STOCKHOLM -- Pope Francis' just-released encyclical on the environment sends a powerful message not just to the world's 1.2 billion Catholics, but to the rest of the global population as well. Firmly rooted in science, the teaching document -- the most significant from the Vatican in over a decade -- recognizes the need for urgent action, as the world confronts potentially catastrophic climate change.
In 2000, the scientists Paul Crutzen and Eugene Stoermer proposed that human activity, particularly in the developed world, was interfering at the planetary scale with the fundamental forces of nature -- the water, carbon, and nitrogen cycles, the ice sheets, biodiversity, the oceans and the forests. The changes were so profound, they suggested, that geologists in the future would see a clear break from the previous geological era, the Holocene, to a new one, which they called the Anthropocene.
Over the last 15 years, scientific evidence has reinforced the conclusion that human activity is fundamentally transforming the planet. The Vatican has already recognized this view explicitly, with the Pontifical Academy of Sciences referring to the Anthropocene in the proceedings of a meeting held in May 2014.
The Holocene, which began 11,700 years ago as the last Ice Age receded, has been a period of remarkable stability. After an age of drastic swings, average global temperatures settled in to a stable pattern within an extraordinarily narrow range of 1 degree Celsius. The relative stability of the climate and predictability of seasons facilitated the emergence of agriculture, which, in turn, enabled the creation of towns and cities.
In other words, the Holocene's defining features are critical to support human civilization as we know it -- a conclusion that the latest encyclical supports. Moreover, as recent evidence indicates, when large natural systems are placed under high levels of stress, they can reach tipping points, at which only a small adjustment is sufficient to trigger their collapse. It seems that many systems are already nearing that point.
"Protecting our planet is a moral imperative."
Last year, researchers working in Antarctica observed that major parts of the ice sheet appear to be collapsing irrevocably. On the other side of the planet, sea ice is on such a rapid downward spiral that, in just a few decades, the Arctic could be open ocean in the summer. This could drive global temperatures even higher, because the darker ocean absorbs solar heat, whereas white sea ice reflects it.
In 2009, my colleagues and I identified nine planetary boundaries relating to areas like climate, biodiversity, nitrogen and phosphorus use, and deforestation that, if respected, would enable us to preserve -- or, at least avoid disrupting further -- Holocene conditions. When we updated our analysis earlier this year, we concluded that we have already violated four of the nine boundaries.
If we do not change our behavior quickly, we may well lose the environmental stability upon which our planet -- and our lives -- depends. This is the main message of the pope's encyclical.
Protecting our planet is a moral imperative. As the Vatican has pointed out, the poor are disproportionately affected by the consequences of climate change; for example, some of our activities threaten to undermine food production in the drier -- and poorer -- areas of the world. But we also face an economic imperative, because reliable access to natural resources is essential for human development and prosperity. And, in fact, increasingly frequent and severe natural disasters carry massive human and economic costs.
As the encyclical makes clear, the future does not have to be bleak. We can take this opportunity to build a new future -- one in which environmental sustainability supports human progress and dignity. It is business as usual that holds out the bleakest prospect for humanity.
The most immediate priority is to tackle climate change and biodiversity loss, which is reaching mass extinction levels. Global temperatures have risen almost 1 degree Celsius in the last century, placing them at the Holocene boundary. If, as the recently published "earth statement" underlines, temperatures reach 2 degrees Celsius above pre-industrial levels, the results could be disastrous. Yet, if current emissions trends hold, temperatures are set to rise by more than 4 degrees Celsius from pre-industrial levels by the end of the century.
"The future does not have to be bleak. We can take this opportunity to build a new future. . . It is business as usual that holds out the bleakest prospect for humanity."
According to Francis's encyclical, the world must work together to reverse this trend, by reconnecting with the biosphere and harmonizing their activities with nature. Taking a strong stance that aligns with our planetary boundaries research, the encyclical underscores humanity's responsibility to sustain Holocene-era stability in support of world development.
But some -- such as the recently published "Ecomodernist Manifesto" -- are less concerned with the environmental risks of the Anthropocene, preferring to rely on our technological capacity to adapt to changing conditions.
To be sure, technological innovation and development will be vital in the shift to a more sustainable world, particularly by enabling the creation of a zero-emissions society by around 2050. But it will not be enough to support good lifestyles for all citizens worldwide. The global transformation that is needed now must be based not on technological advancement, but on our collective values and convictions -- especially our commitment to safeguard the planet's stability and resilience by protecting the global commons.
In September, world leaders will meet to agree on new Sustainable Development Goals, which will guide global development efforts for the next 15 years. Unlike the new targets' predecessors, the Millennium Development Goals, the SDGs will apply to all countries, and will include an explicit focus on environmental sustainability, in addition to human and economic development. In December, when world leaders meet again to hammer out a climate agreement, the quality of their work will, in many ways, determine the trajectory of the planet.
The pope's declaration echoes the draft text for the SDGs: "the future of humanity and of our planet lies in our hands." This is more than mere rhetoric; it represents a shift to a new paradigm, in which humans are the driving force behind planetary developments, and thus have a new responsibility of stewardship. Our choices have never been more important.
