Showing posts with label climate change. Show all posts
Showing posts with label climate change. Show all posts

Tuesday, October 02, 2012

My State of the Planet


State of the Planet 2012
On Oct. 11, 2012, Columbia University and the Earth Institute hosted the State of the Planet Conference. They asked the students and professors to answer some questions that were going to be discussed. Here are the questions and my answers: 
  • What can we do to make the planet habitable for future generations?
First, realize that working within the economic system we have now will not solve the multiple problems we face (environmental, economic, social justice). So the following suggestions only work if the economic system in which we live is reworked (torn down?) and a new one put in its place. The fastest way to resolve a Gordian knot is by severing it.
The other thing we need is a new, Earth-based baseline. We have been using economic baselines and human baselines, now we need to see what an ecological baseline looks like, so that we can put the other two in context. So I thought of an experiment.

Publish and disseminate widely the results of the following Reality Check Exercise as soon as possible (most of the data has probably been collected by universities already; all this exercise needs is global compilation, an agreed-upon framework, analysis and recommendations):
Take a global (GIS-based) inventory of a) built areas (cities/roads/commerce/industry), b) wild and almost-wild areas (wilderness/parks/recreation areas), and c) ‘in-between’ areas (agricultural/logging/mining areas). Define the areas according to biodiversity health. This will give us a global inventory by region, state and nation that tells us which regions have how much of what and in what percentages and absolute numbers. Each county, state, and nation will know the amounts of their built areas, wilderness areas, and 'in-between’ areas in relation to their micro-ecosystem, the larger ecosystem/watershed, and the global ecosystem. Transpose this to Google Earth (or similar software) so that layers can be manipulated easily by all viewers without changing the underlying data.
[For the ‘in-between’ areas, separate denominations should be made for earth-friendly or commercial/industrial uses: industrial agriculture versus organic agriculture, managed forests versus clear-cutting, etc. Beginning with a micro- (as in microclimate) ecosystems, then meso- (regional) ecosystems and ending with a macro- (global) ecosystem, tally the biodiversity, ecological services, hydrological services, and state of health of the various ecosystems on Earth. Also add a layer of what impact 'cradle to cradle' commerce would have, as opposed to the 'cradle to grave' commerce we now have.]

Treat the oceans as an international commons and do the same for them (divide into percentages of ‘clean’ oceans, ‘dirty’ oceans (garbage patches, oil spills etc.), commercialized-areas oceans (oil rigs, shipping lanes, trawling areas, etc.), and add a health component (of coral reefs, of fish stocks, of ocean acidification, of dead zones). Add a layer for sea level rise, ocean currents and the thermohalene current.

 Since we have an ethical debt to future generations to consider (given how our cumulative actions in the past 200 years will impact them so dramatically and so long into the future), add an intra-generational aspect by adding length of time for ecosystems to recover to a ‘livable’ stage from our current polluted state (back to a baseline of environmental health of, say, 1800? That baseline is not a ‘pristine environment’ but it is before population growth’s ‘hockey stick’ went vertical, and before modern wars and the rise of the 'military-industrial complex').

By deciding to have nuclear energy (and its concomitant nuclear waste), we have already decided to impinge on the lives of everything on this planet for the next 100,000+ years and 5000+ generations. This is a responsibility we must honor and take into account in every decision we make in current Climate Change policy, not just in deciding where to site the nuclear storage depots. We have a responsibility of being here to take care of the nuclear waste we have produced.

Add all (global) nuclear waste sites and nuclear reactors to the map, and draw a circle with a 50 mile radius around them. Also add superfund sites, health hazards, and all other variables included in the Measure of America map (http://www.measureofamerica.org/maps/ ), for every nation. For nuclear accidents in particular, wind patterns are important so overlay a wind map over the information map.

We also have an ethical responsibility towards all other living things on this planet, and their right to exist and have their own habitat. Therefore we must deal with the amounts of toxins we use. The annual and accumulated use of toxic chemicals should be inventoried, and expressed numerically [given a rating of which ones are cumulatively toxic to the environment (too much fertilizers degrade the soil and create ocean dead zones, etc.), and which are toxic in even minute concentrations (pesticides)?]. 

Map where the toxic chemicals are currently found, how they travel and where they are concentrated. Outright toxic chemicals should be banned and phased out of all production and use within 3 years. Toxic chemicals that become toxic in high quantities should be used in non-toxic quantities or be phased out within 5 years. All data should be counted cumulatively, adding current uses to the amounts already in the environment, so everyone can have a clearer picture of what we are all doing.

Industrial agriculture should adopt organic and permaculture processes in order to heal the soil, the rivers, the oceans, and all living things. Government should stop subsidies to agribusiness and fund incentives for relocalizing small farmers. GMO seeds should be banned for environmental and social justice reasons (food cannot be the sole province of corporations). Regulation should be put in place that does not allow multinational corporations to cause small farmers to go into bankruptcy through patent infringement or through loss of their organic certification.

