Between 20-22 June, world leaders will join thousands of delegates, business leaders and NGOs at the decade-in-the-making Rio +20 summit.
It will attempt to develop a road map that will provide a framework in which we can enjoy growth today, but not at the expense of future generations.
Formally known as the United Nations Conference on Sustainable Development, it is the latest high-level gathering in a series that stretches back 20 years.
The original Rio summit back in 1992delivered a number of key frameworks that have gone on to shape international environmental policy, including the Climate Change Convention; Agenda 21; and theConvention on Biological Diversity.
There was also a considerable amount of excitement surrounding the Rio+10 summit in South Africa.
However, it delivered little in terms of updating or reshaping the international agenda.
The main outcome was the Johannesburg Declaration - a rather dry document paved with paragraphs of good intentions.
So will the presence of heads of state, this time, really make a difference?
The secretariat has also identified issues they considered to be priority areas; subjects in need of extra effort and attention: food, disasters, oceans, energy, jobs, cities and water.
As well as the main business of the conference, there will be more than 500 other side events being held within the official venues from 13 June until the close on 22 June.
There are too many to list here, but there is a calendar on the official website that gives details of many of them.
Seasoned observers of these events know that such gatherings generate so much material and information, that even the most diligent follower is soon swamped with unread reports and outcomes.
If you want to know what the UN secretariat deems to be the most important matters, then the UN media team will be issuing regular updates.
If you prefer to keep in touch via social media for more on-the-ground, unofficial coverage, there is no shortage of people covering and following proceedings on Twitter.
However optimistic the preamble to the summit may be, the truth is that we are now into the fifth decade, arguably the sixth, of the international community being gripped by environmental concerns, yet how much progress has been really been made?
Biodiversity is still declining; climate change policy is still failing to deliver the goods; consumption of natural resources continues to grow at an unsustainable rate.
Outside the UN bubble, this year also marks the 50th anniversary of the publication of a book that is credited with launching the modern environmental movement: Rachel Carson's Silent Spring.
Published in September 1962, it highlighted the impact of pesticides on wildlife and led to the amendment of public policy around the developed world.
It seems that it is single, high-profile events - occurring in the right place at the right time - trigger long and lasting change.
Many credit the original 1992 Earth Summit in Rio as bring such an occasion.
The 2002 gathering in South Africa was less successful, and it seems as if the 2012 conference has its work cut out if it is to leave an indelible mark on the global green agenda.
Article originally appeared in BBC News.