Human activities have rendered the world considerably dangerous for humans. An 18-member international research team has specifically pointed out that pressing environmental issues including climate change, the loss of biosphere integrity, land-system change, and altered biogeochemical cycles like phosphorus and nitrogen runoff have all passed beyond levels that put humanity in a “safe operating space.”
There are nine so-called planetary boundaries identified within a framework for understanding and defining safe operating space for humanity. First proposed by a group of scientists in 2009, the framework predicts that once human activities have pushed beyond the limits of the planetary boundaries, irreversible and abrupt environmental change may follow.
The boundaries include atmospheric aerosols, biogeochemical cycles, biodiversity loss, chemical pollution, climate change, freshwater availability, land use, ocean acidification, and ozone depletion.
An update to the study recently revealed that humanity has exceeded four of the aforementioned nine planetary boundaries. Published in the January 15 issue of Science and entitled “Planetary Boundaries: Guiding human development on a changing planet,” the new research analysed the changes that transpired within the last 100 years.
Note that Earth had experienced a stable and sustainable state from 11,700 years ago until roughly 100 years ago. Labeled as the Holocene epoch, the researchers enumerate key breakthroughs that catapulted humanity into modernity. These are development of agriculture, the rise and collapse of the Roman Empire, and the Industrial Revolution.
However, over the past century, parameters that made the Holocene epoch so conducive have unfavourably changed.
A new geological epoch
“Human activities could drive the earth into a much less hospitable state. In this research we have more accurately assessed the risk of this happening,” said lead author Professor Will Steffen from The Australian National University and the Stockholm Resilience Centre.
The research compared 12 measures of human activities (including economic growth, population, and energy use) with 12 environmental factors (including biodiversity loss and carbon cycle). The comparison revealed that the acceleration across all measures has been dramatic, especially in the latter half of the 20th century.
“We’ve now entered a new geological epoch, named the Anthropocene, in which the global economic system is the primary driver of change on Earth,” said Steffen.
Accordingly, out of the nine planetary boundaries, humans have already crossed four. These are climate change caused by carbon emissions; loss of biosphere integrity, resulting from high rates of species extinction; land system change; and altered biogeochemical cycles due to farming activities.
Phosphorous and Nitrogen Cycles
Although the aforementioned research has focused on all nine planetary boundaries, biogeochemical cycles are worth highlighting according to Steve Carpenter, one of the researchers and director of the University of Wisconsin-Madison Center for Limnology.
“We’ve changed nitrogen and phosphorus cycles vastly more than any other element,” said Carpenter who attributed the alterations to extensive use of fertilisers and the emergence of large-scale industrial agriculture.
Accumulation of large volumes of phosphorous and nitrogen in the ecosystem has a devastating effect on water quality. For example, phosphorus concentration remains as the leading cause of unsafe algal blooms and oxygen starvation in Lake Erie. Moreover, nitrogen flowing down Mississippi River is rendering several zones within the Gulf of Mexico inhabitable to aquatic life.
Phosphorous and nitrogen are not in excess according to Carpenter. The problem lies in distribution.
“There are places that are really, really overloaded with nutrient pollution,” he says. “Wisconsin and the entire Great Lakes region are some of those. But there are other places where billions of people live that are undersupplied with nitrogen and phosphorus.
“For instance, much of Africa is largely lacking these two essential elements. We’ve got certain parts of the world that are over-polluted with nitrogen and phosphorus, and others where people don’t even have enough to grow the food they need.”
The study does not offer concrete and workable solutions, the researchers stressed out. Instead, it provides information intended to compel governments and communities to act, particularly through policy-making and perhaps, technological innovation.
Nonetheless, the study forms part of the emerging field of Earth Systems Science. This field puts together expertise from other fields including ecology, geology, chemistry, atmospheric science, marine biology, and economics.
Further details of the study of Steffen et al are in the article “Planetary boundaries: Guiding human development on a changing planet” published in 2015 in the journal Science.