Page 13 - SGG_220316_Teachers_Handbook_Module_7

Version for younger students

This visualization shows the annual Arctic sea ice minimum since 1979. At the
end of each summer, the sea ice cover reaches its minimum extent, leaving what
is called the perennial ice cover. The area of the perennial ice has been steadily
decreasing since the satellite record began in 1979.
https://climatekids.nasa.gov/time-machine/

Version for older students

The animated time series below shows the annual Arctic sea ice minimum since
1979, based on satellite observations. The 2012 sea ice extent is the lowest in the
satellite record.

https://climate.nasa.gov/interactives/global-ice-viewer/#/3/7

Glacial Retreat

Mountain glaciers are retreating almost everywhere around the world — including in the Alps,
Himalayas, Andes, Rockies, Alaska, and Africa, although a few glaciers are holding steady or growing in
mass. Generally, however, the trend is overwhelmingly towards glacial retreat and loss.

Decreased Snow Cover
Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has
decreased over the past five decades and the snow is melting earlier.

Extreme Events

The number of extreme events such as heatwaves, droughts, flooding, hurricanes, and intense rainfall
events is increasing.

4. What causes climate change?

The climate on Earth has been changing since it formed 4.5 billion years ago. Over the past one million
years, the Earth has experienced a series of ice ages, including cooler periods (glacials) and warmer
periods (interglacials). Glacial and interglacial periods cycle roughly every 100,000 years, caused by
changes in Earth's orbit around the sun. For the past few thousand years, Earth has been in an
interglacial period with a constant temperature. Until recently, natural factors have been the cause of
these changes.
Even though these natural causes contribute to climate change, we know based on scientific evidence
that they are not the primary cause. Since the Industrial Revolution in the 1800s, human activity has
become the leading cause of changes to the climate. By burning fossil fuels such as coal, oil, and natural
gas, industrialisation, and changing how we use the land, we've been adding more and more
greenhouse gases into the air, trapping more heat. Instead of keeping Earth at a warm, stable
temperature, the enhanced greenhouse effect is heating the planet at a much faster rate.

This project has been funded with support from the European Commission. This communication reflects the
views only of the author, and the Commission cannot be held responsible for any use which may be made of the

information contained therein.