Weather Hazards and Climate change

Question 1

Why does the sun heat the Earths surface unevenly?

Answer 1

1. Due to the curvature of the Earth.
2. The sun’s energy is more concentrated at the equator compared to the poles, therefore temperatures are higher.

Question 1

How is heat transferred to the poles?

Answer 1

1. Winds blow from the areas of high pressure to the areas of low pressure.
2. This helps to transfer heat energy away from the equator and redistributes it around the Earth.

Question 2

How is heat transferred by ocean currents?

Answer 2

1. Ocean currents are large scale movements of water that transfer heat energy from warmer to cooler regions.
2. Surface currents are caused by winds and help transfer heat away from the equator, e.g. the Gulf Stream brings warm water from the Caribbean and keeps Western Europe warmer than it otherwise would be.
3. There are also deep ocean currents driven by differences in water density.
4. When water freezes at the poles, the surrounding water gets saltier, increasing its density.
5. As it gets denser, it sinks, causing warmer water to flow in at the surface, creating a current.
6. This warmer water is cooled and sinks, continuing the cycle. This cycle of cooling and sinking moves water in a big loop around the earth, known as the thermohaline circulation.

Question 3

What are trade winds?

Answer 3

1. Surface winds blowing towards the equator are called trade winds.
2. Trade winds blow from the SE in the southern hemisphere and from the NE in the northern hemisphere.
3. At the equator, these trade winds meet and heat from the sun causes them to rise and form clouds.

Question 4

What are westerlies?

Answer 4

1. Surface winds blowing toward the poles are called westerlies.
2. They blow from the NW in the southern hemisphere and from the SW in the northern hemisphere.

Question 5

What are winds part of?

Answer 5

1. Winds are part of global atmospheric circulation loops called cells.
2. These loops have warm rising air which creates a low pressure belt, and cool falling air which creates a high pressure belt.

Question 6

What are the three cells in each hemisphere?

Answer 6

1. Polar cell
2. Ferrel cell
3. Hadley cell

Question 7

How are ice cores evidence of natural climate change?

Answer 7

1. Ice sheets are made up of layers of ice - one layer is formed each year.
2. Scientists drill into ice sheets to get long cores of ice.
3. By analysing the gases trapped in the layers of ice, they can tell what the temperature was each year.

Question 8

How do tree rings give evidence of natural climate change?

Answer 8

1. As a tree grows, it forms a new ring each year - the tree rings are thicker in warm, wet conditions.
2. Scientists take cores and count the rings to find the age of a tree. The thickness of each ring shows what the clime was like.

Question 9

How do pollen records give evidence of natural climate change?

Answer 9

1. Pollen from plants gets preserved in sediment, e.g. at the bottom of lakes or in peat bogs.
2. Scientists can identify and date the preserved pollen to show which species were living at that time.

Question 10

How does Milankovitch cycles cause climate change?

Answer 10

1. Eccentricity. The path of the Earth’s orbit around the Sun changes from an almost perfect circle to an ellipse and back again about every 96,000 years.
2. Axial tilt. The earth is tilted at an angle as it orbits the sun, varying between 22.1 and 24.5 degrees. This changes over a cycle of around 41,000 years,
3. Precession. The axis of the Earth wobbles like a spinning top on a cycle of about 22,000 years.

Question 11

How do sunspots cause climate change?

Answer 11

1. The Sun’s output of energy isn’t constant - it changes in short cycles of about 11 years. This is known as solar variation.
2. Solar variaton is caused by sunspots. Sunspots are cooler areas of the Sun’s surface that are visible as dark patches. They increase the Sun’s output of energy.
3. Perioids where solar output is less and there are very few sunspots may cause the earth’s climate to become cooler in some areas.

Question 12

How does volcanic activity cause climate change?

Answer 12

1. Major volcanic erruptions eject large quantities of material into the atmosphere.
2. Some of these particles reflect the su n’s rays back out to space, so the Earth’s surface cools.
3. Volcanic eruptions may cause short-term changes in climate, e.g the cooling that followed the eruption in Mount Pinatubo in 1991.

Question 13

What are greenhouse gases?

Answer 13

1. Greenhouse gases are the gases that trap heat.

Question 14

How does farming cause global warming?

Answer 14

1. Agricultural land contributes to 12% of GHG emissions.
2. Use of pesticides releases greenhouse gases such as nitrous oxide which contributes to the enhanced greenhouse effect.
3. Cattle ranching is the biggest cause of deforestation in Brazil - 80% of deforerrested areas being used for pasture.
4. Less trees exrtracting CO2 from the atmosphere.
5. Cows release between 10kg and 120kg of methane per year, methane has a 23x stronger effect on the enhancred greenhouse effect than CO2.
6. Rice paddy fields are one of the largest sources of Methane in the world. As populations increase, rice producton will increase as it is a staple food.

Question 15

How does industry cause global warming?

Answer 15

1. Total GHG emissions from industry almost doubled between 1970 and 2010.
2. Most industry uses a lot of energy.
3. Some industrial processes also release greenhouse gases, e.g. cement is made from limestone, which contains carbon. When cement is produced, lots of CO2 is released into the atmosphere.
4. Industrial waste may end up in landfill sites where it decays, releasing methane.