Past climate change had many effects on people and the environment. Farms and villages in Northern Europe were deserted because the farmers couldn’t grow crops in the cooler climate. Crops couldn't grow properly so wheat was abondoned in favour of potatoes which grew well in damp conditions. Winters were longer and growing seasons shorter which affected the price of food - it rose rapidly as food became scarce. During the harshest winters, bread had to be made from the bark of trees because grains would no longer grow.
Cooling caused glaciers to advance and stunted tree growth. Livestock died, harvests failed, and humans suffered from famine and disease.
Scientists think that megafauna (large animals like the woolly mammoth, sabre toothed tiger and giant sloth) were unable to adapt to new conditions. Weather and plant life were changing, affecting whole food chains. Some places were left drier once the glaciers retreated north (these used to be a source of meltwater)
If food was scarce, the animals may have migrated to try and find food or find warmer climates. Finding the right food, however, may have been difficult and food chains would have been disrupted. Combined with having to adapt to different temperatures which may have made megafauna weaker – the ‘large animals’ didn’t really stand a chance!
Click here for a great video about the evidence we use for past climate change.
We can split the evidence we use into 2 categories: the evidence that allows us to see how the distant past was and the evidence that shows us the recent past.
Distant Climate Change
The discovery of fossilised animals, plants and pollen that no longer live in the UK shows that the climate has changed.
Landforms, such as U-shaped valleys have been created by glaciers we can no longer see. This shows that a glacier must have been present at some point.
Samples from ice sheets contain layers of ice (oldest at bottom & youngest at top). The ice traps carbon dioxide in it which can be measured. More CO2 = warmer.
Recent Climate Change
Old photos, drawings and paintings of the landscapes can show us what it used to look like.
Written records such as diaries, books and newspapers may include descriptions of the weather.
Recorded dates of regular events such as harvests, tree blossom and arrival of migrating birds may alter slightly. This tells us whether it was getting warmer or colder.