All policy going forward should reflect this and support/enhance this in a positive feedback loop. It is incomprehensible that our civilization is killing itself because it does not know how to transition to using safe, non-toxic chemicals, or thinks it cannot be happy living self-sufficiently and communally (instead of inside an unsustainable, rigged and unjust economic system intent on poisoning and destroying our only habitat). Or that our society  thinks that it must monetize toxic substances (originally used in biological warfare) into barely disguised ‘necessary tools’ for growing food crops (pesticides) especially when there are viable alternatives (permaculture) that are not wealth-concentrators, simply because they have already patented the chemicals (Agent Orange, napalm).

Just because we have discovered something does not mean we have to develop it, or develop it in the old (wealth-concentration-economy) way. Web 2.0 and new sharing businesses (zipcar) point to a growing trend for an interest in a sharing economy. Let's grow along those lines.

As part of the experiment, recommend policies solely for the health of Earth, its systems and biodiversity (no political, social or economic concerns at this point – just the health of the planet and its biodiversity in a model that includes adequate space for humans, their shelter, workspace and infrastructure, and sustainable organic food production only).

Create a table with a) absolute size in acres and b) a percentage of each nation's land mass in each of the following areas: 1) Built environment (urban/suburban areas), 2) Agriculture/logging/mining (rural areas), and 3) Wilderness/parks/recreation areas.

Once you have the Actual Land Uses mapped (an educated guess of 20% built, 30% wilderness (including deserts and frozen places) and 50% 'in-between'), create a second map that would delineate zones for each of the three areas (built environment, wild environment and in-between environment) as equitably as possible (say 30% built environment (for future population growth), 30% wild environments and 40% ‘in-between’ environments set aside for agriculture only), so that local, state and national governments can use those two parameters as guidelines for future policy decisions (what it is now and what it should be in order to have a healthy biosphere and stop runaway extinction rates and biodiversity loss).

The idea is to have a reference point so we can act ethically for ALL (human and non-human) stakeholders, including environmental health, for plants and animals, future generations and the resilience of the web of life (which will include 10 billion people by the end of the century). This is also designed to make humanity come face to face with our overpopulation problem as well.

Ranchers that pasture their cattle on public lands would be permitted to use public parklands (but only allowed the minimum of damage to the place, with only one set of guidelines in play), and they cannot decry the loss of some of their cattle to predators, nor can they lobby any government at any level to have any of predators removed, nor pay third parties to do so. If they want none of their cattle to be killed by predators, keep them off public lands where the predators live. 

Conclusions

These maps would give the governments and the people of the world a glimpse of the forces involved in their decision-making; the maps are a stark reminder that decisions made on one side of the planet can kill people on the other side of the planet; that geography trumps economy (for example, pristine forests in the Amazon, the Congo and Papua New Guinea should be saved as the lungs of the planet, and their worth remunerated to those countries in exchange for their leaving them intact). The maps, together, will give us more information on when we are crossing irreversible ethical and ecological thresholds, and when larger bodies (national, international) have to step in to safeguard the ecosystem for the benefit of the whole. Nations, regions, states and municipalities must work out a similar percentage for their areas independently, and then weave them together, giving equal weight to human needs and non-human needs.

Those areas that have overstepped the recommended percentages will know they should reverse course as quickly as possible so they can reach greater equity between priorities, or face sanctions and fines from the nation or global community. There are economic benefits and costs to both types of paths, but the paths being taken now only look better because we are not accounting for externalities correctly. So accounting for externalities is important and must be included.

These new policies and new parameters will also impinge on an individual's ‘freedom’ to decide what to do with their property, as they would have to take into consideration county, national and global environmental needs. Think of it as a new zoning layer.

Lastly, build a marketing program, an educational program and a social media program to go with the launch of these information maps so that in every Town Hall meeting, in every university, and in every political aggregation, people can discuss a) the needs and limits to the local ecosystem in the context of the global system and its needs, and b) all the things that can be done to create a localized, non-toxic, self-sufficient and resilient economy that does no harm to the environment or its inhabitants. We already have climate change reality. We must sell the dream of living self-sufficiently, communally, sustainably and joyfully. Focus on how much better we will be living as conscious, ethical beings.

What’s your plan for reducing the effects of climate change on the most vulnerable segments of our planet?

Stop all wars, and use part of that money for: 1. buying all remaining tropical rainforests and primary forests (Amazon, Congo, PNG, etc. ) and protect them from any ecologically harmful changes to their ecosystems (including building huge hydro-electric generating dams), using active and well-paid locally sourced policing and conservation employees in the areas; and begin a massive study on how best to preserve and enhance the forests and biodiversity and bioculture (and the indigenous peoples living there*) and potential biomimicry adaptations we can glean from the forests. At the same time, launch a global re-forestation project and an archive of indigenous knowledge of local environments.

