Impact of human activities on climate

Let us look at the Impact of human activities on climate

• The effects of human on climate are often negative.
• Three processes are related to understanding the effects of human activities on climate
• These processes are: climate change, global warming and Greenhouse effect.

Action of Human activities on Climate Change

• Climate change” is a broader term that refers to weather trends observed over relatively long periods of time (many decades or longer)
• Climate change can include many variables (temperature, precipitation, wind direction, wind speed) and different geographic scales (over a continent, within an ocean, for the Northern Hemisphere, for the planet

Global Warming

• Global warming” refers to the increase of the Earth’s average surface temperature due to a build-up of greenhouse gases in the atmosphere
• The measurable increases in the average temperature of Earth’s atmosphere, oceans, and landmasses.
• The rise in the temperature of the earth’s atmosphere due to natural causes and human activities.
• Example of natural causes: emissions from volcanic eruptions.
• Example of human activities: burning of fissile fuels and destruction of vegetation cover.
• Scientists believe Earth is currently facing a period of rapid warming.
• Warming brought by increasing levels of heat-trapping gases in the atmosphere.
• These gases are known as greenhouse gases.
• Earth has warmed and cooled many times since its formation.
• This has led to global climate change.

Reasons for global climate change:

• Massive volcanic eruptions, which increased carbon dioxide in the atmosphere.
• Changes in the intensity of energy emitted by the Sun.
• Variations in Earth’s position relative to the Sun, both in its orbit and in the inclination of its spin axis.
• Variations in Earth’s position, known as Milankovitch cycles, combine to produce cyclical changes in the global climate.
• These cycles are believed to be responsible for the repeated advance and retreat of glaciers and ice sheets during the Pleistocene Epoch.
• During this period (pleistocene Epoch), the Earth went through regular cycles of colder “glacial” periods and warmer “interglacial” periods.
• Eras of colder “glacial” periods are known as ice ages. This led to formation of different kinds of landforms of erosion and deposition in Canada and USA.
• In interglacial periods, greenhouse gases (e.g. carbon dioxide and methane) naturally increased in the atmosphere.
• The increase was from increased plant and animal life.
• Since 1750 (Industrial Revolution) greenhouse gases have increased dramatically.
• This is due to rapid growth of human population together with developments in technology and agriculture.
• Human activities now a major cause of global warming and climate change.

The Greenhouse Effect

• When sun’s rays pass through the atmosphere, certain gases trap some of the sun’s heat.
• This causes the earth to warm.
• This natural way of warming the earth is known as green house effect.
• Greenhouse gases occur naturally, and without them the planet would be too cold to sustain life.
• Since the beginning of the Industrial Revolution in the mid- 1700s, human activities have added more greenhouse gases into the atmosphere.
• For example, levels of carbon dioxide, a powerful greenhouse gas, have risen by 35 percent since 1750.
• The rise is largely from burning of fossil fuels such as coal, oil, and natural gas.

How greenhouse effect takes place

• Solar energy enters the atmosphere and is absorbed by the earth.
• The energy is reflected back through the atmosphere.
• Some of the energy is (one third) is trapped by greenhouse gases.
• This increases the warmth of the atmosphere. 

• Examples of greenhouse gases: Carbon dioxide. Methane. CFCs. Nitrous Oxide.
• Water Vapor is the most abundant greenhouse gas.
• It reaches the atmosphere through evaporation from oceans, lakes, and rivers.
• The amount of water vapor in the atmosphere is not directly affected by human activities.
• Carbon Dioxide is the second most abundant greenhouse gas after water vapor.
• It is released into the atmosphere from natural processes and human activities.
• Carbon Dioxide Natural sources include: Eruptions of volcanoes.
• Respiration of animals, which breathe in oxygen and exhale carbon dioxide.
• Burning or decay of plants and other organic matter.
• Carbon Dioxide: Human Activities
• Human activities are causing carbon dioxide to be released to the atmosphere faster than
• Earth’s natural processes can remove it.
• Carbon dioxide can also remain in the atmosphere a century or more before nature can dispose of it.

Adverse effects of global warming and climate change:

• Increase in sea level.
• Decrease in water resources. 
• Change in ecosystems.
• Change in landscapes.
• Change in vegetation zones.
• Increased risk of drought and fires.
• Increased risk of floods.
• Increase in disease levels.
• Increased migration pressures and conflicts.
• More stronger storms and hurricanes.
• Increased economic loss and damage.
• Higher temperatures.
• A decrease in global food production levels.

Solutions to Global Warming

• Reduce methane emissions.
• Reduce emissions of nitrous oxide and ozone Preserve the carbon dioxide sink.
• Reduce greenhouse gases.
• Replace fossil fuels; Replace fossil fuels with cleaner sources of energy.
• Replace with solar power, wind power and hydrogen cells.
• They do not emit any greenhouse gases.
• Preserve and plant trees, Trees absorb carbon dioxide. Need for re-forestation and reafforestation.
• Recycle paper, Recycle paper and buy recycled products.
• Recycling paper saves trees. Recycling paper also saves energy.
• Reduce use of CFCs, use of new chemicals to replace CFCs.
• The substitutes include hydro chlorofluorocarbons (HCFCs), hydro fluorocarbons (HFCs), and per fluorocarbons (PFCs).