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Scientists
Reveal First-Ever Global Map of Total Human Effect on Oceans
More
than 40 percent of world's oceans heavily affected
NSF Press Release 08-024
February 14, 2008-More
than 40 percent of the world's oceans are heavily affected by human activities,
and few if any areas remain untouched, according to the first global-scale study
of human influence on marine ecosystems.
By overlaying maps of 17
different activities such as fishing, climate change and pollution, the
researchers have produced a composite map of the toll that humans have exacted
on the seas.
The work, published in this
week's issue of Science, was conducted at the National Science Foundation (NSF)'s
National Center for Ecological Analysis and Synthesis (NCEAS) at the University
of California at Santa Barbara, and involved 19 scientists from a range of
universities, NGOs, and government agencies.
The study synthesized global data
on human impacts to marine ecosystems such as coral reefs, seagrass beds,
continental shelves and the deep ocean.
"This research is a
critically needed synthesis of the impact of human activity on ocean
ecosystems," said David Garrison, biological oceanography program director
at NSF. "The effort is likely to be a model for assessing these effects at
local and regional scales."
Past studies have focused largely
on single activities or single ecosystems in isolation, and rarely at the global
scale. In this study the scientists were able to look at the summed influence of
human activities across the entire ocean.
"This project allows us to
finally start to see the big picture of how humans are affecting the
oceans." said lead scientist Ben Halpern of NCEAS. "Our results show
that when these and other individual impacts are summed up, the big picture
looks much worse than I imagine most people expected. It was certainly a
surprise to me."
The study reports that the most
heavily affected waters in the world include large areas of the North Sea, the
South and East China Seas, the Caribbean Sea, the east coast of North America,
the Mediterranean Sea, the Red Sea, the Persian Gulf, the Bering Sea and several
regions in the western Pacific. The least affected areas are largely near the
poles.
"Unfortunately, as polar ice
sheets disappear with warming global climate and human activities spread into
these areas, there is a great risk of rapid degradation of these relatively
pristine ecosystems," said Carrie Kappel, a scientist at NCEAS.
Human influence on the ocean
varies dramatically across various ecosystems. The most heavily affected areas
include coral reefs, seagrass beds, mangroves, rocky reefs and shelves and
seamounts. The least impacted ecosystems are soft-bottom areas and open-ocean
surface waters.
"There is definitely room
for hope," added Halpern. "With targeted efforts to protect the chunks
of the ocean that remain relatively pristine, we have a good chance of
preserving these areas in good condition."
The research involved a four-step
process. First, the scientists developed techniques to quantify and compare how
different human activities affect each marine ecosystem. For example, fertilizer
runoff has been shown to have a large effect on coral reefs but a much smaller
one on kelp forests.
Second, the researchers gathered
and processed global data on the distributions of marine ecosystems and human
influences.
Then the scientists combined data
from the first and second steps to determine "human impact scores" for
each location in the world.
Finally, using global estimates
of the condition of marine ecosystems from previous studies, the researchers
were able to ground-truth their impact scores.
Despite all this effort, the
authors acknowledge that their maps are still incomplete, because many human
activities are poorly studied or lack good data.
"Our hope is that as more
data become available, the maps will be refined and updated," said Fio
Micheli, a scientist at Stanford University. "But this will almost
certainly create a more dire picture."
This study provides critical
information for evaluating where certain activities can continue with little
effect on the oceans, and where other activities might need to be stopped or
moved to less sensitive areas.
As management and conservation of
the oceans turns toward marine protected areas (MPAs), ecosystem-based
management (EBM) and ocean zoning to manage human influence, such information
will prove invaluable to managers and policymakers.
"Conservation and management
groups have to decide where, when, and what to spend their resources on,"
said Kimberly Selkoe, a scientist at the University of Hawaii. "Whether one
is interested in protecting ocean wilderness, assessing which human activities
have the greatest impact, or prioritizing which ecosystem types need management
intervention, our results provide a strong framework for doing so."
"My hope is that these
results serve as a wake-up call to better manage and protect our oceans, rather
than a reason to give up," added Halpern.
"Humans will always use the
oceans for recreation, extraction of resources, and for commercial activity such
as shipping. Our goal, and really our necessity, is to do this in a sustainable
way so that our oceans remain in a healthy state and continue to provide us the
resources we need and want."
-NSF-
Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Gail Gallessich, UCSB (805) 893-7220 gail.g@ia.ucsb.edu
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