Changing climates

• What is the Quaternary geological period?


  The last 2.6 million years
• What are glacial periods?


  Really cold periods lasting around 100,000 years
• What are inter-glacial periods?


  Warm periods lasting around 10,000 years
• Evidence for climate change in the past 


  Geological fossil evidence, ice cores, ocean sediments, historical records
• Reliability of geological fossil evidence

  Fossils are up to 60 million years old, but it gives a range of results and not an exact number
• Reliability of ice cores


  Dates back 800,000 years. Most reliable
• Reliability of ocean sediments

  Dates back 5 million years but some sediments might go missing so the timescale is interrupted
• recent evidence for climate change (last 100 years)


  Global temperature data, shrinking ice sheets and glaciers, sea level change
• What is global temperature data?


  NASA has collected information using satellites to find that since 1950 temperatures have increased by 0.6 degrees, especially in the Arctic
• What are shrinking ice sheets and glaciers?

  Snows of Kilimanjaro have melted by 80% since 1912. The Muir Glacier in Alaska, USA has retreated by 50km in the last 120 years
• What is sea level change?

  In the last 100 years global sea level has risen by 10-20 cm
• Natural causes of climate change

  Volcanic eruptions, sunspot activity, Milankovitch Cycle
• How do volcanic eruptions cause climate change?


  Mount Pinatubo eruption released ash causing global temperatures to drop by 0.5 degrees
• How does sunspot activity lead to climate change?


  Large explosions created called solar flares. This cycle lasts 11 years
• Milankovitch cycle types 


  Eccentricity, precession, aerial tilt
• What is eccentricity?


  The earths orbit changes from circular to elliptical in a cycle lasting 100,000 years
• What is a precession?


  a wobble cycle in the earth that lasts 26,000 years
• What is aerial tilt?


  Earth spins in its axis in a period around 41,000 years on a tilt between 21.5 degrees to 24.5 degrees
• carbon dioxide atmospheric lifetime

  50-200 years
• methane atmospheric lifetime

  12 years
• nitrous oxide atmospheric lifetime

  120 years
• halocarbons atmospheric lifetime

  1.5 - 209 years
• Methane global warming potential

  21
• Carbon dioxide global warming potential

  1
• Nitrous oxide global warming potential

  310
• Halocarbons global warming potential

  150 - 11,700
• carbon dioxide contribution to enhanced greenhouse effect

  60%
• Methane contribution to enhanced greenhouse effect

  15%
• Nitrous oxide contribution to enhanced greenhouse effect

  6%
• Halocarbons contribution to enhanced greenhouse effect

  15%
• Paris agreement 2015 (COP21) aims to limit global warming to 1.5 degrees above pre-industrial levels
• Social global impacts of climate change (sea levels rising)

  in Kiribati sea level rises by half an inch each year. 2012 study from Plymouth university said that sea level rise of 3-9 feet would “have a catastrophic effect on the human activities” in Lagos, but sea levels are expected to rise 6.6 feet by the end of the century.
• Economic global impacts of climate change


  Activists invested in advanced flood gates. Russia is warming 2.5 times faster than the rest of the planet
• Environmental global impacts of climate change

  Great Barrier Reef is 1,400 miles long (largest coral reef system), aerial survey by Great Barrier Reef Foundation in 2020 revealed 3rd mass bleaching in 5 years with 60% of coral dying. In Madagascar, 90% of native flora and fauna are endemic like lemurs and the fossa, but rising sea levels could lead to the destruction of habitats like Mangrove forests
• Why is climate change considered global?


  Big Dry, Australia, 2002-2009 led to 4 minute showers and increase in global food prices. Predicted flood damage of £12 billion in the UK by 2080. New Zealand offered people a place to stay from Tuvalu, South Pacific, population of 11,000 and maximum height above sea level of 4.5 metres
• Positive impacts of climate change in the UK


  tourism in the Lake District will increase. new crops like peaches and oranges in southern England.
• consequences of a hotter and drier UK in the future

  By 2050 an increased temperature of 2 - 2.5 degrees will lead to an urban heat island. 20-30% decrease in precipitation will lead to summer droughts in beech woodland
• Consequences of wetter UK winters in the future

  by 2080 over 1 million properties could be at risk from flooding with annual damages reaching £12 billion
• Consequences of rising sea levels for the future in the UK


  agricultural land lost due to managed retreat in The Fens, Eastern England.
• Opportunities created by a hotter and drier UK in the future

  Heating costs will fall. By 2050 increased temperature of 1.5 - 2 degrees will increase yields of wheat, sugar beet and potatoes