While there has been much debate to what extent global warming is real, most scientists do see evidence of it. The basic theory of global warming is as follows: Certain gases are good at absorbing infrared radiation (what we would call heat). As those gases increase in the stratospheric layers above the earth some of the heat re-radiated by the Earth’s surface back out to space is absorbed in the stratosphere and then radiated back down to Earth. The image used is that of a greenhouse where the glass prevents some of the heat from radiating back out and reflects some of it back inwards, keeping the space inside the greenhouse warmer than outside. Since roughly the 1850s, with the start of the industrial revolution and the increased use of fossil fuels (coal, oil and natural gas), the carbon dioxide levels have doubled in the atmosphere. The concern is about the impact of rising earth temperatures on the Earth’s ecosystems and the ability of humans to live.
In 2006, California passed Assembly Bill 32, the Global Warming Solutions Act. This legislation requires Californians to reduce their greenhouse gas emissions back to 1990 levels by 2020 - this is about a 25% reduction in greenhouse gas emissions. The primary greenhouse gases relevant to agriculture include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). CO2 is emitted anytime a fossil fuel or organic matter is burned for energy or fertilizer production. N2O can be emitted from nitrogen fertilizers (both synthetic and natural) by microbial processes in the soil and is about 300 times more potent greenhouse gas than CO2; and methane is produced by cows (digestion and from the waste) and is about 21 time more potent greenhouse gas than CO2. The California Air Resources Board (CARB) has been given the lead responsibility in implementing the Act, though nearly all California agencies have some role to play.
This historic legislation will impact the almond industry all along the supply chain. The primary impact for almond growers will be in increased costs for fossil fuels for running tractors and pumps, as well in fertilizer, pesticide and other crop inputs. It will also affect electricity rates as a cap & trade system is implemented starting in 2011. In addition, CARB is seeking to understand conditions that contribute to nitrous oxide production to see if fertilizer inputs can be regulated.
The Almond Board is funding research to better understand under what conditions nitrous oxide is formed in almond production, as well as reviewing tools to improve fertilizer applications efficiencies.
As of June 2009, the federal government is also considering global warming legislation. Legislation has been introduced in the House and Senate.
Carbon Sequestration (Carbon Credits)
Some activities remove carbon dioxide or other greenhouse gases from the air, thus reducing the amount of greenhouse gases in the atmosphere. As part of the various global warming legislations are systems to give credits for reductions in greenhouse gases that are more permanent or go beyond what has been mandated. These credits can be sold as part of a cap and trade system to greenhouse gas emitters who can’t quite reduce their emissions enough.
The most fundamental process for carbon sequestration is photosynthesis. Green leaves of plants take carbon dioxide and oxygen from the air and with the energy from sunlight (and a complex biochemistry) convert them into sugars and starches – a stored form of energy. (When we are burning fossil fuels we are burning sun energy converted to chemical energy via photosynthesis millennia ago.) So, as a tree grows it is sequestering carbon in the tree biomass – the stem, the roots, the branches, etc. When the tree dies the biomass is converted back to carbon dioxide via microbial processes. However, under certain conditions the amount of biomass in soils can be increased above current rates and the carbon is stored there. For example, prairie soils once had much higher amounts of stored biomass prior to plowing. Currently, Midwestern farmers are getting some credit for their no-till practices that allow plant biomass to build up in the soil. The Almond Board is investigating options for almond growers to get credit for carbon sequestration. However, currently there is very limited data available.
Another area where agriculture may play a role in reducing greenhouse emissions is in the use of plant biomass for energy production reducing the use of fossil fuels. The Almond Board is investigating what options exist for using almond by-products such as tree removals or shells for energy production.
Many retailers and others are now talking about the “carbon footprint” of a food item or a consumer product. What is meant is the amount of greenhouse gases emitted as well as sequestered throughout the production as well as transport to and final consumption or use by a consumer. This requires a life-cycle analysis where all the energy used to produce the inputs, the product, the transportation, the storage, the waste, the cooking, etc. are accounted for. To do this correctly requires a vast amount of data. Any currently available carbon footprints need to be viewed with caution; in particular without understanding which aspects of the production of that item were included in the accounting and which were not.
Often the term “food miles” is used as short hand for the amount of carbon emitted, with the implication being the farther an item has travelled the more carbon emitted. However, the type of transportation is a key factor in the emission produced. Thus transport by air releases the most greenhouse gas emissions and in decreasing order: truck, rail and ship. However, the ability to maintain quality of a product with various means of transport and thus reduce waste also needs to be considered. California Almonds are shipped around the world and the focus is on the word “ship”.