Twenty years later, will world make good on Rio Earth Summit's 'broken promises'? In 1992, nearly every country in the world took part in what was hailed a "historic moment for humanity." The Rio Earth Summit in Brazil delivered a plan of action that would tackle greenhouse gases and climate change, stop species going extinct and save the forests. And if all that wasn't enough, they committed to creating a "safe and just world" for all. Amid the optimism fostered by the fall of communism, global leaders embraced the "revolutionary" new idea of sustainable development - economic progress in harmony with the natural world. Two decades later, that spirit of enthusiasm has been replaced by talk of "broken promises" and "a very uncertain future" in the run-up to this week's unheralded Rio+20 summit, formally the United Nations Conference on Sustainable Development. In 1992, then President George H. W. Bush was at Rio, but his successor Barack Obama has no plans to go this time and other world leaders - like the U.K."s David Cameron and Germany's Angela Merkel - are also expected to stay away from the summit, which begins Wednesday. Indeed, such is the apparent lack of interest, the conference was rescheduled from early to late June partly to avoid a clash with the U.K. queen's Diamond Jubilee celebrations, as it was feared some world leaders would rather celebrate the 60th anniversary of the start of an unelected head-of-state's reign than reach a deal on the future of the planet. Andrew Jordan, professor of environmental politics at the U.K."s University of East Anglia, a world-leading center for environmental research, told msnbc.com that the idea of sustainable development had "gone right down the agenda since Rio in 1992." "I think there's probably still enough support within the U.N. and environmental system to just about keep it on the policy agenda, but you can see a general lack of interest," he said. "I would say the world wouldn't be doing this [Rio+20] unless it was already in the diary," he added. Starting with a blank sheet of paper, they wouldn't have been talking about sustainable development this year or possibly even at all. Jordan said "green growth" - rather than sustainable development - was the new buzz word among industrialized countries, but "really it's growth, old-fashioned growth" with "a bit of a nod towards the environment." World warmer, with fewer species, trees The lack of progress since 1992 is plain to see in a U.N. report, Keeping Track of Our Changing Environment. The much-trumpeted drive to tackle greenhouse gases saw carbon dioxide emissions actually increase by a massive 36 percent between 1992 and 2008. And, between 1992 and 2010, global warming continued apace, with the mean temperature of the Earth rising by 0.4 degrees Celsius (0.72 degrees Fahrenheit); the last decade was also the hottest on record since 1880. As for stopping species from dying out, biodiversity in the tropics has fallen by 30 percent since 1992. And saving the trees? Again, primary forest cover has fallen by 741 million acres - an area larger than Argentina - since 1990. Brazil Senate OKs easing of rules to limit Amazon deforestation In February this year, following a meeting of the world's environment ministers, Achim Steiner, the executive director of the U.N. Environment Programme, called for "bold, transformative decisions " at Rio+20. And he warned that incremental reforms were "leading seven billion down an unsustainable path and [toward] a very uncertain future." Arctic sea ice "megabloom" tied to climate change It was Maurice Strong, the conference secretary-general at Rio in 1992, who described that summit as a "historic moment for humanity" as it came to an end. Since then, the Canadian entrepreneur has complained of "continued broken promises" and is now looking to Rio+20 for real action. If you add up all the commitments they made, if they had implemented them, we'd be a long way down the road. They've not been implemented to any great extent," he told msnbc.com. "If we stay on the same pathway, whatever the politicians say, we'll not be sustainable," he said. The achievement of sustainability needs to be revitalized. "The irony is the science has become more definitive ... since "92 things have got worse," Strong added. On the other hand at the political level ... the will to act has been overshadowed by immediate concerns of a political and economic nature that are less important in the long run. Revolution needed? But he said he was still hopeful "because pessimism is self-fulfilling." "As long as there's a chance, we can do something," Strong said. We need the equivalent of a revolution. Earth nearing 'tipping point,' study warns And there is some hope in U.N. report for those convinced of the need to deal with climate change: Between 1992 and 2009, energy from solar power increased by 30,000 percent, from wind power by 6,000 percent and from biofuels by 3,500 percent. Kate Newman, of environmental campaign group WWF, said she was "optimistic" about what Rio+20 would achieve, so much so that she thought it would be a "positive turning-point for the world." She said the Obama administration