Are deep blue seas fading? Oceans turn to new hue across parts of Earth

study co-author Stephanie Dutkiewicz has long feared.

"I've been running simulations that have been telling me for years that these changes in ocean color are going to happen

then later in the article:

“We don't know what is causing the trend. It could be dissolved organic material, changes in the type and quantity of phytoplankton…all these aspects can affect ocean color," study co-author Emmanuel Boss told EOS Science News.

Are they saying it’s just random chance their simulations match the existing reality? How can they not say what is causing it, if they’ve built a simulation that predicts it happening?