The recent report of the Lancet Commission on Planetary Health is further confirmation that our present system of development is not only ecologically unsustainable, but harmful to health.

Ecologically, we are pushing to and in some cases past the boundaries of sustainability for some of the ecological systems upon which we depend for the necessities of life. Troublingly, the ecological changes we are causing, and the social and economic forces that are driving them, have been growing exponentially, especially since the 1950s.

In a 2004 paper summing up the 1993-2003 International Geosphere-Biosphere Program, Will Steffen and his colleagues from Stockholm University wrote: “The second half of the 20th century is unique in the entire history of human existence on Earth. Many human activities reached takeoff points some time in the 20th century and have accelerated sharply toward the end of the century. The last 50 years have without doubt seen the most rapid transformation of the human relationship with the natural world in the history of humankind.”

This sharp upturn was later dubbed the Great Acceleration. In a 2015 paper in The Anthropocene Review that updates their earlier paper, they publish a series of charts that show the Great Acceleration for both Earth’s natural systems and humanity’s socio-economic systems.

For the former, they chart atmospheric greenhouse gases, surface temperature, ocean acidification, stratospheric ozone, the nitrogen cycle, marine fish capture, domesticated lands, tropical-forest loss and terrestrial-biosphere degradation. For the latter they chart population, economic growth, water use, primary energy use, fertilizer consumption, paper production, urbanization, transportation, telecommunications and international tourism. In almost all cases, the dramatic increase in use and impact since 1950 is very obvious.

So what does all this have to do with health? First, as Chief Seattle reputedly said some 150 years ago: “We are part of the web of life, and whatever we do to the web of life, we do to ourselves.” When we snip threads in the web, we are snipping the threads that support our own lives.

We have no idea how many threads we can afford to snip, or which ones are crucial. But the demise of key pollinator species such as bees seems particularly troubling to me, as does the acidification of the oceans and the threat that may pose to marine life.

Second, those who study the Earth’s natural systems are concerned with “planetary boundaries,” another topic that Will Steffen and his colleagues have explored. They are concerned about “the risk that human perturbations will destabilize the Earth system at the planetary scale.” And they find that we have already entered a zone of high risk for three of the nine key Earth system processes they studied: climate change, biosphere integrity (specifically loss of genetic diversity—the start of a sixth great extinction), and biogeochemical flows of nitrogen and phosphorus.

The danger is that in complex systems, dramatic growth can end with dramatic non-linear change, otherwise known as a state shift, resulting in decline or even collapse. And when natural systems decline or collapse, so too will the societies embedded within and dependent upon them.

Moreover, the health impacts will be much more severe for the poorest, most vulnerable members of those societies. Classically, they live downwind, downstream and downhill, on the worst, most marginal lands, and have the least capacity to protect themselves and manage crises.

Third, we are undermining many of the key ecosystem processes that underpin our food supply, including climate stability, water supply, land degradation and the aforementioned changes to pollinators and marine life. How we are to feed the nine to 10 billion people that we are expected to have by the middle of the century is one of our greatest challenges.

This is more challenging when the demand for a higher-meat diet is growing in many parts of the world.

This is why ecologically unsustainable development—our current economic model—is also socially unsustainable. But if unsustainable development is bad for our health, it follows that sustainable development is good for health—and in that lies hope. These are the topics of my next two columns.