Data covering the marine environment, including fisheries, coral reef  health, ocean chemistry, and coastal zones.

oceans-seas-coasts

Oceans, Seas, & Coasts

### Overview  
  
This dataset shows projections of aragonite saturation in the world’s oceans from 2006-2099. The aragonite saturation state (Ωarag) is commonly used to track ocean acidification because it is a measure of carbonate ion concentration, which indicates the availability of the calcium carbonate that is widely used by marine calcifiers, from lobsters to clams to starfish. Aragonite itself is the building block of stony corals that are the primary framework and habitat builders of coral reef ecosystems. Corals and other calcifiers are most likely to survive and reproduce when the aragonite saturation state is greater than 4. Saturation above 3.5 is adequate; above 3 is considered marginal, with growth difficult. When the saturation state falls below 3, these organisms are in danger. Below 1, reefs, shells, and other aragonite structures begin to dissolve entirely.

  
  
These projections are based on future greenhouse gas emission rates determined by the Intergovernmental Panel on Climate Change’s (IPCC’s) Representative Concentration Pathway (RCP) 8.5. The RCP 8.5 scenario presumes no decrease in greenhouse gas emission rates within the 21st century. More information on these scenarios can be found [here](http://tntcat.iiasa.ac.at:8787/RcpDb/dsd?Action=htmlpage&page=about). The projections have a spatial resolution of 1 degree, and cover the entire globe, although the significance of carbonate ion concentrations outside of areas containing warm-water coral reefs is beyond the scope of this discussion.  

  
  
The dataset was created by the National Oceanic and Atmospheric Administration (NOAA) National Environmental Satellite, Data and Information Service (NESDIS) as part of their Coral Reef Watch program. It was created as a way to both incite and inform discussions about the effects of climate change on coral reefs. These may be dramatic: the predicted acidification during the 21st century would be a greater change than possibly at any time in the last 300 million years.

  
  
Coral reefs are among the most biologically rich and productive ecosystems on earth and provide valuable ecosystem benefits to millions of people in coastal areas. They are, however, widely threatened by both local threats (such as overfishing, pollution, and direct physical damage) and the global threats of ocean warming and acidification. These have already caused widespread damage to most of the world’s coral reefs, resulting in reduced areas of living coral, increased algal cover, diminished species diversity, and lower fish abundance, as well as degraded economic and social benefits to many coastal communities.
  
  
### Methodology  
  
Ensembles of climate models were used to generate projections of the year when severe coral bleaching events will start to occur annually, and of changes in Ωarag. The models were used to generate projected monthly data for the following variables: sea surface temperature (SST), surface pressure of CO₂, pH, and salinity. Each model independently generated monthly data for the listed variables, and these model outputs were then adjusted to the mean and annual cycle of observations of SST based on the [OISST V2 1982‐2005 climatology](https://www.ncdc.noaa.gov/oisst/optimum-interpolation-sea-surface-temperature-oisst-v20). 

  
  
Projections were generated for all four RCP scenarios (known as RCP 2.6, 4.5, 6.0, and 8.5); those corresponding to RCP 8.5 were produced using 9 fully coupled models in the [Coupled Model Intercomparison Project 5 (CMIP5)](https://esgf-node.llnl.gov/projects/cmip5/). For each model, Ωarag was computed independently on the basis of those four key variables, as forecast by that same model, by adopting the routines of the Matlab program [CO2SYS](https://cdiac.ess-dive.lbl.gov/ftp/oceans/co2sys/CO2SYS_calc_MATLAB_v1.1/). Finally, the calculated Ωarag projections from all models were combined, as averaging over multiple models can reduce errors and generally increases the accuracy, skill, and consistency of model forecasts.

  
  
All modeled data were remapped to a 1º resolution. Some model outputs were reduced to a sub-set of only reef locations. These were obtained from the United Nations Environmental Program-World Conservation Monitoring Center’s [Millennium Coral Reef Mapping Project Seascape](http://imars.usf.edu/MC/). A cell was counted as a reef cell if it contained any tropical coral reefs according to the original Seascape database.

  
  
For the full documentation, please see the source [methodology](https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.12394).
  
  
### Additional Information  
  
Resource Watch shows only a subset of the dataset. Ωarag is projected annually, but shown on Resource Watch only at decadal intervals. The full dataset also includes projections of coral bleaching and reductions in calcification, as well as additional ocean acidification projections, under four climate scenarios (RCP 2.6, 4.5, 6.0, 8.5). For access to the full dataset and additional information, click on the “Learn more” button.  
  
### Visualizing the Data  
  
Our team reformatted this dataset before displaying it on Resource Watch. See the documentation on how Resource Watch processed the data on [Github](https://github.com/resource-watch/data-pre-processing/tree/master/ocn_006_projected_ocean_acidification).  
  
### Disclaimer  
  
Excerpts of this description page were taken from the source metadata.

National Oceanic and Atmospheric Administration (NOAA)

Projections of Coral Bleaching and Ocean Acidification for Coral Reef Areas

ocn-006a-projected-ocean-acidification-rw

ocean-watch

Ocean Watch

2080 Projected Aragonite Saturation State

2020 Projected Aragonite Saturation State

2060 Projected Aragonite Saturation State

2010 Projected Aragonite Saturation State

2070 Projected Aragonite Saturation State

2090 Projected Aragonite Saturation State

2050 Projected Aragonite Saturation State

2099 Projected Aragonite Saturation State

2040 Projected Aragonite Saturation State

2030 Projected Aragonite Saturation State

Projected level of ocean acidification, as indicated by carbonate ion concentration

Projected Ocean Acidification