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Climate Change (4.1-4.5)
What is climate change?
It is a long-term change in the earth’s climate, especially a change due to an increase in the average atmospheric temperature.
What is the trend for global temperatures?
Global temperatures have been cooling gradually over the last 5.5 million years, but increasing in recent decades - especially since the mid-1970s.
What recent evidence is there for climate change?
Shrinking glaciers and melting ice, rising sea levels and seasonal changes.
What are the three main natural causes of climate change?
Orbital changes (the Milankovitch cycles), solar activity and volcanic activity.
How does solar activity cause climate change?
The surface of the Sun has dark patches called sunspots which mark short-term regions of reduced surface temperature. They are usually accompanied by explosive, high-energy solar flares increasing heat output.
Over a period of around 11 years, sunspots increase from a minimum to a maximum, and back again.
How does solar activity cause climate change?
Volcanic ash can block out the Sun, reducing temperatures on Earth. This is a short-term impact.
Sulphur dioxide is also released in large amounts which converts to droplets of sulphuric acid, which when in the atmosphere reflects solar radiation back into space: in the long run reducing temperatures.
What are the three Milankovitch cycles?
The three distinct cycles increase and decrease the distance from the sun are eccentricity, axial tilt and precession.
What is eccentricity?
It is how much the shape of Earth's orbit differs from a perfect circle.
Every 100,000 years or so the orbit changes from almost circular, to mildly elliptical (oval) and back again.
What is axial tilt?
It is the tilt in the axis (the invisible line around which an object rotates, or spins) of the Earth.
Every 41,000 years the tilt of Earth’s axis moves back and forth between 21.5° and 24.5°.
What is precession?
Is how much the Earth wobbles like a spinning top.
Over a period of about 26,000 years, the axis wobbles from one extreme to the other.
What is the greenhouse effect?
The greenhouse effect is a process that occurs when gases in Earth's atmosphere trap the Sun's heat, keeping the Earth naturally warm enough to support life.
How does the greenhouse effect work?
When the Sun's energy reaches the Earth's atmosphere, some of it is reflected back to space and some is absorbed and re-radiated by greenhouse gases.
How are humans enhancing the greenhouse effect?
In recent years, amounts of greenhouse gases in the atmosphere have increased. CO2 is the most important, contributing approximately 60% of the net warming by greenhouse gases.
Where do CO2 emissions come from?
Most CO2 emissions come from burning fossil fuels in industry and power stations but transport, farming an deforestation of tropical rainforests by burning also contribute heavily.
Where are the CH4 emissions coming from?
They are mostly coming from the ever-increasing numbers of livestock on farms, rice farming , sewage treatment. However the emissions from landfill sites, coal mines and natural gas pipelines are growing even fast that CO2.
How can climate change be managed?
Some ways it can be managed is through:
alternative energy sources
carbon capture
planting trees
international agreements
How do alternative energy sources manage climate change?
The burning of fossil fuels accounts for 87% of all CO2 emissions. Alternative sources of energy such as hydroelectric power, nuclear power, solar, wind and tides represent sustainable, low carbon alternatives, reducing CO2 emissions, in theory reducing the greenhouse effect or stopping it from growing.
How does carbon capture manage climate change?
Although not economically viable, carbon capture and storage (CCS) uses technology to capture CO2 that is produced when burning fossil fuels in electricity generation and industrial processes. Once captured, the CO2 is compressed, piped and injected underground for long-term storage in suitable geological reservoirs, such as depleted oil and gas wells, reducing CO2 in the atmosphere, in theory reducing the greenhouse effect.
How does planting trees manage climate change?
Trees act as carbo sinks, removing CO2 from the atmosphere by the process of photosynthesis, reducing CO2 in the atmosphere, in theory reducing the greenhouse effect. Trees also release moisture, producing more cloud and so reducing incoming solar radiation.
Tree planting is well established in many parts of the world. In fact, plantations are more efficient at absorbing CO2 than natural forests.
How do international agreements manage climate change?
Governments are negotiating towards a more sustainable future. For example, the Paris Agreement (2015) was the first binding global climate deal . It aims to limit global temperature increases to above 1.5°C above pre-industrial levels.
What are the global impacts of climate change?
reduced crop yields and water supplies
more heat-related illness and disease
low-lying coastal areas threatened by flooding
changing ecosystems and animal habits
more extreme weather events, such as droughts and floods
stronger tropical storms
desertification
How can we adapt to climate change?
There is no 'one-size-fits-all-solution' - adaptation can range from agricultural adaptation to reducing the risk from rising sea levels.
How can we adapt agriculturally to manage the impacts of climate change?
introduce drought-resistant crops
new irrigation systems
educate farmers in water harvesting techniques
shade trees can be planted to protect seedlings from strong sunshine
new cropping patterns can be introduced
How can we adapt to reduce the risks from rising sea levels because of the impacts of climate change?
construct sea walls
restore coastal mangrove forests - their tangled roots trap sediment and offer protection from storm waves
construct artificial islands so that people at risk could be relocated
building houses that are raised off the ground on stilts
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