There are two causes of climate change.
One is well-known: the variations that have been going on throughout earth history.
The last ice age was about 11,000 years ago, but there are lesser fluctuations; e. g. the dry, warm period of about AD 1100, when peoples in the southwest had to leave their lands and move to places where there were better water conditions.
The melting ice caps and the increasing water temperatures which are killing large areas of reef life are another result.
A current equivalent is taking place in the highlands of central Africa, where the famed snows of Kilamanjaro and sources of water are disappearing, with severe drougth and heat killing crops and cattle, displacing many thousands in Ethiopia, Kenya and contiguous areas.

The second factor, man-made, is contributory and is becoming increasingly serious. According to some scientists, the effects began with the industrial revolution.
The best evidence for this are the analyses of ice cores taken from the Greenland and Antarctic ice caps.
The ice core analyses clearly show the increase in greenhouse gases and toxic chemicals since the industrial revolution, and the almost exponential increase in the last 100 years.

The man-made effects may be lessened by 'green' practices such as reduction of greenhouse gases and stopping destruction of forests. The natural cycles also must be planned for; rising sea levels as a result of ice cap melting causes coastal peoples to move to higher, often less productive ground, fishing and agricultural practices must change, etc., etc.
An entire nation, the Maldives, will disappear beneath the sea if sea levels continue to rise.

In other words, planning and action is called for regardless of the causes of climate change.