As Donald Trump launched his immigration policy and a more detailed outline of “the wall” across the US-Mexico border (not that it was his idea in the first place), it seems only sensible to explore why the human story has been adorned with barriers, barrages and barricades for much of its history. We, the wall- builders, may well have taken our inspiration from nature. No man is an island, but islands exist and thrive thanks to their isolation. The highest indigenous diversity is found on islands. Their separation produces hotspots of biological and social diversity. Think Madagascar, New Caledonia or Borneo and a huge range of unique extraordinary creatures rise from the mists of your imagination. Islands offer protection from the outside world, be it for religious isolation, such as Papa Stronsay in Orkney, or for fear of attack, such as North Sentinel Island in the Bay of Bengal, which has a human population that has never been contacted by modern humans. Islands can also be used to enclose as well as exclude. Napoleon died on his island prison, St Helena.
For almost the entirety of life on earth, barriers have played crucial roles in shaping the diversity of the planet. High levels of ultraviolet radiation initially prevented life from moving on to land until an ozone barrier reduced this harmful energy. Mountain ranges, water and inhospitable terrains have isolated land masses allowing species to survive in small pockets of habitats. Yet freedom of movement was also important. Many species migrate across vast distances each year, chasing the rain and its productive outpouring of food. Indeed, it is an irony that the master wall builders themselves, humans, first emerged as nomadic hunter gatherers in a world without borders, walls or fences.
And it was our decision to settle down, grow our food and launch the Agricultural Era, some 12 000 years ago, that generated the need for walls. Now we owned stuff, and that meant we had to protect it, be it fertile land, cities, access to the sea or water supplies. And early in our transition to settled ownership, the walled city began to make its appearance. The walls of Babylon, Jericho and Uruk are still with us, ten thousand years later. Walled cities abound across the world, such as in Derry and Lucca in the Tuscan hills, protecting their inhabitants for centuries.
In certain circumstances, walls have been built around cites by opposing forces, in an attempt to isolate populations. This is most clearly seen in the West Bank Wall, built by Israel but transgressing the agreed border with Palestine, often by as much as 12 miles. Some nine percent of land belonging to the Palestinian people has been enclosed into Israel by this wall. The Moroccan Western Sahara Wall, 1 700 miles long and containing the longest minefield in the world, is an even more extreme version, where Morocco has built a wall around an entire nation, Western Sahara, in order to maintain its authority over it. Western Sahara is rich in oil, fish resources and phosphate. The wall was built in the Eighties and is manned by 120 000 troops. Its mines have injured 2500 people and isolated thousands of Sarhawi refugees from being able to return home from refugee camps in Algeria. Scotland has had walls built by foreign forces, including Hadrian’s Wall and the Antonine Wall.
Walls can also appear within cities. The so-called Belfast peace walls are made up of 99 separate walls dividing protestant and catholic communities while the Berlin Wall separated communist and capitalist ideologies. Sau Paulo has thirty-three walled enclaves for the super-rich, called Alphaville, separating them from the extreme poverty surrounding them.
Another form of wall acts as a protection against the environment. The dykes of the Netherlands dating back to the first century AD, protect against flooding while also reclaiming vast areas of land through landfill, are well known and vastly developed in recent years in the form of the Delta works. A much larger but less well known sea wall is found in China. Dubbed the New Great Wall, it stretches for 6800 miles along the Chinese coastline, and is dedicated to land reclamation. Interestingly, President Trump has a less well known wall in his plans. At 13 ft high and two miles long, this is not a big wall. What is interesting is his reasons for requesting planning permission. The Application claims that global warming will lead to sea level rise, threatening his golf course at the Trump International Golf Links and Hotel in Doonbeg, County Claire in Ireland. Ironic to say the least. The plans were rejected by the An Bord Pleanála and are being re-submitted.
A different kind of protectionism from the environment can be found in the two great fences of Australia, the Dingo Fence running from New South Wales to South Australia, and the Rabbit (or State Barrier) Fence in Western Australia, both doing exactly what they say on the fence post.
