The earths climate has never been stable.During the Earths 4.6 billion year history there have been a series of ice ages. the ice age we are currently in began 2 million years ago in the quaternary age.There have also been other significan ice ages including the Huronian in the proterozoic era 2500 million years ago. This grapg shows the warm and cool periods in the Earths history there seems to be a trend that the earth naturally warms up and then cools down.so the graph suggests that global warmimg is just actually the Earth naturally warming up.
climate change over the last 1 million years
The trend is the same in that the naturally cools down and warms up.But the term ice age means a geological period of long term reduction in the temperature of the Earth's surface and atmosphere.So for an ice age to occur there has to be a sustained period of cold temperatures.within long term ice ages pulshes of extra cold weather are called glacials.The last glacial was 100,000 years ago where the temperature dropped by 11 degrees below the average.the earth is currently warming up this is called the Holecene.