 (*strict regulations as to how much interchange between ‘civilization’ and indigenous cultures must be set up so that indigenous groups can live fully in the jungle, but their members who now live in the city would be given a choice (live in the city or the forest, but you can’t go back and forth) to avoid bringing with them noxious ideas, viruses and behaviors. Also, allow as little outside influence or intervention as possible from ‘civilized’ people. Like the Amish, who allow their children to visit the outside world once they reach maturity and let them decide whether they want to stay or come back - only stricter.)

2. Launch a global hydrology cycle study, inventory global freshwater. Eliminate environmentally unnecessary virtual water transfers (transfers created solely for economic reasons), and model for the most efficient use of water in each hydrological region. Create a global body of hydrologists that monitor and manage the Earth’s hydrological systems at every level (local, national, international).

3. Halt all Arctic oil exploration, all deep water exploration, all oil drilling in vulnerable areas, all tar sands excavation, and all coal and natural gas (hydraulic fracturing) extractions. Change the laws so that the companies have the burden of proof in court. Immediately change the fossil fuel industry’s focus to solar and wind energy (just as we did in WWII from building cars to building trucks, planes and weaponry! Only in reverse!).

Get alternative energy to as many households as possible as cheaply and rapidly as possible. Solve how to transition away from centralized energy grids to communal or regional grids according to regional advantage (some have more sun, some more wind, some have hydro etc.). Include building codes that allow for 'Passiv Haus' parameters and local building materials (cob, strawbale, bamboo, wood, plaster, adobe and any future ways in which we might be able to build our homes ourselves out of natural local materials).

Change perceptions among humans that everything has to be ‘on’ all the time. Nurture the idea of ‘down time’ in electricity use and in work lives. Imbue corporations with a ‘use forever’ product mantra instead of a ‘throw-away-and-buy-again’ mantra. Explain to corporations and their employees that what they are doing is bringing an old way of life to an end, and creating a healthy new one in its stead. Explain that helping households within an energy self-sufficient and food secure community become self-reliant and resilient is the ultimate goal, not monetizing new ways of concentrating wealth. Helping soon-to-be-downsized workers transition to becoming entrepreneurs and consultants must also be implemented rapidly.

4. Anything that has to be mined out of the earth is to be left in the ground during an indefinite moratorium on extractive practices.

 5. We must give our research universities and national laboratories an Environmental Manhattan Project’ mandate, a chance to come up with other, multidisciplinary, viable mining/energy alternatives that do not include harming the earth, the air or the water, and that allows the economy to transition from a wealth-concentrating model to an equitable wealth model that includes sharing of large, newly denominated Common Lands (all previously designated wildernesses/parks/recreation and agricultural/logging/mining lands would come into a local, national and global ‘land escrow account’ where locals would have a say in the use of the lands, but national and global members would also have a say, and veto power, with regards to its noxious use within the larger framework of the Earth Ecosystem.

6. In conjunction with the ‘Environmental Manhattan Project’, we need a Global Marshall Plan for each nation to transition to the new conditions of climate change, social justice and economic egalitarianism.

7. Have all universities dedicate some significant portion of their research in every department on how each discipline can help humanity transition from the current economic, environmental, and social crises by focusing on creating local-scale communities as healthy, self-sufficient, food-secure and energy-independent as possible. This is meant to gear academic resources towards making humanity part of the ecosystem again (communal economy), so we can continue to be here for thousands of years, living within Earth’s means. This should influence all other courses, programs and teachings in the university to have a basis of ecologic sustainability first, then sustainability in everything else. It may also break the stranglehold corporations have on funding research and development programs for private benefit.
Artisans and craft workers must have a chance at becoming entrepreneurs with viable local businesses. We would need to grow materials for making clothes (flax, linen, silk, wool, leather), for making household utensils and tools, for building, for growing food, and for generating energy and for transportation, and they all have to be non-toxic, reusable or recyclable.  This could form the basis of an additional, less academic curriculum.

8. Begin a worldwide patent search on 19th century mechanical products to see which ones can be best adapted to today’s problems, and focus our technology transfer mechanisms into delivering those that can most easily, affordably and cleanly be adapted, and built from local natural resources (e.g. a bicycle frame made from bamboo, or wood, or extruded recycled plastic, depending on where you live).

9. Decree an immediate 80% reduction goal of all CO2 emissions from any source within 5 years. Decree that only mass transportation and home heating emissions are to be allowed less significant emissions reductions, but that all emission sources will be audited and reduced to the barest bones in the developed world (enough energy to power per household: one refrigerator, one stove, one house-wide temperature control {A/C and heater}, one television, two lights per room; and per person: one cel phone, one computer, one digital reader, one digital camera, one radio. Period. Anything extra pays double for it.)

