NASA, 2006).
What evidence is there beyond CO 2 and temperature data?
The Snows of Kilimanjaro 1993 2000
A Peruvian Glacier 1978 2000
Argentina's Upsala Glacier
Rhone Glacier in Switzerland 1906 2003
Antarctica’s ice sheet lost approximately 150 cubic kilometers of ice annually between 2002 -2005 (1 cubic km = 260 billion gallons of water) (NASA, 2006)
What are other potential impacts of climate change? ØLoss of Biodiversity (species extinction is 1000 times the background rate) Ø Health Risks Ø Increased Energy Usage Ø Shifting Agricultural Patterns Ø Diminished Water Resources ØMore Extreme Weather Events Ø Thermohaline Circulation Disruption Ø Rising Sea Levels
What multi-media tools do we have? Climate Change Cinema
Why does there still seem to be a global warming debate? In 1988, the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) which is comprised of ~2, 500 of the world’s best atmospheric scientists. The role of the IPCC is to “understand climate change, its impacts, and options for adaptation and mitigation. ”
The Response from Business and Industry… Global Climate Coalition Founded in 1989 by 46 corporations representing a "voice for business in the global warming debate. " Greening Earth Society Founded in 1998 by the Western Fuels Association to promote the view that increasing levels of atmospheric carbon dioxide are good for humanity.
Key players in a well-funded misinformation campaign Designed to frame climate scientists as “alarmists” And climate change as a “theory” fraught with “uncertainty”
George Marshall Institute and the Oregon Institute of Science and Medicine “The Petition Project” designed to undermine and discredit the scientific authority of the IPCC. Petition was sent to 1000 s of scientists with an article formatted to mimic the journal of the National Academy of Sciences. The NAS released a strong statement disclaiming any connection to this effort and reaffirming the reality of climate change.
“In my more than three decades in the government I've never witnessed such restrictions on the ability of scientists to communicate with the public. ” “Politicians are rewriting the science. ” James Hansen, NASA Goddard A survey of federal scientists reveals that 46 percent felt pressure to eliminate the words “climate change, ” “global warming” or similar terms from communications about their work.
What Can We Do? Replace incandescent bulbs with compact fluorescent light bulbs Move your thermostat down in winter and up in summer Clean or replace filters on your furnace and air conditioner Wrap your water heater in an insulation blanket Weather-strip windows and doors Use less hot water
Turn off and unplug electronic devices you’re not using Reduce, reuse, and recycle Plant trees Buy local products Eat less meat Try walking, biking, carpooling or mass transit when possible
Encourage your school or business to reduce emissions Encourage development of renewable energy Protect and conserve forests worldwide Tell politicians to act Vote --- for candidates who are interested in mitigating climate change! Educate and Inspire! www. climatecrisis. net