The Greenhouse Effect

Like a greenhouse, our planet traps heat – How does it work? Greenhouse gases trap heat radiating from earth – Water vapor – Carbon dioxide – Methane – Is it good or bad? Not only good, but absolutely necessary! Without the greenhouse effect, earth would be too cold to sustain life – With greenhouse: average temperature of 58 o F – Without greenhouse: average temperature of -1 o F

So, what’s global warming Too much of a good thing We add greenhouse gases to our atmosphere everyday (industry/automobiles more now than ever before) – Like thickening the glass on the greenhouse – Venus has an atmosphere made up of 97% carbon dioxide (ours is.04%) Venus has an average temperature of 864 o F

how do we know global warming is our fault and not just nature doing its thing? Greenhouse gases can become trapped in ice We have taken ice samples from ancient glaciers and determined greenhouse gas concentrations from millions of years ago As the temperature rises, the greenhouse gases escape from the ice The results…

Based on the graph, fluctuations are normal so…??? There is a correlation between periods of high carbon dioxide levels and warm temperatures and low levels and cool temperatures and carbon dioxide levels fluctuate naturally BUT the fluctuations occurred every hundred thousand years or so Additional green house molecules like CO 2, causes less heat to escape, so it’s pushing us into warmer period too fast.

Okay so…who cares? Warmer weather sounds kind of nice actually... Several dangers that can affect our quality of life – Higher average temperatures (as little as 1 o F increase) Heat related illness and disease – Example: increasing range of mosquitoes carrying malaria – Wildlife at risk Coral reefs “bleaching” from slight changes in temperatures Polar bears could face extinction in next century – Increased drought, fire and flooding Higher temps = increased evaporation, exaggerating drought and fires and increasing chance of flooding when rainfall does occur – Changing landscapes Shifts in where and how much vegetation can thrive will affect human and populations that depend on it

More dangers – Rising seas Thermal expansion (warm water takes up more space) Glaciers release fresh water into ocean (and more greenhouse gases into atmosphere) Estimates say sea levels could rise 4 – 36 inches in next 100 years – 100 million people live within 3ft of sea level, this would swamp every city on the East Coast in the USA from Miami to Boston – Some people in small island countries have already starting abandoning their homes – Stronger storms Tropical storms and hurricanes get their energy from the ocean, warming surface temps provide storms with more energy – Economic losses All of these things = $$$$

Irony Global warming can trigger cooling – Example: Gulf Stream ocean current brings water from the tropics to Great Britain and northwestern Europe, making that area much warmer than it would be without it – Fresh water pouring into ocean from melting glaciers can slow this current down causing extreme cooling and freezing

More scary facts The global average surface temperature rose 0.6 to 0.9 degrees Celsius (1.1 to 1.6° F) between 1906 and 2005, and the rate of temperature increase has nearly doubled in the last 50 years Sound insignificant? – at the end of the last ice age, when the Northeast United States was covered by more than 3,000 feet of ice, average temperatures were only 5 to 9 degrees cooler than today.