This is not an argument for or against climate change, or whether or not climate change is caused by man.
It seems that we are measuring more carbon dioxide in the atmosphere than we used to. So if we can reduce the levels of atmospheric carbon dioxide to, say, pre-industrial revolution levels, that's good, right?
Worldwide, small farms have a significant role to play in reducing greenhouse gases by doing just that, sucking carbon dioxide down out of the atmosphere and storing it underground. On the Central Coast, many of our small urban and wild farmlands are already top-of-the-line in mitigating greenhouse gases...
about terrestrial Carbon
Before we talk about removing carbon from the air, let's talk about the carbon in the ground. There is much more carbon in the earth's soil (terrestrial carbon) than there is in the atmosphere. It is estimated that the earth's soil stores 2,500 billion tons of carbon, compared with 800 billion tons in the atmosphere (e360.yale.edu).
Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide for long periods of time.
Agricultural land in the United States alone has the capacity to sequester about 650 million metric tons of carbon dioxide (CO2) every year, offsetting up to 11% of U.S. greenhouse gas (GHG) emissions annually (soils.org). Farmlands account for about 41% of this amount.
If we restored the degraded soils in abused ecosystems worldwide, we could store an additional 3 billion tons of carbon in the ground annually. This would sequester another 11 billion tons of CO2 emissions from the air. For context, burning fossil fuels worldwide generates about 32 billion tons of CO2 emissions annually. (e360.yale.edu)
HOW DOES CARBON SEQUESTRATION HAPPEN?
Plants draw carbon out of the air to form carbon compounds via photosynthesis. What the plant doesn’t need for growth is released via the root system, which in turn feeds the underlying soil ecosystem.
At this stage, the carbon is stable and doesn't want to go anywhere, unless something nudges it. Keep in mind most of our knowledge about carbon and soil ecosystems is limited to the top 30 centimeters (~12 inches) of topsoil. Scientists theorize that deeper down, more carbon is stored.
There is a lot more to soil science than we can get into here, but it is not surprising to note that the best soil for storing carbon is also the healthiest and most biodiverse soil. The most effective carbon capturing crops are perrenial woody crops, like grapes, most berries and orchards.
How well do farmlands sequester carbon relative to other land? From the Office of Indian Energy and Economic Development:
(In Metric Tons)
|Wetland||2.23 - 3.71|
|Farmland||0.20 - 0.60
|Grassland||0.12 - 1.00
|Forest||0.05 - 3.90|
CARBON sequestration on The central coast
The Central Coast is blessed with beautiful grasslands, forests, farmlands and some precious pockets of coastal wetlands. We boast some 488,785 acres of farmland. The farms in just our three counties alone could sequester between 98,000 and 293,200 metric tons of carbon dioxide per year.
More than 65% of the farms on the Central Coast are small farms of less than 50 acres, making them, by far, the single biggest farming group in our region. The vast majority of these small farms are already using natural sustainable farming techniques and many of them grow woody perennials, making them top-of-the-line for farmland carbon sequestration.
For us lucky folks living on the Central Coast, we don't need to plant trees or buy carbon credits to fight global warming. All we need to do is support our local climate change underground, the small sustainable farmers. Go out and buy some healthy, tasty fresh produce at a local produce stand, farmer's market or CSA. Always ask if the produce is grown locally, and be sure to thank the farmer for sequestering a few metric tons of carbon dioxide this year.
The Wild Farmlands Foundation champions ecosystem sustainability through the preservation of small urban and wild farmlands.