Human activities heavily influence ecosystems, but scientists are not always able to quantify those influences at a global scale. A new study measured cumulative human impact on the world’s coastlines and found that just 15.5% had low anthropogenic pressure. The findings were published in Conservation Biology.
“We knew it would be high, but it was surprising how much human influence there was across the coastal regions,” said coastal ecologist Brooke Williams, a postdoctoral researcher at the University of Queensland, who led the study.
Canada, along with Greenland and Russia, had the largest amount of intact coastline, which researchers defined as regions with low levels of human influence. The intactness was likely due to relatively small numbers of inhabitants.
“It stands to reason that areas that are more remote are going to…have less human pressure on them. But it is sort of amazing to see, essentially, the whole world [has] these pressures,” said Merryl Alber, a University of Georgia coastal ecologist who was not involved in the new study.
A Study of Land and Sea
Researchers made use of two separate data sets from 2013 measuring human impact on terrestrial and marine environments. Land-based human footprint data included built environments, population density, electric grids, and navigation structures like roads and railways. Human influences on marine environments, meanwhile, took into account fishing, climate change factors such as sea level and ocean acidification, watershed pollution (including agricultural runoff), and oceanic shipping activities. Researchers designated intact coastal areas within a 50-kilometer radius of a given coastal point.
Science about terrestrial and aquatic environments tends to be conducted (and funded) separately, a frustration for coastal ecologists. Bringing these data together, said Alber, was the paper’s biggest contribution.
“It used to be that if you were working in the coastal areas, sometimes you couldn’t even figure out where to look for funding because each agency thought the other side was funding it,” Alber said. “Making sure that we recognize that both sides [land and water] influence and impinge on these areas is a really important point.”
Cumulative Human Pressure
The study showed that more than 60.1% of coastal regions around the world were under high human pressure in 2013, with the biggest impacts on coastlines with seagrasses, savannas, or coral reefs. In contrast, deserts, forests, and salt marshes composed the coastal areas less pressured by human activity.
Even among specially designated, protected coastal zones, 43.3% showed high levels of human impact. Countries including Denmark, Finland, and Singapore, for instance, ranked high in governmental effectiveness in protecting coastlines but had low intactness scores. (Some other countries with high governmental effectiveness, like Australia and the United States, fared better.) Williams said these results don’t necessarily mean leaders in these countries are doing a poor job: “A lot of those coastal regions are already quite badly damaged; they’re already degraded.”
Williams stressed that the research provided a good general outline of the impact of human activity on coastlines but was not specific or prescriptive. “We are estimating cumulative human pressures, not actual realized state at the biological levels,” she said. “Quantifying ecological conditions in the actual state of ecosystems across Earth is extremely complicated. There [are] so many things that make up these ecosystems and biological assemblages…from really tiny scales to big scales.”
Overall, though, Williams said she’s not pessimistic about these findings. She hopes they encourage individuals to educate themselves and become more involved in helping to protect coastal ecosystems through voting and mindful consumerism.
“If people were more aware of how companies were earning their money…then maybe they would be more inclined to support companies that are more sustainable, and to support politicians who are in favor of regulating these big companies,” she said.
—Robin Donovan (@RobinKD), Science Writer