Forest fires have historically been viewed as catastrophic events. Thanks to climate change, forest fires are now a threat for much longer periods of the year, rather than being limited to the traditional warm-weather season. Since 2017, most of the years with the highest number of extreme forest fires have occurred, and these fires are generally becoming more intense over time.
While there is no denying that forest fires cause an incredible amount of damage to the landscape, they burn as well as send a large amount of carbon dioxide emissions into the atmosphere, there is a silver lining to forest fires. That silver lining is that forest fires can benefit ocean life. This is hard to believe, yet it is true.
Forest Fire Smoke Can Be A Benefit To Marine Life
Forest fire smoke carries ash containing high levels of iron, an element that helps marine life thrive.
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It seems counterintuitive to think of forest fires as a positive thing for the planet. When they are smaller fires that are put out within a short period, the fires create new habitats for plants and animals to live in, the soil is cycled to become nutrient-rich, seeds are dispersed to create new life, and larger, uncontrolled forest fires are prevented from occurring.
According to a new study published in Nature Climate Change, forest fires have even been found to benefit marine life. This is because, as forest fire smoke is blown in the direction of the coast by the wind, the smoke carries iron-rich ash with it. Areas like the North Atlantic, where iron levels are not plentiful, especially benefit from forest fire smoke.
As climate change is anticipated to increase the number and intensity of annual forest fires, the amount of iron deposited into oceans has been calculated to be 1.8 times greater than it is today. In the North Atlantic alone, this could translate to up to a 40% increase in phytoplankton productivity during the summer growth season.
Why is an increase in phytoplankton important? The increase is significant due to the amount of carbon that phytoplankton consume, and the amount of oxygen released into the environment. By knowing just how much iron will be deposited into oceans, according to the study co-senior author Maria Gonçalves Ageitos, who is a researcher at the BSC and the Universitat Politècnica de Catalunya, it is easier to predict how climate change will affect oceans in the future.
“The results of this study are crucial for improving projections of the carbon cycle and ocean health under a changing climate,” Gonçalves Ageitos explains to Earth.com, “paving the way for more accurate climate models and better-informed future climate change adaptation policies.”
This information provides scientists with a better understanding of how much carbon emissions need to decrease to slow climate change.
As Phytoplankton Grows, Carbon Dioxide Emissions Decrease In The Atmosphere
Phytoplankton grow into large blooms when enriched with iron, which increases oxygen on Earth while decreasing carbon dioxide emissions.
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When phytoplankton are enriched with iron, they can grow to their full potential. By covering the upper portion of the ocean, these organisms are capable of absorbing carbon dioxide from the atmosphere, while providing approximately 80% of the world’s oxygen, both above and below the water’s surface.
As iron provided by forest fires nourishes phytoplankton, it grows larger. The larger the phytoplankton grows, the greater its ability to decrease carbon emissions. It is estimated that the world’s oceans absorb about 30% of human carbon dioxide emissions, with phytoplankton playing a major role in this process.
The phytoplankton alone are responsible for consuming as much carbon as all land plants. Once the phytoplankton dies, it takes the carbon it has absorbed to the bottom of the ocean, where it is stored. This is why researchers believe that if the amount of carbon emissions began to decrease, over time, the oceans could make the planet healthier as carbon dioxide is absorbed. But, as much as forest fires can help oceans, they can be equally as harmful to the animals that live below the waves.
Forest Fire Smoke Can Fertilize Algae That Harm Marine Animals
Iron-rich ash also fertilizes algae, creating disastrous red tides.
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Along with the ash fertilizing the phytoplankton, the forest fire smoke carrying the ash can fertilize algae in the ocean. When this happens, an algae bloom can grow out of control, causing problems for marine life that swim through it.
When forest fire ash fertilizes algae, it can lead to a deadly algal bloom known as a red tide. Harmful algal blooms occur annually in some regions of the world, including Indonesia. But it was not a naturally occurring event that caused a red tide in Sumatra, according to a 2003 study published in Science. Instead, the red tide was caused by wildfires in the region. The bloom in 1997 occurred in Indonesia amid a massive forest fire. According to the study, the bloom grew so large that it depleted the ocean of oxygen, killing a Sumatran coral reef and numerous fish that came in its path.
“Iron fertilization by the 1997 Indonesian wildfires was sufficient to produce the extraordinary red tide,” the study states, “leading to reef death by asphyxiation.”
Consequently, while ash can be helpful from the aspect of adding iron to oceans, allowing organisms to thrive, it can also be a burden when the wrong organisms grow out of control.
Blocked Sunlight Can Lead To Temporary Depleted Oxygen Levels In The Ocean
The smoke from the forest fires can block the sun, stunting phytoplankton growth.
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Although the ash from wildfires entering the oceans can be beneficial, the smoke can be problematic. This is because the more fuel the wildfire has to burn through, the thicker the smoke becomes, choking out the sunlight.
The oceans require sunlight to enable the process of photosynthesis, which is how green plants produce their own food. The phytoplankton in the sea is one of those organisms that act like terrestrial plants, as they contain chlorophyll, which requires sunlight for nourishment. When the sun is blocked by the smoke for days on end, photosynthesis cannot occur, which spells problems both for phytoplankton and the ocean in general.
Phytoplankton cannot grow without sunlight. The smaller the phytoplankton, the less oxygen the organisms will produce and the less carbon dioxide they will absorb. Reduced oxygen levels in the ocean can be detrimental to fish and other marine organisms if they persist for an extended period. Therefore, while the ash falling into the oceans can help phytoplankton by increasing iron levels, if there is not enough sunlight, the oxygen-creating organisms will not benefit as much from the falling ash as they would with sunlight shining down from above. Consequently, while forest fires can benefit the oceans, the costs may outweigh the benefits in this situation.
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