One hundred years ago, roughly 15 percent of the planet was used to tend to crops and livestock. Since then, the global population has quadrupled and our dominance of the Earth (land and sea) has radically expanded.

According to an article published in Nature, as much as 77 percent of land and 87 percent of ocean excluding Antarctica has been directly impacted and altered by human activity. Which leaves just 23 percent of the planet as so-called wilderness – that is, a space of 10,000 kilometers (3,800 square miles) squared or greater, free of human pressure.

Astonishingly, 94 percent of that space is confined to 20 countries, while the top five (Russia, Canada, Australia, the US, and Brazil – in that order) possess 70 percent of the world's remaining wilderness. 

Why is this important? Aside from the severe strain placed on biodiversity as many of the Earth's eco-systems shrink and shrivel, study upon study shows that these isolated reservoirs of wilderness are "increasingly important buffers" against climate change, the authors say. 

Take Canada and Russia's boreal forests as an example. These forests span across the world and together make up 14 percent of the world's landmass and 33 percent of its forests. Not only is it the most intact ecosystem on the entire planet, the authors say, but it captures and stores around a third of the Earth's terrestrial carbon. Destroy it and you risk pushing the plant past a tipping point, unleashing a runaway effect that puts us on a path to climate Armageddon. 

Add that to the fact that dismantling wildernesses like the boreal forest and the Amazon, whether through logging, burning or mining, adds to global greenhouse gas emissions. According to the article, as much as 40 percent of above-ground carbon emissions in the tropics is caused by deforestation and even seagrass meadows can turn from being carbon sinks to carbon sources if damaged. 

In the more short-term, these natural environments can also be extremely important bulwarks against extreme weather events, like tsunamis and hurricanes. The authors point to simulations that show healthy coral reefs (versus unhealthy coral reefs) offer coastlines double or more the amount of protection against tsunamis. 

The good news is that there are laws in place designed to protect these lands (and seas), including the 1964 US Wilderness Act. The not-so-good news is that these laws are not universal nor are they always properly defined, mapped, and enforced. This means they are exposed to the whims of politicians and local landowners – see Trump's plans to drill Alaska and the new Brazilian president's support of what would effectively be the privatization of the Amazon.

The authors recommend imposing global targets within existing frameworks to protect these remaining ecosystems, saying "Already we have lost so much. We must grasp this opportunity to secure the wilderness before it disappears forever."