10. Repurpose old waste dumps: start a plastic extraction drive, pay indigents that already scavenge dumps to get metals, glass and plastics out. Research ways in which dumps can be transformed, not into sterile mounds, or waste-to-energy centers, or cleaned up urban parks: but be actually cleaned. Institute high recycling regulations, from packaging to lifecycle, to materials used, and make everyone accountable for their wastes.

11. Stop ALL commercial fishing in all the oceans immediately. Allow some small coastal fishing to go forward (in boats less than 40’ with no ‘Mother Vessels’ to take their catch in the high seas, and never near the coast or on coral reef areas), and establish marine reserves every 50 nautical miles with no-fishing zones, and pay locals to protect the area and guide the tourists to it. Repurpose the commercial fleets for cleaning the various garbage patches of the oceans. Begin serious research on how to mitigate ocean acidification (ways to de-acidify the ocean, not just less CO2 in the atmosphere).

12. Put considerable resources towards helping India/Pakistan/Afghanistan create sustainable water use programs. Work towards resolving the nuclear threat there, and help the Afghans rebuild Afghanistan in a way that they keep their money and their resources. Keep working to decommission all nuclear armaments around the world. Help Israel and Palestine resolve their differences, help the Palestinians build their state and Israel feel more secure.

13. Put considerable resources towards researching and helping China stay away from producing and consuming so much fossil fuel, especially coal.

14. Add Environmental Anthropology (how past peoples lived within the environment) and Sociological Environmentalism (how we can best, as a society, transition from a consumerist society to a ‘Do only Good’ society - also bringing added meaning to economic ‘how we are doing’ indexes – like the Happiness Index is trying to do) to mainstream discourse. Most importantly, add Herman Daly's Ecological Economics as a core requirement for graduating from university.

15. Form a partnership between the insurance industry and government disaster relief and disaster preparedness agencies, whereby each helps the other in symbiotic ways, and each watches the other work solely for the benefit of the victims of climate change. The insurance industry can make good money, but not obscene money off of disaster victims, and homeland security cannot funnel funds to the military surreptitiously. They need to be transparent, and the insurance agencies need to give people coverage that they can use (e.g. “I can only afford to pay for 50% of the value of my paid-up house if it floods out. What good is that? I need affordable replacement value!”)

16. Tax the Derivatives markets 90% and make them transparent (the market is at $1.2 Quadrillion dollars as of May 2012 – 20 times world GDP – and they are where all the profits in the world are going, and not allowing us to spend money where it is truly needed). By taxing them, there would not be a ‘casino’ mentality where hedge fund managers could make billions of dollars on one bet, and it would eliminate the biggest development stopgap and economic wealth-concentrator we have. Use the profits for education, infrastructure repair, transitioning to a new economy, all of the above projects, and communicating the importance and benefits of the ‘New Economy’.

We have to remove all the monetary incentives that make us believe we can grow indefinitely. Poverty is eradicated through education (for all), which must be made available and affordable. And not just elementary education, but the opportunity for high level education (Masters’, PhD’s) for all. We should all be in school until we are 30 years old if we want to, and education should be heavily subsidized by the state.

In Conclusion: Think of the mobilization we had in WWII, and the way we felt we were doing the right thing and that we would do anything to save each other. How good it must have felt to act morally and ethically on such a grand scale! Well, that is what we need again! The problem is that a majority of people with good paying jobs will lose them, and will have to train for or learn new ones, which none of them will want to do unless forced to do so.

  [What we have now – ecocide on a global scale – or genocide cubed (humans, other life forms, and the environment)– affects everything. We have found the enemy and the enemy is us. We are killing ourselves, and taking baby steps to save ourselves will not save us.]

We in the developed world have to change ourselves first, radically and immediately. We cannot continue our denying, delaying, whining, trying to ‘game’ the outcome. Those that are denying are just trying to have enough time to have one last 'play' where they can amass more wealth before everything crashes. If you don’t have wealth now, it's too late. We have to stop this endless overconsumption. We have to begin to live as thriving, sharing communities and not continue as greedy, short-sighted individuals.

How can developing countries eliminate extreme poverty without turning to economic practices that further harm the environment?

First, by seeing us, the developed world, transition to a more conscious way of living, to see our real desire to share and integrate developing countries into a global whole, by seeing us cut back our waste and over-consumption, and live more simply and equitably, by seeing us help them help themselves, without ulterior motives (like the nefarious colonial self-interested help in exchange for ownership of natural resources).

By seeing us regulate the national and global banking system, tax the financial risk markets and use that money for education, and take back the power of all that money being held back in private accounts (offshore accounts) and regulating it so as to diminish wealth concentration through time instead of helping individuals amass it.

By seeing, once and for all, that we, the developed world, have realized that there are, in fact, limits to our growth, and that we cannot – physically, economically or ethically - sidestep the reality that we have accumulated more than is justly ours, and must now give some of that back (redistribute the wealth) and help other nations to rise up from poverty into self-reliant, economically stable, food-secure countries.

