NEW YORK CITY—The state of the planet is grim, whether that assessment is undertaken from the perspective of economic development, social justice or the global environment. What's known as sustainable development—a bid to capture all three of those efforts in one effort and phrase—has hardly advanced since it was first used in the 1980s and the world is hardly closer to eradicating extreme poverty, respecting the dignity and rights of all peoples or resolving environmental challenges, whether climate change or the extinction of plants and animals. Or so argued the participants at the Earth Institute's State of the Planet 2012 meeting on October 11.

The primary force behind all three of these challenges is of course, humanity, which now puts more nitrogen into the soil than biogeochemical processes and hijacks some 40 percent of the photosynthetic product of plants on land. Our species has also become the determining factor in the carbon cycle, emitting more than 40 billion metric tons of carbon dioxide per year and slowly changing the chemical composition of the atmosphere. No wonder some scientists have argued that this is a new era in the planet's history, one best described as the Anthropocene.

Earth Institute director and economist Jeffrey Sachs, a member of the Scientific American advisory board, delivered this indictment of current human activity to start the day and the dire prognosis was then reaffirmed by everyone from college students in Kazakhstan presenting via video conference to the deputy secretary general of the United Nations, Jan Eliasson. As a student from Brazil noted, even the reduction in deforestation in the Amazon has proved temporary, ramping back up this year.

But there is hope. As Eliasson observed: "Nobody can do everything but everybody can do something."

After all, the world has tackled and resolved big problems before: we are on the way to phasing out the pollutants behind the annual ozone hole and eliminating lead from gasoline in most countries. Christiana Figueres, executive secretary of the U.N. Framework Convention on Climate Change, who has to try to get the world to agree on what to do about global warming, argued that the climate meeting in Durban last year represented a commitment to doing "something" about greenhouse gas pollution, even if it is "not enough." Durban represented a "signal that we are going forward with a low carbon economy," she said via videoconference. "A few years from now, low carbon will be the norm, not a novelty."

That had better be the case, given the loading of the climate "dice" that has been ongoing since climatologist James Hansen first testified about global warming to the U.S. Congress back in 1988. Those dice are still loaded and "becoming more loaded," Hansen said. "We've only felt half the warming from the gases already added to the atmosphere," thanks to the long lag time in warming the oceans, a process also already well under way. As a result, the world can expect at least as much warming of average global temperatures as has already happened—0.8 degree Celsius—even if all greenhouse gas emissions stopped today.

As a result, the Anthropocene may prove too hot to permit permanent ice in polar regions. Already, summer sea ice in the Arctic has reached perilously low levels and Hansen suggests it is already a foregone conclusion that it will be gone in coming summer seasons.

Climate change is also, obviously, having an impact on the weather. Extreme weather is becoming the norm, like the drought in the Horn of Africa in 2011 that saw an already dry region receive just 5 percent of its "normal" rainfall. For comparison's sake, last year's severe drought in Texas stemmed from receiving only 35 percent of that region's normal rainfall, noted atmospheric scientist Lisa Goddard, director of the International Research Institute for Climate and Society at Columbia University. "A lot of countries that had zero to do with climate change are being pummeled by climate change," Sachs added, suggesting aid to these regions is really compensation.

The problem in addressing climate change, which Sachs also called the biggest and hardest challenge ever to face humanity, may be human nature itself. Fossil fuels remain the cheapest fuel source, and as long as they do, we will continue to burn them, Hansen noted, arguing for a carbon tax on coal, oil and natural gas with the proceeds distributed to citizens of the countries collecting the tax. And climate change timescales are "longer than human memory and longer than terms in political office," Goddard noted. "Human experience is also largely local, and it's hard to notice a global trend."

At the same time, the more than a billion people mired in energy poverty must be given access to modern energy. If that comes from fossil fuels, it may prove difficult to solve global warming. Engineer Vijay Modi of Columbia University has come up with a way the energy poor can avoid burning kerosene or the like: micro-grids powered by the sun. Modi's Shared Solar combines a village wired by the government with a privately funded solar installation run by a smart meter and doled out on a prepaid basis to villagers. So, for example, the village of Segou in Mali, which has such a system, has a vendor with a smart phone who uses an app to sell increments of electricity generated by the sun to his neighbors.

Shared widely via a new effort called the U.N. Sustainable Development Solutions Network, or perhaps just the burgeoning population of Internet-connected mobile phones, such technology could provide light at night for a girl to study by—and the education of women is a crucial part of any bid to address poverty, social justice and environmental problems. Or it can empower local entrepreneurs, such as a women's fishing collective that now has a refrigerator to store its catch or the local tailor and his new light. If such technology ends up fueling economic development, social justice and environmental improvement, then the state of the planet just might improve this century. After all, as Eliasson observed, when asked if the world needs a plan B given its dire state, "there is no planet B."