Natural and Human impacts on Weather and Climate

Climate Average weather conditions over a long period of time. (temperature and precipitation)

Natural Impacts El Nino/La Nina El Nino: unusually warm current off the coast of S. America: (caused by weak winds) makes South America warmer and rainier than usual. Causes storms in U.S. Can weaken hurricanes. La Nina: the more common colder current off the coast of S. America. S. America is cooler and drier.

Volcanic Eruptions Ash and dust may block sunlight making global temperature cooler. Excess CO2 may increase the Greenhouse effect and make global temperature warmer.

Sun Spots High sunspot activity: warmer climate Low sunspot activity: cooler climate (the Little Ice Age from 1645-1716)

Shifts in Earth’s orbit A more circular orbitcooler climate A more elliptical orbitwarmer climate when the Earth is closer to the Sun

The Earth’s Precession Every 14000 years the northern hemisphere summers occur when the Earth is also closer to the Sun. This intensifies summer heat.

Human impacts on Global climate

Urban heat islands Excess pavement and buildings release heat back to the atmosphere rather than plants absorbing the heat.

Burning hydrocarbons Mining gasoline and coal, etc. and then burning it releases excess CO2 that was stored underground. This leads to intensified Greenhouse effect and global warming.

Burning wood Destroys trees which when alive removed CO2. Adds CO2, other gases and particulate pollution Reduces animal habitats

Greenhouse Effect The greenhouse effect itself is good! It allows us to have moderate temperatures for survival. EXCESS CO2 traps heat in the atmosphere causing global temperature to rise (global warming)

Deforestation: Slash and burn agriculture Soils in tropical rain forests tend to be poor in nutrients Farmers burn the trees off, and use the land for a brief time before the nutrients are depleted They then move to another plot.

Deforestation: over farming Dust will be blown into the atmosphere increasing particulate pollution

(dust bowl, 1930s)

Deforestation: removal of wild habitat to support human dwellings, etc.

Industrial byproducts Sulfur dioxide and nitrogen oxides are added to the atmosphere along with excess CO2 and particulates.

Acid precipitation Various chemicals released into the atmosphere cause acids to form. examples: Sulfur dioxides and nitrogen oxides Precipitation has a pH of less than 5. Effects of acid rain at Mount Mitchell, NC

Chlorofluorocarbons/aerosols CFCs destroy ozone in the upper atmosphere. This means that the ozone layer is less effective at blocking UV light This could mean more cases of skin cancer.

The Carbon Cycle

What can we do? Create a poster with words and pictures showing how we can reduce AIR pollution and global warming. List ideas in each category: World My family and I