Ch 13 Air pollution Page 350

Climate LONG term prevailing weather conditions at a particular place based upon records taken Ex – Seattle=cool and moist Phoenix=hot and dry

Factors that determine climate Latitude Atmospheric circulation patterns Oceanic circulation patterns Local geography Solar activity Volcanic activity and Distance to the equator!!!

Circulation Patterns

Ozone Shield (pg. 359) *In the stratosphere that absorbs most of the UV from the sun. *Being destroyed from CFC’s!

Chlorofluorocarbons (CFC’s) At first were thought to be great – nonpoisonous, nonflammable, noncorrosive. Used widely and many sources 1970’s – awareness of their destruction to ozone begins

CFC’s discovered to be bad! Within 10 -20 years of being released, they make their way to the ozone layer where they are chemically unstable and break apart. 1 CFC molecule can break apart up to 100,000 ozone molecules

Ozone hole (page 360) = a thinning of stratospheric ozone that occurs over the poles during the spring due to the cold weather there

Where is it the worst? Why? Polar Stratospheric clouds form here during the dark months. CFC’s accumulate in them. When sunlight returns seasonally at once, the Chlorine atoms rapidly begin to attack ozone. South Pole (Antarctica) Spring

Can we use Ground Level Ozone to replace it? No! Ozone produced by pollution (GLO) is chemically unstable. It either breaks down or combines with other substances before it can reach the stratosphere.

Thinning Ozone Effects Humans *more UV goes thru the ozone layer destroying more DNA which is linked to cancer! Animals and Plants Kills Phytoplankton which is a major producer for the oceanic food chain and oxygen producer! Increased UV also kills amphibian DNA in eggs reducing their populations. Damages photosynthesis of plants and our crop yield.

Montreal Protocol (pg 362) Good news… 1987 – group of nations agreed to hault production of CFC’s 1992 – developed countries agree to eliminate most cfc’s by 1995 U.S. agreed to ban all substances that pose a significant danger to ozone by 2000 Bad news… CFC molecules remain active in the stratosphere for 60 – 120 years

13.3 Global Warming Similar to the way light energy travels threw windows but the heat energy cannot escape and make the car warmer… *The greenhouses gases trap solar radiation and return it to earth – hence warmer the planet!

Major Greenhouse Gases… *Water vapor *Carbon dioxide CFC’s Methane Gas Nitrous oxide * 2 most abundant

CO2 seasonally fluctuates! Plants grow more rapidly in summer therefore using more CO2, therefore causing carbon dioxide levels to drop in the summer. In the winter, leaves and grass decay releasing the stored CO2, therefore causing levels to rise again

But the trend is still UP, UP , and away! Each year the CO2 levels are getting higher and higher

More CO2 = More heat! A comparison of carbon dioxide in the atmosphere and average global temperatures of the past 400,000 years supports this view.

Global Warming! An increase in the average temperature at the earth’s surface. This increase is rising at the same level as the increase in greenhouse gases This creates the hypothesis that the globe is warming due to greenhouse gases! It does NOT mean that temps are rising at a constant rate or rising in all parts of the world!

Consequences of a warmer earth today(page 366) In U.S. some birds are nesting 11 days earlier In Britain, 200 species of plants are flowering up to 55 days earlier These are both influenced by temperatures!

Effects of a warmer earth But these effects will be different everywhere because: some ecosystems are less sensitive Countries vary in their ability to respond to problems caused by climate changes. Change in weather patterns Rise in sea levels

Melting ice and rising sea levels… And… Coastal freshwater aquifers become too salty and no longer available for fresh water sources! Wetlands and low lying areas disappear Homes lost and sources of income Beaches eroded Salinity changes in bays and estuaries

Global weather patterns… A warmer earth means the oceans will absorb more heat = more typhoons/hurricanes! Change in ocean currents = change in weather! ex- droughts, floods

Human health problems… Heat waves = death Flowers last longer = bad for allergy sufferers! (ME!) Mosquitos would be able to survive in other areas and spread more disease, etc.

Plants and animals… PLANTS… Decrease in crop yields = starvation! Increases the demand on irrigation and therefore drains aquifers even more! ANIMALS… Might die due to warmer conditions Some might shift geographical ranges

Kyoto Protocol 1997 Requires developed countries to decrease emissions of carbon dioxide and other GHG’s by an average of 5% below their 1990 levels BY 2012 But by 2035 the developing countries will increase to 50%

Nitrous oxide gives rise to NO (nitric oxide) on reaction with oxygen atoms, and this NO in turn reacts with ozone. Human activity is thought to account for 30%; tropical soils and oceanic release account for 70%.