The final set of barriers is the most recognized, that of national borders. This is where the so-called Wall of Trump fits in. These barriers are set in place to control movement of humans and trade, both legal and illegal. Perhaps the most famous example of all is the Great Wall of China, stretching for 5500 miles and designed to repel Mongol raiding parties. The Indo-Bangladeshi Barrier, some 2100 miles long, almost entirely encloses Bangladesh, and focuses on controlling narcotics and cattle movement. Cattle, sacred in Hindu India but staple fare in Muslim-dominated Bangladesh, fetch much higher prices in Bangladesh. The Korean Demilitarized Zone is probably the most intensely armed barrier in the world. The Evros Wall between Greece and Turkey is one of the newest walls to prevent refugees moving freely, and similar walls are being built along other European borders.
Drowned out in this entire issue is the environmental cost of walls. Yet lots of evidence exists in scientific literature to highlight that walls are very bad for Nature, and thus, very bad for us. Nature is built along very different borders than those found on a map. Rivers, mountain ranges, coasts and islands provide the barriers for most species. Human walls rarely run along these lines. Walls cut across wildlife corridors and fragile ecosystems. The impact of climate destabilization makes these corridors all the more important, not to mention the implications for the millions of human climate refugees expected as a consequence of our lust for energy, in countries like Bangladesh (surrounded by the Indo-Bangladeshi Barrier) and at the borders of an increasingly isolationist Europe. The dingo fence has had significant negative impact on biodiversity with the removal of a keystone predator. The Delta works coastal barriers have led to an accumulation of heavy metals in the sediment along with a loss of estuarine habitat. Professor Zhijun Ma of the Institute of Biodiversity Science, Fudan University, Shanghai has calculated that the Chinese coastal works has led to a fifty percent loss in wetlands, representing US$31 billion in ecosystem services. These areas are now pollution sources rather than pollution sinks. Increased vulnerability of human coastal populations to extreme weather events is another consequence. The loss of coastal wetlands in China has contributed to the rapid decline of water bird populations in the East Asian– Australasian flyway, which currently is the migratory path for the highest proportion (19%) of threatened water bird populations among the global flyways.
Dr Matthew Hayward, from the University of Wales, Bangor, points to a number of challenges for wildlife faced with fences. These include the inability to naturally recolonise a site after local extinction, difficulty in responding to climate change, restriction of animals during ﬁres which can limit their ability to escape injury/mortality, the creation of artiﬁcial roost sites that increase avian predator hunting success and longer term evolutionary costs, wherein isolated populations are unable to participate in evolutionary processes and face a reduced gene-pool, reducing variation and thus limiting possible solution space to increasingly chaotic environmental challenges.
Add to this the impact of high voltage lighting upon nocturnal species, including bats, moths, nocturnal migrating birds and turtles, increased roadkill on roads and reduced access to important extreme-weather recovery zones such as year-round watering holes, and the wall can be seen as a terrible burden upon native species already bowed low under the chaos that we have introduced to our planet. From a human standpoint, this risks the collapse of the essential ecological services that functioning ecosystems provide for us.
The Mexican border holds an incredible wealth of beautiful but endangered wildlife. Ocelots, Mexican gray wolves, bison, road runners, bighorn sheep, pronghorn antelope, mountain lions are all threatened with extinction in the United States and cross this border frequently. Pygmy owls only fly at a height of 1.5 metres and thus a fence can be deadly. Matt Skroch, director of the Sky Island Alliance says that “If they build it [the wall], we could really say goodbye to the future of jaguars in the US”.
What is needed is a coalition between ecology and politics, where social and human dignity, justice and sustainability can be achieved. The challenges of a destabilized climate, prompting Trump to build a wall to protect his Irish golf course, will require all of the resilience that the natural world can muster if we are to continue enjoying our planet. Human barriers will only weaken this resilience, and so if he really wants to make America great again, a functioning biosphere is a fundamental foundation to any such aspirations. This isn’t his wall, but he has the opportunity to correct the errors of previous administrations of Clinton, Bush Jnr. and Obama and think beyond the human obsession with wall building.