In the global effort to mitigate **climate change**, both humanity and **natural ecosystems** play a **crucial role**. Among nature’s tools to combat global warming are carbon sinks, systems that **can enhance the absorption of carbon (CO2) by the oceans**, reducing its concentration in the atmosphere.
This way, **the oceans** become **the largest natural carbon sink**, absorbing around 50% of anthropogenic CO2 emissions. Organisms such as plankton, corals, algae, and certain fish contribute to this task by playing an essential role in this process, as they **help regulate the planet’s climate**. However, this capacity has limits. When the oceans absorb too much CO2, the pH decreases, causing acidification and negatively affecting key marine species such as corals and mollusks.
Faced with the challenge of limited capacity of natural sinks, researchers are exploring **different techniques based on natural processes** to increase carbon absorption by the oceans. One of them is ocean alkalinity enhancement (OAE), which uses minerals such as carbonates and silicates to modify seawater chemistry. This approach aims to **increase CO2 storage in the form of bicarbonates and carbonates**, minimizing the effects of acidification.
In this regard, a recent study led by marine biologist Nicolás Sánchez from the Helmholtz Centre GEOMAR evaluated the environmental impacts of ocean alkalization on marine ecosystems. The results, published in *Science Advances*, highlight its potential as a mitigation tool, although its ecological repercussions are not yet fully understood.
## **Experiment in Gran Canaria: impact on zooplankton**
The experiment, conducted in 2021, used large structures known as mesocosms to simulate an alkalinity gradient in seawater. Over 33 days, researchers analyzed **how these modifications affected zooplankton**, a crucial component of the marine food web.
The findings revealed minor and transient impacts that did not significantly alter the nutritional properties of zooplankton as fish food. However, **a slight decrease in the nutritional quality of particulate matter** was observed, although this did not affect the zooplankton due to limited food conditions in the subtropical region studied.
## **A step towards safe and sustainable carbon mitigation and absorption**
The study represents progress towards understanding the **ecological effects of balanced alkalization**, laying the groundwork for the development of an environmentally safe operational framework. Nevertheless, **further research is needed on other OAE approaches** and their application in different marine environments to ensure their viability as a climate solution.
In the context of climate change, increasing ocean alkalinity stands out as **one of the most promising strategies to reinforce the oceans’ role** as carbon sinks, aligning with the goals of the Paris Agreement to limit global warming.
## **How can you contribute to carbon absorption?**
Oceans are not the only tools that can help with carbon absorption, but also:
– **Planting trees:** Trees act as carbon sinks, meaning they retain CO2. Planting native species is recommended.
– **Supporting reforestation:** Reforesting degraded forests helps absorb CO2.
– **Avoiding deforestation:** Supporting measures to prevent deforestation and forest fires.
– **Practicing conservation tillage:** This practice aims for minimal soil disturbance, helping retain carbon.
– **Crop rotation:** Varying the amount and type of plant residues integrated into the soil can improve carbon sequestration levels.
– **Applying organic fertilizer:** Compost and manure can enhance carbon sequestration in the soil.
– **Cultivating algae:** Algae are aquatic plants with a high carbon absorption capacity.
There are also **other actions to reduce CO2 emissions**, such as buying fresh and local products, opting for sustainable mobility, harnessing renewable energy sources, and calculating carbon footprint.
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