From nitrogen pollution to gene drives: UN highlights five key emerging issues

Urgent action from nations around the world is required to tackle emerging environmental challenges that will have profound effects on our society, economy and ecosystems, the United Nations Environment Programme has warned.
According to the Frontiers 2018/19 report, the five key issues are the latest developments in synthetic biology, landscape connectivity; thawing permafrost peatlands, nitrogen pollution and maladaptation to climate change. “In the first decade of the 20th century, two German chemists – Fritz Haber and Carl Bosch – developed a way to produce synthetic nitrogen cheaply and on a large scale.

 Their invention spurred the mass production of nitrogen-based fertilizers, and thus transformed farming around the globe,” Joyce Musya, Acting Executive Director of UN Environment wrote in the foreword to the report. But this also marked the beginning of our long-term interference with the Earth’s nitrogen balance. “Every year, an estimated US$200 billion worth of reactive nitrogen is now lost into the environment, where it degrades our soils, pollutes our air and triggers the spread of “dead zones” and toxic algal blooms in our waterways,” she added. “The issues examined in Frontiers should serve as a reminder that, whenever we interfere with nature – whether at the global scale or the molecular level – we risk creating long-lasting impacts on our planetary home.”

The first chapter covers the opportunities and challenges that synthetic biology holds for society. “Gene-editing techniques are advancing rapidly, bringing the promise of many biological and ecological benefits, from eradicating human diseases to preventing species extinction. CRISPR-Cas9 is the latest, quickest tool in the genetic editing tool box, allowing extraordinary precision in the manipulation of genomes,” the authors write. However, “this ability to create synthetic life and alter existing DNA carries with it the risk of cross contamination and unintended consequences,” they warn. “CRISPR-based gene drives (…) require multifaceted societal debate because of their power to modify, suppress or replace the entire population of the target species.”

The authors stress that the release of only a few gene-drive-bearing organisms into the environment can transform an entire species population and potentially the whole ecosystem. “The intentional or accidental release of genetically engineered organisms into the environment could have significant negative impacts on both human and environmental health. Misuse of these technologies and a failure to account for unintended consequences could pose significant geopolitical threats.” The authors point to the rise of DIY biohackers and garage labs, recognizing that regulating the use of easily accessible and low-cost technologies like CRISPR and gene editing kits will be a challenge for authorities. There is also concern that the technology could be misused by terrorists to destroy agricultural crops or turn harmless microbes into biological weapons.

The second key issue is ecological connectivity – the linking and bridging of fragmented habitats into a connected landscape to prevent species extinctions. Large-scale industrialization has caused widespread fragmentation of previously intact landscapes around the globe, causing a spiralling decline of some species as they can no longer disperse to find food or mates.

There are promising initiatives to promote landscape connectivity across the globe, but much more focus in planning to reconnect habitat patches or preserve existing connectivity is needed. Another environmental threat is the thawing of permafrost peatlands – the ground in the northern hemisphere that remains permanently frozen and holds approximately half of the world’s soil organic carbon. With rising global temperatures, the Arctic is warming twice as fast as the global average and scientists are becoming increasingly alarmed at the accelerating rate of permafrost thaw. Permafrost thaw could set in motion an uncontrollable snowball effect, as carbon is released from the thawing peat and heats the atmosphere, thus worsening climate change ad infinitum.

Nitrogen pollution – the disturbance of ecosystems, human health and economies by massively altering of the global nitrogen cycle through human activity – is another major threat. Nitrogen is largely benign in its unreactive forms. In the form of nitrous oxide, however, it is 300 times more powerful than carbon dioxide as a greenhouse gas, in addition to the effects of various nitrogen compounds on air quality and the ozone layer. “Altogether, humans are producing a cocktail of reactive nitrogen that threatens health, climate and ecosystems, making nitrogen one of the most important pollution issues facing humanity,” the report warns. “Yet the scale of the problem remains largely unknown and unacknowledged outside scientific circles.”

A cohesive global approach to nitrogen management is needed in order to transform the nitrogen cycle into a sustainable, non-polluting, profitable circular economy. Chapter five focuses on the various ways in which adaptation to climate change can go wrong, from processes that do not work to adaptive actions that damage resources, compound the problem faced by vulnerable populations, or pass on responsibility for solutions to future generations. But Joyce Musya remains optimistic: “By acting with foresight and by working together, we can stay ahead of these issues and craft solutions that will serve us all, for generations to come.”