Recent research shows that terrestrial plants have boosted global photosynthesis from 2003 to 2021. This increase, detailed in a study published in Nature Climate Change, contrasts with a decline in photosynthesis from marine algae. Understanding these changes is crucial for managing ecosystems and predicting climate change effects.
Photosynthetic organisms, like plants and phytoplankton, are vital to life on Earth. They use sunlight to convert carbon dioxide into organic matter. However, they also release carbon through respiration, similar to how we breathe. The balance of carbon gained and lost defines net primary production, which is a measure of ecosystem health. Yulong Zhang, a research scientist at Duke University, emphasized that net primary production supports nearly all other life forms, highlighting its significance for food security and climate stability.
Previous studies mainly focused on either terrestrial or oceanic ecosystems, leaving a gap in our understanding of the interplay between both. This study bridges that gap by examining annual global trends in net primary production across land and oceans. Co-author Nicolas Cassar pointed out the need for comprehensive evaluations of primary production, noting that foundational research hadn’t been updated in over two decades.
Satellite technology plays a key role in this research. Satellites can continuously monitor the greenness of the earth’s surface, which indicates the abundance of chlorophyll. By utilizing six satellite-based datasets from 2003 to 2021, researchers could track changes in net primary production across ecosystems.
Over the study period, terrestrial net primary production increased by approximately 0.2 billion metric tons of carbon each year. This growth was mainly observed in temperate and boreal regions, while the tropics saw a stagnation in growth. In contrast, marine net primary production declined by about 0.1 billion metric tons per year, especially in tropical and subtropical oceans, notably in the Pacific.
The reasons for these changes are linked to various environmental factors. While warming temperatures have extended growing seasons for plants on land, the same warming has hurt phytoplankton in the oceans. Rising sea temperatures can prevent essential nutrients from mixing in cooler waters, affecting marine algae’s ability to thrive.
Interestingly, ocean ecosystems demonstrated more sensitivity to climate events, such as El Niño and La Niña. Co-author Shineng Hu noted that these events significantly influence ocean primary production, more so than land. After 2015, La Niña events correlated with a decline in oceanic primary production, indicating the ocean’s heightened vulnerability to climate variability.
The implications of this research are far-reaching. While terrestrial ecosystems are compensating for declining marine productivity, significant decreases in tropical and subtropical waters could jeopardize food webs, biodiversity, and local economies. This could weaken tropical regions’ effectiveness as carbon sinks, potentially exacerbating climate change impacts.
Experts emphasize that understanding the balance between terrestrial and oceanic ecosystems is vital for maintaining planetary health. Coordinated, long-term monitoring will be essential in answering how these dynamics will evolve and what it means for life on Earth.
For more in-depth information on the study’s findings, visit [Duke University’s Nicholas School of the Environment](https://nicholas.duke.edu/). Tracking these trends is crucial for future climate action.
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Ecology; Global Warming; Forest; Environmental Issues; Environmental Science; Ecosystems; Rainforests; Air Quality
