Humans and their environment

04.19.2020
08:51:51
Biology/ grade 10- Today’s topic-pollution- green house gases- pages 299 to 301.
Main points-
A greenhouse gas is a gas that absorbs infrared radiation from the Sun so it remains trapped in the Earth’s atmosphere
This is important to ensure Earth is warm enough for life, however if levels of these gases in the atmosphere increase it leads to an increase in the greenhouse effect which causes the Earth’s average temperature to rise
There are many greenhouse gases, the most important are:
Water vapour
Carbon dioxide
Methane
Nitrous oxides
CFCs

The Sun emits rays that enters the Earth’s atmosphere.
The heat bounces back from the Earth’s surface.
Some heat is reflected back out into space.
Some heat is absorbed by greenhouse gases and is trapped within the Earth’s atmosphere – this is normal.

However, as the levels of greenhouse gases in the atmosphere rise due to human activities the Earth’s average temperature rises beyond normal (an enhanced greenhouse effect), causing global warming.

Consequences of global warming due to an enhanced greenhouse effect:-

Ocean temperatures increase which causes melting of polar ice caps / rising sea levels / flooding / coral bleaching.
Increasing temperatures can cause extreme weather like super storms, flooding, droughts
These extreme weather events can lead to changes in or loss of habitats .
This means that there will be a decrease in biodiversity as food chains are disrupted and extinction rates increase.
There could also be increases in migration of species to new places, increased spread of pests and disease.

What can humans do to slow down the enhanced greenhouse effect?

Reduce use of fossil fuels / coal / oil / natural gas as burning of these produces carbon dioxide which is a major greenhouse gas
Increase use of alternative energy sources such as nuclear / wind / solar –  means less fossil fuels are used to generate electricity.
Reduce deforestation / plant more trees and plants as photosynthesis is the only process that takes carbon dioxide out of the atmosphere.
Car share / use public transport / cycle / use electric cars as petrol comes from fossil fuels and so burning it produces carbon dioxide and nitrous oxides which are both greenhouse gases.










Homework worksheet is given on Humans and their environment.