Two weeks after the event it is still too soon to assess the value of the Rio +20 summit. This hasn't stopped pundits from either labelling it a disaster and the final agreement "283 "paragraphs of fluff", or flagging up reasons for optimism and perspective.
All global summits are written off in the immediate aftermath. While the outcomes from Rio+20 may not currently give grounds for much optimism, its value is likely to be in less tangible, longer-term changes in attitudes and understanding.
Here are five things I think we have learned from the Rio process, which will shape those longer-term assessments and frame key issues that need to be followed-up over the news few years:
1. Sustainable development is still a long way from the top table of policy and power.
One of the most striking images of the summit weekend was of Angela Merkel celebrating another German goal against Greece in Warsaw. She had no problem finding time to watch her national football team, but there was no likelihood of Merkel taking a detour from the G20 meeting in Mexico to be in Rio.
If anything, the summit constituted a step back in the decades-long effort - which started with the Brundtland Commission in the late 1980s - to place equity, sufficiency and international collaboration at the heart of global and national policy.
Many governments are still represented by environment or development ministers, while their counterparts from finance, planning and business are few and far between. By contrast, heads of corporations such as Unilever, Puma, and the biggest Brazilian companies were ubiquitous in Rio, some bullishly asserting that if governments won't take steps to fix global problems then they will step into the gap.
Twenty years on from the original Earth Summit, it's a major indictment of sustainability wonks and advocacy organisations that our leaders still don't 'get' the basic significance of sustainable development, and also that it's so easy for them to relegate it to a policy footnote.
2. Southern governments are more assertive and have clear agendas - even if, for some, this currently only entails saying 'no'.
Thirty months ago in Copenhagen, European governments had a blunt awakening when they were sidelined in the climate change negotiations by a stitch-up between the US, China and India.
This shift in power was less evident in Rio+20 - perhaps because there was thought to be less at stake. But the growing influence of the G77 countries was a striking feature of the event.
The governments of Colombia, the United Arab Emirates and Guatemala were closely associated with the Sustainable Development Goals (SDGs); African countries expressed strong interest in the notion of the 'green economy' as a means to plan their future development trajectories; and China focused on the potential impact that a greater focus on environmental wellbeing could have on job creation.
On the flip side, many Latin American countries vociferously rejected what has been termed the 'commodification of nature' through policy tools, such as payments for ecosystem services and valuation systems that put a monetary worth on environmental resources. And the G77 collectively turned down EU efforts to introduce targets and timetables into the negotiated text.
Perhaps the most positive reflection to draw is that as middle-income countries that are outside the G20 continue to grow, they increasingly need an effective and stable multilateral system to provide the rules and systems they require. Unlike the biggest countries, they can't secure this stability through their own influence alone.
This seems to lie behind Colombia's push for clear goals and commitments, and there is surely potential for this positive critique to spread more widely in future.
3. The UN multilateral process doesn't work - at least not for a global negotiation on sustainable development.
The Rio +20 juggernaut was set on a two-year course for failure from day one. It certainly didn't help that many countries were suspicious and confused by the agenda which emerged from the UN General Assembly. This was particularly evident in the poorly-defined 'green economy' elements, which could have been a positive and new area for exploration, but were never satisfactorily explained or put in context.
But the more fundamental problem is with the UN consensus process itself. As Virgilio Viana of the Brazilian organisation Fundação Amazonas Sustentável (FAS) put it, if UN negotiators had to decide whether they should all have coffee or a beer then they would never reach agreement. So imagine how much more challenging it is to arrive at a set of strong, collective commitments across the broad agenda set for the Summit - with entrenched vested interests, suspicions and ideological differences to accommodate. The process is also severely hampered by a lack of credibility: governments conveniently removed any assessment of the (lack of) progress in implementing previous global commitments, or attention to trends heading dangerously away from stability and fairness.
Despite all these shortcomings, governments still failed to reach agreement on the final outcome document; a day before their heads of state arrived only 28 percent of the text had been finalised.
The Brazilians cut the Gordian knot by substituting in a 'take it or leave it' communiqué that stripped out any strong commitments but (as a result) could be endorsed by all. This was enormously attractive because it avoided a Copenhagen-style collapse and allowed leaders to talk glibly about the successful outcome.
But the Rio+20 agreement is of little value going forward - it is woefully thin on commitments or agreed actions; it doesn't actually reflect hard-won consensus across governments; and it fails to establish better governance arrangements to tackle these global challenges.
On the plus side, this should represent the death knell for these overblown UN processes, but it's less clear how something more positive can take their place.
4. We need a narrative for systemic change; 'natural capital' and green economy approaches could provide the framework.
It's hugely frustrating that Rio +20 didn't present sustainable development as the best means the world has to tackle economic volatility, social unrest and inequality, and the dangers posed by exceeding environmental limits and reaching system tipping points.
This once-in-a-generation global event failed to resonate with anyone beyond those directly involved or interested.
"We can't claim on any major indicators that we've turned the corner, but underneath the global meta-level of analysis there is extraordinary innovation and practice," said the head of the UN Environment Programme, Achim Steiner. "We're inventing a million times the different solutions, but unless we can create the structures and systems to promote change we will remain the laboratories and test grounds to show what could be done."
Such initiatives must engage and challenge the mainstream. The emerging alliance focused on 'natural capital,' an approach that extends the economic notion of capital to natural ecosystems, has the potential to build momentum for change.
The transformative effects of a green economy approach were discussed in detail at the International Institute for Environment and Development's Fair Ideas conference prior to Rio+20. One of the conference's key conclusions was that a green economic approach has the potential to lift people out of poverty through a better use of natural resources, and wouldn't act as an anti-competitive brake on development, as many fear.
Yet the concerns expressed by many in Rio are well-founded, and a green economy approach which doesn't prioritise poverty reduction, equity and environmental stability in the interests of the poorest countries and people would constitute a major setback.
5. Sustainable Development Goals must track improvements and increase accountability.
The Sustainable Development Goals could chart a course to a fairer and more sustainable world.
To do so, they must pinpoint problems with the unsustainable current economic model which UN Secretary General Ban Ki-moon called an environmental "global suicide pact," and they must track improvements and increase accountability at all levels of governance.
This is a tall order. It will mean directly challenging powerful vested interests and putting long-term wellbeing above short-term benefits.
How to get from an idealistic vision to an agreed set of goals is far from clear. Meaningful goals won't emerge from a negotiation between governments - and they will be of most value initially to those advocating major change rather than to those locked into political constraints and trade-offs.
The relationship between the SDGs and a post-Millennium Development Goals framework for international development assistance is another thorny problem to address.
Many obstacles lie along the way, but if current thinking is challenged and new, measurable environmental goals get set to track progress, then the summit could leave an important legacy.
Tom Bigg is head of partnerships at IIED. This blog first appeared on the IIED blog site.