Causes of Climate Change Flashcards
Name the three natural causes of climate change
Natural Causes of Climate Change:
Solar Output
Volcanic Activity
Orbital Changes
How does Orbital changes cause climate change
The Earth’s orbit is sometimes circular, and sometimes more of an ellipse (oval). This is called Eccentricity. The Earth encounters more variation in the energy it receives from the sun when Earth’s orbit is elongated than it does when the Earth’s orbit is more circular
The Earth’s axis tilts. Sometimes it is more upright, and sometimes more on its side. Tilt - The tilt of the Earth’s axis varies between 22.2 degrees Celsius and 24.5 degrees Celcius. The greater the tilt angle is, the more solar energy the poles recieve.
The Earth’s axis wobbles, like a spinning top about to fall over. This is called precession. This is when a gradual change, or “wobble”, in the orientation of the Earth’s axis affects the relationship between the Earth’s tilt and eccentricity.
These three changes alter the amount of sunlight the Earth receives. They also affect where sunlight falls on the Earth’s surface. On timescales of thousands of years, the changes would be enough to start an ice age, or end one. These changes are called Milankovitch Cycles.
How does Volcanic eruption cause Climate change
Big volcanic eruptions can change the Earth’s climate.
Small eruptions have no effect – the eruptions need to be very large and explosive.
Volcanic eruptions produce ash and sulphur dioxide gas.
If the ash and gas rise high enough, they will be spread around the Earth in the stratosphere (2nd layer of the Earth’s atmosphere) by high level winds.
The blanket of ash and gas will stop some sunlight reaching the Earth’s surface. Instead, the sunlight is reflected off the ash and gas, back into space.
This cools the planet and lowers the average temperature.
Examples of volcanic eruption cooling down the earth
In 1991, Mount Pinatubo in the Philippines erupted, releasing 17 million tonnes of sulphur dioxide. This was enough to reduce global sunlight by 10%, cooling the planet by 0.5°C for about a year.
Mount Pinatubo was very small-scale compared to the 1815 eruption of Tambora in Indonesia. This was the biggest eruption in human history. In 1816, temperature around the world were so cold that it was called ‘the year without a summer’ and up to 200 000 people died in Europe as harvests failed. The effects lasted for four to five years. Sunlight reaching earth was reduced by 10%
How does Solar Output cause Climate change
The Sun’s output (amount produced) is not constant.
Cycles have been detected that reduce or increase the amount of solar energy.
Over 2000 years ago Chinese astronomers started to record sunspots.
These are black areas on the surface of the sun.
Sometimes the sun has lots of these spots.
At other times they disappear.
Even though the sports are dark, they tell us that the sun is more active than usual.
Lots of spots mean more solar energy being fired out from the sun towards Earth.
Temperatures are greatest when there are plenty of sunspots – because it means other areas of the Sun are working even harder.
Examples of solar output
Cooler periods, such as the Little Ice Age, and warmer periods, such as the Medieval Warm Period, may have been caused by changes in sunspot activity.
Some people think that, on average, there were more volcanic eruptions during the Little Ice Age, and that this added to the cooling.
However, climate change on timescales of a few hundred years, and 1-2°C, cannot be explained by volcanoes – but it might be explained by sunspot cycles.
Give examples of fossil fuels
Examples of fossil fuels:
Coal
Oil
Natural Gas
How does Orbital changes cause Climate change (more generally)
As the earth orbits elliptically around the sun, when it is closer to the sun, temperatures are warmer. The earth is also tilted closer to the sun during certain times of the year, which makes temperatures warmer.
Explain how shifts in the Earth’s orbit can cause a change in the climate.
The Earth has natural warming and cooling periods caused by Milankovitch cycles or variations in the tilt and/or orbit of the Earth around the Sun. If the Earth is closer to the sun, the Earth’s climate will be warmer. If it is further away, it will be colder.
What is the Green House effect
The Greenhouse Effect is a naturally occurring phenomenon that keeps the Earth warm enough for life to exist.
What would happen without the greenhouse effect
Without the Greenhouse Effect, the earth would be approximately 33°C cooler than it is now, so therefore life as we know it would not exist.
Describe the Greenhouse effect
1) The Sun’s infrared heat rays enter the Earth’s atmosphere.
2) The heat is reflected from the Earth’s surface.
3) The natural layer of greenhouse gases (water vapor, carbon dioxide, methane, nitrous oxide and ozone) allows some heat to be reflected out of the Earth’s atmosphere.
4) However, some of this heat is trapped within the atmosphere and keeps the earth warm enough.
What is the enhanced Greenhouse effect
The enhanced Greenhouse effect is the increase in the effects of global warming due to human activities
Give examples of Greenhouse gases
77% carbon dioxide
14% methane
1% chlorofluorocarbons (CFCs)
8% nitrous oxide
How many times potent is methane and nitrous oxide compared to carbon dioxide
Methane is 25 times (nitrous oxide is 125 times) the global warming potential over 100 years, when compared to carbon dioxide.
