Global Issues and Human Impact Notes

Overpopulation The first homo sapiens walked the earth 200,000 years ago. It took until 1804 for the global population to reach 1 billion. 123 years later in 1927, it reached 2 billion. 34 years later in 1961, it reached 3 billion. 13 years later in 1974 it reached 4 billion.

13 years later in 1987 it reached 5 billion. Today it reached 7,377,334,325 In 2025 it is projected to hit 8 billion!

Ever since then we have been putting TOO MUCH stress on the planet!! Overpopulation Earth’s Carrying Capacity In 1961 the earth had 3 billion people. They were using ½ of the Earth’s resources. In 1987 the earth had 5 billion people. They were using ALL of the resources. Ever since then we have been putting TOO MUCH stress on the planet!!

►overexploiting fisheries. ►overgrazing to the point of desertification. ►destroying forests. ►polluting the waters and atmosphere, including greenhouse gasses.

At the rate we are going, we will need 2 WHOLE planets to sustain our appetites by 2050. Something has obviously got to give!!

How it Hurts!! Because of the stress we are putting on the planet several global issues are now SERIOUS problems. Deforestation Acid Rain Ozone Depletion Biological Magnification Global Warming These are NOT the only problems caused by overpopulation…but they are the ones we will focus on.

There are, of course, other reasons…but these are the main reasons Deforestation The cutting down of trees WHY? Two MAIN reasons: 1. Raw materials (paper, housing, firewood, etc.) 2. Space (industrial use – homes, schools, factories, etc) There are, of course, other reasons…but these are the main reasons

So What!?! What are the consequences of deforestation? NUMEROUS!! Here are the main consequences: More CO2 and Less O2 – due to a lack of photosynthesis Increased soil erosion and lower soil quality Loss of habitats for animals – this disrupts food webs & ecosystems Messes up the water cycle - lessens the amount of transpiration & lowers the water table

Loss of Biodiversity In 1960 a person with leukemia had a 1 in 5 chance of survival In 1980 the chance of survival was 4 in 5 This was due to the Rosy Periwinkle flower Out of 32 common chemotherapy drugs…28 of them came from plants!! So far scientists have only explored 1% of plant and animal species for medicinal use. Scientists estimate that 100 species go extinct every day!! What happens if you need a medicine one day to survive…but we killed off the plant species that it comes from?

Acid Rain

Sulfur Dioxide (SO2) and Nitric Oxides (NOx) are emitted as car exhaust and factory emissions. They combine with water vapor in the atmosphere forming acid droplets. They become part of the water cycle…and fall to the Earth as acid precipitation.

So What !?! Rivers, streams and lakes become acidic Fish and other aquatic species die Ground water can become acidic Vegetation and trees die

Acid rain affects trees by washing away the minerals and nutrients in the soil that help trees to grow. Acid Rain Normal Rain

Concrete, marble and stone are weakened Over 40% of the nations bridges and overpasses and “structurally deficient” That means they could collapse!! BEFORE AFTER

Ozone Depletion We have already explored the Ozone…what does it do for us? Absorbs dangerous UV rays so it doesn’t reach the Earth

CFC’s – Banned in 1978 Chlorofluorocarbons were found in: styrofoam air conditioners & refrigerators aerosol cans

How Does CFC Destroy Ozone?

Ozone Depletion was recognized as a Global issue around 1975. It took until September 24, 2010 for the ozone damage to FINALLY stop! Scientists think that the Ozone will regain its healthy density around 2050. 75 years later!! Can we afford to wait 75 years to solve our other Global Issues?

Biomagnification When chemicals (like pesticides) are added to the ecosystem, they get into the food web… Pesticides are often NONBIODEGRADABLE, this means they DO NOT BREAK DOWN!!

As animals eat other animals, the chemicals build up in their body…causing serious illness or death!! DDT (a spray to kill mosquitoes) caused the death of most Bald Eagles – putting them on the Endangered Species List for 40 years (1967-2007)

Even the ones HUMANS are a part of! This can affect ANY food chain!! Even the ones HUMANS are a part of!

Biological Controls Using a natural predator is an environmentally friendly way to control pests!! No chemicals added into the ecosystem!

BUT BEWARE!! You need to be careful when adding a species into an environment…they could TAKE OVER!! Cane Toad

SKIP TO GLOBAL WARMING

Greenhouse Effect vs. Global Warming ☼ NORMAL trapping of some of the Sun’s heat ☼ Keeps our planet warm enough to support life Global Warming ☼The thickening of the atmosphere with greenhouse gasses (CO2, CH4 and N2O) ☼More of the Sun’s heat gets trapped…increasing the planet’s temperature.

Causes of Global Warming Two main causes for higher levels of CO2 1. Increased burning of fossil fuels (cars, factories, etc.) 2. Increased deforestation is limiting the conversion of CO2 back into O2 for us to breathe

So What!?! Some of the consequences of global warming: Spread of disease As northern countries warm, disease carrying insects migrate north, bringing plague and disease with them. Warmer Waters – More Hurricanes As the temperature of oceans rises, so will the probability of more frequent and stronger hurricanes.

Increased Probability and Intensity of Droughts and Heat Waves Although some areas of Earth will become wetter due to global warming, other areas will suffer serious droughts and heat waves. Africa will receive the worst of it, with more severe droughts also expected in Europe. Water is already a dangerously rare commodity in Africa, and according to the Intergovernmental Panel on Climate Change, global warming will worsen the conditions and could lead to conflicts and war.

The ice caps melting is a four-pronged danger. Polar Ice Caps Melting The ice caps melting is a four-pronged danger. First, it will raise sea levels. With all glaciers melted, the seas would rise about 230 feet. Second, melting ice caps will throw the global ecosystem out of balance. The ice caps are fresh water, and when they melt they will desalinate the ocean, or in plain English – make it less salty. The desalinization of the Gulf current will ”mess up" ocean currents, which regulate temperatures.

Third, temperature rises and changing landscapes in the Arctic Circle will endanger several species of animals. Only the most adaptable will survive. Fourth, global warming could increase with the ice caps gone. Ice caps are white, and reflect sunlight, much of which is reflected back into space, further cooling Earth. If the ice caps melt, the only reflector is the ocean. Darker ocean absorbs sunlight, further warming the Earth.

Desertification of Soil Other Consequences Floods Stronger Storms Wildfires Desertification of Soil

Loss of Biodiversity & Habitats Species Extinction Diminished Food & Water Supply Death of Phytoplankton Phytoplankton do MORE THAN 50% of the planets photosynthesis!!

Time to Change Your Thinking!?!