By seeing that we understand that we have to solve all our problems at once: save our habitat, change our economy, our way of life, our culture and our way of doing business. 9 billion people will need a better managed everything.

Second, we must help developing countries attain self-reliance, and do away with the current model of conspicuous consumption of foreign-made goods and the dream of amassing untold personal riches. We have tried concentrated wealth and that experiment did not work. Now we have to change that narrative and begin thinking of ourselves as part of a community and part of the web of life on Earth, and living well by using only what we need, and sharing everything.

 • Will developed countries take more responsibility in their overuse of the planets’ resources and demonstrate a more sustainable example?

That will only happen if an impressive majority of We, the People, tell the political leaders that is what we want. The politicians depend on the money special interests give them to keep their jobs. So politicians have to go back to only using government funds for their campaigns; and the people of the world have to be educated as to that it means to live consciously and have a clear picture of what their vote means for the environment.

 And by educated I don’t just mean university degrees. I mean concerted efforts to use the vast potential we have in our media outlets to inform people of facts, (instead of only watching shows of has-been celebrities dancing, tacky women dressing up 24/7, or political blowhards).

 Use these powerful media tools to educate those that cannot or will not go to school, and use it to keep alive the conversation and the interest in the topics. This means redesigning the purpose of TV, radio, and all marketing and public relations functions, by making them pay for equal time of instructive, entertaining television as they pay for ‘airhead’ television. The current situation where any radio announcer has an opinion and it is weighted equally with more educated and nuanced thinkers is untenable. I mean using media to speak the truth, not spew political propaganda.

Oh! And corporate personhood has to be abolished. It is just another way to concentrate money. Corporations are a tool for business, not a shield from responsibility.

Change these things, and we might see the dawning of the next millenium.
Monica Perez Nevarez
Columbia University
Master of Science in Sustainability Management '12

Friday, February 26, 2010




From ocean to ozone: Earth's nine life-support systems
18:00 24 February 2010 by Fred Pearce, New Scientist, http://www.newscientist.com/special/ocean-to-ozone-earths-nine-life-support-systems

We have already overstepped three of nine planetary boundaries and are at grave risk of transgressing several others

EARTH'S NINE LIVES

UP TO now, the Earth has been very kind to us. Most of our achievements in the past 10,000 years - farming, culture, cities, industrialization and the raising of our numbers from a million or so to almost 7 billion - happened during an unusually benign period when Earth's natural regulatory systems kept everything from the climate to the supply of fresh water inside narrow, comfortable boundaries.

This balmy springtime for humanity is known as the Holocene. But we are now in a new era, the Anthropocene, defined by human domination of the key systems that maintain the conditions of the planet. We have grabbed the controls of spaceship Earth, but in our reckless desire to "boldly go", we may have forgotten the importance of maintaining its life-support systems.

The demands of nearly 7 billion humans are stretching Earth to breaking point. We know about climate change, but what about other threats? To what extent do pollution, acidifying oceans, mass extinctions, dead zones in the sea and other environmental problems really matter? We can't keep stressing these systems indefinitely, but at what point will they bite back?

Last year, Johan Rockström, director of the Stockholm Environment Institute in Sweden, sat down with a team of 28 luminaries from environmental and earth-systems science to answer those questions. The team included Nobel laureate Paul Crutzen, NASA climate scientist James Hansen, Gaia researcher and "tipping point" specialist Tim Lenton, and the German chancellor's chief climate adviser Hans Joachim Schellnhuber.

They identified nine "planetary life-support systems" that are vital for human survival. They then quantified how far we have pushed them already, and estimated how much further we can go without threatening our own survival. Beyond certain boundaries, they warned, we risk causing "irreversible and abrupt environmental change" that could make the Earth a much less hospitable place (Ecology and Society, vol 14, p 32).

The boundaries, Rockström stresses, are "rough, first estimates only, surrounded by large uncertainties and knowledge gaps". They also interact with one another in complex and poorly understood ways. But he says the concept of boundaries is an advance on the usual approach taken by environmentalists, who simply aim to minimise all human impacts on the planet. Instead, he says, boundaries give us some breathing space. They define a "safe space for human development". And here they are.

Earth's nine life-support systems: Acid oceans

Boundary: Global average aragonite "saturation ratio" no lower than 2.75:1
Pre-industrial level: 3.44:1
Current level: 2.90:1

Diagnosis: Safe for now, but some oceans will cross the threshold by mid-century
This is a relatively new issue, rarely discussed until 10 years ago. More carbon dioxide in the atmosphere means more is absorbed by the oceans, creating carbonic acid. Since the industrial revolution, the pH of the ocean surface has fallen from 8.16 to 8.05, equivalent to a 30 per cent increase in the concentration of hydrogen ions.

