One of the thorniest issues of climate change is how to get some of the carbon out of the atmosphere before widespread catastrophe makes earth uninhabitable for millions of people. Green plants depend on CO2 in the air to perform photosynthesis which gives us food and oxygen. But pre-industrial levels of about 275 parts per million (ppm) significantly contrast with today’s 412 ppm and its associated changes to climate. Carbon can hang around in the atmosphere for hundreds of years or longer so finding a solution is paramount.

Phytoplankton blooms off Alaska.

Suggestions for climate solutions include limiting emissions and actively removing carbon from the air. But slowing emissions, which is what limiting means, doesn’t solve the problem. It just slows down the rate of addition, so that’s not a solution by itself.

Others have recommended shading the planet to keep it cool but that also has problems like limiting food production. Natural experiments caused by volcanic eruptions in the middle ages and up to the present show that shading the planet due to volcanic ash in the upper atmosphere caused food shortages and wide-spread starvation in the middle ages and earlier.

Still others advocate mechanical processes to extract CO2 from the air which is not a difficult process. The challenge comes from what to do with the CO2 we capture. Carbon dioxide is a gas at normal temperature and pressure. You can condense it to a liquid or solid (we call it dry ice) but when exposed to the environment again it gasifies leaving you where you started. Some people suggest pumping captured CO2 into the earth with the expectation that it will stay there. But if you’ve ever seen a video of a burning water faucet in a home near a fracked natural gas field, you understand that gasses can easily leak from the earth.

Green plants excel at both removing carbon from the air and stabilizing it so that it doesn’t immediately return. Plants turn CO2 into carbohydrates which they and other living things can convert into fats and proteins all of which are stable at normal temperatures and pressures. Of course, living things also metabolize these products to derive the energy they need for life, a process that returns carbon dioxide and water to the air.

That’s called the carbon cycle and it points the way to solving the most vexing challenge of reversing climate change. Green plants offer a partial solution as you’ll see below. A full solution requires human involvement and the cooperation of the world’s oceans.

The ocean

The ocean is a living thing, an ecosystem, and a food web. Understanding these characteristics is necessary for figuring out how it can help control climate change — not by using oceans as a dumping ground but as a dynamic tool that, with a little judicious prodding, can do much to benefit life all over the planet.

Life evolved in the oceans about 3.5 billion years ago. The first life forms were able to metabolize simple organic molecules that coalesced in Earth’s reducing atmosphere, one that contained no free oxygen but many other simple molecules and elements like methane (CH4), ammonia (NH3), and hydrogen (H2). With energy sources including heat from Earth, radiation from the sun, lightening, and radioactivity, also from Earth, simple organic molecules could form spontaneously, providing some of the building blocks of life and food for early single-cell organisms.

But there would be more consuming organisms than food, which is usually the case in the wild. So any organism that could make its own food supply had an advantage. That’s exactly what photosynthesis enabled early plantlike organisms to do. In time, organisms that made their food also became food sources for organisms that consumed other molecules.

We think of the sea as teeming with life, but predominantly, that life teems close to the continents. As it turns out, most of the photosynthesis in the sea occurs closer to land than it does in the open ocean. We can tell where photosynthesis is taking place because closer to land the sea has greenish tint but farther out, away from land, the ocean turns to a vivid blue.

The ocean’s food web begins with microscopic plants that contain chlorophyll. These plants, called phytoplankton to distinguish them from animals of a similar size, zooplankton, form the bottom of the food chain for all sea life. In the ocean, big fish eat smaller fish and the smallest fish eat plankton. And it’s not just the smallest fish that eat plankton; some of the largest animals in the sea, baleen whales for instance, also subsist on plankton. These whales and other species like manatees, green sea turtles, and parrotfish are some of the great herbivores of the ocean, comparable to grass eaters like elephants and cows on land.

Greening the far ocean

For many years, scientists wondered why there was so little photosynthesis in the open ocean. There was ample carbon dioxide and solar energy, and there was plenty of nitrogen in the air (as well as dissolved in the water), and there was also sufficient phosphorus. Nitrogen is an essential element in making proteins, of which enzymes — chemical catalysts essential to life — are a part. Also, phosphorus is integral to forming DNA, without which life on this planet could not continue. With these elements in good supply, it was puzzling that mid-ocean areas were so desolate of life.

Some scientists like Joseph Hart, an English biologist of the 1930s, hypothesized that some micronutrients were not present in the middle of the oceans; John Martin later speculated that iron carried by airborne dust from landmasses was responsible for fertilizing coastal waters to encourage phytoplankton growth and with it, photosynthesis producing the greenish tint.

Adding intrigue, there were many observations of sporadic and unpredictable plankton blooms in parts of the oceans where seemingly nothing special was going on. Studying the dynamics of sea currents led to an understanding that periodic upwellings could bring nutrients from deep in the sea to the surface, providing the necessary micronutrients to temporarily support blooms. When ocean currents meet underwater formations, the result can be an upwelling on a more or less consistent basis — as long as the currents run true — producing rich marine habitats. Volcanic eruptions can have a similar effect, bringing nutrients to the sea via dust that settles to the water’s surface.2

So there it was, a conundrum for the 20thcentury scientific community. Eventually, the bluer areas of the ocean farther from land came to be known as high nutrient, low chlorophyll (HNLC) zones and what was needed was some experimental data to test the hypothesis of insufficient micronutrients.

