Twenty years ago, the first Earth Summit in Rio de Janeiro marked the arrival of environmentalism as a potent force in international affairs. That 1992 conference produced the United Nations Framework Convention on Climate Change, which aims to set limits on global emissions of greenhouse gases, and the Convention on Biological Diversity, which promotes ecosystem conservation. At the time, Chris Flavin of the Worldwatch Institute crowed, “You cannot go to any corner of the globe and not find some degree of environmental awareness and some amount of environmental politics.” With socialism in disrepute, Flavin said, environmentalism had become the “most powerful political ideal today.”

Two decades later, that ideal is in disarray. A 20th anniversary conference in Brazil last June, the United Nations Conference on Sustainable Development—nicknamed Rio +20—was an undisguised flop. Greenpeace spokesperson Kumi Naidoo judged Rio +20 a “failure,” while Oxfam Chief Executive Barbara Stocking called it a “hoax.” More than 1,000 environmentalist and leftist groups signed a post-conference petition entitled “The Future We Don’t Want,” a play on The Future We Want, the platitudinous document that diplomats from 188 nations agreed on there. Naidoo lamely vowed that disappointed environmentalists would engage in acts of civil disobedience.

Should the people of the world share the greens’ despair over the “failure” of the United Nations Conference on Sustainable Development? No. First of all, “sustainable development” is a Rorschach blot. The United Nations defines it this way: “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” That fuzzy concept can be used by anyone to mean anything he likes. So it is not at all surprising that the representatives from rich and poor nations meeting in Rio could not agree on anything substantive under this heading.

Since that first Earth Summit, the world has experienced a lot of beneficial development. In 1992, 46 percent of the planet’s population lived in absolute poverty (defined as income equivalent to less than $1.25 per day). Today that number is down to 27 percent, in inflation-adjusted terms. During the same period, average life expectancy has increased by three and a half years.

At Rio +20 environmentalists and the leaders of poor countries were hoping to shake down the rich countries for hundreds of billions of dollars in annual development assistance. But most of the development achieved during the last two decades was not the result of official assistance (a.k.a. taxpayer dollars) from the rich to the poor. In fact, a study published in the February 2012 issue of the Canadian Journal of Economics by a team of German development economists found that aid often retards economic growth, having “an insignificant or minute negative significant impact on per-capita income.” Most of the aid is stolen by the kleptocrats who run many poor countries, while the rest is “invested” in projects that are not profitable.

So what has produced so much improvement in the lives of poor people in developing countries since the first Earth Summit?

“Remember in the 1960s, official development assistance accounted for 70 percent of the capital flows to developing nations, but today it amounts to only 13 percent, while at the same time, development budgets have actually increased,” explained U.S. Secretary of State Hillary Clinton at Rio +20. “Why is that? Well, you know very well. Because while continuing to provide assistance, the private-sector investments, using targeted resources and smart policies, have catalyzed more balanced, inclusive, sustainable growth.” Summary: The way to development is trade, not aid.

Activists, frustrated at their inability to effect wealth transfers, are now fixated on a particularly puzzling and disturbing goal: to maintain and expand open-access commons, which are unowned properties available to be exploited by anyone. Many participants at the People’s Summit for Social and Environmental Justice, a parallel Rio gathering of 200 environmentalist groups, advocated a green twist on an old red ideology, even postulating that property is theft.

Canonical Marxism predicted that capitalism would collapse under the weight of its class “contradictions,” in which the rich get richer and the poor get poorer until reaching a social breaking point. In the environmentalist update, capitalism will collapse because the pollution produced by its heedless overconsumption builds to an ecological breaking point. For the hard core, the solution to environmental problems is a kind of eco-socialism in which nature is prevented from being “privatized” or “commodified.” This trend in environmentalist thinking might be called commonism.

Looking across the globe, it is true that various aggregate environmental measures have deteriorated. Since 1992, the United Nations Environment Program (UNEP) claims, biodiversity has declined by 12 percent, and 740 million acres of primary forests have been cut down. Today 53 percent of fish stocks are fully exploited and the share that is overexploited, depleted, or recovering has risen from 10 percent to 32 percent since 1974. But are these calamities the result of rapacious capitalism? Not really.

The same UNEP report notes that 80 percent of the world’s forests, which harbor the bulk of the world’s biodiversity, are government-owned. Also, in nearly every place where some kind of environmental calamity is under way, it is taking place in an open-access commons. Polluted river? No one owns it. Forest getting cut down? Same problem. Overfishing? Likewise. A water shortage? Ditto. Empirically, calling for the enlargement or reimposition of a commons with respect to an environmental resource or amenity is tantamount to calling for its eventual destruction.

Countries with strong property rights generally see environmental improvement such as reductions in air and water pollution, stable fishery stocks, and expanding forests. That’s because owners protect their resources, since they directly suffer the consequences of not doing so. Furthermore, countries with strong property rights are more prosperous and can thus afford the costs of environmental regulations, even inefficient ones, applied to those commons that still remain.

Two decades on, what was once the “most powerful political ideal” on the international scene crashed and burned at Rio +20. The failure of environmentalism as an ideology was inevitable, since it has so badly misconstrued the causes of many of the problems it claims to address. It will be interesting to see in which direction those cherishing a permanent animus against democratic capitalism will now go.