This cumulative impact index ranging from ranging from 0 (no change) to 1 (maximum change) for the impact of climate change on oceans was calculated using sea surface temperature (SST), ocean productivity measured by chlorophyll (CHL), and ocean circulation by Ramirez et al. (2017). The data to calculate were from the longest time series of remote-sensing records (annual composites) on SST (1980-2014), CHL (1979-2014), and marine currents (1980-2014) available to provide finest-scale measurements of the impacts of climate change on the marine environment globally.
Pixel basis, least-squares linear regression of annual information from SST, CHL, and the eastern and northern components of water speed were used for deriving the significance of temporal trends and its magnitudes (slopes; that is, annual changes in target features) over the past 3 decades. CHL data were sourced online as annual composites, whereas data on SST and marine currents were obtained on a monthly basis and averaged yearly to generate a linear relationship to extract slopes. This calculation was repeated for every pixel of the globe. These magnitudes were combined to obtain the spatially explicit Cumulative Impact Index.
Different layers were first resampled following a bilinear interpolation procedure to match the spatial resolution of the coarsest SST product (that is, 1° grid). Absolute values for the slopes of obtained trends (a proxy to the magnitude of environmental changes) were then standardized to the maximum value to make all variables comparable. These relative values were subsequently added on a pixel basis and standardized again to the maximum value. In this way, researchers obtained a dimensionless index ranging from 0 (no change) to 1 (maximum change), thereby providing information about spatial heterogeneity in the magnitude of environmental changes and highlighting those marine areas that have undergone the largest changes in their environmental conditions. Resource Watch shows only a subset of the data set. For access to the full data set and additional information, see the Learn More link.
Global Distribution of Cumulative Environmental Impacts
1980–2014 (SST),1979–2014 (CHL), 1980–2014 (marine currents)