Acidification per se isn't a problem, but it has serious knock-on effects on other aspects of ocean chemistry. The most important of these is that it lowers the amount of calcium carbonate dissolved in surface waters.

This doesn't matter much right now. But a critical point will be reached if waters become too low in aragonite, a form of calcium carbonate used by many organisms, including corals, to build their shells. Below a certain threshold, aragonite shells and coral dissolve in seawater.

So far, the average aragonite "saturation ratio" in the oceans has fallen from a pre-industrial level of 3.44:1 to 2.9:1. That means, on average, that there is still almost three times as much aragonite as is necessary to keep shells from dissolving. There are wide regional variations, however, and recent studies suggest parts of the Arctic and Southern Oceans could drop below the crucial aragonite saturation ratio of 1:1 by 2050.

Nobody knows quite what would happen then. Some species might be eaten away by the acidic water. It could be the coup de grâce for many corals already poisoned by pollution and bleached by warming waters. Emptier oceans would be able to absorb less CO2, accelerating global warming. To prevent any ocean waters from entering this parlous state, Rockström proposes keeping the average global aragonite saturation ratio above 2.75:1. That would mean keeping atmospheric CO2 levels below about 430 parts per million, which is lower than the 450 ppm that scientists say is the safe upper limit for global warming.

Earth's nine life-support systems: Ozone depletion

Boundary: Average concentration of stratospheric ozone no lower than 276 Dobson units
Current level: 283 Dobson units

Diagnosis: Safe, and improving

The ozone hole that formed in the stratosphere over Antarctica in the 1970s was a classic example of an environmental tipping point. Ozone-destroying chemicals built up in the frigid stratosphere until they abruptly - and unexpectedly - caused the ozone layer over the Antarctic to shift into a new state, with ozone all but absent in the spring. Nobody saw it coming, as nobody understood at the time that the chemistry of polar stratospheric clouds makes ozone-destroying chemicals more potent, leading to runaway ozone destruction.
The world acted quickly to heal the hole. With most of the culprit chemicals now banned, the worst of the danger has passed.

It is not over entirely, however. One concern is global warming. Trapping more heat close to the Earth's surface leaves the stratosphere colder. This means that the Arctic stratosphere could get cold enough in coming years for the remaining ozone-eating chemicals in the atmosphere to open up an ozone hole over the northern continents.

Away from the poles we look safe, unless there is some unknown quirk of atmospheric chemistry waiting to trip us up. Rockström and Paul Crutzen of the Potsdam Institute for Climate Impact Research in Germany - who won his Nobel prize for ozone-layer chemistry - recommend preventing stratospheric ozone concentrations outside the polar regions from falling by more than 5 per cent, or below a global average of 276 Dobson units (a measurement of the density of stratospheric ozone). With the concentrations of ozone-eaters still falling, it seems likely that we will stay within this planetary boundary.

Earth's nine life-support systems: Fresh water

Boundary: No more than 4000 cubic kilometers of fresh water consumed per year
Current level: 2600 cubic kilometers per year

Diagnosis: Boundary will be approached by mid-century

Humans now control most of the world's rivers, damming and diverting many of them to death. Thanks to us, a quarter of the world's river systems no longer reach the ocean for at least part of the year. This is drying out swathes of the landscape, emptying wetlands and destroying fisheries.

Excess water use threatens humans in three ways: shortage of drinking water, loss of irrigation for agriculture, and changes in climate. Over the past 50 years, dams on rivers in central Asia have dried up the Aral Sea. Without the influence of the sea on climate, the entire region has become hotter in summer, colder in winter and more arid all year.
We need to limit the consumption of river water to around 4000 cubic kilometers per year, but we have a way to go before we hit that limit.

Meanwhile, as rivers run dry, we are pumping out ever more of the underground reserves held in the pores of rocks, many of them fossil reserves that will never be replaced by the rains. And we are disrupting other parts of the hydrological cycle by draining wetlands and razing forests. Deforestation of the Amazon will reduce evaporation rates in the tropical Americas, potentially changing weather patterns in the northern hemisphere, including the Asian monsoon.

Rockström, who is a hydrologist, suggests that preventing regional water crises from disrupting our global life-support systems will require limiting the consumption of river water to around 4000 cubic kilometers per year. That is roughly one-third of the flow down accessible rivers, excluding remote untamed rivers in rainforests and the Arctic. We have a way to go before we hit that limit. Current use is about 2600 cubic kilometers. But the excess is "largely committed already" for irrigating the crops needed to feed the growing world population, says Rockström. To keep within the boundary while feeding the world, we might have to curb irrigation of non-food crops like cotton or biofuels.

