The environmental damage deep-sea mining causes has been vastly underestimated, scientists say, warning against planned new rules which would allow "high-impact, full-scale mining" of the seabed worldwide.
They say "misconceptions and knowledge gaps" have the potential to lead to rules which would destroy habitats which can take millions of years to form.
"As a team of deep-sea ecologists, we became alarmed by the misconceptions present in the scientific literature that discuss the potential impacts of seabed mining," said Craig Smith of the University of Hawaii.
"We found underestimates of mining footprints and a poor understanding of the sensitivity and biodiversity of deep-sea ecosystems, and their potential to recover from mining impacts. All the authors felt it was imperative to dispel misconceptions and highlight what is known and unknown about deep seabed mining impacts."
In an article for journal Trends in Ecology and Evolution, the 13 scientists say the United Nations' International Seabed Authority is drafting new rules to allow more intensive mining activities. Though its rules only apply to areas outside of each country's exclusive economic zone, international law requires member countries to have environmental protections at least as stringent.
Much of the new mining is planned to take place in the Pacific, at a scale never seen before in the history of humankind, says Dr Smith.
"Polymetallic-nodule mining (as currently planned) may ultimately impact 500,000 square kilometres of deep seafloor in the Pacific, an area the size of Spain, yielding perhaps the largest environmental footprint of a single extractive activity by humans."
Dr Smith says the mining industry and scientists have both underestimated the damage it could cause.
"The bottom line is that many deep-sea ecosystems will be very sensitive to seafloor mining, are likely to be impacted over much larger scales than predicted by mining interests, and that local and regional biodiversity losses are likely, with the potential for species extinctions."
The full extent of the damage might not be known for decades, when it's too late to fix, with computer simulations unable to recreate the "spatial scale, intensity and duration of full-scale mining" - particularly when so little is yet known about life on the seabed.
"Despite significant funding by governments and industry for deep-sea research, basic documentation of biodiversity and natural variability in areas targeted for deep-seabed mining is incomplete. Recent discoveries underscore the remarkable, unknown species richness and complexity of these communities."
Just recently, the scientists say, about 2000 animal species unknown to science were found in an area of the deep sea east of Hawaii known as the Clarion Clipperton Zone - which is also rich in minerals ripe for extraction.
"The deep sea contains many of the most pristine, poorly studied, and evolutionarily remarkable ecosystems on our planet," the article concludes. "Scientific knowledge addressing the full scales and intensities of seabed mining should be obtained and properly applied to sustain biodiversity and ecosystem functions in the deep sea if mining is to proceed."