Data from: Blue carbon benefits from global saltmarsh restoration

Coastal saltmarshes are found globally, yet are 25–50% reduced compared to
their historical cover. Restoration is incentivised by the promise that
marshes are efficient storers of ‘blue’ carbon, although the claim lacks
substantiation across global contexts. We synthesised data from 431
studies to quantify the benefits of saltmarsh restoration to carbon
accumulation and greenhouse gas uptake. The results showed global marshes
store approximately 1.41–2.44 Pg carbon. Restored marshes had very low
greenhouse gas (GHG) fluxes and rapid carbon accumulation, resulting in a
mean net accumulation rate of 64.70 t CO2e ha-1 y-1. Using this estimate
and potential restoration rates, we find saltmarsh regeneration could
result in 12.93–207.03 Mt CO2e accumulation per year, offsetting the
equivalent of up to 0.51% global-energy-related CO2 emissions – a
substantial amount, considering marshes represent <1% of Earth’s
surface. Carbon accumulation rates and GHG fluxes varied contextually with
temperature, rainfall and dominant vegetation, with the eastern costs of
the USA and Australia being particular hotspots for carbon storage. Whilst
the study reveals paucity of data for some variables and continents,
suggesting a need for further research, the potential for saltmarsh
restoration to offset carbon emissions is clear. The ability to facilitate
natural carbon accumulation by saltmarshes now rests principally on the
action of the management-policy community and on financial opportunities
for supporting restoration.