Topic 4 - Climate Change Flashcards
Unit 1: Living with the Physical Environment (Section A - The Challenge of Natural Hazards)
What is weather?
short-term day-to-day changes in things like temperature, wind, cloud cover and rainfall
What is climate?
an average of these weather conditions, measured over 30 years
What are some examples of evidence of past climate change?
- 12,000 years ago, rhinoceroses and elephants roamed around London
- Huge ice sheets stretched from the North Pole as far south as London
What are some examples of physical evidence of past climate change?
- Fossilised animals, plants and pollen have been found that no longer live in the UK.
- Landforms, like U-shaped valleys left behind by retreating glaciers
- Samples of sea ice
What are ice cores?
- Ice sheets are like time capsules.
- They contain layers of ice, oldest at the bottom, youngest at the top.
- Each layer is one year of snowfall.
- Trapped within the layers of ice are air bubbles.
- Locked in air bubbles is C02.
- Measure the amount of trapped C02 in ice layers
What is the Quaternary Period?
- The Quaternary (the last 2.6 million years of geological time)
- Warm periods (interglacials) lasted for between 10 000 and 15 000 years
- Cold periods (glacials) lasted about 80 000 – 100 000 years.
- During some glacials it became so cold that the earth plunged into an ice age.
- Huge ice sheets extended over continents in the Northern hemisphere.
What are the global effects of climate change?
- Many of the world’s glaciers and ice caps are shrinking.
- Arctic sea ice is less extensive than in the past, affecting wildlife such as polar bears. However, this may provide opportunities for ships to use the North-West Passage in the future.
- Low-lying Islands such as the Maldives and Tuvalu are under threat from sea-level rise.
- Sea levels may rise by 1 m by 2100 flooding agricultural land in Bangladesh, Vietnam, India and China.
What are some examples of written evidence for climate change?
- Old photographs, drawings and paintings of the landscape
- Written records, such as diaries, books and newspapers
- The recorded dates of regular events, such as harvests, the arrival of migrating birds and tree blossom
What does written evidence suggest in terms of climate change?
- Suggests that climate changes every few hundred years
- Average temperatures over the past 2000 years have varied between 1-2 °C
What are the natural causes of climate change?
- Changes in the Earth’s orbit
- Variations in heat output from the sun
- Volcanic activity
How do variations in heat output affect climate change?
- There are cyclical changes in solar energy output linked to the presence of sunspots.
- A sunspot is a dark patch that appears from time to time on the surface of the Sun. - The number of sunspots increases from a minimum to a maximum and then back to a minimum over a period of about 11 years.
- This 11-year period is called the sunspot cycle.
- When sunspot output is at a maximum, the Sun gives off more heat. Large explosions occur on the surface of the sun resulting in solar flares.
- When sunspot output is at a minimum the solar output is reduced. This can lead to lower temperatures on Earth.
How does volcanic activity affect climate change?
- Violent volcanic eruptions blast huge quantities of ash, gases and liquids into the atmosphere.
- Volcanic ash can block out the Sun, reducing temperatures on the Earth. This tends to be a short-term impact.
- The fine droplets that result from the conversion of sulphur dioxide to sulphuric acid act like tiny mirrors reflecting radiation from the Sun. This can last a lot longer and can affect the climate for many years.
- The cooling of the lower atmosphere and reduction of surface temperatures is called a volcanic winter.
What is an example of a volcano erupting, affecting climate change?
Eruption of Mount Tambora, 1815
- In 1815 there was a massive volcanic eruption of Mount Tambora in Indonesia. Ash and sulphuric acid caused average global temperatures to fall by 0.4°C - 0.7°C.
- Across the world many harvests failed. There were major food shortages throughout North America and Western Europe, including the UK. Food prices rose sharply and there were riots and looting in European cities. It was the worst famine in Europe in the nineteenth century, resulting in an estimated 200,000 deaths.
What are the Milankovitch cycles (orbital changes)?
- Eccentricity
- Axial tilt
- Precession
How do the Milankovitch cycles affect climate change?
Scientists believe that these cycles affect the timings and seasons of the Earth’s climate
What is Eccentricity?
- Describes the path where the Earth orbits the sun
- The Earth’s orbit is not fixed - it changes from being almost circular to being an ellipse.
- A complete cycle from circular to an ellipse and back to circular again occurs about every 100000 years.
- The 100,000 year eccentricity cycle coincides closely with the alternating cold (glacial) and warm (inter-glacial) periods in the Quaternary period.
What is Axial tilt?
The Earth’s axis is currently tilted at an angle of 23.5 degrees. However, over a period of about 41,000 years, the tilt of the Earth’s axis moves back and forth between two extremes - 21.5 degrees and 24.5 degrees.
What is Precession?
- This describes a natural ‘wobble’.
- A complete wobble cycle takes about 26,000 years.
- The Earth’s wobble accounts for certain regions of the world, such as northern Norway, experiencing very long days and very long nights at certain times of the year.
What is the greenhouse effect?
- Glass allows radiation (heat) from the Sun to enter the greenhouse. However, this heat cannot easily escape through the glass. As a result, the greenhouse becomes warmer than the air outside and is ideal for growing tomatoes and other plants which need constant warm conditions.
- Like a greenhouse, the atmosphere allows most of the heat from the Sun (short-wave radiation) to pass straight through it to warm up the Earth’s surface (diagram B). However, when the Earth gives off heat in the form of long-wave radiation, some gases such as carbon dioxide (CO2) and methane are able to absorb it. These gases are called greenhouse gases.
- In the same way that glass traps heat inside a greenhouse, the greenhouse effect keeps the Earth warm. Without this ‘blanketing’ effect it would be far too cold for life to exist on Earth.
What are some examples of greenhouse gases?
- CO2
- Methane
- Nitrous oxides
How has CO2 increased in the atmosphere?
- Car exhausts
- Deforestation and the burning of wood
- Burning fossil fuels (e.g., oil, gas, coal) in industry and power stations to produce electricity
How has Methane increased in the atmosphere?
- Rice farming
- Burning biomass for energy
- Farm livestock
- Decaying organic matter in landfill sites and compost tips
