Words Can't Describe It: Humans' Impact on the World's Oceans

human impact on oceans

Image courtesy of B.S. Halpern

The verdict is in, folks, and, to no one's surprise, it ain't pretty: over 40% of the world's oceans are heavily impacted by anthropogenic activities with few - if any - left unaffected. The map, the product of four years' worth of meticulous research and number-crunching, was created by Benjamin Halpern and his colleagues at UCSB's National Center for Ecological Analysis and Synthesis.On the center's website, Halpern explains the process he and his colleagues followed to make the composite map:

"1. We gathered or created maps (with global coverage) of all types of human activities that directly or indirectly have an impact on the ecological communities in the ocean's ecosystems. In total, we used maps for 17 different activities in categories like fishing, climate change, and pollution. We also gathered maps for 14 distinct marine ecosystems and modeled the distribution of 6 others.

2. To estimate the ecological consequences of these activities, we created an approach to quantify the vulnerability of different marine ecosystems (e.g., mangroves, coral reefs, or seamounts) to each of these activities, published in Conservation Biology, October 2007. For example, fertilizer runoff has been shown to have a large effect on coral reefs but a much smaller one on kelp forests.

3. We then created the cumulative impact map by overlaying the 17 threat maps onto the ecosystems, and using the vulnerability scores to translate the threats into a metric of ecological impact.

4. Finally, using global estimates of the condition of marine ecosystems from previous studies, we were able to ground-truth their impact scores."

As Science's Eli Kintisch notes, the impact scores, which range from 0 to 20, mean little to the scientists in terms of concrete damage; without more hard data, Halpern acknowledges it is difficult to move beyond the use of vague terms such as "degraded" to describe the ecosystems' state. Larry Crowder, a marine ecologist at Duke University, deemed the effort a "bold attempt" though he said it is still far from comprehensive.

Halpern and his colleagues hope other scientists will use the map as the basis for updating and studying new data sets to form a clearer overall picture. Despite some of its more noticeable gaps, it's clear that the map paints a bleak picture of the oceans' health. As Dennis Heinemann, a senior scientist at the Ocean Conservancy and a co-author on the study, explained to blogfish's Mark Powell:

"On a global scale, the study determined that coral reefs and sea-grass habitats, places important to maintaining the diversity and productivity of ocean life, are suffering from some of the most significant cumulative threats from humans. We fear that few areas of the ocean are left without compromised resilience in the face of the ongoing and increasing threats of overfishing, pollution and ocean climate change."

Take a look at NCEAS' website to learn more about the study's methodology and implications (and to see a great informative video).

Via ::blogfish: Map of global human impact on oceans (blog)

See also: ::Loss of Deep-Sea Species Could Precipitate Oceans' Future Collapse, ::The 10 Solutions to Save the Oceans, ::Live from Pop!Tech: For Ocean Health, "Climate Change More Important than Fishing Practices"

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