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).