Climate Change

Climate Change

Weather - day to day changes in the atmosphere

Climate - Average of these weather conditions measured over 30 years

Distant Past

Evidence that the climate was different in the past

 - fossilised animals and plants that no longer live in the UK

 - landforms like U-shaped valleys caused by glaciers

 - samples from ice sheets like Greenland

Ice

- like a time capsule

 - oldest at the bottom youngest at the top

 - air bubbles trapped in the ice give scientists clues what the climate was like from that time

 - warmer periods are interglacial(between 10000-15000 years)

 - colder periods are called glacial, some became ice ages(between 80000-100000)

 - during the ice ages ice sheets extended to continents in the northern

hemisphere 

Recent Past

Evidence of more recent climate

 - photographs, drawings, paintings

 - written records, diaries, newspapers

 - they are not very accurate as they are not intended to record climate, can give us some idea of the overall climate at the time

Causes of climate change - theories

Eruptions Theory

 - Big eruptions can change the Earths climate

 - Produces ash and sulphur Dioxide

 - if they rise high enough they can be spread around the Earths stratosphere due to high winds

 - ash can stop some sunlight reaching the Earth

 - cools the planet and lowers average temp.

 - 1991 Mt Pinatubo erupted releasing 17million tonnes of sulphur dioxide reducing sunlight by about 10% for that year 

 - cooled planet by 0.5 degrees

 - 1815 Tambora erupted releasing a lot more ash

 - 1816 was a year called the year without summer

 - up to 200,000 people died in Europe because of failed harvests

 - in general volcanoes effects only last for a few years

Sunspot Theory

 - over 2000 years ago Chinese scientists started recording sunspots

 - Darker areas on the sun tell us it is more active than usual

 - lots of spots mean lots of solar energy being fired out to Earth

 - cooler periods may have been caused by changes in sunspots

 - effects usually last for a hundred years

Orbital Theory (Milankovitch cycles)

 - colder glacial periods were 5-6degrees colder than today

 - some interglacial periods were 2-3degrees warmer

 - Earths orbit changes over long periods of time

 - takes 100,000 years for orbit to change from being circular to ellipse then back again

 - takes 41,000 years for Earths orbit to tilt, straighten and tilt again

 - takes 26,000 years for axis to wobble, straighten and wobble again

 - these three changes affect the amount of sunlight the Earth receives

 - also affects where the sunlight falls

 - on timescales of thousands of years the changes are enough to start and ice age or end one

Viking Greenland

 - Erik the red was a Norse viking who was banished to Greenland in 982

 - him and about 500 other vikings found a piece…