Photo: NASA Goddard Photo and Video
Greenland is slowly, but surely, melting. And though we aren’t sure of all the varied effects that this will have on local and global climate, the iron within this ice could cause a boom of tiny plants and animals in our oceans, a new study suggests.
Global warming has many climate scientists worried that rising ocean temperatures and acidity will kill off all kinds of marine life, but these tiny algae, called phytoplankton, form the base of the food chain in the Ocean, and increasing their numbers could have a large impact on ocean life.
That’s according to research published March 10 in the journal Nature Geoscience. In the study researcher Maya Bhatia from the University of British Columbia and her colleagues found that melting glaciers near the Arctic are releasing significant amounts of iron.
“Glacial runoff has only recently been considered a potentially important source of nutrients that are usable, or bioavailable, to downstream ecosystems,” Bhatia said in a press release from the Woods Hole Oceanographic Institution. “We believe our study now adds iron to that list of nutrients, and underscores the potential for a unique but as-yet-undetermined chemical impact from increasing ice sheet meltwater runoff.”
In the paper the scientists theorized that the high levels of iron running off of the Ice Sheet may be connected to recent phytoplankton blooms near Greenland. As the climate warms and ice continues to melt, the ice sheet could continue to release iron.
It is not certain what the long-term effects will be, but it is known that phytoplankton — tiny drifting algae, are at the very bottom of the ocean’s food chain, which means that larger creatures need these small guys to survive.
Previous studies published in journals such as Nature, had suggested that phytoplankton levels had begun to decrease over the last century, which has had many scientists worried about whether much of the other life in the ocean would vanish along with it.
When they examined water samples taken from streams and rivers running off the ice sheet, the scientists found about half of the iron was bioavailable — meaning it came in a form that could be used as a nutrient for budding phytoplankton.
Photo: NASA Goddard Photo and Video
Microscopic algae use this iron along with other minerals to grow and reproduce. Other tiny “animal” plankton consume the phytoplankton that grows, larger creatures in turn eat those plankton, and so on.
The researchers estimated that the increasing meltwater from the Greenland Ice Sheet could double the amount of iron entering the ocean currently — and could be an important source of bigger phytoplankton blooms. Currently, iron in the water is a limiting factor for how much plankton can grow.
If melting glacial ice sheets can produce enough iron to boost plankton growth in the ocean, there could be downstream effects on all ocean species.
“We don’t have enough historical measurements to say that this iron contribution is an increase over past conditions, but if it is working the way we think it is, the contribution would be greater as meltwater discharge increases,” Bhatia says. “It is interesting to think that, as ice sheets melt, there are biogeochemical considerations beyond changing sea level.”
Large plankton blooms have been known to suck up carbon dioxide from the atmosphere, and some have even proposed adding iron to the ocean as a way to mediate the effects of climate change. Researchers can’t be sure how big the effects of Greenland’s iron melt may be, but it’s possible the plankton bloom could mediate climate change in a small way.
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