Climate Change 1

• What is climate change?

  Climate change is the long-term shift in the planet's weather patterns or average temperatures
• What is the quaternary period

  The most recent geological time period, spanning from about 2.6 million years ago to the present day where temperatures have fluctuated a great deal
• 4 effects of global climate change

  -many of the worlds glaciers and ice caps are sinking

  -low lying Pacific islands (Tuvalu and Maldives) are under threat from rising sea levels

  -sea levels may rise by 1m by 2100 flooding agricultural land ( Bangladesh, Vietnam, India)

  -arctic sea ice is less extensive than in the past
• explain rising sea levels


  The average global sea levels has risen between 10 and 20cm in the past 100 years
• How do sea levels rise

  When temperatures rise, freshwater ice melts resulting in more water in seas

  When ocean water warms it expands in volume- thermal expansion
• Explain seasonal changes


  The timing of natural seasonal activities such as tree flowering and bird migration is advancing
• Example of a seasonal change


  A study showed that bird nesting in mid 1900s discovered that 65 species nested on average of 9days earlier
• Explain shrinking glaciers and melting ice

  Glaciers throughout the world are shrinking and retreating
• Example of shrinking glaciers and melting ice (arctic sea ice)

  Arctic sea ice has thinned by 65% since 1975 and in 2014 it's extent was at an all time low
• What is happening to the arctic sea ice

  Arctic sea ice is less extensive than in the past affecting wildlife such as polar bears. This may provide opportunities for ships to use the North West Passage in the future
• What are ice cores


  Cylinders of ice drilled out of an ice sheet or glacier
• How can scientists use ice cores to tell them what the global temperatures were like in the past

  Scientists can study the oxygen in ocean sediments and water molecules in ice to calculate the temperature
• What are the three main natural causes of climate change

  orbital changes, solar activity, volcanic activity
• What are orbital changes also called

  Milankovitch cycles
• What is eccentricity?


  When the shape of the earth's orbit changes from a circular to elliptical orbit which happens every 90,000-100,000 years. This means at some point the Earth becomes further away from the sun, therefore making it colder
• What is axial tilt?


  The tilt of the earth axis moves back and forth between 21.5 and 24.5 every 41,000 years. The northern hemisphere will get more sun when the tilt is at 24.5 and less when the tilt is at 21.5
• What is a precession of the Earth?

  A slow change or wobble in the orientation of the Earth axis over a period of 26,000 years. When the Earth tilts to one side more the days become longer
• What are the short term impacts of volcanic activity

  Block out sun, reducing temperatures on Earth
• What are the long term impacts of volcanic activity


  Sulphur dioxide is released from the volcano which converts to sulphuric acid which acts like a mirror reflecting radiation from sun which over many years will reduce temperatures
• Example of volcanic activity (1991)


  Mt. Pinatubo, 1991

  Earths surface cooled for 3years after eruption by as much as 1.3degree
• Example of volcanic activity (1816)


  Mt Tambora, Indonesia 1816

  Most powerful eruption in the world for 1600years

  Average temps fell by 0.4-0.7degrees
• Impacts of volcanic activity

  -radiation from suns is reflected so doesn't reach earth

  -global temperatures fall

  -crop failure therefore famines, health issues from ash, distress etc

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• What is a sunspot?

  A dark patch on the surface of the sun which produces heat
• How do sunspots effect temperatures on Earth

  The amount of radiation emitted by the sun fluctuates. If sunspot activity is at a maximum then the sun gives of more heat
• Example of sunspots effecting the climate

  'Little Ice Age'- 1645-1715

  very few sunspots were observed causing a colder climate across Europe with severe winters