NEW YORK, BRONX (ORDO News) — Satellite measurements carried out over two decades have revealed striking changes in the color of the surface of the world‘s oceans. Once dark blue waters are gradually taking on a greener hue, signaling possible changes in marine ecosystems around the world. This phenomenon was discovered by researchers led by B.B. Keila, from the UK‘s National Oceanography Centre, shows the impact of climate change on the delicate balance of ocean life.
Ocean color may seem like a trivial matter, but it is a critical indicator of the health and composition of marine ecosystems. Phytoplankton, microscopic organisms that live near the ocean’s surface, play a critical role in the aquatic food web and the carbon cycle. The greening of the sea surface indicates significant changes in these fundamental processes, with far-reaching consequences for marine life.
Analyzing data collected by NASA‘s Aqua satellite’s MODIS instrument, the research team found that the color of 56% of the world’s ocean surface has changed significantly over the past 20 years. The predominant change was an increase in green hues over large areas of the ocean. These changes are particularly pronounced in tropical and subtropical regions, excluding higher latitudes and coastal areas with natural noise in the data.
Chlorophyll levels are a critical metric for scientists studying phytoplankton abundance and productivity. Traditionally, remote sensing scientists have relied on a limited range of colors in the visible spectrum to estimate chlorophyll levels. However, a recent study used the full spectrum of colors, providing a more complete picture of the ecosystem as a whole. Black dots on the map indicate areas where chlorophyll levels have also undergone significant changes.
The availability of long-term data from a single satellite sensor is a rare and valuable resource in the field of remote sensing. The Aqua satellite, which exceeded its planned service life of six years and celebrated its 20th anniversary in orbit in 2022, provided researchers with a unique opportunity to identify long-term trends. By analyzing extensive information on ocean color collected by the satellite, the team of researchers was able to confirm a trend that climate models had predicted, but which would have taken 30 to 40 years to detect using traditional chlorophyll estimates. The new method, which takes into account all visible light, was robust enough to detect this trend within two decades.
Dr B.B. Kael, the study’s lead scientist, emphasized the significance of the findings: “These changes in ocean color are not just an aesthetic curiosity; they reflect fundamental shifts in the marine ecosystem.” Greening the oceans has far-reaching implications for biodiversity, carbon cycling and fisheries. Dr Stephanie Dutkiewicz, from MIT’s Department of Earth, Atmospheric and Planetary Sciences, added: “This is a ‘canary in the coal mine’ warning sign that something is changing in the oceans.”
The impact of climate change on the oceans is a matter of concern to scientists and experts around the world. According to a report by the Intergovernmental Panel on Climate Change (IPCC), rising temperatures, melting ice caps and increasing carbon dioxide are causing significant changes in marine ecosystems. The greening of the ocean surface is just one visible manifestation of these changes.
Historically, the color of the ocean has been associated with its health and productivity. A study published in the journal Nature Communications found that changes in ocean color may be linked to fluctuations in phytoplankton abundance. Phytoplankton account for approximately half of Earth’s oxygen production and play a critical role in regulating carbon dioxide levels in the atmosphere.
The greening of the ocean surface is the result of an increase in phytoplankton abundance, which is likely influenced by rising sea surface temperatures and nutrient availability. As temperatures rise, nutrient-rich waters rise to the surface, creating ideal conditions for phytoplankton growth. Increases in phytoplankton have cascading effects throughout the marine food web, affecting the abundance and distribution of fish and other marine organisms.
The implications of ocean greening are far-reaching. The study, published in the journal Science Advances, warns that changing ocean color could upset the delicate balance of marine ecosystems, leading to declines in biodiversity and fisheries. These changes could also affect the global carbon cycle, as phytoplankton play a critical role in absorbing carbon dioxide from the atmosphere.
Scientists and experts are calling for urgent action to mitigate the effects of climate change on the world’s oceans. Dr. B.B. Kael emphasizes the need for further research and monitoring: “Understanding the drivers of these changes is critical to developing effective conservation and management strategies.” Dr Stephanie Dutkiewicz adds: “We must act now to reduce greenhouse gas emissions and protect our oceans for future generations.”
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News agencies contributed to this report, edited and published by ORDO News editors.
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