Topic 1: Hazardous Earth Flashcards
(56 cards)
What happens at low pressure?
Air is heated and rises as it is less dense. As it rises, air cools and condenses causing rain and clouds.
Less air at surface = low pressure
What happens at high pressure?
Cool air sinks and transfers heat to the ground. It warms as it falls leaving behind clear skies and little or no rain
More air at surface = high pressure
How is solar radiation distributed?
It is unevenly distributed as some areas receive more than others. Solar radiation has to travel through more atmosphere to get to the poles but less to get to the equator, meaning low latitude countries are hotter than high latitude.
How do winds transfer heat?
Differences in temperature cause differences in air pressure. Winds blow from areas of high pressure to areas of low pressure, transferring heat away from the equator. Winds are involved in global atmospheric circulation cells of high and low pressure belts.
How do ocean currents transfer heat?
They are movements of water that transfer heat energy from hotter to cooler regions. Surface currents are caused by winds and help to transfer heat away from the equator.
When water freezes at the poles it gets more dense and sinks causing warmer water to flow in at the surface.
How does global atmospheric circulation cause variations in climate?
Arid - sinking air from Hadley and ferrel cells meeting causes high pressure and prevents rainfall and causes hot temperatures.
Tropical - rising air from two Hadley cells meeting cause low pressure and lots of rainfall. Temperatures are hot all of the time and rainfall is high.
Polar - sinking air from polar cells create an area of high pressure at the poles. Temperatures are low and there is little rainfall.
How do orbital changes naturally cause climate change?
• They are variations in the way the earth moves around the sun which can affect the amount of solar radiation that the earth receives and may have caused glacial/interglacial periods.
- Eccentricity is how the path of the earth’s orbit changes from circle to ellipse.
- Tilt is how earth’s axis is tilted at an angle.
How does volcanic activity naturally cause climate change?
Major volcanic eruptions eject large quantities of material into the atmosphere. This can reflect the Sun’s rays back out to space so the earth’s surface cools. It can cause short term changes in climate.
How does solar output naturally cause climate change?
The Sun’s output of energy changes in cycles and periods when solar output is reduced may cause the earth’s climate to become cooler.
How do asteroid collisions naturally cause climate change?
Asteroids hitting the earth’s surface can throw up huge amounts of dust into the atmosphere. This can prevent the Sun’s energy from reaching the earth’s surface so global temperatures fall.
How do tree rings provide evidence for natural climate change?
Most trees produce one ring within their trunks every year and scientists take cores through tree trunks and date the tree rings and observe its thickness which can show what the climate was like each year. Thicker ring = warmer climate.
How do ice cores provide evidence for natural climate change?
Ice contains bubbles of air from each year and scientists can drill into ice sheets to get cores of ice and analyse the bubbles in each layer to see how much CO2 and other gases they contain, giving an idea of what the temperature may have been.
How do historical sources provide evidence for natural climate change?
Global temperatures have been measured accurately since the 1850s giving a reliable short term record of climate change. Historical records such as photos, drawings, written records and diaries can show what climate was like in the past however often aren’t accurate.
What is the greenhouse effect?
The earth receives and gives out heat/energy from the sun. The incoming radiation is short wave and the outgoing is long wave. Greenhouse gases such as carbon dioxide and methane in the atmosphere act like an insulating layer - they let short wave radiation in but trap long wave radiation, preventing it from escaping.
How is agriculture a human activity that enhances the greenhouse effect?
- Farming of livestock produces a lot of methane.
- Methane is over 20 times more powerful than CO2 and has increased by 250% since 1850.
- Flooded fields and rice paddies emit methane.
- When trees are cleared for agriculture, the absorption of CO2 decreases, leaving more of it in the atmosphere.
How does producing energy enhance the greenhouse effect?
- Carbon dioxide is released into the atmosphere when fossil fuels like coal, oil and natural gas are burnt.
- 89% of greenhouse gases produced are carbon dioxide and is caused by burning fossil fuels and deforestation.
- Most of our energy is produced by burning fossil fuels.
How is transport a human activity that enhances the greenhouse effect?
- Most cars, lorries, ships and planes run on fossil fuels which release greenhouse gases such as nitrous oxide.
- Nitrous oxide is 250 times more powerful than CO2 and has increased by 16% since 1850.
- Car ownership is increasing in developing countries meaning more cars are used and more gases are released.
How does industry enhance the greenhouse effect and cause climate change?
- Most industry uses a lot of energy and uses gases such as halocarbons.
- Halocarbons are 3000 times more powerful than CO2 and are not natural.
- Some industrial processes also release greenhouse gases, e.g. cement is made from limestone which contains carbon.
- Industrial waste may end up in landfill sites and decay, releasing methane.
What are the consequences of climate change on people?
• Impacts farming - crop yields are smaller due to higher temperatures.
• More deaths due to heat.
• Lower crop yields - can cause starvation and malnutrition.
• Countries may be impossible to live in due to sea level rise.
• More extreme weather events means money has to be spent to reduce impacts and prepare.
How is global temperature rise evidence for human activity causing climate change?
Temperatures have increased by nearly 1°C since 1880. The 10 warmest years since records began have been since 2000. Graphs show a steep rise in global atmospheric temperature recently.
How is decline in arctic sea ice evidence that human activity has caused climate change?
The extent of Arctic sea ice in winter has decreased by more than 3% each decade for the past 35 years. Warmer global temperatures means more ice is melting.
How is sea level rise caused?
• Since 1901 sea levels have risen by almost 0.2m. It is caused by:
- Warmer temperatures cause large glacier and ice sheets to melt, meaning that water stored on land as ice returns to the ocean, causing sea levels to rise.
- Water in oceans expands as it gets warmer by thermal expansion, causing sea levels to rise as there is more water.
What are the different scenarios of predictions about greenhouse gases in the future?
Minimum Emissions - Best outcome, greenhouse gases peak then reduce meaning greenhouse gas emissions are significantly reduced.
Stabilising Scenarios - Greenhouse gases continue to increase but level off after action is taken to reduce emissions.
Maximum Emissions - worst outcome, production of greenhouse gas levels end up very high as rate of production of emissions continues to increase.
Why is is difficult to predict future climate change?
Emissions - we don’t know how emissions will change, which can depend on things like population increase and economic development, it is hard to know how global population will change or how much development will take place.
Complexity - lots of natural processes makes it difficult to predict what will change and what impacts they could have on climate change.
Management - don’t know what attempts there will be to manage the amount of greenhouse gases in the atmosphere and whether they will be successful.
