9.0-9.1

• Earth's climate is warming

  • Yearly average temperatures increased in the Arctic twice as fast as the tropics and temperate areas

  • 90% of Arctic glaciers are retreating at fast rates

  • Sea ice has been declining

  • Permafrost is melting during summers

  • Fires are more common

  • Animal populations are decreasing

• Public perceptions on climate change

  • In the U.S. 2016 study, only 48% believe climate change is caused by humans

  • Opinion is political and financial

• International and scientific consensus on climate change

  • Based on "facts" that support agendas, in some cases

  • 2015 Paris Agreement is flawed and limited in its scope

• Long-term climate patterns

  • Earth's climate has been dynamic over the past millions of years

  • In the past 10,000 years, Earth has grown warmer with ups and downs

  • Pleistocene period: Earth cycled between colder and warmer periods

  • Holocene period: Earth in a warm interglacial period, with shifts in climate

9.2

• Measuring global warming

  • Earth has warmed significantly since the Industrial Revolution

  • Difficult to measure global annual surface air temperature

  • Models, sampling stations, and examining patterns are used

• Causes of natural climate variation

  • Solar forcing

  • Regional variation in annual temperatures (land vs. water)

  • El Niño/Southern Oscillation, which changes ocean currents and alters weather patterns

  • Volcanic eruptions cool the atmosphere

9.3

• Causes of global warming

  • Temperature of Earth's atmosphere affected by the amount of solar radiation, Earth's orbit, and human influences

  • Human influences include the chemical composition of the troposphere, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)

• Greenhouse effect

  • Gas molecules absorb heat, known as greenhouse gases

  • Water vapor (H2O) is the most abundant naturally occurring greenhouse gas

  • Other greenhouse gases include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)

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• Human impacts on global warming

  • Anthropogenic (human-caused) increases in greenhouse gases, such as CO2

  • Deforestation, fossil fuel use, and synthetic greenhouse gases like chlorofluorocarbon (CFC) compounds

• Impact of anthropogenic greenhouse gases

  • Global warming potential (GWP) measures the long-term impact and capacity to absorb infrared light/retain heat

  • Gases like CO2, methane (CH4), and nitrous oxide (N2O) trap heat from Earth's surface

• Sources of greenhouse gases

  • Total greenhouse emissions expressed in carbon dioxide equivalents (CO2e)

  • Burning fossil fuels and industrial processes contribute to greenhouse gas emissions

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• Consequences of global warming

  • Climate patterns are changing, leading to drier and wetter conditions

  • Melting glaciers and ice sheets, with over 80% of Earth's glaciers retreating

  • Rising sea levels due to thermal expansion and glacial meltwater

• Changing populations and ecosystems

  • Climate plays