Earlier this year, I joined a Greenpeace expedition to explore the Amazon Reef, 75 miles off the coast of the Brazilian state of AmapÃ¡. The scale of this reef was revealed in April 2016, when it was celebrated by scientists as one of the most important in marine biology in recent decades. Ronaldo Francini, one of the scientists who revealed it to the world, called it “a hotspot for biodiversity.” The region is home to manatees, green turtles, river otters, as well as local communities whose livelihoods depend on the ecosystem.

As a Greenpeace marine biologist and submarine pilot, I worked with a team of Brazilian scientists to map a portion of the reef and discover some of its inhabitants for the very first time. Every dive was a revelation, with new discoveries that changed our understanding of this remarkable reef. We watched in awe as the sub descended slowly into underwater gardens populated by species likely unknown to science before the expedition. Some areas were carpeted with soft corals, while others were dominated by bright yellow sponges. Underlying everything was a bed of rhodoliths, the accumulations of calcareous algae that created the foundation of the entire reef.

As with many of our world’s most precious places, the Amazon Reef is under urgent threat. Oil giants Total and BP plan to drill near the reef, which could begin within a matter of months. An oil spill could permanently damage this unique ecosystem shortly after it has been revealed to the world.

Recently, the Brazilian Institute of the Environment and Renewable Natural Resources rejected Total’s oil spill modeling, stating that “it does not adequately represent the environmental variability of the region” and that the companies failed to comply with previous requests for information. IBAMA also criticized the company’s modeling as “statistically incoherent.”

On May 4, the federal prosecutor of the State of AmapÃ¡ recommended the suspension of environmental licensing to Total for their planned deep water drilling near the vulnerable Amazon Reef biome. According to the prosecutor’s public statement, Total "did not take into account the important ecosystem of the coral reef of the mouth of the Amazon River. Thus, exploration in an area close to [the reef system] corals, without adequate environmental impact study, can cause irreparable damage to this unique and little known biome."

Drilling in this area will mean a constant risk of an oil spill. As we learned firsthand while exploring the Amazon Reef this year, the extreme conditions in the region make operations difficult and unpredictable. The depth, strong currents, remoteness, and the ever shifting location of the Amazon plume itself should not be underestimated. If and when something goes wrong, it will be extremely hard to deal with. The Cape Orange National Park, at the northernmost point of AmapÃ¡, is home to the world’s largest continuous mangrove ecosystem and there is no technology capable of cleaning up if an oil spill reaches it.

Opening a new oil frontier ignores the urgent need to tackle climate change and keep global temperatures below 1.5 degrees Celsius. We already have more secured reserves than we can afford to burn. This oil must stay in the ground in keeping with the Paris climate agreement. More than one million people around the world have already demanded that Total and BP cancel their plans to drill at the mouth of the Amazon River. Add your voice to theirs.