Shocking Discovery: 56% of World’s Oceans Undergo Significant Color Changes Linked to Climate Change

Ocean Colors Changing Due to Human-Induced Climate Change, Study Finds

A recent study conducted by scientists from MIT and the National Oceanography Center in the U.K. has revealed that human-induced climate change has caused significant changes in the color of the world’s oceans. Over the past 20 years, an estimated 56% of the oceans have experienced notable shifts in color, particularly in equatorial tropical regions. These changes in color serve as indicators of the transformation happening within marine ecosystems. Additionally, the research suggests that monitoring ocean colors could serve as a more accurate method of detecting these changes.

The study, published on July 12 in the journal Nature, emphasizes that the observed changes in ocean color cannot be accounted for solely by natural year-to-year variations. These subtle color shifts have encompassed a vast portion of the world’s oceans, surpassing the total land area on Earth. The researchers specifically noted a consistent greening of tropical ocean regions near the equator over time. Such alterations in ocean color signal concurrent changes in the ecosystems within the surface ocean, as the color of the ocean directly reflects the organisms and materials present in its waters.

To monitor these changes, scientists analyzed measurements of ocean color collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite. The MODIS satellite has been tracking ocean color for the past 21 years. Utilizing seven visible wavelengths, including the traditional colors used to estimate chlorophyll, researchers identified subtle differences in color that are imperceptible to the human eye. Through a statistical analysis of two decades worth of satellite data, the team discovered a discernible trend in ocean color changes that exceed natural year-to-year variations.

Lead author B. B. Cael PhD ’19 from the National Oceanography Center noted that this trend is likely driven by human-induced climate change. Cael’s analysis aligned with a previous model developed by co-author Stephanie Dutkiewicz, senior research scientist at MIT’s Department of Earth, Atmospheric and Planetary Sciences and the Center for Global Change Science. Dutkiewicz’s model simulated the Earth’s oceans under two scenarios: one with the addition of greenhouse gases and another without. The findings from the model accurately predicted the observed trend in ocean color changes over the past 20 years, providing further evidence of anthropogenic climate change.

Monitoring ocean colors beyond chlorophyll could equip scientists with a faster and more precise method of detecting climate-change-driven alterations in marine ecosystems. As Dutkiewicz explains, the changes in ocean color will impact plankton communities and everything that depends on them for sustenance. Moreover, different types of plankton have varying abilities to absorb carbon, thus affecting the ocean’s capacity to store carbon dioxide. The researchers hope that these findings will be taken seriously, as they present tangible evidence of the ocean’s transformation due to climate change.

This study was funded in part by NASA.