Quaternary= the last 2.6 million years
Evidence of past climates:
-Fossilised remains of aniamls tell us that long ago animals adapted to the cold inhabited the UK eg wooley mammouths (mega fauna) found in the North Sea
-Land forms like U shaped valleys indicate that ine giant glaciers carved out paths froming valleys
-Samples (Ice cores) from ice sheets and glaciers tell us about the CO2 levels in different time zones, the more CO2 the hotter the climate showing that it was an interglacial period
-Dendrochronology (the study of tree rings) help tell us about previous climates because thinner rings in the trees indicate that it was a hot dry season where the tree didn't grow so much
-Isostatic rebound tells us that in the past glaciers weighed down the ground and the ground is noe spring back up as the glaciers have melted
-Painting and diaries show a picture of Britain being a colder place although these may be exagurated or in accurate
-Historical records of harvest show us whether there were poor growing climates in the past
Why has climate changes in the past?
Eruption theory: Ash and gas rise to the stratospher and high winds carry it round the earch blocking sunlight. The sunlight reflects off of the ash lowering the temperature. eg. mount pinatubo released 17million tonnes of sulpher, blocking 10% of sunlight, reducing global temperatures by 0.5 degrees.
Sunspot theory: This started 200 years ago when chinease astronimers started stufying sun spots. Sun spots are black area on the suns surface where there is high nuclear activity. The more sunspots the more energy released and the warmer the earth gets. eg. the medieval period was warmer whilst there were increased sunspots
Obital theory (Milankkovich theory): When the earth orbits the sun sometimes it goes closer (eliptical orbit) and sometimes closer (circular orbit). Also, the position of the earth's tilt sometimes changes, as well as it wobbling on the tilt either closer or further from the sun.
Asteroid collisions: Asteroids that hit the earths surface blast tonnes of ash and duct into space. This could block out the sun cooling down the climate. A 1km sized asteroid hits every 500,000 years. When one was exploded just above Russia it flatterned 80 million trees (1908). It is believed a 10km one killed the dinosaurs.
How has past climate change impacted people:
In the 900's there was an interglacial period, so vikings settled in Greenland because it was ice free. By 1100, there were 3000-4000 people on 200 farms, they had regular hunting trips to the artic circle. In 1350 the 'little ice age' hit causing colder weather and long winters. This meant sea ice increased so there was less trade with Iceland, fewer crops were grown (less grass and animal food) and hunting trips became impossible. All of this resulted in less food, overgrazing and soil exhausting. They edventually starved to death.
How has past climate change effected plants and ecosystems
During the little ice age low temperatures…