Coral reef monitoring

Monthly average temperatures and thermal regimes

Research indicates that coral reefs will not survive the rapid increases in global temperatures and atmospheric carbon dioxide forecasted for this century by the UN’s Intergovernmental Panel on Climate Change. Coral reefs are threatened by overfishing, coastal pollution, global warming and ocean acidification.

To help the World Bank monitor the health of coral reefs in the Caribbean, ESA led a project that generated state-of-the-art EO-based information to understand the capabilities of resistance and recovery from disturbances of coral reefs off the coast of Belize.

The project incorporated sea-surface temperature data from the Along-Track Scanning Radiometer and the Advanced Along-Track Scanning Radiometer on ESA’s ERS-2 and Envisat satellites, wind speed and direction data from the Active Microwave Instrument (AMI) on ERS-2 and imagery from NASA’s Landsat to identify coastline and reef-crest areas.

Using these data, scientists from the University of Exeter mapped a number of important factors influencing coral health in the Northern Mesoamerican Barrier Reef System (NMBRS). These included chronic and acute thermal stress regimes, wave exposure areas and reef connectivity (for larvae dispersion).

Results showed that those areas predicted to fare better under climate change (from a thermal perspective) are rare and scattered across the study area. Also, if over-fished, some areas are more vulnerable to becoming dominated by seaweed with a resultant loss of corals (for example, north of the barrier reef and the seaward side of the atolls). Finally, the reefs are in general well connected, facilitating the dispersion of larvae.

The demonstration confirmed EO data can be used to map the locations of reef habitats and to understand better what regions are more vulnerable and likely to experience coral bleaching.

"Space-based observations are an essential element of climate monitoring in Latin America and a complement to ground-based stations," said Walter Vergara, Lead Engineer-Latin America Environment Department at the World Bank. "ESA instruments and observation protocols are particularly applicable to the type of information that needs to be collected over time in the Americas."

Coastal change monitoring

Trends of erosion in Bangladesh

According to the UN, Bangladesh is one of the few countries to experience potentially catastrophic consequences of climatic change. A critical variable that determines the vulnerability of the South Asian country to climate change impact is the magnitude of sea-level rise.

ESA carried out projects to demonstrate the potential of different EO data and methodologies for coastal change mapping to provide improved input data for models that try to describe the long-term effects of possible sea-level rise due to global warming.

Using EO data from the Disaster Management Constellation (DMC), SPOT, NASA’s Landsat Enhanced Thematic Mapper, ASTER, Ikonos, and QuickBird from the last decade over the majority of Bangladesh’s coastal region, scientists were able to illustrate how EO can contribute to coastal monitoring.

The situation is very complex owing to large tidal effects in the area. The individual annual erosion and accumulation rates observed from EO satellites show strong spatial variability, as seen in the image above.

"The coastline of Bangladesh is extremely dynamic, making it difficult to predict how sea-level rise may impact the southern part of the country," said Winston Yu, Water Resources Specialist at the World Bank. "These preliminary results from EO are interesting and merit further investigation into the accretion and erosion processes occurring."

Coastal Cities

ESA and World Bank discussions

ESA is now starting an additional project to quantify land subsidence from EO over the last decade for the city of Alexandria, Egypt, which extends widely along the coast of the Mediterranean Sea. This information will be used, together with many other sources, in a World Bank study to assess the exposure and risk of coastal cities to the possible effects of climate change in the future.

"There is very little scientific evidence of the subsidence that has been taking place along the Nile Delta coastline, and whether the city of Alexandria has been affected as well," said Anthony Bigio, senior urban specialist at the World Bank for the Middle East and North African region. "We therefore very much look forward to EO filling this gap, and we are sure that it will be an important input for the study we are carrying out on climate change adaptation and natural disaster preparedness in the coastal cities of North Africa."

Next Developments

These initial demonstrations have raised interest from the World Bank in European EO capabilities, and further requests for support are in the pipeline. Discussions are under way for ESA to support additional projects such as sea-level rise in the Caribbean, forest degradation in the Amazon, and water resources management in the Maghreb and Middle East regions.

There are many other possibilities for EO information to be put to use in World Bank activities; both organisations look forward to a longer-term and more formalised form of collaboration.