The Global Mangrove Watch (GMW) Takeo Tadono (JAXA) Ake Rosenqvist (JAXA/soloEO) Pete Bunting (Aberystwyth Univ.) Richard Lucas (Aberystwyth Univ.) Lisa Maria Rebelo (Int’l Water Management Inst.) Lammert Hilarides (Wetlands International) Nathan Thomas (NASA GSFC) Max Finlayson (Charles Sturt Univ) Chris McOwen (UNEP-WCMC) Takuya Itoh (RESTEC)

Global Mangrove Watch An international collaborative project established as part of the Japan Aerospace Exploration Agency (JAXA) Kyoto & Carbon (K&C) Initiative science program. Technical leads: Aberystwyth U. (U.K.) & soloEO (Japan) Aim to provide geospatial (map) information about mangrove extents and changes at national to global scales for Ramsar Contracting Parties, NGO’s and the public GMW part of STRP WP Task 1.1 and the GEO-Wetlands Initiative plan to develop a Global Wetlands Observation System (GWOS) Potential for SDG6.6.1 reporting on wetlands extents (national-global)

Objectives: Overall: Mapping of extent and changes in global mangrove areas using satellite data at 25m-30m spatial resolution Generation of updated baseline maps of the global mangrove extent for the year 2010 Generation of maps of annual changes in the global mangrove areas (at present 7 time epochs between 1996 and 2017).

Existing global mangrove datasets USGS 2000 (Giri, 2010): First global baseline - derived from Landsat (optical) satellite data. Baseline now 15 years old (1998-2000). World Atlas of Mangroves (Spalding, 2010): Compiled from different data sets. Inconsistent across countries. World Forest Watch (Hansen et al): does not distinguish mangrove from other types of forest

Satellite Radar (JERS-1, ALOS PALSAR, ALOS-2 PALSAR-2): acquisitions regardless of clouds, smoke and haze. Sensitive to vegetation structure and changes. Satellite Optical (Landsat): Sensitive to distinction of mangrove / non-mangrove. Increase prio 1 polygon from N60 to N70 deg JAXA radar mosaic data available for public download at https://www.eorc.jaxa.jp/ALOS/en/palsar_fnf/fnf_index.htm 5

Datasets used 1996: JERS-1 SAR 1998/2000: USGS (Giri et al) and World Mangrove Atlas (Spalding at al) 2007–2009 : ALOS PALSAR 2010: ALOS PALSAR & Landsat-7 2015–2016 ALOS-2 PALSAR-2

Methodology Analysis undertaken in the RSGISLib software (www.rsgislib.org) and associated python modules.

Challenge – many different types of changes Losses Aquaculture Oil and gas exploration Urbanization and infrastructure Logging for firewood and other uses Degradation Climate change… Gains Natural migration Seaward expansion (natural / anthropogenic) Inland expansion (e.g. due to sea level rise and flooding) Large-scale replanting projects

Anthropogenic changes: Aquaculture and infrastructure Input: Multi-temporal radar image tiles Output: Mangrove extent and change map

2010 global mangrove extent Baseline (v2.0) completed Status October 2018 2010 global mangrove extent Baseline (v2.0) completed Classification accuracy was assessed with over 53,800 randomly sampled points across 20 randomly selected regions. Overall accuracy 95.25 % Omission error: 2.5% Commission error: 6.0% Global mangrove extent (and changes rel. to 2010) completed. Validation ongoing.

Global 2010 baseline available for viewing and free download Online viewing: www.globalforestwatch.org Download: data.unep-wcmc.org/datasets/45

Transparency and open data All satellite data, classification algorithms and software and mangrove maps utilized in GMW is open and free of charge. Mangrove maps 25m satellite radar image tiles 30m optical data JRC water occurrence dataset SRTM elevation data Classification software (open source: RSGISLib.org) Users are able to use the maps “as generated by GMW”, or access the original satellite data, classification software to replicate, validate, or improve the mangrove classifications.

Data availability and References The 2010 GMW baseline is available for free public download at the UNEP-WCMC Ocean Data Viewer: http://data.unep-wcmc.org/datasets/45 Online viewing: www.globalforestwatch.org (select “Mangroves” in “Land Cover” menu) GMW maps for 1996, 2007, 2008, 2009, 2015 and 2016 will be made available for viewing and download after validation has been completed (Q1 2019). References: Bunting P., Rosenqvist A., Lucas R., Rebelo L-M., Hilarides L., Thomas N., Hardy A., Itoh T., Shimada M. and Finlayson C.M. (2018). The Global Mangrove Watch – a New 2010 Global Baseline of Mangrove Extent. Remote Sensing, 2018, 10, 1669; doi:10.3390/rs10101669 Global Mangrove Watch (2018). www.globalmangrovewatch.org JAXA K&C www: www.eorc.jaxa.jp/ALOS/en/kyoto/mangrovewatch.htm