Mention the time period of the following
A. Beginning of Palaeolithic Period-
B. Beginning of Mesolithic Period-
C. Beginning of Neolithic Period-
D. Beginning of ChalcolithicPeriod-
E. Major climatic changes in the world-

The following points may help you:

a. Beginning of Palaeolithic Period-  It is the Paleolithic period that covers 99% of human history. ​It is considered to be the oldest stone age, and is believed to extend from 2 million years ago to about 12,000 years ago​.The palelithic period has been divided into Lower, Middle and Upper Palaeolithic​.

b. Beginning of Mesolithic Period- It is around in the period 10,000 to 5,000 BC.

c.  Beginning of Neolithic Period-Beginning about 10,200 BC.

d. Beginning of ChalcolithicPeriod-5,500 - 3,000 BC, when people started using copper.

e. Major climatic changes in the world- You may refer to ice age that began 2.6million years ago, with five major ice ages experienced. You may also refer to major climate changes that have taken place from 1880 onwards. Over the past few years there has been rise in Global mean surface temperature.