How mountains could supercharge carbon uptake in the ocean

Scientists often study Antarctica to understand our planet’s future. The continent looks frozen, yet its deep processes shape ocean life far beyond its shores.

New work now reveals a slow but powerful natural system that links exposed mountains, ancient ice, and carbon absorbing waters.

The research offers a glimpse of how tiny chemical changes in rock can influence the atmosphere over immense timescales.

Newly exposed sources of iron

As glaciers thin, mountain tops lift into open air after long burial. These exposed peaks produce loose rock that carries high levels of iron. The new data show that these surfaces hold more labile iron than earlier records suggested.

Weathering forms both fresh iron compounds and older crystalline forms that remain useful for life in the sea. Warm summer sunlight heats dark rock far above air temperature, which drives these slow chemical changes.

“Our results show that exposed bedrock in Antarctica acts like an iron factory,” said Dr. Kate Winter, sssociate professor in the School of Geography and Natural Sciences at Northumbria University and lead author of the research paper.

Dr. Winter noted that sunlight heats the rock to over 20°C in summer, even when the air stays cold.

A fresh ocean carbon sink

The researchers measured two main forms of extractable iron. One dissolves easily and supports phytoplankton growth. The other dissolves more slowly but becomes more available in seawater after biological processes.

Nunatak samples showed much higher levels of the slower dissolving iron. Several samples carried visible rust, which signaled strong weathering.

Glaciers pick up this material and carry it at different depths. Iron travels near the ice base, within the ice, or near the surface. When ice reaches the coast, melting and calving release sediment into the Southern Ocean.

Coastal waters near glacier outlets show recurring blooms of phytoplankton. These organisms absorb carbon dioxide through photosynthesis.

“The exciting thing is that we can take some hope from these findings because we know that carbon dioxide is a really important factor in climate change,” noted Dr. Winter.

Ice delivers iron very slowly

The new study confirms a long delay in this nutrient delivery system. Ice flow simulations show that iron-rich sediments may need ten thousand to one hundred thousand years to reach the coast.

Sediments shift slowly through deep ice, change along the way, and release their iron only when ice melts near the ocean.

Dr. Sian Henley is a marine scientist from the School of GeoSciences at the University of Edinburgh.

“While the sediments we examine in the mountains today will take a long time to reach the ocean, we know from seafloor surveys that iron-rich sediments have been delivered to the coast for millennia,” explained Dr. Henley.

A hidden nutrient system

The paper shows that thinning ice will expose more peaks. These peaks will produce more weathered material. Rock slope failures may increase as temperatures rise, letting more sediment reach glaciers.

Warm periods inside ice can break down minerals, which helps generate additional loose grains. Glaciers then lift this mix of fresh and altered iron toward the coast.

Large icebergs offer another route. As they drift, their melting spreads iron far from the source region. Coastal currents then carry these nutrients along the Antarctic margin. This increases the area where phytoplankton can thrive.

Repeated blooms appear each summer near the outlets of several glaciers. These blooms stretch many kilometers offshore. They show how this hidden system adds iron to waters that struggle with nutrient scarcity.

Processes that influence the carbon cycle

Antarctica’s mountains may look barren, yet they hold chemical processes that echo far beyond the ice.

Rising rock exposure, active weathering, and glacial transport build a slow pipeline from land to sea. The pipeline moves iron into waters that use it to take carbon from the air.

This system cannot counter rapid climate change on human timescales. But the research shows that natural processes still influence carbon cycles across long periods.

The study will help scientists predict how a warming Antarctica may shift ocean biology in centuries to come.

As the ice sheets thin further, more rock surfaces will emerge and continue to produce iron-rich sediment. Glaciers will pick up this material and carry it toward the ocean, even if that journey takes thousands of years.

Linking mountains to ocean life

When the iron finally reaches the sea, it becomes part of the nutrient mix that fuels phytoplankton growth. These tiny organisms drive one of the planet’s most important carbon-absorbing systems.

Although the full effect unfolds slowly, understanding this link between mountains, ice, and ocean life gives researchers a clearer picture of how Earth’s natural processes respond to warming.

The research also highlights how even the most isolated landscapes play a role in shaping global climate patterns.

The study is published in the journal Nature Communications.

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