Earth's nine life-support systems: Biodiversity

Boundary: Annual species extinction rate no more than 10 per million per year
Current level: At least 100 per million per year

Diagnosis: Boundary far exceeded

Humans are driving species to extinction by plowing up or paving over their habitats, by introducing alien species like rats and weeds, by poisoning them with pollution, by hunting them for food and, increasingly, by changing the climate. Individual species may not matter much on their own, but collectively they form ecosystems that provide a range of vital "ecosystem services", such as recycling waste, cleaning water, absorbing carbon and maintaining the chemistry of the oceans.

Although we know that high levels of biodiversity are essential to healthy ecosystems, it is not yet clear how much can be lost before ecosystems collapse, nor which species are the key players in a given ecosystem. So Rockström's team settled on crude extinction rates as the best "interim indicator" of the state of ecosystems. They put the current extinction rate at more than 100 extinctions per million species per year, and rising. That compares with a natural "background" extinction rate of around 0.3. Up to 30 per cent of all mammal, bird and amphibian species will be threatened with extinction this century.

This cannot go on safely. Current rates may even mirror those of the "big five" mass extinctions of the past half-billion years, including the meteorite strike that did for the dinosaurs. While the world carried on after those events, it was massively transformed. To avoid a repeat, they suggest a safe long-term annual extinction rate of no more than 10 per million species per year. By that measure, they say, "humanity has already entered deep into a danger zone... if the current extinction rate is sustained".

Earth's nine life-support systems: Nitrogen and phosphorus cycles

Boundary 1: No more than 35 million tons of nitrogen fixed from the atmosphere per year
Current level: 121 million tons per year
Diagnosis: Boundary far exceeded and effects worsening
Boundary 2: No more than 11 million tons of phosphorus to flow into the oceans per year
Current level: 9 million tons per year
Diagnosis: Boundary not yet exceeded

Nitrogen is an essential component of all living things, yet only a small amount of the planet's stock of nitrogen is in a form that living things can absorb. This is "fixed" out of the air by bacteria in a range of leguminous plants. But you can have too much of a good thing. So other microbes "denitrify" ecosystems, converting the element back into forms not available for living things. This is the nitrogen cycle.

Farmers have always interfered with the cycle, because nitrogen availability often limits the fertility of soils. They have boosted production by planting more leguminous crops, like clover.

Then, a century ago, the nitrogen cycle changed forever when Fritz Haber, a German chemist, invented an industrial process for fixing nitrogen from the atmosphere to make chemical fertilizer. Today, 80 million tons of nitrogen is fixed from the atmosphere in this way each year and poured onto the world's fields.

But farming inefficiencies mean that most of this nitrogen runs off the land into rivers and oceans. Much of the nitrogen that does get into crops is later excreted by humans into sewers. We further fix nitrogen by cultivating legumes and burning fossil fuels, timber and crops. Put all that together, and we fix around 121 million tons of nitrogen a year, far more than nature does - and nature cannot cope.

The excess nitrogen is acidifying soils, killing vulnerable species and saturating ecosystems so that they lose the ability to recycle the nitrogen back into the air. Meanwhile, some over-fertilized lakes and seas in heavily farmed regions fill with "blooms" of aquatic life which then die and decompose, sucking all the oxygen out of the water in the process. The legacy of such blooms is anoxic "dead zones". At the last count there were more than 400 such zones in the oceans, covering 250,000 square kilometers, including parts of the Gulf of Mexico, the Baltic Sea and waters between Japan and Korea.

Rockström tentatively sets the safe level for human additions to the nitrogen cycle at about 35 million tons a year, one-quarter of the current total. Reaching that figure while continuing to feed the world is, to say the least, a tough ask.

Phosphorus, also used as fertilizer, is potentially part of the same problem. Around 20 million tons of phosphorus is mined from rock deposits annually and about half of this ends up in the ocean - about eight times the natural influx - where it contributes to blooms and dead zones. Rockström's team estimates that we can add up to 11 million tons of phosphorus per year without serious repercussions.

Earth's nine life-support systems: Land use

Boundary: No more than 15 per cent of ice-free land to be used for crops
Current level: 12 per cent

Diagnosis: Boundary will be approached by mid-century

The spread of farming into natural ecosystems, especially tropical forests, continues apace. Half the world's tropical rainforests are gone and large areas of grasslands once open to wildlife are now fenced in for livestock ranching. According to Rockström, the expansion of agriculture is the major driver behind loss of ecosystem services and threatens to both exacerbate climate change and damage the freshwater cycle. Meanwhile, urban areas are spreading across more densely populated regions like east and south Asia, Europe and North America.

Rockström sets his land-use boundary at the conversion of no more than 15 per cent of global ice-free land to growing crops. But he says how safe that will prove depends a lot on how we use the land. Will biologically rich and hydrologically important ecosystems be protected? Will farms be allowed to empty rivers and fill the wider world with nitrogen? Will cities contain their pollution?

Currently we have converted around 12 per cent of ice-free land to farming - about 16 million square kilometres. The boundary will likely be reached in the next few decades. To avoid going beyond it will require, above all, concentrating farming more intensively in the most productive areas, while containing its wider impact.

