The issues of illicit drug use and the degradation of the Earth's environment are global in scope and may not at first glance appear to be related. But the policies we are using to tackle the cultivation and trafficking of drugs are not only failing, they are deeply counterproductive – not least because they are accelerating our planet's ecological crisis.

For forty years, the main focus of drug policy has been to destroy crops and chase down traffickers. This has sometimes even been done in the name of environmental protection, to justify destroying drug fields carved from rain forest.

Yet it would hard to conceive of a drug policy regime that is more damaging for the environment. In response to pressure from law enforcement, drug farmers and traffickers must push their operations deeper into the world's last frontiers, clearing primary forests and endangered habitats from the Amazon to Myanmar to California. Global drug prohibitions keep prices high and allow traffickers in particular to reap huge profits, which they launder in the illegal and highly profitable exploitation of resources in and around their drug transit hubs: trafficking in timber and endangered wildlife; harvesting animal parts like shark fin and fish bladder; engaging in illegal gold mining and clearing land for cattle or oil palm production.

The loss of these unique and irreplaceable habitats increases climate change, helping to fuel the global deforestation that contributes up to 20 percent of annual global greenhouse gas emissions. For indigenous groups whose territories are invaded by drug traffickers, the human costs are unacceptably high. Dispossessed of their lands by narco-capitalized land speculators, some indigenous peoples flee to cities; those who remain are coerced into working for traffickers; those who dare to speak out about the criminal gangs operating with such impunity are killed.

I have seen firsthand the disastrous consequences that drug interdiction policies can have. For two years in the mid-90s I conducted research in the Mosquitia region of Honduras (the Mosquito Coast) and made visits there through 2002. In 2011, I returned to start a new project and was horrified to find that vast expanses of forest had been cut down, converted to cattle pasture and palm-oil plantations. One entire village had left their narco-threatened lands and moved to Nicaragua. As traffickers offered enormous sums of cash to illegally buy native lands, communities were being torn apart. People I knew were killing each other over land sales to drug traffickers. Those traffickers had only moved into the region after other trafficking zones had become too "hot." In fact, Honduras became the world's most murderous country after drug traffickers were pushed out of other countries (especially Mexico and Caribbean nations) by zealous drug-control and militarized 'war on drugs' efforts.

This ongoing cat-and-mouse game is an ecological as well as a human tragedy. As long as the global drug policy regime continues to focus on punishing farmers, traffickers and users, these ecological disasters will multiply. The current agenda serves some countries better than others. Countries in the global South have been paying a huge ecological and human price for drug policies driven primarily by affluent nations of the global North. This disproportionate burden carried by poorer countries includes lost economic opportunities, pollution and health problems caused by defoliants, the enriching of militaries and elites, cities ravaged by violence – not to mention the steep environmental costs.

It is no surprise, then, that it is from Latin America and elsewhere in the global South that we are hearing the loudest calls for drug policy reform. As the U.S. and Canada also explore more humane drug policies, I am optimistic that the momentum is building to enact drug policy changes that will benefit both hemispheres.

First, we must acknowledge the scale of the problem and recognize how drug policies are intractably tied to our long-term environmental goals. For too long, drug issues have been "siloed" within the United Nations Office on Drugs and Crime, making it harder to think about, and act on, the way in which drug policies are profoundly tied up with development, conservation and climate change mitigation efforts. It is high time for other U.N. agencies – including the United Nations Development Programme, the U.N. Environment Programme, the U.N. Collaborative Programme on Reducing Emissions from Deforestation and Forest Degradation and the U.N.'s Permanent Forum on Indigenous Peoples – to contribute centrally to building just and effective drug policies. The place to begin this rapprochement is at the United Nations General Assembly's Special Session on drug control to be held in April 2016, which will provide a welcome forum for broad public debate on these issues.

Indeed, the upcoming General Assembly special session signals broader global momentum to reform drug policies. Many states, including Uruguay and Bolivia, are already posting significant success with measured and careful drug legalization efforts. Many U.S. states are doing the same. As new policies like these spread, they build confidence that there is a way out of the inhumane morass that drug policy orthodoxy has mired us in for almost half a century.