Visualizing Planetary Boundaries

Visualizing Planetary Boundaries

Putting the planet on a path towards stabilized greenhouse gases is no easy task. This week, as COP-16 opens in Cancún, we can already prepare ourselves for much political jostling over emissions targets, adaptation measures, technology transfer, and, critically, who will pay for it all.

With seasoned COP veterans already predicting a stand-off over climate finance, we figured it was time to refocus attention on what's at stake: According to the best available climate models, world temperatures are now on track to 5.2°C (9.2°F) by 2100—frighteningly far past the scientifically prescribed "safe" value of 2°C.

Of course, no one knows with absolute certainty where the safety zone lies: Like all complex adaptive systems, the climatic one exhibits multiple positive and negative feedbacks that make any hard CO2 targets a sophisticated guesstimation at best. Still, some very smart earth scientists, aided by increasingly sophisticated climate models, are growing concerned that there does exist a greenhouse-gas boundary that, once crossed, might pitch the planet into a dramatically different state.

Are we nearing this planetary "tipping point?" If so, how do we get back? In a seminal paper published last year in Nature (and in a longer version, in Ecology and Society), a contingent of the world's leading environmental researchers set out to answer this question. And they didn't stop with climate change, but identified a total of nine environmental processes that, they felt, could disrupt the planet's ability to support human life. For each of these processes they suggested a limit, a boundary for maintaining a habitable Earth.

An elegant thought experiment, the "planetary boundaries" concept not only provides a crisper definition of safety limits — 350 ppm, for instance, for atmospheric concentration of carbon — it also gives us a sense of how those limits might influence each other. Land-use change, for example, usually means converting forests into farmland. This transition, of course, affects climate warming, which in turn affects biodiversity loss.

With all of those dynamically shifting boundaries, each shaping the other, we wondered what the "safety zone" at their center would look like. How would we visualize a "safe operating space for humanity?"

That's the challenge we wagered to some intrepid student designers earlier this month, when we invited them to New York City for our very first Visualizing Marathon. The visualization you see here, by a team of students from the School of Visual Arts, is one of our favorites, as it shows how the world has crept toward the nine boundaries (and in some cases beyond) over historical time.

For instance, drag the grey bar all the way leftward to "Pre-industrial" time, and you can see that global population hovered around 2 million, carbon levels were well below 350ppm, and stats for many of the other boundaries were not even on the charts. Pull the bar into the 1970s, and nitrogen levels are the first to shoot out of bounds. By 2010, we've overshot two more critical boundaries: the 350ppm threshold for CO2 (today, it hovers at 387ppm), as well as the 10 species-per-million-year bounds for biodiversity (experts estimate today's losses at somewhere between 100 and 1,000 times that rate). Meanwhile, ocean acidification, land-use change, and ozone depletion are creeping dangerously close to their prescribed limits.

The tabs at left reveal that many drivers and impacts of global change are interrelated: A click on both "Ocean Acidification" and "Climate Change," for instance, shows a common cause: as we pump more greenhouse gas into the atmosphere, causing global temperatures rise, the oceans also absorb vast quantities of CO2, which in turn lowers their pH. Similarly, chopping down forests is both a driver of biodiversity loss and a symptom of changing land use across the Earth.

Visualizing the planet's boundaries as a collective set, rather than as a set of individual limits, can be disspiriting— so many impending disasters to tackle at once! On the other hand, it also suggests that just as the problems are interconnected, so too are the solutions. Making headway on carbon emissions will help to curb both climate change and ocean acidification. Investing in revolutionary agricultural practices, such as precision agriculture, integrated pest-management, and more efficient water and fertilizer use will be a royal flush, helping to combat land-use change, biodiversity loss, nitrogen and phosphorus pollution, climate change, and freshwater use.

With all nations pinching their wallets even tighter than at this time last year, Cancún deliberations are likely to beeline into gridlock over money. In the next two weeks, world leaders will inevitably claim that aggressive commitments are just too expensive in today's economic climate (see here for a new World Bank estimate of costs). Visualizations like these are a potent reminder that while cutting carbon is hard, doing so will have multiplicative effects. And the rewards — keeping the planet habitable — just might be worth the effort.

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