Lesson Notes By Weeks and Term v4 - JHS 3
CLIMATE CHANGE AND GREEN ECONOMY
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CLIMATE CHANGE AND GREEN ECONOMY
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Subject: Science
Class: JHS 3
Term: 3rd Term
Week: 11
Grade code: B9.5.4.1.1
Strand code: 5
Sub-strand code: 4
Content standard code: B9.5.3.2
Indicator code: B9.5.4.1.1
Theme: HUMANS AND THE ENVIRONMENT
Subtheme: CLIMATE CHANGE AND GREEN ECONOMY
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Climate change is the long-term change in average weather conditions (temperature, rainfall, wind patterns) over many years. In Ghana, learners experience it through irregular rains, flooding in cities like Accra and Kumasi, longer dry seasons in the north, coastal erosion in Keta, and reduced crop yields. Understanding natural and human factors that influence climate change helps learners make informed choices that support a green economy—an economy that grows jobs and income while protecting the environment and using resources wisely.
A. Climate vs Weather Weather: daily conditions (today’s rain, temperature, wind). Climate: average weather over a long period (usually 30 years or more). B. Climate Change Climate change is a long-term shift in climate patterns, especially temperature and rainfall. It can be caused by: Natural factors (from nature, not caused by people) Human factors (activities that increase greenhouse gases or reduce carbon sinks) C. Greenhouse Effect (Foundation idea) The greenhouse effect is the warming of Earth when gases in the atmosphere trap heat. Sunlight enters the atmosphere. Earth’s surface absorbs energy and releases heat (infrared radiation). Greenhouse gases (GHGs) trap some of this heat, warming the planet.
Main greenhouse gases (simplified for JHS): Carbon dioxide (CO₂): from burning fuelwood, charcoal, petrol/diesel, bush burning, cement production. Methane (CH₄): from livestock (cattle), rice fields, landfill sites, leaking gas. Nitrous oxide (N₂O): from nitrogen fertilisers and some industrial processes. Water vapour: natural, but increases as the atmosphere warms (feedback).
> Key point: The greenhouse effect is natural and necessary for life, but too many GHGs cause extra warming.
D. Natural Factors that Influence Climate Change (NaCCA Exemplar 1) Volcanic eruptions Volcanoes release ash and gases (like sulphur dioxide) into the atmosphere. Ash can block sunlight, causing temporary cooling. Some gases can also affect atmospheric chemistry. Changes in solar radiation (Sun’s energy) The Sun’s energy output varies slightly over time. More solar energy can warm Earth; less can cool it. Earth’s orbital changes (Milankovitch cycles) Over thousands of years, Earth’s orbit and tilt change. This affects how much sunlight different regions receive, contributing to ice ages and warm periods. Ocean currents (e.g., El Niño/La Niña) Oceans store and move heat around the world. Changes in currents can shift rainfall and temperature patterns. Even though El Niño is not a Ghana event, ocean temperature changes can influence global weather systems that affect West Africa. Natural changes in greenhouse gases Wetlands naturally release methane. Natural forest fires (from lightning) can release CO₂ (though many fires today are human-caused).