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Fertilizing The Ocean | Earth Wise

January 23, 2023 By EarthWise Leave a Comment

There are a variety of schemes for removing carbon dioxide from the atmosphere. Some require advanced and generally not-very-well developed technology. Others, such as planting vast numbers of trees, are nature-based but are daunting with respect to the scale to which they need to take place in order to be truly effective.

Researchers at the Pacific Northwest National Laboratory in Richland, Washington have been examining the scientific evidence for seeding the oceans with iron-rich engineered fertilizer in order to feed phytoplankton. Phytoplankton are microscopic plants that are a key part of the ocean ecosystem.

Phytoplankton take up carbon dioxide as they grow. In nature, nutrients from the land end up in the ocean through rivers and from blowing dust. These nutrients fertilize the plankton. The idea is to augment these existing processes to increase the growth of phytoplankton. As they eventually die, they sink deep into the ocean, taking the excess carbon with them.

The researchers argue that engineered nanoparticles could provide highly controlled nutrition that is specifically tuned for different ocean environments. Surface coatings could help the particles attach to plankton. Some could be engineered with light-absorbing properties, allowing plankton to consume and use more carbon dioxide.

Analysis of over 100 published studies showed that numerous non-toxic, abundant, and easy-to-create metal-oxygen materials could safely enhance plankton growth. According to the researchers, the proposed fertilization would simply speed up a natural process that already sequesters carbon in a form that could remove it from the atmosphere for thousands of years. They argue that given the current trends in the climate, time is of the essence for taking action.

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Fertilizing the Ocean to Store Carbon Dioxide

Photo, posted August 2, 2007, courtesy of Kevin McCarthy via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Arctic As A Carbon Source

December 16, 2019 By EarthWise Leave a Comment

According to a new NASA-funded study, the Arctic may now be a source for carbon in the atmosphere rather than being the sink for it that is has been for tens of thousands of years.

The study, published in Nature Climate Change, warns that carbon dioxide loss from the world’s permafrost regions could increase by more than 40% over the next century if human-caused greenhouse gas emissions continue at their current pace. Worse yet, carbon emitted from thawing permafrost has not even been included in most climate models.

Permafrost is the carbon-rich frozen soil and organic matter that covers nearly a quarter of Northern Hemisphere land area, mostly in Alaska, Canada, Siberia, and Greenland. Permafrost holds more carbon than has ever been released by humans from fossil fuel burning, but it has been safely locked away by ice for tens of thousands of years.

As global temperatures rise, the permafrost is starting to thaw and release greenhouse gases into the atmosphere.

The recent findings indicate that the loss of carbon dioxide during the winter in the Arctic may already be offsetting carbon uptake during the growing season. The researchers compiled on-the-ground observations of carbon dioxide emissions across many sites and combined these with remote sensing data and modeling. They estimate that the permafrost region is now losing 1.7 billion metric tons of carbon during the winter season but taking up only 1 billion during the growing season.

The major concern is that as the Arctic continues to warm, more carbon will be released into the atmosphere from the permafrost region, which will further the warming. Climate modeling teams across the globe are trying to incorporate these findings into their projections.

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Arctic Shifts to a Carbon Source due to Winter Soil Emissions

Photo, posted July 27, 2015, courtesy of Gary Bembridge via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

How Much CO2 Can The Oceans Hold?

May 2, 2019 By EarthWise Leave a Comment

The carbon dioxide that enters the atmosphere doesn’t necessarily stay there. As part of the natural carbon cycle, much of it goes into plants, soil and, very significantly, the ocean. In fact, the world’s oceans are a sink for human-generated carbon dioxide without which the extent of global climate change would be far worse.

Oceans takes up CO2 in two steps: first the CO2 dissolves in the surface water. Then, the ocean’s overturning circulation distributes it. Currents and mixing processes transport the dissolved CO2 from the surface deep into the ocean’s interior, where it accumulates over time.

A long-standing priority for climate researchers is to determine how much of the CO2 we produce is being absorbed by the oceans and, ultimately, how much can they hold?

An international team of scientists has recently provided some answers. As reported in Science, the researchers have determined that the oceans have taken up from the atmosphere as much as 37 billion tons of human-made carbon between 1994 and 2007. This figure corresponds to nearly a third of all the anthropogenic CO2 emitted during that time.

Furthermore, they found that the percentage of CO2 taken up by the oceans has remained relatively stable compared to the preceding 200 years even as the absolute quantity has increased. So, evidently, the oceans’ capacity for carbon dioxide has not yet been saturated.

That’s the good news. The bad news is that putting all that CO2 into the oceans has a steep price: the dissolved CO2 acidifies the water. The consequences for a wide range of marine life including coral reefs are serious and getting worse. We need to drastically reduce carbon emissions.

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Ocean sink for human-made carbon dioxide measured

Photo, posted November 5, 2018, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Examining Sea Level Rise

January 17, 2019 By EarthWise Leave a Comment

It’s no secret that sea levels along the East Coast of the United States are rising. But what’s less known is that the water isn’t rising at the same rate everywhere. As the climate continues to change, some cities may remain dry while others struggle to keep water out.

During the 20th century, sea levels rose about 18 inches near Cape Hatteras in North Carolina and along the Chesapeake Bay in Virginia. During that same time period, New York City and Miami experienced a 12 inch sea level rise, while the waters near Portland, Maine only rose 6 inches. According to a study recently published in the journal Nature, there’s an explanation for this.

The variation is a result of a phenomenon called “post-glacial rebound.” During the last ice age, huge sheets of ice once covered land areas in the Northern Hemisphere, including parts of the Northeast U.S. The weight of the ice weighted down the land like a boulder on a trampoline. At the same time, peripheral lands such as the U.S. mid-Atlantic coast rose up. As the ice melted, the previously weighted-down regions rebounded while the peripheral lands began to sink. While these ice sheets disappeared some 7,000 years ago, this see-sawing of post-glacial rebound continues to this day.

Researchers combined data from GPS satellites, tide gauges, and fossils in sediment with complex geophysical models to produce this comprehensive view of sea level change since 1900. While post-glacial rebound accounts for most of the sea level variation along the East Coast, researchers noted that when that factor is stripped away, “sea level trends increased steadily from Maine all the way down to Florida.”

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