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Saving the Biosphere by Conserving Half of Earth

A book review of Half Earth: Our Planets Fight for Life by Edward O. Wilson

Bopi Biddanda, Morgan Lindback and Katie Ringler, Annis Water Resources Institute, Grand Valley State University

“The only solution to the Sixth Extinction is to increase the area of inviolable natural reserves to half the surface of the Earth or greater.” – E. O. Wilson (2016).

Overwhelming evidence that human activity is adversely affecting our planetary life-support system has been gathering over the last century.  Climate disruption, species extinctions, loss of ecosystems, environmental contamination, and the ubiquitous human footprint on Earth’s natural resources are no longer a possibility of the future but are our reality in the present.  For example, James Watson reported in the June 2016 issue of the journal Nature that one of Australia’s celebrated marsupials, the Bramble Cay Melomy went extinct – drowned by sea level rise in its only island habitat.  It is conceivable that continuing along this “business as usual” trajectory makes it extremely likely that by the time of our grandchildren, Earth’s life support system that is critical for our well-being will be irretrievably damaged.  In his new book, Half Earth: Our Planet’s Fight for Life, Harvard ecologist and Pulitzer Prize winner E. O. Wilson takes a long-term view and proposes a radical new approach for ensuring a sustainable world: Save half of the Earth’s surface from further human exploitation now (Figure 1).

Book Cover

Figure 1.  Cover of “Half Earth: Our Planet’s Fight for Life” by E. O. Wilson (Liveright, 2016. 261 pp, ~$25), and a recent photo of the author (

The book begins discussing evidence for previous five mass extinction events on Earth in the distant past, and brings to bear considerable new evidence that our planet is currently in the midst of the sixth mass extinction event driven primarily by humans.  Wilson goes on to discuss the importance of the biosphere and biodiversity in the context of a human-dominated world – and makes his proposal for saving nature for its own sake as well as for our benefit.  In the first section of the book (The Problem), Wilson describes his central thesis: Earth’s biodiversity and its ecosystems sustain humanity – that there can be no humans without nature.  Thus, preserving a sustainable biosphere is critical for our own future.  We can be part of Earth’s future biosphere by setting aside one half of the planet as a zone of wilderness free from human exploitation.  He asks us to imagine a chain of uninterrupted protected wild landscapes and seascapes spread across both the hemispheres that amount to half the surface area of the planet.  While the proposal is quite audacious, Wilson compels his readers to arrive at the same conclusion after a dialectic presentation of a highly interactive and interconnected biosphere, of historical records of mass extinctions in the geologic past, and the present-day Earth wherein humans are a dominant force driving biodiversity and ecosystem loss – and ecosystem services on which humanity depends (Figure 2).  Over half a century ago, Hardin (1968) recognized that competitive exploitation of Earth’s resources by the world’s nation states would lead to the “Tragedy of the Commons” for our global commons: air, soil and water.  As Hardin explained and Wilson urges us, leaving areas unprotected results in over-exploitation of Earth’s natural resources in unsustainable ways.

Coral bleaching

Figure 2. This before and after image shows the corals in American Samoa, in the South Pacific Ocean, before (image taken in December 2014) and after the bleaching event (image taken in February 2015). Corals get their rainbow hues from the microscopic algae called zooxanthellae that live in their tissues and photosynthesize to produce food for the corals. In return, the algae have a snug place to live … that is unless conditions in the water become inhospitable and they die off. (Photo Credit: XL Catlin Seaview Survey  In the past year couple of years, we have witnessed the third and largest global coral bleaching event in our recorded history.  These dramatic and widespread changes have been linked to anthropogenic warming of surface oceans.  With business as usual, we face a future in which the world may lose most of its coral reef ecosystems and the biodiversity therein within the next century or two.  

In the second section (Living World), Wilson reminds us why we should care. He takes the reader on a journey through many of the planet’s biomes. The reader explores the Redwood forests, the ancient woodlands of Mexico, the Guiana Shield, the lost world of the Tepuis, the Amazon river basin, the grasslands of the Cerrado, the wetlands of the Pantanal, forests of the Congo and the grasslands of the Serengeti, the Sathe primeval forest of Belarus, the wilds of Siberia, isolated islands in the Indian Ocean, the Western Ghats of India, the scrublands of Australia, the McMurdo Dry Valleys of Antarctica, and more – such as lakes, rivers, estuaries and oceans.  The exercise proves that diverse ecosystems are worth conserving for their own sake – even without the multitude of ecosystem services they provide us.  United Nations Educational, Scientific, and Cultural Organization (UNESCO) are currently attempting to expand World Heritage sites to the open ocean ( And just like humans, ecosystems cannot exist in isolation.  Indeed, fragmented ecosystems suffer biodiversity loss at far greater rates than larger ecosystems.  Thus, there is a critical need for conserving a working set of vast, expansive and contiguous landscapes and seascapes to ensure a sustainable biosphere.

While there is little doubt that we need to conserve the biodiverse regions of the planet as best as we can, it is equally vital that we do not neglect to protect the vast and bio-diversity poor biomes such deserts and high seas that are no less critical for the functioning of the biosphere.  For example, the ocean gyres are essential to the biodiversity of coastal coral reefs just as continental deserts fertilize the open ocean with micronutrients in soil dust and enable tropical rainforest to thrive elsewhere.  Still the question remains: How can we save it all?

Wilson presents his answer in the third and final section of the book (Solution) elaborating his vision of having half of the Earth’s surface set aside for natural habitat undisturbed by humans. By now, the science is quite clear that humanity’s modern day planetary footprint – climate disruption, species extinction, ecosystem loss, pollution, as well as population and consumption increases – are collectively on track to making life for 10 billion humans unsustainable on the long run.  Clearly, the window of time available for implementing a global sustainability plan is short.  With each passing day, the problems not only become worse, but also become more expensive and difficult to solve.  Why save half the Earth as wild?  Policy makers can relate better to numbers such as the 2°C limit on global warming that was set at the Paris Climate Conference last year.  Currently, only ~15% of land and 3% of oceans are protected as preserves and sanctuaries (Figure 3), even though the multi-national Convention on Biological Diversity recommends protecting 25-75% of Earth’s lands and waterways in order to maintain biodiversity and ecosystem function and services.  Such wholesome approach of saving one half of the Earth is a move away from the piecemeal approach of just protecting individual and favored species towards protecting entire ecosystems and their connecting corridors for perpetuity.  In seriously dedicating one half of our planet’s terrestrial and aquatic surface area to nature, Wilson envisions a middle road to saving humanity by saving its life-sustaining biosphere.  It is time to heed Wilson’s clarion call for conserving half of our home planet.  Our collective future may very well depend on it.

For additional information including how you can be part of bringing Project Half-Earth to life, visit the website.

Interactive map

Figure 3.  Screenshot from showing an interactive map of the distribution of protected areas currently covering 17% of our planet.  E.O. Wilson’s plan envisions protecting an additional 33% to achieve a sustainable biosphere over the long run.