Here are two more 2% Solutions – short case studies of practices that soak up CO2 in soils, reduce energy use, sustainably intensify food production and increase water quality. The collection is available at:

Rooftop Farming

I had never climbed three flights of stairs before to visit a farm.

That’s what I did after emerging from a subway station in Greenpoint, Brooklyn, and walking along Eagle Street to a warehouse owned by a television company called Broadway Stages. On the roof I saw hundreds of vegetables set in neat rows of dark, rich soil. Walking to the edge, I saw the East River, and beyond it a sweeping view of mid-town Manhattan and the Empire State Building.


I had come to Eagle Street Farm to see the nation’s first commercial rooftop farm in action and meet Annie Novak, the charismatic co-founder of Eagle Streeta Chicago girl who grew up reading Vogue magazine with dreams of “being fabulous” in New York City, who became a fabulous rooftop farmer.

The week after graduating college, Annie landed an internship that turned into a seasonal job at the New York Botanical Garden teaching children how to grow food. In the years that followed, she balanced her city job with farming upstate, starting a nonprofit organization, and dabbling in the restaurant business. Eagle Street happened when the owners of Broadway Stages decided to install a green roof. Originally, the plan had been to create an ornamental plant nursery, but Annie and co-founder Ben Flanner convinced the owners to give veggies a chance instead. They added compost to the soil mix, planted crops they knew were tolerant to heat and water stress, organized volunteers, studied weather forecasts, and crossed their fingers. It worked.

Today, the farm grows a wide range of crops, specializing in heat-loving and dry-tolerant chiles. The farm also keeps bees, rabbits, and hens. It sells its produce on-site and to local restaurants.

It hasn’t all been a bed of roses, however. Wind storms and unseasonable heat have bedeviled both the veggies and their handlers at times. Space is a limitation – she can’t expand the farm even though she would very much like to. Fertilizer was another challenge, since it needs to be hauled up the stairs every time it is needed. This challenged was solved when Annie introduced rabbits and chickens to the farm, which she calls “my little poop machines.”

Then there was the pollinator problem.

“Because there aren’t a lot of green spaces in the city,” she said, “we don’t get a lot of pollinators and that’s a bigger issue than most people think.” They resolved to start growing their own bees, but quickly learned that Mayor Giuliani had made bee-keeping illegal (putting them in the same category as poisonous snakes). Eventually, new regulations were passed allowing apiaries, but then a cold winter killed all of Eagle Street’s bees.

The economics of rooftop farming are a challenge as well. The for-profit farm relies on value-added products like its hot sauce (called Awesome Sauce) to raise the $1.50-$3 per square foot value needed to farm unprocessed crops. At 6,000 square feet with no room to grow, farming at that scale makes just enough income to support a few part-timers, management included.

Given the farm’s small size, the most frequent question Annie gets is ‘can New York City feed itself?’ Her response is unexpected: ‘does New York want to?’ She thinks not. “The quality of our air and water is protected by upstate organic growers,” she said. It’s important to her that farmers, and the watershed in which they work, be supported by New York City residents.

Eagle Street has inspired others to give rooftop farming a try.

In 2010, a group of young farmers formed a for-profit organization called the Brooklyn Grange and opened what has become the world’s largest rooftop farm, totaling 2.5 acres (108,000 square feet). They grow more than 40,000 lbs of organic produce a year. Their goal is to create a fiscally sustainable model for urban agriculture while producing healthy food from what they call the “unused spaces of New York City.”

The work of Brooklyn Grange has quickly expanded to include: (1) egg-laying hens; (2) a commercial apiary and bee-breeding program (for city hardiness); (3) a farm training program for dozens of interns; (4) hosting thousands of New York City youth for tours and workshops; (5) launching the New York City Honey Festival in 2011; and (6) providing a unique setting for corporate retreats, dinner parties, and weddings.

And tackle environmental challenges peculiar to metropolitan areas. With a grant from New York’s Green Infrastructure Stormwater Management Initiative, Brooklyn Grange sited its second farm on the 65,000 square foot roof of a building in the historic Brooklyn Navy Yard, which allows them to manage over one million gallons of stormwater a year.

There’s another environmental benefit: the 2.5 acres of soil under management of the Grange are soaking up atmospheric CO2. It isn’t much, but it’s a start – which raises a question: how many rooftop farms could New York City accommodate?

In 2013, rooftop farming spread to Boston with the launch of Higher Ground Farm occupying 40,000 square feet on top of the Boston Design Center, becoming the world’s second-largest rooftop operation. The brainchild of two young farmers, the mission of Higher Ground is similar to what Annie Novak and the folks at Brooklyn Grange pioneered: (1) make a dent in the urban heat island effect with a green roof; (2) help with stormwater management (3) reduce carbon in the air and improve air quality; (4) increase access to fresh, healthy food; (5) provide habitat for biodiversity and habitat; and (5) provide educational opportunities as well as many other community co-benefits.

“When I’m on a rooftop all I’m doing is listening to the sound inside a tiny seashell and trying to hear a larger ocean,” Annie said. “If you live in a city, take advantage of it. Soak up the street smarts and the rush of city living that also embraces outdoors and fresh tomatoes. You have to grow a small plot with a big picture in mind.”

