Ecological Marine Units


GIS provides a better understanding of ocean ecosystems

Announcing Ecological Marine Units (EMU) 2018


The new release of the EMU 2018 incorporates approximately three million additional ocean observations. The result is the most current, globally comprehensive, standardized analysis layer that supports climate change impact studies and marine spatial planning.

Learn more about EMU 2018

Public-private partnership led by USGS & Esri


Ecological Marine Units are published in the journals Nature and Oceanography.

View Ecological Marine Units
Esri Partners

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 (EMU) are baseline 3D mapped ecosystems of the ocean that have been classified through statistical clustering. They are published in the peer-reviewed journal Oceanography.

EMU greatly benefit the design of marine protected areas (MPAs). Their use is also valuable for scientific research and classroom instruction.

The problem


The ocean's health is fundamental to earth's survival, yet 95 percent of the ocean remains 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 pressures, a better understanding of the ocean is necessary to reduce the risk of critically damaging or exhausting marine resources.

A fish hiding in colorful coral reef

The solution


The Group on Earth Observations (GEO), a consortium of over 100 nations and over 100 other organizations, commissioned a global map of EMU to promote sustainable use of ocean resources and environmental resilience. Rigorous statistical clustering produced 37 distinct 3D volumetric regions of ocean properties most likely to drive ecosystem responses. With this, conservation-minded organizations, academic institutions, or citizen scientists can gauge positive or negative trends and use data to make better-informed decisions that preserve marine environments.

A scuba diver swimming with hundreds of orange fish above a colorful coral reef

How EMU work


EMU comes from a 3D point mesh framework of 52 million global measurements of six key ocean variables collected over 50 years at a horizontal resolution of 1/4˚ by 1/4˚ (~27 km x 27 km at the equator), over 102 depth zones. Multivariate statistical methods clustered the data into EMU, which were then verified by leading oceanographers. The result is a standardized, rigorous, and ecologically meaningful set of units that may be used as a basemap beneath an organization's GIS data to support climate change impact studies, conservation priority setting, economic and social valuation, and marine spatial planning.

A 3D map showing wave heights diminishing as they come into contact with landmass