Title: Scientists Discover 56% of World’s Oceans Changing Color Due to Climate Change
Subtitle: Ocean color changes reflect significant shifts in essential marine ecosystems
Researchers from MIT and the National Oceanography Center in the U.K. have made a groundbreaking discovery, finding that more than half of the world’s oceans have undergone significant color changes in the past two decades. These changes, attributed to human-induced climate change, have major implications for marine ecosystems. The study suggests that monitoring ocean colors could serve as a valuable tool for detecting and understanding these changes.
Published in the journal Nature, the study reveals that the alterations in ocean color observed over the last 20 years cannot be explained solely by natural variability. Instead, the researchers believe that human activities, particularly those affecting climate change, are the primary driver.
The team focused on equatorial tropical regions where the observed color shifts have been most pronounced. They discovered that these areas have become progressively greener over time. These changes in color indicate corresponding shifts in marine ecosystems, as the color of the ocean directly reflects the organisms and materials within it.
To track these ocean color changes, scientists relied on data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite, which has been monitoring ocean color for over two decades. By analyzing measurements taken in seven visible wavelengths, the researchers were able to detect subtle color differences that are imperceptible to the human eye.
While the study does not provide a conclusive explanation for the specific changes occurring in marine ecosystems, the researchers are confident that human-induced climate change is the underlying cause. Stephanie Dutkiewicz, a senior research scientist at MIT’s Department of Earth, Atmospheric and Planetary Sciences, expresses her concern over the results, emphasizing that the changes in color are consistent with simulations predicting such shifts.
Lead author B. B. Cael of the National Oceanography Center states that these findings offer further evidence of the extensive impact of human activities on Earth’s biosphere. Understanding how climate change affects essential marine ecosystems is crucial for preserving biodiversity and mitigating further damage to the planet.
The research sheds light on the importance of monitoring ocean colors beyond just chlorophyll, which has traditionally been used as an indicator of changes in marine ecosystems. By considering a broader range of colors, scientists can more accurately and rapidly detect climate change-driven alterations.
The study underscores the urgent need to address the implications of these color changes on plankton communities, the foundation of the marine food web. The researchers stress that these shifts will impact all organisms dependent on plankton, including krill, fish, seabirds, and marine mammals. Furthermore, changes in ocean color also affect the ocean’s ability to capture and store carbon dioxide, an essential factor in regulating climate change.
The scientists call for a concerted effort to address this issue, urging the public and policymakers to take the research seriously. They hope that the recognition of visible changes in the ocean, combined with the mounting evidence from models and real-world satellite data, will lead to proactive measures to protect marine ecosystems and mitigate the effects of climate change.
Reference: “Global climate-change trends detected in indicators of ocean ecology” by B. B. Cael, Kelsey Bisson, Emmanuel Boss, Stephanie Dutkiewicz, and Stephanie Henson, 12 July 2023, Nature.
DOI: 10.1038/s41586-023-06321-z
This research received partial support from NASA.