changing climates

• the climate is the average weather overtime
• climate change is the changes in the long-term temperature and precipitation patterns that can be either natural or linked to human activities
• quaternary period - the last 2.6 million years is known as the quaternary geological period
• really cold parts are called glacial periods and last for 100,000 years

  hot parts are called inter-glacial periods and last for 10,000 years
• the temperatures have decreased in the last 2.6 million years but during this, the temperature fluctuates showing that climate change is a natural thing - as well as being caused by us. As CO2 levels fluctuate the temperature fluctuates
• the little ice age led to intensely cold winters between 1300 to 1890. the coldest parts were in the 15th to 17th century where many people died due to lack of food
• evidence for climate change:

  • geological fossil evidence
  • ice cores
  • ocean sediments
  • historical records
• geological fossil evidence

  you can use plant and animal fossils to investigate different climates in the past

  different species like different environments so looking at their fossils suggest the climate when they were alive

  fossils up to 60 million years ago can be done - but doesn't give the exact climate
• ocean sediments:

  you can use samples from the ocean floor to investigate past cliates

  by studying oxygen isotopes trapped within these sediments, it has been possible to calculate past atmospheric temperature

  scientists have been able to drill into sediment over 5 million years old but not every sediments will be 5 million years old
• ice cores

  you can use ice cores and air bubbles to learn about past global temperatures

  layers of snow are built up and create layers, so drilling into the ice means you can see the layers and can accurately date it and calculate the temperature of the atmosphere when the snow fell. the bubbles tell us the concentration of greenhouse gases in that year

  the base can be 800,000 years old but it may be difficult to drill and its only 800,000 years old
• historical records: historical records can provide additional evidence of climate change (using paintings, diaries, and records). records of extreme weather are used to suggest that extreme weather events have become more frequent. the timing of natural seasonal activities is advancing so the world could be warming. diaries also provide evidence of climate change through personal accounts. not very reliable as it shows it was cold at the time but has no numbers
• natural causes of climate change

  • volcanic eruptions
  • sunspot activity
  • eccentricity
  • precession
  • axial tilt
• volcanic eruptions:

  Mount Pinatubo colled the world's climate by 0.5 degrees. the ash was released into the atmosphere where it blocked out the sun leading to a reduction in surface temperature. winds carry ash across the globe, creating cooler conditions in many other regions. ash doesn't usually stay in the atmosphere for more than a few weeks so will not have a long term impact to the climate
• sunspot activity:

  sunspots are dark patches on the sun that have an 11-year cycle from minimum to maximum number of sunspots. the solar radiation builds up below the sunspot and when the spot bursts there is a solar flare which can increase the global temperature
• Milankovitch cycle: eccentricity

  the earth changes orbit from circular to elliptical and back to circular in 100,000 years. the circular orbit is colder as it is further away from the sun and less solar energy is received. the elliptical orbit is hotter as it is closer to the sun
• Milankovitch cycle - precession

  there is a cycle of 26,000 years. this is a natural wobble that makes days longer which may lead to changes in global temperature / changes the temperature in certain areas
• Milankovitch cycle:

  axial tilt - the earth spins on an axis in a 41,000 year cycle, changing from 2 extremes - 21.5 degrees and 24.5 degrees. a higher degrees of tilt is associated with having a higher average global temperature
• greenhouse effect - natural warming of the atmosphere as heat, given off from the earth, is absorbed by liquids and gases such as co2
• natural greenhouse effect

  1. the sun releases energy as short-wave radiation, some pass through a layer of greenhouse gasses into the earth's atmosphere and warms the earth's surface
  2. some energy is reflected back into space as long-wave radiation - some passes back through the greenhouse layer and into space (not as easily as short wave radiation)
  3. some energy is reflected back to earth and some is absorbed by greenhouse gasses
  4. the earth is warmed more
• enhanced greenhouse effect

  this warms the planet even more than the natural greenhouse effect caused by human activity. CO2 contributes the most to this effect with a contribution of 60% - this is because it has a high atmospheric lifetime of 50-200 years and has a high rate of humans burning fossil fuels and burning wood due to deforestation. As more greenhouse gasses are in the atmosphere, the long-wave radiation finds it harder to escape through the layer into space so more long-wave radiation is reflected back to earth, warming the planet even more than the natural effect
• Paris Agreement 2015 - cop21

  the Paris climate conference is the first legally binding global climate deal. it aims to limit global warming to 1.5 degrees above pre-industrial levels
• the worldwide impact of climate change

  • extreme weather events - higher temperatures lead to more wildfires which worsen natural disasters such as the big dry (2002 to 2009). this impacts food production, decreasing yields and exports, affecting the cost and availability of food globally, this can damage the global economy
• the worldwide impact of climate change

  • sea levels rising - leading to property damage due to coastal erosion and flooding (12 billion in UK damage by 2050) and the destruction of low-lying communities like Tuvalu in the South Pacific. Tuvalu has a population of 11,000 who will all have to relocate if sea levels rise as the island only has a maximum height of 4.5 metres above sea level. new Zealand offered the people of Tuvalu a place to stay to help them cope with global migration
• UK impact of climate change

  • social - by 2050 an increased temperature of 2 to 2.5 will lead to increased heatwaves. they lead to deaths among the elderly living in cities like London. local scale but it will worsen over time so overall negative net impact
• UK impact of climate change

  • economic - by 2050 increased temperature of 1.5 to 2 degrees will increase agricultural productivity so increased yields of wheat, sugar beets, and potatoes, so more money, better economy, more trade, national effect, positive net outcome
• UK impact of climate change

  • environmental - beach woodland is susceptible to droughts with a 20 to 30% drop in precipitation - national scale - negative net impact as there will be a loss of wildlife across the country
• UK impact of climate change

  weather patterns - old people are vunerable, pressure on the NHS, falls in deaths due to cold weather, up to 24000 premature deaths saved, heavy rainfall so sewers overflow and water contaminated, 330000 properties at risk of flooding and could increase to between 630,000 and 1.2 million by 2080
• UK impact of climate change

  seasonal changes - beech woodland is susceptible to summer droughts with a 20 to 30% drop in precipitation. dipper eats insects but these insects will fall by 1/5 due to 1 degree rise so dipper won't get as much food for its babies in spring and will have to change its breeding season to adapt to amounts of food
• UK impact of climate change

  changes in the industry - wider opportunities for tourism - tertiary industry, new crops / increasing yields - wheat, sugar beets, and potatoes. industries may face water shortages and restrictions on water use