The increasing trend of rising tropospheric temperatures due to the global climate change is reflected in the efficacy of Indian monsoons too. It is imperative to have a high level, skilled mechanism to monitor and predict this trend to help manage preparedness.

An unprecedented rain event on 26-27 July 2005 at Mumbai motivated several research programmes on point-and-area-averaged extreme rainfalls to understand the association between atmospheric circulation and extreme rainfall.

The evolution of Oriental Monsoon is a very complex phenomenon. Still more complex is the issue of climate change. It involves a whole range of climatic conditions which include solar radiation, temperature, pressure, wind, cloud and precipitation in a given period compared to the preceding periods and has a considerable impact on settled ecosystems.

The intensity and variability of monsoon rain depend upon several parameters of atmospheric circulation, which in turn are interlinked with global climate. Changes in global temperatures are likely to make about 1500 billion cubic metres of surplus rainwater annually available. To capture this, and to cope up with variability, India would need to develop appropriate science, technology and skill.

Ample surplus rainwater is available in river basins of India. Any use and exploitation of this surplus rainwater must be based on an analysis of 4 to 10 times longer data of the past.

The analysis of changes in the moisture regions over the past hundred years indicate a net effect of drier all India moisture conditions in the recent decades.

Understanding climatic changes of the Holocene Period (past 11,000 years¬¬¬¬) is crucial to assess the impact of global warming on the Indian environment. In the following discourse we provide an overview of climatic changes over the Indian subcontinent based on instrumental records (1813-2008 AD) and as reported by historians (600 BC-1800 AD), archaeologists (3000–600 BC), mythologists (8,000-3,000 BC) and palaeo-climatologists (prior to 8,000 BC).