If you’re a scientist, you love a challenge like this. John Martin was an oceanographer at theMoss Landing Marine Laboratories (part of the California State University System), who was puzzled by this data set and decided to investigate. Martin agreed with Hart and hypothesized that photosynthetic life must need some trace elements to make the mechanism of life work, much like people need trace elements in their diets for the same reasons. Does sea life need its own vitamins and if so, which ones?

Martin’s work led to the discovery that the blue ocean had little life in it because there was little iron in the water. He proved this through experiments on water collected from blue-water ocean areas in which he demonstrated that adding small quantities of iron did indeed promote significant phytoplankton growth.

Martin died in 1993 before he could test his hypothesis in an open ocean experiment, but numerous experiments by colleagues after his death support what’s known today as the iron hypothesis.

Using iron to sequester carbon

There’s been much discussion since Martin’s death on the question of using ocean-iron fertilization to promote phytoplankton growth and possibly to sequester carbon in the process. A May 1, 2007, article by Matt Richtel in The New York Times, “Recruiting Plankton to Fight Global Warming”provides a summary. Ken Buesseler, a senior scientist at the Woods Hole Oceanographic Institution, says in the article that it’s widely accepted by scientists that dumping iron in certain areas of the ocean can cause plankton to bloom. But there is considerable skepticism over whether doing so will lead to long-term absorption of carbon dioxide from the atmosphere.4

Indeed there is.

As mentioned above phytoplankton are a food source and form the base level of the ocean’s food pyramid. Other organisms eat phytoplankton and eventually return carbon to the air and water. So iron fertilization isn’t a permanent solution to carbon absorption. Or is it?

The long carbon cycle

The fossil fuels we burn today are, by definition, remnants of once living things. Petroleum is formed when microscopic plants and algae die and slowly sink to the ocean floor. There is very little oxygen and little life down there and rather than decaying, the bodies of these creatures accumulate along with other sediments. Over millions of years this sediment gets buried deep in the ocean floor and, when it reaches a depth of between 7,500 feet and 15,000 feet, the earth is warm enough to “cook” these remains and form petroleum. Petroleum geologists even have a name for this zone–the kitchen.

About 20 percent of dead plankton sink deep enough into the ocean to join the long cycle that produces petroleum. With this we have the components of a carbon capture and sequestration program. It has these parts.

1. Plankton that doesn’t sink becomes part of the food chain and since food is the limiting component of population growth, more food will encourage more life in the oceans. It will promote growth of many species including those of commercial value to the fishing industry. So some of the carbon captured by plankton will be stored, at least temporarily in living things including people. This is not a perfect solution but feeding people is never a bad idea. There’s more to this story so hang on.

2. If we were to fertilize the ocean with iron, 20 percent of the plankton produced would likely sink and be sequestered for a very long time. So this suggests an ongoing effort of fertilization and harvest in the form of fishing as well as sinking.

A medical analogy

This approach is similar to how modern medicine deals with disease. We like to think about cures for diseases but increasingly we don’t cure disease so much as we manage it. Consider diabetes. Until the 20thcentury when insulin became available to treat or manage the disease, diabetes was fatal. But with insulin the disease becomes a manageable problem requiring modest lifestyle changes.

Diabetes is not the only disease like this. People take an array of medicines that help manage (that word again) things like high blood pressure and arthritis to name a couple more. There’s also AIDS. People aren’t’ dying like they once did from this disease if they have access to a cocktail of medicines that keep the AIDS causing virus in check. Again, not a cure but a solution. All of these solutions have in common the ability to change an emergency situation into a chronic one.

Ocean iron fertilization is like that. It would be a program that might need to continue for a long time but at a reasonable cost and with two very useful effects. Ocean iron fertilization will improve the world’s food supply at a time when new food sources are essential to feeding a population growing at 1 billion people per decade. It will also help humanity to manage carbon concentration in the atmosphere. It’s a chronic solution to an acute problem.

Involving the UN

A program involving ocean iron fertilization is not a perfect solution, but like many solutions of its kind, it prevents the worst scenario from occurring and gives us time to figure out what to do next.

Unfortunately, not much work on commercializing ocean iron fertilization has taken place since John Martin and his colleagues conducted their first experiments. The Law of the Sea convention is an agreement among nations concerning the appropriate use of the oceans and seas of the world and it is overseen by the United Nations. Current thinking around the law and ocean iron fertilization is that iron is a pollutant and treaty signatories have agreed not to dump this pollutant into the ocean. It’s ironic and sad that plastic can’t fulfill the function of iron because there’s a lot of plastic in the ocean. But I digress.

The first step in capturing carbon by sea creatures like phytoplankton begins with enlisting the UN to change its policy or to at least sanction a few experiments to either prove or disprove the efficacy of the solution.

Summing up

What’s really exciting about arresting climate change is that virtually all of the solutions are already available. The science and much of the technology already exist. We can change the energy paradigm to renewables and that’s happening; we can take carbon out of the environment in sufficient quantity to stabilize the situation and even reverse some of the damage.

What’s missing is the human will to take action. A variety of special interests work overtly and subtly to prevent change thus protecting the broken paradigms we now have. All is not lost though. We might not be able to directly absorb carbon, but we can influence legislators and other leaders. We can also make green decisions as we live our lives like driving hybrid or electric cars, purchasing green electricity for our homes, and making green decisions about what we buy and eat. Millions of changes like this are driving the evolution of a new age of sustainability.