PAST CLIMATES
Scientists know that climate was different in the past. They
can use physical evidence such as:
• Fossilised plants and animals and pollen that no longer
live in the UK
• Landforms like U-shaped valleys left by retreating
glaciers
• Samples from ice-sheets of Greenland and Antarctica.
Ice sheets contain layers of ice, with the oldest at the
bottom, trapping air bubbles are they form, which allows
climatologists to reconstruct past temperatures.
Recent evidence also comes from:
• Old photographs, drawings and
paintings of the landscape
• Written records, such as diaries,
books and newspapers
• The recorded date of regular
events, such as harvests, arrival of
migrating birds and tree blossom.
Grade D/E: Describe the changes in the UK temperature over the past 800,000 years and since 400BC
Grade C: Describe the evidence that we can use to suggest climates were different in the past .
Grade A/A*: Explain the link between CO2 emissions and global temperatures.
CAUSES OF CLIMATE CHANGE
Grade E:
Name the three natural
causes of climate change.
Grade C:
Explain how big volcanic
eruptions might change
our climate.
Grade B:
Explain how orbital
changes affect our
climate.
Grade A/A*:
Which theory will have
greatest impact on our
climate?
Eruption Theory
Big volcanic eruptions can change
the Earth’s climate. Volcanic
eruptions produce ash and sulphur
dioxide gas. They can reach the
stratosphere and this blanket of
ash will stop some sunlight
reaching the Earth’s surface,
reflecting sunlight back into space.
This cools the planet and lowers
the average temperature.
Orbital Theory
The Earth’s orbit changes over long
periods of time, which may explain why
there are big changes in the Earth’s
average temperatures.
The Earth’s orbit is sometimes circular,
and sometimes more of an oval shape.
The Earth’s axis tilts. Sometimes it is
more upright, and sometimes more on
its side.
The Earth’s axis wobbles, like a spinning
top about to fall over.
On timescales of thousands of years, the
changes in the orbit of the Earth, called
Milankovitch cycles could explain the
changes in climate.
Sunspot Theory
Sunspots are black areas on the suface of
the sun. Sometimes the sun has lots of
these black spots, and at other times they
disappear. This dark spots tell us the sun is
more active than usual, which means more
energy being fired out from the sun to the
Earth.
IMPACT OF CLIMATE CHANGE
Viking Greenland
Warmer climates in Greenland meant that by 1100 Greenland
had:
•
Over 200 farms – keeping goats, sheep and cows, and
growing hay (grass) to feed the animals
•
A population of 3000-4000 Vikings
•
Trade links with Iceland and Norway
•
Summer hunting expeditions north of the Arctic circle, for
seals and Whales.
However, by the time the Little Ice Age arrived:
•
Deforestation and soil erosion meant that the Viking farms
probably produced little food as they had damaged the land
they depended on.
•
The trade route between Iceland and Norway stopped
because of sea ice
•
The Greenland Vikings were not very adaptable.
•
They became very isolated in a damaged environment with
no way to change their lifestyle.
Little Ice Age
During the Medieval warm period (900-1350AD) new land
was given over to farming. However, when the Little Ice Age
took hold (1315AD):
• Cold and rain lashed Europe in the spring and summer of
1315
• Wheat and oats did not ripen and the harvest failed
• The cool wet weather continued into 1316 and 1317
• By 1317 the ‘Great Famine’ had begun, and it lasted until
1325
• In some areas 10-20% of the peasant farmers may have
died from hunger.
The arrival of the Black Death in 1349 was probably made
worse by a colder climate and more challenging farming
conditions.
In the Alps glaciers advanced down the valleys, destroying
villages and farmland. Many farmers stopped growing wheat
as it became difficult to farm, and instead grew potatoes
from South America, which liked the wet and cold.
Grade E:
Impact on Wildlife:
When climates have changed, it has spelled disaster for some
plants and animals.
Megafauna are big animals that weigh more than 40kg. As the
climate warmed after the last Ice Age many animals migrated
as they tried to find new areas to live in where the climate
suited them. Finding the right plants to eat would have been
difficult and a warmer climate would have disrupted food
chains, leaving some animals short of food. Climate stress may
also have made megafauna weaker than normal.
What impact did a warmer climate mean for the Vikings?
Grade D/C:
Explain the impact of the Little Ice Age on the UK.
Grade A/A*:
What impact did the end of the Little Ice Age have on
wildlife?
CLIMATE CHANGE
% of
greenhouse
gases
produced
Sources
89%
Burning fossil fuels
(coal, oil and gas),
deforestation which
releases CO2.
Methane
7%
Gas pipeline leaks,
farming rice in paddy
fields, cattle farming.
Nitrous oxide
3%
Jet aircraft engines, cars
and lorries, fertilizers
and sewage farms
1%
Used in industry,
solvents and cooling
equipment
Greenhouse Gas
Carbon Dioxide
Halocarbons
Grade E: What are the four main greenhouses gases?
Grade D: Make a list of human actions that add to
greenhouse gases.
Grade C: Explain what the enhanced greenhouse effect is.
Grade A/A*: Explain why people in the developing world
produce only small amounts of greenhouse gases.
CLIMATE FUTURES
Climate change has been evidenced because:
• Global temperatures have risen by 0.75C between 1905 and 2005.
• Sea levels have risen by 195mm from 1870 to 2005 – due to thermal expansion.
• 19 of the 20 warmest years have been since 1980
• Floating sea ice in the Arctic shrank from 7.6m km2 in 1980 to 4.4m km2 in 2007
• Over 90% of the world’s valley glaciers are shrinking
Scientists estimate that temperatures will rise between 1.1C and 6.4C by 2100 and that sea
levels could rise by between 30cm and 1 metre by 2100.
Possible impacts on the UK are:
• Low-lying coasts like East Anglia and Essex
could flood
• Some coastlines could erode more rapidly so
coastal defences could cost more
• Heatwaves, just like in summer of 2003
• Flooding, just like summer 2007 & January
2014
• Storms, like 1987 and in1990
• Greater insurance claims
• More money spent on infrastructure resilience
to lessen the impact of flooding
• Water shortages could become more common
• There could be more illnesses such as
heatstroke and skin cancer
• Farmers might have to change crops to those
than need less water and more sunshine
• Some plants and animals might die out if the
UK gets too hot
• More people could holiday in the UL
• New crops might mean new sales
opportunities
• More land could be farmed at higher latitudes
Predicting the future climate is going to be very difficult because we don’t know:
• What the world’s future population will be;
• If we will continue to use fossil fuels or use cleaner renewable energy
• If people will change their lifestyles, e.g. recycle more
All countries need to work together to reduce the
impact of climate change:
• We could reduce our consumption of fossil fuels and
switch to ‘green energy’
• We could recycle more
• We need to use cars less and public transport more
• We need tor reduce our ecological footprint
Grade E: Identify two pieces of evidence that suggests
UK’s climate is changing.
Grade D:Why is it hard to predict how temperatures
might change in the future with global warming
Grade C:How might the UK be affected by climate
change
Grade B: How might international co-operation help
reduce the impact of climate change?
Grade A/A*: Describe how global warming might bring
costs and benefits to the UK.