Changing climate

• What period is Earth currently in?

  The Quaternary period
• How long has the Quaternary period lasted?

  1. 6 million years
• What defines an ice age?

  An ice age is defined as any period of time when Earth has permanent ice sheets
• What are the two types of periods in an ice age?

  Glacial periods and interglacial periods
• How long do glacial periods last?

  About 100,000 years
• How long do interglacial periods last?

  About 10,000 years
• How has Earth's temperature fluctuated during the Quaternary period?

  It has mostly been colder than today but has fluctuated a lot
• What do scientists believe has caused the increase in temperature since 1880?

  Human activity
• What are ice cores?

  Long tubes of ice removed from the Arctic and Antarctic
• How do scientists determine past temperatures from ice cores?

  By analyzing the amount of carbon dioxide (CO₂) trapped in each layer
• Why are ice cores considered reliable evidence?

  They have been compared with other types of data, such as recorded temperatures
• What do satellite photos show about Arctic sea ice?

  The amount of the Arctic covered in frozen sea ice
• When is the minimum amount of sea ice observed?

  In September
• When is the maximum amount of sea ice observed?

  In March
• What do weather stations record to monitor global temperature?

  Daily temperatures
• What has been observed about Earth's climate since 1880?

  It is getting hotter
• How many of the ten hottest years since 1880 have occurred since 2002?

  Nine
• What is a limitation of past temperature data collection?

  It was not collected with accurate equipment
• What can old paintings and diaries provide evidence of?

  Earth's climate before temperature data was collected
• Why are paintings and diaries not particularly reliable for climate evidence?

  They reflect day-to-day weather rather than long-term climate
• What are the three main reasons Earth's climate changed before humans were alive?

  Milankovitch cycles, sun spots, and volcanic eruptions
• What are Milankovitch cycles?

  Natural changes in Earth's orbit and axial tilt that affect climate
• How often does Earth's orbit change from circular to elliptical?

  Every 100,000 years
• What is precession in relation to Earth's climate?

  Earth wobbles on its axis, changing the timing of the seasons over a 23,000-year cycle
• How does obliquity affect Earth's climate?

  Changes in the angle of tilt affect how much sunlight Earth receives
• What is the cycle of sun spots?

  There is an 11-year cycle of sun spot activity
• How do volcanic eruptions affect Earth's climate?

  They release dust that can block sunlight and cool the climate
• What are greenhouse gases?

  Gases that trap radiation from the Sun and keep Earth warm
• What is the enhanced greenhouse effect?

  Humans have added more greenhouse gases, trapping more radiation and causing global warming
• What is the main greenhouse gas causing the enhanced greenhouse effect?

  Carbon dioxide (CO₂)
• What percentage of the enhanced greenhouse effect is caused by carbon dioxide?

  60%
• What are some sources of methane?

  Landfill sites and cows
• What are halocarbons and where do they come from?

  They come from refrigerators and air conditioning
• What is nitrous oxide and where does it come from?

  It comes from fertilizers and car exhausts
• What happens to energy from the Sun as it reaches Earth?

  Some energy is reflected back out to space as long-wave radiation
• Which country emits the most CO₂?

  China
• Why is it more sensible to study CO₂ emissions per capita?

  It gives a better understanding of individual contributions to climate change
• Which countries emit the highest amount of CO₂ per capita?

  Advanced countries (ACs) like the USA, Canada, and Australia
• What is the impact of climate change on sea levels?

  Climate change is making sea levels rise
• What are the three reasons for rising sea levels due to climate change?

  Thermal expansion, melting glaciers, and melting ice sheets