Humans and the Environment Notes

Interconnectedness

• The entire planet is interconnected through our oceans and atmosphere.
• Maintaining the biodiversity of our planet is important.
• We do not know enough about how everything interacts to afford to lose even one species.

HIPPCO: Causes of Biodiversity Loss

• HIPPCO is an acronym that represents the major causes of biodiversity loss:
  • Habitat Destruction
  • Invasive Species
  • Population (human)
  • Pollution
  • Climate Change
  • Over-harvesting

Issue: Habitat Destruction

• Many things can cause habitat destruction, which reduces the available habitat for species.
• Deforestation: Clearing forests for timber is a type of habitat destruction.

Issue: Soil Erosion

• Erosion: The process of soil particles being picked up and carried away by water or wind.
• Soil erosion due to human activities is an increasing problem, such as:
  • Clearing forests
  • Overgrazing by livestock
• Conserving soil:
  • Terracing
  • Crop rotation
  • Contour plowing

Issue: Invasive Species

• Invasive species: Animals coming to an environment in which they don't belong, disrupting the food web.
• Examples of invasive species:
  • Lionfish
  • Domestic cat
  • Asian carp

Issue: Population

• The growing human population causes many of our problems, as we attempt to house and feed almost 8 billion people.
• World population figures:
  • 4 million in 10,000 BCE
  • 190 million in the year 0
  • 600 million in 1700
  • 990 million in 1800
  • 1.65 billion in 1900
  • 2 billion in 1928
  • 3 billion in 1960
  • 4 billion in 1975
  • 5 billion in 1987
  • 6 billion in 1999
  • 7 billion in 2011
  • 7.7 billion in 2019
• Mid 14th century: The Black Death pandemic in Europe kills 200 million people.
• The average growth rate from 10,000 BCE to 1700 was just 0.04% per year.

Issue: Pollution

• The growing human population causes many of our problems, as we attempt to house and feed almost 8 billion people, leading to increased pollution.

Issue: Ozone Hole (caused by pollution)

• Ozone layer: Protects us from the sun's radiation.
• Types of UV radiation:
  • UV-A
  • UV-B
  • UV-C
• Ozone hole: There is currently a hole in the ozone layer over Antarctica.
• Major cause is CFCs (chlorofluorocarbons).

Issue: Acid Rain (caused by pollution)

• Air pollutants combining with water in the atmosphere causes rain with a pH < 7.0.
• Causes fish, tree, and other organism death.
• Chemical compounds involved:
  • H_2O (Water)
  • SO_2 (Sulfur dioxide)
  • NO_2 (Nitrogen dioxide)
  • H2SO4 (Sulfuric acid)
  • HNO_3 (Nitric acid)

Issue: Global Climate Change

• The average global temperature is increasing.
• Causes: Burning of fossil fuels (produces CO_2).
• Natural Greenhouse Effect: Solar radiation warms the earth; some heat escapes into space; re-radiated heat is trapped by the atmosphere.
• Intensified Greenhouse Effect: Intensified by human activities; less heat escapes into space; more heat re-radiates to Earth; contributes to global climate change.
• Annual CO_2 emissions from fossil fuels and industry are increasing.
• Consequences of Climate Change:
  • 1°C: Decreased crop yields.
  • 2°C: Water shortages, retreating glaciers, and rising sea levels.
  • 3°C: Coral reef/rainforest ecosystem collapse, extinctions.
  • 4°C: More storms, hurricanes, droughts, forest fires, and floods.
  • 5°C: Weakening of the Gulf Stream, collapse of Antarctic ice sheet.

Issue: Overexploitation

• Renewable resource: Replaced at the same rate at which they are consumed.
  • Examples: wind and solar energy; trees
• Nonrenewable resource: Form at a rate much slower than they are consumed.
  • Examples: minerals, fossil fuels.

Environmental Solutions

• Sustainability: Ability to meet human needs in such a way that the human population and resource population can survive indefinitely.
• Conservation: Identify, manage, and protect natural areas.
  • Conservation is preferable to restoration.
• Restoration: Scientists try to "fix" extreme cases of ecosystem destruction.