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Skip to 0 minutes and 1 second Over geological time, the amount of ice on the planet has varied considerably. Currently, something like 10% of the Earth’s surface is covered in ice, but over the Earth’s history, there have been huge, repeated and dramatic changes in the extent of ice cover. Throughout its history, the earth has experienced periods known as icehouse phases when global average temperatures are well below 0C and vast parts of the globe are covered in ice. However, there have also been periods known as greenhouse phases when temperatures are much warmer and there was little or no ice cover on the earth.

Skip to 0 minutes and 43 seconds Changes between these two phases take place over hundreds of millions of years, and are controlled by things like the solar luminosity, volcanism and movement of the continents. However, superimposed upon these largescale changes have been periods of fluctuating ice volume, known as glacials and interglacials. These changes take place over comparatively shorter time scales and are controlled by shorter-term changes in environmental conditions. There are lots of natural drivers that control how much ice exists on our planet. However, in recent decades, by far the most significant control on our planet’s temperature and thus ice cover is the amount of anthropogenic greenhouse gases that exist in our atmosphere.

Skip to 1 minute and 22 seconds In the pre-industrial era, natural controls were the most important drivers of a varying climate, but since the industrial revolution, this has been overtaken by anthropogenic effects – in other words, what we, as human beings, are doing to the planet. There are more anthropogenic greenhouse gases in the atmosphere now because we burn more fossil fuels, because of extensive livestock farming, because of the manufacture of cement and because we chop down forests. Anthropogenic climate change is perhaps the greatest challenge facing all living things on planet Earth. This conclusion is unequivocal. Anthropogenic climate change is real and is a danger to all living things on planet Earth.

Skip to 2 minutes and 0 seconds Its existence is not open for debate, or indeed something that we get to choose whether we ‘believe’ in or not.

Glaciers and climate change

In this video, David Rippin explains how the amount of ice on the Earth has varied considerably throughout its history, as a consequence of a varying climate. Whilst in the past, natural drivers were the most dominant control on our climate, in recent decades, by far the most significant control on our planet’s temperature and thus ice cover is the amount of anthropogenic greenhouse gases that exist in our atmosphere.

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This video is from the free online course:

Tackling Environmental Challenges for a Sustainable Future

University of York