Y8-Term 2 Final Revision

Earth's Temperature Changes

  • Earth's temperature has fluctuated since its formation 4.5 billion years ago.

  • Initially, Earth was hot, soft, and ice-free; it gradually cooled and formed a crust and atmosphere.

  • Throughout history, Earth has experienced warming and cooling cycles.

Snowball Earth

  • 650 million years ago, during a period called Snowball Earth, the planet was entirely ice-covered.

  • Following the melting of this ice, evolution flourished and more species emerged.

  • Ice ages followed, leading to extinction of species unable to adapt to cold conditions.

  • Dinosaurs thrived during warmer periods with no ice.

Last Ice Age

  • The last ice age started 110,000 years ago, reaching its peak with 30% of Earth covered in ice (northern Britain included).

  • The last ice age ended about 10,000 years ago, leaving only 10% of Earth covered in ice today.

Causes of Climate Change

  • Global Warming: Long-term increase in global temperatures due to human activities (especially greenhouse gas emissions).

  • Greenhouse gases, like CO2 and methane, trap heat in Earth's atmosphere enhancing the greenhouse effect.

  • Changes in Earth's tilt and solar energy output also contribute to temperature fluctuations.

Greenhouse Gases Impact

  • The warming effect of greenhouse gases leads to an increase in average temperatures.

  • Human activities release excess CO2 through burning fossil fuels, deforestation, and industrial processes.

  • Methane is released from livestock and landfills, contributing further to the greenhouse gas effect.

Climate Change Effects

  • Changes in climate patterns, including altered rainfall and increased extreme weather events (droughts, floods, storms).

  • Melting ice sheets and glaciers lead to rising sea levels, threatening low-lying areas with flooding.

  • Ecosystem shifts: some species unable to adapt will face extinction.

  • Potential for new agricultural opportunities in some regions, contrasted with crop failures in others, leading to food insecurity.

Socioeconomic Impacts

  • Poor countries are more vulnerable to climate change, suffering significant impacts from droughts, crop loss, and flooding.

  • Wealthy nations historically have contributed more to carbon emissions but poorer nations suffer disproportionately from climate effects.

Local Actions, Global Effects

  • Individual actions (e.g., leaving lights on) contribute to global issues like climate change, affecting people worldwide.

Options for Addressing Climate Change

  • No action, mitigate CO2 emissions, enhance adaptation strategies, or modify solar radiation reach on Earth.