Exploring Ecological Marine Units

Redefining the notions of the ocean to teach, conduct research, and collaborate for marine science advancement.

A healthy ocean can reduce poverty, combat hunger, limit the impacts of climate change, and improve the global economy. To achieve these ideals and support ocean sustainability, it is necessary to have a baseline method for understanding of the ocean’s ecosystems and a framework to detect change. Ecological Marine Units (EMUs) are baseline 3D mapped ecosystems of the ocean that have been classified through statistical clustering. They are published in the peer-reviewed journal Oceanography.

While EMUs greatly benefit communities regulating marine protected areas (MPAs), their use is also valuable for academic instruction, scientific reference, and increased understanding of the world’s ocean resources.

The Problem

The health of the ocean is fundamental to the entire planet’s survival, yet 95% of its environments remain a mystery. With so little of the ocean explored in detail, authoritative data and the insights it yields are lacking, limiting the extent to which vital marine ecosystems can be managed properly. In a world of accelerating climate change and population demands, a better understanding of the ocean is necessary to reduce the risk of critically damaging or exhausting marine resources. Absent verifiable data, the opinions of regional experts and socio-political considerations will do little to protect the oceans in the long term. Without acting proactively, a bleak horizon for future generations is all but assured.

The Solution

Acknowledging a need for greater understanding, the Group on Earth Observations (GEO), a consortium of over 100 nations with an intergovernmental protocol related to Earth observation, commissioned a global map of EMUs to support the wise use of ocean resources and the preservation of environmental resilience. The strength of EMUs is that they differ from existing maps of marine ecoregions or biogeographic realms by being globally comprehensive, quantitatively data driven, and truly 3D. Rigorous statistical clustering produced 37 physically and chemically distinct volumetric regions where the chemical properties most likely to drive ecosystem responses are readily available to all interested MPAs, conservation-minded organizations, academic institutions, or citizen scientists. With these insights in hand, individuals can gauge indicators of positive or negative trends and use data to make informed decisions that preserve marine environments.

How EMU's work

EMUs are comprised of an aggregation and computation of an unprecedented 3D point mesh framework spanning 52 million points and global measurements of six key variables over a 50-year period of the ocean’s water column. To build the EMUs, climatology data was extracted at 1/4˚ by 1/4˚ (approximately 27 km x 27 km at the equator) intervals at variable depths before being spatially analyzed and clustered using a multivariate statistical method and then verified by leading oceanographers. The result is a standardized, rigorous, and ecologically meaningful set of ocean ecosystem units which may be used as a basemap alongside an organization’s own GIS overlays for climate change impacts studies, biodiversity priority-setting, economic and social valuation studies, research, and marine spatial planning.

The Ecological Marine Units project is an innovative public-private partnership led by Esri and the USGS.

EMU Explorer partnership
Ecological Marine Units are featured in the journal, Nature and published in the journal Oceanography.

Enlighten the next generation of scientists with EMUs.

Open a world of possibilities for students by teaching them how to access the ocean’s authoritative open 3D data source.


Apply EMU research and analysis to impact an ecosystem.

Use the EMU Explorer web app to unearth insights previously undiscovered. You’ve got the figures; now figure out how to make a difference.


Advance marine science by contributing to an international effort.

EMUs are the result of a global partnership. Improve the ocean’s outlook by building upon existing research, sharing your data, and collaborating with peers worldwide.