had showed "a lot of enthusiasm" about Rio+20 and dismissed the president's decision not to go, saying "he doesn't attend many of these events." World's cities to expand by more than twice the size of Texas by 2030 Newman said that many countries had been introducing policies to promote sustainable development. No matter what happens in Rio, those policies will stand. Countries are already doing important things in anticipation of Rio," she said. Newman said that China, for example, planned "to show the world what they've done in their own country to move to a green economy" at Rio. Fossil fuel subsidies in firing line? Nick Nuttall, spokesperson for the U.N. Environment Programme, told msnbc.com that he didn't think Rio+20 was "intended to be a place of big agreements," but pointed to several areas where there could be significant changes. The world, including the U.S. and many developing countries, spends about $600 billion a year on subsidizing fossil fuels, Nuttall said, compared to about $70 billion on renewable energy. Clinton highlights importance of oil-rich Arctic "There is a sense the issue of fossil fuel subsidies may be dealt with" at Rio, he said. "One of the myths about fossil fuel subsidies is that many developing countries do it to protect the poor from oil price shocks," he said. Many of the poor never benefit because they don't use fossil fuels. "The fact is all the analysis shows what these fossil fuel subsidies do is create inefficiencies," Nuttall added. He also said the Environment Programme could be upgraded to a more powerful body, like the World Trade Organization or World Health Organization. "At the moment if you are a health minister and you go to the annual assembly of the WHO and you decide you are going to phase out some terrible disease across the world in 10 years, that is so decided," Nuttal said. "But if environment ministers of the world meet under the auspices of UNEP and they decide to have a 20-year program to get rid of cadmium, a heavy metal, [for instance] from the world, that decision then has to go to the General Assembly of the United Nations," he added. Rio could also spell the beginning of the end for Gross Domestic Product, with progress on what Nuttall described as a "more sustainable, sophisticated measure of wealth that takes into account the human side, the environmental side." Sustainable development pioneer: Vote Obama The idea of sustainable development - controversial to some - was given life by the 1987 report of the World Commission on Environment and Development, which was chaired by then Norwegian Prime Minister Gro Harlem Brundtland. The report defined sustainable development as "meeting the needs of the present without compromising the ability of future generations to meet their own needs." Speaking to msnbc.com, Brundtland said the concept had been a "revolutionary breakthrough in thinking." "Across the world there was a realization that something dramatic was ahead of us and we must change path," she said. It was all quite amazing what the world was willing to sign up to 20 years ago. Jeff Moore/The Elders Former Norwegian Prime Minister Gro Harlem Brundtland, second right, talks to two of the "Youngers," Marvin Nala, left, and Esther Agbarakwe, right, during the Elders+Youngers dialogue in Oslo, Norway. Brundtland said progress since then had been slow, but added "we know as politicians that change takes time." "Those statistics [on emissions, climate change etc.] would have been much worse today without Rio and without the whole awareness," she said. Watch Elders+Youngers video: It's our future, it's our time She said it was "a pity" that Obama and other world leaders would not be at Rio+20, but said she was "quite certain that he is aware of the seriousness of the issues" and added that she hoped he would win the November election. "He is struggling with an American scene and a political system that is really difficult with polarization and climate deniers, a scene that is very different from the European scene," Brundtland said. "I do believe in people, I do believe there are a number of progressive leaders who see further than one year ahead and they will feel a responsibility to deliver," she added. But if world leaders fail to step up to the plate, Brundtland and other former world leaders in the "The Elders" group are hoping to inspire a grassroots movement of "Youngers." Watch Elders video: What kind of world do we want to leave our great-great-grandchildren? "Elders and Youngers is our attempt to try and mobilize civil society, certainly on behalf of young people ... who may be pessimistic about their future," Brundtland said. Every human being is responsible for the future. It's not enough to point at politicians and expect them to do the right thing," she added. We all have to try to make a difference, we all have to mobilize. This Rio is absolutely dependent on public participation. "I think it will not be a failure," Brundtland said, but added, "maybe it's because I'm always keeping my optimism as a driving force." United Nations Conference on Sustainable Development will be held in Rio de Janeiro, Brazil, June 20 to 22.