Becoming a parent or retiring from work appear to be the strongest drivers that encourage people to take stock of their environmental impact - and act to reduce it.
According to research based on five independent studies carried out for Defra, it is these two milestones in most people's lives that lead them to change their environmental behaviour.
The studies also show that consumers accept they have a responsibility towards the environment and that most members of the public believe that government should take the lead on helping to protect the planet.
The five provide an in-depth analysis of the public's current expectations and aspirations of pro-environmental behaviour.
The projects looked at public understanding of sustainability in five key areas:
Finance and Investment
Leisure and Tourism
Consumption of Food
The research also shows that many myths surround public understanding of what they can do to reduce their impact on the environment.
These include an assumption that 'good' daily behaviour legitimises occasional 'bad' behaviour and that products and behaviour which are good for the environment are often more costly and of poorer quality.
Environment Minister, Joan Ruddock said: "This research shows public expectations of government are high and we should be leading by example. We need to help people understand the impacts of their own behaviour and suggest simple, affordable ways of making a difference.
"The government's 'Act on CO2' carbon calculator encourages people to find out about their carbon footprint and how to reduce their CO2 emissions. Over half a million people have already visited the calculator website.
With 40% of emissions arising from our homes, the use of appliances and personal travel, everyone can contribute to reducing emissions."
The research also identified a number of motivators for and barriers to environmental behaviour change including:
As well as changes in circumstances such as the arrival of children or retirement, the desire to save money, ensure good health and the 'feel good factor' of doing the right thing were also found to be key motivators for pro-environmental behaviour.
Cost, inconvenience and mistrust of information from both government and industry, and suspicion about their motives, were listed as the main factors preventing people from making choices which would help reduce their impact.
By Sam Bond