Evidence

• What is happening to glaciers throughout the world?

  They are shrinking and retreating
• Why has the average global sea level risen?

  Due to thermal expansion of ocean water
• How much has the average global sea level risen?

  Between 10-20 cm
• What happens to ocean water as it warms?

  It expands in volume
• What changes have been observed in tree flowering and bird migration?

  They are advancing
• How much ice has melted in Antarctica since 2002?

  134 billion tonnes
• What do ice cores provide evidence of?

  Long-term climate change
• What can be measured from ice cores extracted in Antarctica?

  Subtle changes in temperature
• What type of geological evidence can be studied for climate change?

  Rocks and fossils
• What does limestone found in Yorkshire indicate?

  It was formed on a warm seabed
• What has been observed in Greenland and the Arctic?

  Thinning of ice sheets
• What was the minimum extent of Arctic sea ice in September 2020?

  1. 74 million square kilometres
• What does the National Snow and Ice Data Centre (NSIDC) report about Arctic sea ice?

  It is the second lowest in 42 years
• What evidence shows glacial retreat?

  Photographs and satellite images
• What factors contribute to glacial retreat?

  Lack of snowfall and glacial melting
• What does pollen analysis reveal about climate?

  Changes in vegetation types over time
• How has ocean acidity changed since the Industrial Revolution?

  Increased by about 30%
• What causes the increase in ocean acidity?

  More carbon dioxide emissions
• What does the diagram show about global temperature variations?

  Variations from 1850-2020
• Which years are tied for the warmest on record?

  2016 and 2020
• What is the overall trend in global surface temperatures since the 1970s?

  An increase in temperatures
• What is the term used for the trend of increasing global temperatures?

  Global warming