From Pixels to Policy: How Maps Inform Climate and Conservation Decisions

The first known human-made map, etched onto a clay tablet, depicts Babylon in 700-500 BCE and includes the Euphrates River and wetlands—one of countless examples of people settling around ecosystems that provide benefits including food and water.

Today, maps still help us understand the world we live in and are important tools for scientific study and the formation of policy. A well-designed map can effectively communicate many layers of information, including the types and extent of wildlife populations, habitats, and threats to both in a visual format that people can quickly interpret. For example, the Intergovernmental Panel on Climate Change (IPCC) uses maps to communicate predictions to a global audience, inform policy, and drive global climate action.

On regional and local levels, maps also play a key role in guiding environmental decisions. For example, The Pew Charitable Trusts’ protecting coastal wetlands and coral reefs project team supported the first field-validated seagrass mapping and carbon assessment effort in Seychelles. This was an ambitious step toward achieving the western Indian Ocean country’s Paris Agreement goals, which include:

• Fully mapping the extent of mangrove and seagrass ecosystems and conducting a first-time assessment of seagrass carbon stocks within Seychelles’ waters.
• Ensuring that at least 50% of the nation’s mangrove and seagrass ecosystems are protected by 2025 and 100% are protected by 2030.
• Establishing a long-term monitoring program for seagrass habitats and including the nation’s blue carbon ecosystems within Seychelles’ National Greenhouse Gas Inventory by 2025.

Coastal ecosystem maps, such as those of blue carbon ecosystems like mangroves and seagrass, are critical for ensuring that these ecosystems are included in climate policies. “Blue carbon” refers to carbon naturally captured by coastal wetlands and marine ecosystems. Seagrasses are one of only three marine ecosystems—alongside saltmarsh and mangroves—currently recognized by IPCC as ecosystems that can make measurable contributions to help a country reduce its emissions. These blue carbon ecosystems not only sequester carbon at a rate three to five times greater than that of terrestrial forests, but they also then store this carbon, often for millennia, within their submerged soils. 

The Seychelles seagrass example shows how maps create the enabling conditions for countries to meet their policy commitments related to climate. Now, the Seychellois government can plan precisely how to achieve some of its nationally determined contributions (NDCs) under the Paris Agreement, including protecting and monitoring seagrass ecosystems.

Seagrass meadows provide habitat for marine species, support livelihoods and food security, and store carbon in their roots, stems, and underlying soil, making protecting these ecosystems a “nature-based solution” to climate change. Without accurate maps, the protection of seagrass ecosystems would be more challenging to implement, and the biodiversity and climate co-benefits they provide would not be fully realized.

Seychelles Seagrass Mapping and Carbon Assessment Project

Despite their value and recent advances in mapping technology, maps remain underutilized in the effort to bridge conservation science with policy. This is because of the many barriers to both the mapping process itself and the interpretation of existing spatial data and maps.

Data collection in coastal ecosystems is often difficult due to technological and resource limitations. Some satellite maps of coastal ecosystems are not entirely accurate because those areas might be shaded, submerged in water, or indistinguishable from other benthic covers. In these cases, verification of ecosystems through in situ field research is essential for accurate mapping. However, such efforts require time and resources.

Further, even when maps are field verified, the methodology used by research teams collecting data may not always be consistent (especially when data is collected by different organizations, at different times, and for different purposes). Maps are only as good as the methodology used to create them. Also, data collection processes in coastal ecosystems are physically demanding. Heat, mud, and swarming mosquitoes are part of a normal workday for those collecting data in the field.

Seychelles Seagrass Mapping and Carbon Assessment Project

Field data must then be entered into geographic information systems —computer-based tools for visualizing, analyzing, and interpreting spatial data—a task that requires advanced technical skills and technology. When ecosystem maps are finally created, they must then be visualized and published in a way that communicates useful information clearly to policymakers and stakeholders. Throughout each step, data must be organized and managed in such a way that it can be stored and shared as needed. Again, these processes take personnel, staff time, and resources.

Researchers estimate that only 20% of global seagrass extent has been fully mapped. Many areas, such as the coastlines bordering the Indian Ocean, remain data deficient. To fill this data gap, and to create enabling conditions for blue carbon ecosystems to be included in national and international climate policies, Pew’s protecting coastal wetlands and coral reefs team is launching a project to map western Indian Ocean seagrass ecosystems by the end of 2026.

The effort endeavors to use satellite imagery and cloud computing methods to identify seagrass ecosystems, with additional field-validation efforts in Kenya, Madagascar, Mozambique, and Tanzania. This project would set the stage for accelerated seagrass conservation and management throughout the western Indian Ocean by creating the enabling conditions for countries to include seagrass conservation in policies such as their NDCs.

Seychelles Seagrass and Carbon Mapping Project

Project will provide the scientific information needed to support country’s climate action

1. Mapping seagrass using satellite imagery

In the first phase of the project, researchers collect countrywide satellite images of the ocean. These images show the presence of seagrass, along with other ocean habitats, such as coral reefs. Because cloud cover and water clarity can affect the quality of the satellite imagery, field data is also collected to differentiate the images.

2. Field data collections on seagrass meadows

Researchers collect seagrass data throughout Seychelles, gathering information on the different species and density of seagrass, and taking soil core samples to estimate the carbon stored beneath the meadows.

3. Data is analyzed to estimate seagrass extent and carbon stock

The satellite images and field data are analyzed and used to produce a high-accuracy, field-validated map of seagrass distribution and extent. The soil cores are analyzed for their carbon content and used to generate a first-time estimate of carbon stock for seagrass meadows in the country.

4. Scientific information informs policy decisions

This scientific information on the distribution of seagrass and its associated carbon stock gives policymakers the information they need to include the protection of seagrass in their NDCs as a nature-based solution to climate change.

Maps are important, and at times vital, tools for bridging science and policy. Looking ahead, Pew will continue to work in the western Indian Ocean through the new seagrass mapping project to help countries accurately assess their seagrass beds and leverage their potential to fight climate change, protect nature, and help communities thrive.

Anelise Zimmer and Kate Meyer are principal associates with The Pew Charitable Trusts’ protecting coastal wetlands and coral reefs project.