Earth's nine life-support systems: Climate Change

Boundary: Atmospheric CO2 concentration no higher than 350 parts per million
Pre-industrial level: 280 ppm
Current level: 387 ppm

Diagnosis: Boundary exceeded

This is the big one. Voluminous historical evidence shows that carbon dioxide in the atmosphere is the planet's main thermostat, and that raising CO2 concentrations warms the planet. We have done that in spades by burning fossil fuels, raising atmospheric levels from a pre-industrial 280 parts per million to the current 387 ppm. Politicians still debate what a dangerous level might be, but Rockström's team, advised by James Hansen, director of NASA's Goddard Institute for Space Studies in New York, says we passed the danger threshold more than 20 years ago, when we exceeded 350 ppm.

Why choose 350 ppm? After all, we have passed that already, and we are still here. The answer is that we haven't yet experienced all the warming from that amount of CO2, not by a long chalk.

Every degree of warming caused directly by CO2 is amplified by feedback processes. Melting sea ice exposes dark ocean, which means that the planet absorbs more solar heat. Warmer temperatures increase evaporation and so raise atmospheric levels of water vapor, another potent greenhouse gas. These feedbacks are the basis for the IPCC's warning that a warming of 1 °C due to CO2 will escalate to around 3 °C.

It may get even worse. Some climate scientists, notably Hansen, argue that there are other "slow feedbacks". For example, warming will eventually destabilize natural reserves of CO2 and another greenhouse gas, methane, stored in soils and permafrost. If so, warming of 1 °C due to CO2 could eventually escalate to 6 °C.

This is far too much to handle, says Rockström. To keep the big polar ice sheets largely intact and prevent massive flooding will require limiting warming to just 2 °C. The widely-accepted target to achieve that is 450 ppm, but if the slow feedbacks are correct we will have to pull CO2 levels back under 350 ppm to reach that target.

The good news is that we may have a bit of time, because those long-term feedbacks will take a while to kick in fully. Probably.

Earth's nine life-support systems: Aerosol loading

Boundary: Not yet identified
Diagnosis: Unknown

Human activity churns up the earth, creating dust, while burning coal, dung, forests and crop waste fills the atmosphere with soot, sulphates and other particles. We have more than doubled the global concentration of these aerosols since pre-industrial times. That haze influences the climate and is a threat to human health, so "aerosol loading" should be considered a potential planetary boundary.

The impacts are highly variable, though. Some aerosols, like sulphates, reflect solar radiation, causing cooling. Others, like soot, absorb and re-radiate it, causing warming. The global balance of these heating and cooling effects is unclear.

Aerosols also affect the climate in other ways. For example, the near-permanent brown haze across southern and eastern Asia is a subject of intense research as it appears to influence both the timing and the positioning of the monsoon.

Meanwhile, aerosols reduce crop yields by falling on fields, and also clog up human lungs, contributing to millions of deaths from lung and heart disease.

The damage from aerosols can be great, but their highly variable impacts left Rockström's team unable to put a number on safe limits.

Earth's nine life-support systems: Chemical pollution

Boundary: Not yet identified
Diagnosis: Unknown

There are approaching 100,000 different human-made chemical compounds in use around the world today, in millions of different products. Additional compounds are created as by-products of manufacturing.

Chemicals are mainly a worry because of their impact on the health of humans and wildlife. Among those of greatest concern are toxic heavy metals like lead, organic pollutants that accumulate in tissues, and radioactive compounds.

A handful of these are already controlled. For instance, the "dirty dozen" persistent organic pollutants - which include DDT, PCBs and dioxins - are controlled under the Stockholm Convention on Persistent Organic Compounds. But the impact of most others remains undiagnosed. And even apparently benign chemicals may combine to produce toxic effects greater than the sum of their individual effects.

One idea considered by Rockström's group is that autism and ADHD in children may result from the widespread exposure to low concentrations of cocktails of these chemicals in the environment, creating what they call "a silent pandemic of subtle neuro-developmental disorders in children, possibly on a global scale".

An all-encompassing "chemicals boundary" could be valuable. But, say the authors, it is too early to say how or where it should be set.

CONCLUSION

However you cut it, our life-support systems are not in good shape. Three of nine boundaries - climate change, biodiversity and nitrogen fixation - have been exceeded. We are fast approaching boundaries for the use of fresh water and land, and the ocean acidification boundary seems to be looming in some oceans. For two of the remaining three, we do not yet have the science to even guess where the boundaries are.

That leaves one piece of good news. Having come close to destroying the ozone layer, exposing both ourselves and ecosystems to dangerous ultraviolet radiation, we have successfully stepped back from the brink. The ozone hole is gradually healing. That lifeline has been grabbed. At least it shows action is possible - and can be successful.