Science & Technology in Action

12th Edition

Climate change ― an overview

Teagasc Department of Communications, Climate Action and Environment

The Earth’s climate has always been changing. However, scientists have now concluded that there is a 95% probability that the global warming of the last 50 years is due to man-made greenhouse gases (GHGs). This is because the Earth’s natural greenhouse effect has been enhanced by these emissions.
Download

Contains the full lesson along with a supporting toolkit, including teachers’ notes.

Lesson excerpt

What is climate change?
Climate can be described as the average global and regional weather patterns experienced over long periods of time (minimum 30 years). Climate change refers to significant change in the average of climate variables, such as temperature and rainfall.

The Earth’s climate has always been changing. However, scientists have now concluded that there is a 95% probability that the global warming of the last 50 years is due to man-made greenhouse gases (GHGs). This is because the Earth’s natural greenhouse effect has been enhanced by man-made emissions of GHGs and this has resulted in global warming which is now taking place at a faster rate than previously experienced. Projected climate changes will affect all aspects of Ireland’s economy, environment and society.

What is causing current climate change?
Since the industrial revolution, human activities have significantly increased the levels of GHGs in the atmosphere. Atmospheric carbon dioxide (CO2) has increased by 40% to a level that has not occurred for at least 800,000 years. This is caused by the use of fossil fuels and land use changes such as deforestation. Gases, such as CO2, create a greenhouse effect and trap additional heat in the Earth’s climate system. The effects of this include:

  • increase in global temperatures by almost 1°C over the last century
  • mean sea-level rise of about 20 cm in the last century
  • loss of glaciers and sea-ice
  • regionally more extreme weather conditions including intense rainfall and droughts.


What is the effect of climate change in Ireland?
Irish temperature records show a mean temperature increase of 0.8°C between 1900 and 2015, i.e. an average increase of 0.07°C per decade.
Other observations include:

  • Fifteen of the twenty warmest years since 1900 have occurred since 1990.
  • The number of frost days has decreased.
  • Average annual rainfall has increased, especially in western areas.


The effects of climate change are expected to increase in the coming decades and during the rest of this century. The potential effects for Ireland include:

  • sea level rise
  • more intense storms and rainfall events
  • greater probability of river and coastal flooding
  • summertime water shortages in the east
  • reduced water quality
  • changes in distribution of plant and animal species.

Quiz questions

  1. The Earth’s climate was constant until the Industrial Revolution. false
  2. The burning of fossil fuels has enhanced the natural greenhouse effect. true
  3. The average global temperature has increased by 1°C in the last 20 years. false
  4. The mean sea-level has risen 20 cm in the last century. true
  5. The goal of the Paris Agreement is to keep the average global temperature to within 2°C of pre-industrial levels. true
  6. The ‘adaptive capacity’ of a country or region is its ability to adapt to environmental change. true
  7. If a factory emits no CO2 it is said to be ‘carbon neutral’. false
  8. ‘Sustainable development’ refers to development that, in the long term, does not deplete essential natural resources. true

Glossary of terms

mitigation
reducing the severity of something
climate change
periodic or long-term trends in the Earth's overall climate due to natural variability or to human activity
greenhouse gases
the gases that contribute to the greenhouse effect including carbon dioxide, methane, nitrous oxide, ozone and water vapour
adaptation
changing to cope with a changing environment
adaptive capacity
ability of change in order to adapt to a changing environment
aggregate reduction
total reduction
carbon neutrality
absorbing as much carbon dioxide as is released
CO2 equivalents
having the same greenhouse effect as a specified amount of carbon dioxide
enhanced
made larger or having a greater effect
fossil fuels
coal, oil and gas
industrial revolution
a period in history from about 1760 to 1840; a period of rapid application of mechanisation in industry
Mt
megatonne; one million metric tonnes
National Climate Change Adaptation Framework (NAF)
a national plan to cope with climate change
natural greenhouse effect
the greenhouse effect due to natural processes and events, i.e. excluding man-made industrial sources
resilience
ability to deal with change
stabilisation
maintaining a steady or stable state
statutory
by law
sustainable development
development that can be maintained indefinitely