Scientists agree that mankind is pushing the planet beyond sustainable boundaries. Who’s listening?

Watch two video interviews of James Lovelock and Jim Hansen, as they discuss the need for boundary conditions and what can be done to save our planet.
In the 20 years since NASA physicist Jim Hansen alerted the world to global climate change, a broad consensus has emerged among scientists.

Most scientists agree that the planet is warming and that human behavior is largely to blame. Intense use of fossil fuels release clouds of carbon dioxide that absorb heat from the sun and, in turn, warm land and ocean.

Scientists have also concluded that, because of the carbon dioxide already in the atmosphere, the Earth will continue to warm, even if there were to be a dramatic cut on new carbon emissions today.

And, they generally agree that extreme weather—hurricanes, floods, droughts, high winds, extreme heat and even sudden cold snaps—will occur more frequently because of the changing climate. Dry places, like California and the Southwest, will get drier, and wet places, like the upper Midwest, will get wetter.

Those changes are in the pipeline, and scientists and researchers are modeling the future and exploring the paleoclimate record to understand the potential results of this increasing stress on the Earth’s climate.

The latest effort focuses on identifying fail-safe points in the planet’s ecological systems.

“We need to start exploring boundaries, planetary fences within which mankind can safely operate,” says Dr. Johan Rockström, executive director of the Stockholm Environment Institute and of the Stockholm Resilience Center.

Rockström’s specialty is the management of water and natural resources, and he is now working with some of the world’s leading scientists to identify the planet’s ecological weak spots from a multidisciplinary perspective. Whatever the parameter, “if we pass [certain] boundaries, we come into danger zones and move toward potentially catastrophic tipping points. It’s not a doomsday concept,” he says. However, “the planet itself has absolute limits.”

Our unique rollover feature shows you how the different boundary conditions affect the environment and how the levels certain environmentally hazardous materials have risen since the Industrial Revolution.
Looking for Limits

Dr. Rockström recently helped to gather 20 of the world’s leading scientists and environmental experts—representing the entire range of natural sciences—in Tällberg, Sweden to identify the most important planetary boundaries.

The guiding principle of their work was a simple one, as summarized by Hansen, who participated in the meeting: “we must avoid consequences we could not bear, under any sensible concept of humanism.”

Global warming is only one environmental consequence of human behavior. Increasing ocean acidity—caused by excessive build up of carbon dioxide—threatens drastic reduction in fish stocks.

Dramatic changes in the flow of rivers—caused in part by disappearing snowcaps (which makes for dry summers) and also by other effects of global warming—means that fresh water is becoming scarce in many parts of the globe. Biodiversity is declining rapidly: more species have been extinguished or endangered in the past 50 years than at any other time in human history. The list goes on.

Watch Johan Rockstrom and Kevin Noone—two participants of the conference in Tallberg—discuss the Earth’s tipping points.

The meeting in Sweden was the first time leading global experts have convened to discuss how all these impacts interact and to define what they believe to be the most important boundary conditions. Although it is a work in progress, the experts proposed quantitative levels for most of the boundaries beyond which the science indicates that the Earth’s environment will become endangered.

Stabilizing concentrations of carbon dioxide is the first priority for planetary safety. Today, the world’s coal, oil and natural gas industries dig up and pump about seven billion tons of carbon each year. We burn nearly all of it to produce energy, thereby releasing carbon dioxide into the atmosphere.

The relationship is simple and circular: more carbon in the atmosphere produces more global warming, which further changes the climate, which pushes the Earth towards more tipping points, which produces more carbon dioxide.

The scientists reached a key conclusion: carbon dioxide levels should not exceed 350 parts per million, even though the scientific panel advising the United Nations had recommended 400 as a target. The scientists at Tällberg agreed that above the 350 mark the risk of dramatic change increases substantially. For example, the disintegration of the Arctic and Antarctic ice sheets would likely accelerate with catastrophic consequences.

The bad news is that we passed 350 several years ago: carbon dioxide levels are now around 385, increasing about 2 ppm per year.

The scientists also agreed that the planet has passed at least two other critical boundaries: biological diversity and nitrogen flow into lakes and rivers.

On the other hand, concerted world action over the last two decades has managed to somewhat reverse the extent of atmospheric ozone depletion, which had created large holes over Antarctica.

Each of the boundary issues identified requires the same sort of action, in part because they are part of an integrated system.

“Glaciers melting in Greenland interact with…ocean acidification. And land use changes the way water cycles around the planet,” says American scientist Kevin Noone of the International Geosphere-Biosphere Programme. He believes that the only way to make real progress is to look at the boundary conditions as parts of an integrated system, and take action on all of them.

Taking a cue from British author Mark Lynas, we present you with an interactive feature that outlines exactly what will happen to the U.S. if the global temperature is raised by one degree, two degrees…all the way to six degrees.Bringing It Home

Today, the average American is responsible for releasing more than 20 tons of carbon dioxide into the atmosphere every year, a much bigger individual “carbon footprint” than the citizens of any other nation.

In a recent global ranking of the environmental performance of 150 countries, the United States placed 39th, behind most of Europe and much of Latin America. Unless the world’s largest per-capita carbon dioxide emitter changes its behavior radically, there can be no solution.

Yet even as the majority of scientists have moved from asking “what” and “why” to asking “how much” and “when,” American attitudes have not changed much.

A McKinsey poll (PDF) last year found that, of the 56 percent of Americans who say they are concerned about the environment, only 15 percent said their concern had actually translated into some sort of action. And, according to a Gallup poll, 58 percent of Americans still believe global climate change won’t seriously affect them in their lifetimes.

How hot does it have to get before Americans take action?

In our interactive feature, find out exactly how you would have to change your lifestyle every day to live within a carbon footprint allowance that could help slow climate change.