Here’s a view of Eagle Street Rooftop Farm:Image Removed

A Carbon Sweet Spot

For a minute, I thought I had stepped into that scene from Lawrence of Arabia where T.E. Lawrence, approaching the Suez Canal, sees a ship sailing across the sand. I had parked on a levee at the north end of Twitchell Island, in the middle of the great Sacramento-San Joaquin river Delta, east of San Francisco. In front of me was prime farmland and just beyond a slight rise in the distance I saw a big cargo tanker plowing its way slowly across a field – plowing the middle of the San Joaquin River, of course.

I didn’t drive to Twitchell Island to see farmland, however. I wanted to see a carbon sweet spot in action. Sweet spots are where big things happen in small places for a minimum amount of effort. On Twitchell, a whole suite of big things had happened on just fourteen acres in only a few years with very little cost.

The Delta was once a vast freshwater marsh thick with tule reeds, cattails, and abundant wildlife. At least six thousand years old, the marsh caught sediment that washed down annually from the Sierra Nevadas, building up soil that eventually extended sixty feet deep in places. When the delta began to be settled in the 1860s, following California’s famous Gold Rush, farmers couldn’t believe their luck. Since the soil had been often submerged – a consequence of flat terrain, frequent flooding, and tidal action – it had essentially become peat, rich in carbon and other organic minerals. Crops grew vigorously in the rich soil. Soon, a new gold rush was on – to claim land in the Delta, drain it, and grow row crops by the bushel-load.

Fast-forward to today, and the Delta is in big trouble. Innumerable ditches and levees have broken up the marsh into 57 separate islands, 98% of which are now below sea level. Pumps work continuously to keep the roots of the crops dry enough to grow and be harvested. Salt intrusion from the Bay is creeping inland, threatening not only the crops but the drinking water supply for two-thirds of all Californians and much of its agriculture. Not many people know that central California is a vast plumbing project, cris-crossed by a complex network of canals, ditches, and pumping stations. And most of the water in this plumbing system originates in the southern part of the Delta.

However, the islands are sinking, sea level is rising, and the 1100 miles of levees that protect it all are feeling the stress, literally. It’s called ‘subsidence’ and it places tremendous hydrostatic pressure on the levees, requiring constant maintenance – and creating perpetual anxiety. What if the levees were breached by a massive flood? What if salt water poured through, ruining crops and drinking supplies?

In an attempt to alleviate these worries, a group of scientists with the U.S. Geological Service in 1997 came up with a novel idea: employ nature, not technology, to reverse the subsidence. Here was their bright idea: when the early farmers drained the Delta they exposed the peat soil to the atmosphere, causing the organic material – previously under water – to oxidize rapidly. The carbon in the soil literally blew away, causing the land to compact and subside over time. That’s how the islands ended up below sea level – as much as 25 feet in some places! The scientists wondered if this process could be reversed? In other words, could the land be built back up if the marsh ecology, including periodic flooding, could be resurrected?

To find out, they implemented an experiment on two 7-acre, side-by-side plots of farmland adjacent to a ditch that bisected Twitchell Island. They flooded the western plot to a depth of 25cm, and the eastern plot to 55cm. Tules were planted in a small portion of both plots. By the end of the first growing season, cattails had colonized both plots (the seeds arriving on the wind), which provided a screen for other plants, including duckweed and mosquito fern. Then things really took off. After just a few short years, and annual managed flooding, the western plot had developed a dense canopy of marsh plants, as did the eastern plot, though it maintained some open water.

Then they took measurements of the soil and were amazed to discover that after seven years the soil in both plots had risen 10 inches – the result of 15 tons of plant material growing and dying per acre per year. This answered their question: subsidence could be reversed by returning natural marsh processes to the land.

But the good news was just beginning. The researchers next tested the amount of CO2 that had been sequestered in this new soil as a result of their experiment. They suspected that 10 inches of dense, carbon-rich peat soil likely soaked up a lot of atmospheric CO2 – and they were right. In fact, as much as 25 metric tons per acre per year were sequestered in the study plots, according to their analysis. In comparison, a typical passenger vehicle emits 5 metric tons of CO2 per year. The fourteen acres in the study plots sequestered the equivalent emissions of 70 passenger vehicles per year! And that doesn’t even count the CO2 emissions eliminated by not farming the land. And that doesn’t count all the other ecosystem services generated by a functioning marsh, including water purification and wildlife habitat.

The researchers called what they did a “carbon-capture farm” and hoped that the project would demonstrate that it is highly feasible to use managed wetlands to sequester carbon and reduce subsidence simultaneously. The key word is managed, which raises another whole set of questions, especially about working at scale.

Although the specifics of this project are likely limited to the Sacramento-San Joaquin Delta, it is nonetheless a very good example of a sweet spot. On just fourteen acres, the project demonstrated how to (1) reverse subsidence; (2) reduce the risk of levee failure; (3) sequester a lot of carbon; and (4) provide wildlife habitat, especially for birds on the Pacific flyway.

Sweet spots are important literally and figuratively for what they can do for the land, and for what they can teach us. They’re not a mirage, like a ship in a field. They’re all around us, if we know where to look.

Here’s a graphic of C banking courtesy of the Bay Area News Group:Image Removed