Scientists think that they were unable to adapt to new conditions. Weather and plant life were changing, affecting whole food chains. Some places were left drier one the glaciers- a source of meltwater - retreated north. If food was scarce, some megafauna would have died out naturally.
There is an opposing argument that says that humans were to blame rather than changes in the climate. This theory claims that towards the end of the Ice Ages, humans migrated around the world in large numbers and that whether they went they haunted nature megafauna species such as the mammoth- until they eventually became extinct. Remains of mammoths have been found at many settlement sites dating from this time.
The amount of carbon dioxide in the air and the temperature fluctuates throughout time. There frequently a rapid increase then a rapid decrease. When the levels of carbon dioxide increase, the temperature increases and when the levels of carbon dioxide decrease, the temperature decreases. The highest amount of carbon dioxide is 350 which is today and the lowest amount is just under 200. The highest temperature was 4 degrees Celsius and the lowest was -10.
Human causes of Climate Change
enhanced greenhouse gas effect
Burning fossil fuels
Burning fossil fuels
The fossil fuels are: coal, oil and natural gas
They are called fossil fuels because they are formed from the remains of ancient plants (coal) and marine animals (oil)
When we burn these fuels, we release millions of tonnes of carbon dioxide into the atmosphere. There has been an enormous increase in these greenhouse gases since the industrial revolution began about 200 years ago. Power stations are one of the main produces of greenhouse gases such as carbon dioxide. Vehicle exhausts are the main source of Nitrous oxides (another greenhouse gas)
The huge increase in world population and in the area of lang given over to crops in general and to rice production in particular, has led to a rapid rise in global methane production. Farmland for rice has doubled in 45 years. Ruminants produce methane- when cows eat grass, they produce methane. A cow can burp/fart about a quarter of a kg of methane a day. The number of cattle has doubled in the past 40 years. sheep, goats and camels are also ruminants. There are now 1.3+ billion cattle, each burping/farting methane several times a minute.
Forests absorb carbon dioxide and release oxygen, if they are cut down, atmospheric levels of CO2 must rise as a consequence. Burning forests adds to the population as well as CO2 inside the trees. Clearing forest by burning releases huge amounts of stored CO2 back into the atmosphere. The smoke from the fires also adds to global air pollution.