Causes Of Climate Change

Question 1

What are some changes in climate caused by

Answer 1

Changes in how the Suns energy is received/trapped/distributed around the earth
When more energy is received=earth will get hotter
When less energy is received=earth will get cooler

Question 2

What are some changes in climate caused by

Answer 2

Human activity

Question 3

What is variations in the earths orbit

Answer 3

The way the earth moves around the sun affects the way the earth receives energy from the sun
Earths movement around the sun changes gradually in 3 ways-which in turn affect global climate

Question 4

3 ways the earths movement around the sun changes

Answer 4

Stretch
Tilt
Wobble

Question 5

Explain stretch

Answer 5

Path of the earths orbit around the sun changes from an almost perfect circle to an ellipse and back again about every 96,000 years
Changes the distance from the sun to earth so the amount of energy the earth receives from the sun is different at different times of year
Elliptical right now-closest to sun in January, furthest away in July

Question 6

Explain tilt

Answer 6

Earth is tilted at an angle as it orbits the sun, called its axis (currently 23.5 degrees)
Changes between 21.8 degrees and 24.4 degrees over a 41,000 cycle
Change in tilt changes the amount of energy that different latitudes receive, changing global climate
When the tilt is greater (24.4 degrees) areas that relieve lots of energy, such as tropics, will be larger. Other climate regions such as the temperature zone beyond the tropics, will be smaller

Question 7

Explain wobble

Answer 7

The axis of the earth also wobbles like a spinning top on a cycle of about 22,000 years
Because the earth is closest to the sun in January, winter in the northern hemisphere is mild and summer is cool-wobble of axis means this gradually changes, seasons will eventually swop over
When this happens, earth will be closest to the sun in January but this will now be the summer in the northern hemisphere, earth will be furthest away from the sun in July, but this will now be winter in the northern hemisphere
In the northern hemisphere, winter would then be colder because it will be at the time when earth is further away from the sun, summer will be hotter as it is closest to the sun

Question 8

Explain variations in solar output

Answer 8

The Suns output of energy is not constant
Sunspots are darker areas on the sun that increase solar energy output
Sunspots are thought to increase/decrease in number in an 11 year cycle-though there is variation in this cycle
Eg. period of cooling in the late 17th century called the little ice age is thought to have coincided with a period when sunspot activity was very low

Question 9

Explain meteor impacts

Answer 9

Impact of meteor (up to 10m across) or an asteroid (larger than 10m across) forms a large creator and can throw up lots of metrical into the atmosphere
Can result in a lot of sunlight (energy) being blocked for months/years
Eg. mass extinction of dinosaurs is widely thought to have been caused by the climate change brought by a massive asteroid impact

Question 10

Explain volcanic eruptions

Answer 10

Major volcanic eruptions also eject large quantities of material into atmosphere
Can block out sunlight (energy) which changes the climate
Eg. eruption of Mount Tambora in Indonesia in 1815 is thought to have lowered the global temperature by 0.5 degrees c

Question 11

Is the recent rise in global temperature (global warming) and the rate of this increase usual or unusual

Answer 11

Unheard of in historical terms

Question 12

Scientific consensus that the temperature rise is caused by

Answer 12

Human activity

Question 13

Explain enhanced greenhouse gas emissions

Answer 13

Greenhouse gases include CO2, methane, ozone and water vapour
The greenhouse effect is where greenhouse gases absorb outgoing energy, so less is lost in space-essential for keeping planet warm
But too much greenhouse gas in the atmosphere means too. Ice energy is trapped and the planet warms up
CO2 is released into the atmosphere when fossil fuels like coal, oil, gas and petrol are burnt p, eg power stations, cars
Since the industrial revolution in the mid-19th century levels of atmospheric CO2 have increased from 280ppm to 380ppm (parts per million)-the level had been broadly stable for the previous 10,000 years
Increase in CO2 has caused the increase in temperature (global warming) over the same period because of the enhanced greenhouse effect

Question 14

Explain destruction of natural CO2 sinks

Answer 14

CO2 sinks store CO2, keeping it out of the atmosphere-so it is not contributing to the greenhouse effect
Biggest sinks are the oceans-CO2 dissolves in sea water and gets move to the deep ocean by natural currents
Another big sink is plants-plants take in CO2 and convert it into organic matter using photosynthesis-also stored in the soil as organic matter
cO2 released into the atmosphere when trees are burnt by forest fires to make way for agriculture
Was thought that a lot of greenhouse gas emissions from humans could be stored in CO2 sinks, now thought that they will not be able to keep pace with increasing emissions so more CO2 will go directly to the atmosphere