Changing climate

• The global climate has been changing since time began and will continue to change into the future. The Earth's temperature has fluctuated in the last few hundred years. However, since around 1950 there has been a dramatic increase in global temperatures. This increase is known as global warming
• Global warming

  The rise in the average temperature of the Earth's surface.
• The Earth's average temperature has changed over the last 500,000 years. There are times when the global climate is warmer (interglacial phases) and times when it has been cooler (glacial phases) when there have been ice ages. The last major cold period was known as the Pleistocene. It started 2.6 million years ago and ended just 10,000 years ago. Since then, conditions have been warmer. This current warm phase is known as the Holocene. The Holocene and Pleistocene are part of the Quaternary Period of Earth's history.
• On-going temperature recordings using thermometers have shown a clear warming of the Earth's temperature over the past few decades
• The Earth’s average surface air temperature has increased by around 1°C since the year 1900
• The period between 2010 and 2020 was the warmest decade on record, with 2016 and 2020 being the warmest years since records began
• The degree to which the climate warms in the future will depend on natural climate variability and the level of greenhouse gas emissions
• If greenhouse gas emissions continue

  Average global temperatures will rise
• Average global temperatures rising

  Some regions such as the Arctic will warm faster than others
• Over the past 50 to 100 years, photographic evidence has shown that the world's glaciers have been melting, which has caused them to retreat. The increase in global temperatures is causing glaciers to disappear and is increasing the melting of sea ice in the Arctic.
• Scientists often use ice cores to detect changes in temperatures. When snow falls it traps air into the ice. When scientists take a core of ice it reveals the atmospheric gas concentrations at the time the snow fell. This is used to calculate temperature at that time. The ice can reveal the temperature of each year for the past 400,000 years. Scientists that study the ice cores say there is clear evidence that there has been a rapid increase in temperature in the past decades.
• natural function of the Earth's atmosphere is to keep in some of the heat that is lost from the Earth. This is known as the greenhouse effect.The atmosphere allows the heat from the Sun (short-wave radiation) to pass through to heat the Earth's surface.The Earth's surface then gives off heat (long-wave radiation).This heat is trapped by greenhouse gases (eg methane, carbon dioxide and nitrous oxide), which radiate the heat back towards Earth.This process heats up the Earth.
• Some human activities increase the greenhouse gases in the atmosphere: Burning fossil fuels, eg coal, gas and oil - these release carbon dioxide into the atmosphere. Deforestation - trees absorb carbon dioxide during photosynthesis. If they are cut down, there will be higher amounts of carbon dioxide in the atmosphere. Dumping waste in landfill - when the waste decomposes it produces methane. Agriculture - agricultural practices lead to the release of nitrogen oxides into the atmosphere.
• Impacts of climate change in the UK

  sea levels could rise, covering low lying areas, in particular east England droughts and floods become more likely as extreme weather increases increased demand for water in hotter summers puts pressure on water supplies impact on some industries, eg Scottish ski resorts may have to close due to lack of snow
• Impacts of climate change around the world sea level rise will affect 80 million people tropical storms will increase in magnitude (strength) species in affected areas (eg Arctic) may become extinct diseases such as malaria increase, an additional 280 million people may be affected
• What is the name of the most recent geological period that spans from 2.6 million years ago to the present day?


  quaternary period
• How do tree rings show climate change?

  Every year, a new ring forms in the trunks of trees.Rings are thicker in good conditions for growth (temperate and wet climate).Counting the number of tree rings can show that tree's age.Tree rings give us data on the climate and temperature for up to the last 10,000 years.