How We Turn Local Environmental Problems Into Global Problems Through The Engineering Of Nature
The current coronavirus pandemic is a poignant example of our hyperconnected planet. A small infection located in Wuhan, China, quickly spread around the world on transcontinental flight paths in a remarkable and transformative way.
The consequences of a massively connected globe are real and, unfortunately, are not limited to disease pandemics.
As an ecologist who studies the connectivity of landscapes in natural and human-altered environments, I think about how human activities make new connections across Earth and strengthen others – and their consequences.
One of the main human impacts on the planet comes from land modification, where large-scale conventional agriculture replaces high-diversity ecosystems with low-diversity crops.
At first glance, one might imagine that this fragmentation of natural habitat reduces connectivity. But a closer look reveals that the modifications work to move nutrients from fertilizers through farmers’ fields and into rivers, lakes and oceans with dramatic results.
Flowing water, flowing fertilizer
Conventional agricultural fields often use an underground pipe system to drain wetlands and avoid soggy landscapes. The combination of these drainage tiles, lost wetlands, and the absence of trees and other plants (called riparian buffers) means that unused fertilizer and sediment moves quickly through streams and rivers.
These streams and rivers are often channeled (straightened and sometimes remelted in concrete or metal) to move water quickly through an area. But they also end up quickly transporting excess nutrients to large bodies of water, like a lake or ocean, where they rest en masse.
In this distant ecosystem, the fertilizer does what it was designed to do: stimulate the exponential growth of plants, but in this case, it nourishes the algae of the coastal ecosystem. In nature, this runaway growth is a feature of ecological instability.
Because algae is not edible for animals, it accumulates and forms large green carpets in surface waters. The algae then die and slowly sink into the depths of the water, where in the dark, bacteria proliferate on the dead algae. These enormous densities of bacteria render deep waters deprived of oxygen, forming “dead zones” and killing much of the local aquatic life.
Connected aquatic ecosystems
Global dead zones are increasing in number and size on the planet, producing a pandemic of diseased ecosystems. Notably, this excessive algae growth is also fueled by global warming.
Again, nature’s deep connection may not end there. Other even larger impacts may occur, as coastal areas may be linked to ocean currents that gather and move fertilized algae around the world. Tourist hot spots in the Caribbean and the Gulf of Mexico have mysteriously found Sargassum, a macroalgae, collected in gigantic and expensive piles on beaches for nearly a decade.
Using impressive satellite images, the scientists showed that the algae-laden beaches were likely due to distant actions in the Amazon, the Sargassum belt of the Grand Atlantic. The story is familiar.
Agricultural runoff from fields in the Amazon River watershed enters the ocean and, in a warming climate, fuels the exponential growth of Sargassum algae. This time, the large algae are captured by an ocean current system that moves them thousands of miles towards the Caribbean, Florida and Africa.
Other examples of macroalgae beach deposits, now collectively referred to as green and golden tides for the color of algae, seem to populate the globe with increasing frequency.
Greedy snow geese
Other distant impacts caused by nature’s nutrients and connectivity are also occurring.
Populations of snow geese, for example, that overwinter in the southern United States and feed on grains have has grown enormously since the 1950s. Scientists have documented the increase in snow geese alongside the increased application of industrial nitrogen as a fertilizer.
The geese then migrate each summer to the Hudson Bay lowlands thousands of miles away. There, dense herds of crop-subsidized geese overgraz entire swamp ecosystems, leaving behind only muddy mud flats.
While the news of the globe’s hyperconnectivity is grim, it also contains a simple and hopeful solution. The flip side of nature’s connectivity is that âacting locallyâ is indeed âthinking globallyâ.
It is important to note that farmers recognize these problems. Farmer groups like ALUS in Canada take the state of the environment seriously and play a leading role in agricultural land use approaches that tackle these serious issues.
At a time when the damaging effects of an over-connected planet are very clear, we also need to slow down the transmission of nutrients that expand the diseased ecosystems of the planet.