Global warming's present and future impact on climate is like a ship sailing in uncharted waters, according to many scientists. Receding glaciers, thawing permafrost in Alaska and warmer temperatures are some troubling signs that a warning flag is being raised.

That's a key reason why most would rather err on the side of caution by controlling greenhouse gases, such as carbon dioxide, nitrous oxide and methane, to reduce the risk of global warming.

Policymakers and others are also rallying to enlist farmers' help in mitigating greenhouse gases. They're embracing the proven capability of various cropping and tillage systems — including forestry — to “capture” a major greenhouse gas like carbon dioxide and “deposit” it into the bank of organic matter where it can help improve soil structure, increase soil water-holding capacity and reduce erosion.

Most cropland soils have lost one-third or more of their carbon since they were first converted to crop production about 200 years ago, according to USDA.

However, conservation tillage, residue cover, better nutrient and water management and erosion control could replenish this soil carbon deficit. Scientists estimate that about 322 million metric tons of carbon per year could potentially be restored back to soils through such measures — about 60% of that coming from agriculture — namely, cropland and grasslands.

The marketplace is also prepared to pay farmers to sink carbon dioxide back into the soil by following beneficial cropping and tillage practices. This helps build soil carbon levels. Scientists call it “carbon sequestering.” You might like to think of it as “cash for carbon.”

Some cash for carbon projects are already in place. For example, in November 2003, the Iowa Farm Bureau (IFB) launched a four-year pilot program to begin aggregating carbon credits by enrolling farmers who use continuous no-till or reduced tillage practices.

The IFB will aggregate the credits earned from carbon sequestration for trading on the open market at the newly formed Chicago Climate Exchange (CCE) — a coalition of North American businesses, including car manufacturers, agribusinesses and municipalities.

Research shows that no-till cropping sequesters at least ½ ton of carbon dioxide per acre yearly, while pastureland captures up to ¾ ton/acre yearly, explains Dave Miller, IFB commodity services director.

One hundred acres of no-tilled cropland would generate 50 carbon credits yearly to be sold on the CCE, he adds.

As a credit aggregator, the Iowa Farm Bureau will enroll land into the program, handle credit exchanges and distribute payments to farmers. Miller estimates that carbon credits may generate $1-5/acre/year for participants, although values will rise and fall just like other commodity exchanges.

The IFB planned to enroll at least 100,000 acres into the program by Spring 2004, adds Miller.

Another example of carbon trading can be found in the Pacific Northwest. Here, the novel approach of “leasing” was mainly chosen over “selling” carbon credits outright on the open market.

In mid-April 2002, the Pacific Northwest Direct Seed Association (PNDSA) — along with help from the Environmental Defense (ED) — negotiated a 10-year contract to “lease” carbon credits to Entergy — an energy company (based in New Orleans) serving customers in Louisiana, Texas and Arkansas. These credits were generated through direct seeding practices.

An average of 30,000 metric tons of carbon dioxide equivalent credits are leased yearly to Entergy. PNDSA was paid $75,000 to aggregate a base of growers for this project. By November 2002, PNDSA enrolled 77 grower members — representing 6,470 acres — to meet its obligation with Entergy. The contract also allowed Entergy to buy carbon dioxide offsets based on reduced fuel consumption from no-till practices.

In another move, in 2002 the Bush administration requested that USDA recommend ways to help reduce greenhouse gases and increase carbon storage through targeted incentives for landowners.

The goal was to reduce greenhouse gas emissions by 18% within 10 years — a target the administration claimed could be achieved by incentives in the marketplace.

Some of the steps taken by USDA include:

  • The Natural Resources Conservation Service (NRCS) offers states guidance on rewarding actions that provide greenhouse gas benefits within the Environmental Quality Incentives Program (EQIP) ranking system.

  • New rules for the private sale of carbon credits from land enrolled in the Conservation Reserve Program.

  • New accounting rules for carbon sequestration and greenhouse gas reductions. USDA is also helping fund a task force of scientists — known as the Consortium for Agricultural Soils Mitigation of Greenhouse Gases (CASMGG — pronounced chasm). The group includes nine land grant universities and the U.S. Department of Energy's Battelle-Pacific Northwest National Laboratory.

Helping to lead that consortium has been Chuck Rice, a Kansas State University soil microbiologist.

“The future, indeed, does look bright for carbon trading,” says Rice. “Admittedly, many realize that current prices for carbon credits may be somewhat low or discounted; however, once more projects are in place and as we gain more confidence in them, don't be surprised if the values edge upwards to perhaps $3 or even $10/acre/year.”

Rice says the consortium is working on various fronts to help develop better methods and programs to sequester greenhouse gases. Some of those efforts include:

  • Conducting research on the role soil aggregates or soil particles play in storing carbon, as well as how it's stored.

  • Working with plant breeders to determine what characteristics would enhance carbon sequestration in soils, such as better root/shoot ratios or reduced lodging.

  • Conducting research to quantify and validate amounts or rates of carbon sequestration for different cropping/rotation systems, grass plantings and tillage practices so sellers and buyers of carbon credits have accurate methods to develop contracts.

  • Developing model software programs on carbon sequestration for decision-making efforts.

  • Analyzing cost/benefit ratios of various cropping/tillage systems, and evaluate other extra agronomic benefits of carbon sequestration.