When we consider the state of wildlife on the planet, the general consensus is that humanity hasn't had the best track record with species extinctions.

Over the past 500 years, approximately 500 land-based species have gone extinct because of human actions, but compare that with the ocean and things look much better—scientists have only counted 15 extinctions under the sea.

A new paper published in the journal Science examines the past, present and future of marine wildlife and asserts that ocean animal populations are as healthy as their land kin were hundreds, if not thousands, of years ago, before major ecological damage took place.

"We wanted to know how the health of wildlife on land matches up to the health of wildlife in the oceans," said Douglas McCauley, a lead author of the paper and professor of ecology, evolution and marine biology at the University of California, Santa Barbara. "What we see when we line up the amount of impact we've had is the oceans are in good shape if you compare them to how badly we've trashed wildlife on land."

But as the ocean becomes increasingly industrialized, the authors say the next 100 years might make the situation underwater as grim as it is up top.

History has been kinder to ocean wildlife
The researchers synthesized data from a number of studies to compare the industrial revolution on land with current patterns of human use of the oceans.

Thousands of years ago humans began hunting animals with simple tools—think spears and mammoths, McCauley said. Then, we began using more sophisticated tools such as nets and bows and arrows. Then, we traded those in for shotguns, while also affecting wildlife indirectly though habitat degradation—building cities and factories, clearing forests and other natural habitats to do it.

McCauley said if we take that narrative and see how it's unfolding under the oceans, a lot of the early part of the narrative is already at play, but it's only within the last 50 years, relatively much later in the process, that humans have begun using more industrial tools to catch sea animals.

"Now we're seeing 700-foot trawlers and finding fish with satellites," he said. "We've put all of our technology into our tackle box, and that has really upped the ante on the impacts we're having on ocean wildlife."

When the researchers plotted the rates of change in the oceans and compared them with what we already know from land, they found that society is at the precipice of the marine industrial revolution.

"In a lot of ways, this research is like realizing that climate change is taking place around us 75 years ago," McCauley said. "We really could have done something had we figured it out ahead of time, but with the oceans we still have that chance."

Existential crisis may loom in the future
The authors emphasize that the relative health of the oceans means we can still make a difference.

Creating more marine-protected areas, managing fishing efforts and regulating the industrial uses of the ocean are all steps we can take, said Stephen Palumbi, director of Hopkins Marine Station and professor at Stanford University.

Climate change, however, is a dark cloud hanging over both land and ocean ecosystems, added Palumbi, a co-author of the paper.

"All the marine protected areas in the world aren't going to save the oceans if we don't get off our current emissions curve," he said. "That I think is an existential crisis that the ocean is going to face. We're not there yet, but we will be."

McCauley sees the message from this paper as one of both warning and hope. Still, time is of the essence.

"On a number of fronts, the damage in the ocean isn't so severe that we can't initiate recovery," he said. "With 15 bricks missing from the foundation of life in the oceans, it remains relatively easy for you or I to get out there with a trowel and some cement and shore things back up. When entire sections of this foundation go missing, this becomes a major construction job."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500