Maine Organic Farmers and Gardeners Association

John Aber (left) and Ivan Fernandez, along with Glen Koehler (not shown), discussed how climate change will affect farmers in the Northeast at MOFGA's Spring Growth Conference. English photo

Farming in the Face of Climate Change, MOFGA's Spring Growth 2015 conference, featured keynote speaker John Aber from the Department of Natural Resources and the Environment at the University of New Hampshire. Aber talked about climate change generally and about ways to increase the efficiency and lower the cost of milk and vegetable production by closing cycles, using his innovative composting experiment at UNH as an example. His work was funded by grants from Northeast SARE and the N.H. Agricultural Experiment Station. After Aber's talk, Ivan Fernandez and Glen Koehler from UMaine discussed climate change in our state.

Regarding climate change, Aber said that change has been the norm in New England, with glaciation and deglaciation, settlement and deforestation, industrialization, farm abandonment and reforestation, and post-industrialization. We have succeeded through these changes through innovation, education, strong communities and a history of independent thought and action.

Aber noted that atmospheric carbon dioxide (CO2) concentrations have increased from about 310 parts per million (ppm) in 1956 (measured at the Mauna Loa Observatory in Hawaii) to nearly 400 ppm in 2013. The Intergovernmental Panel on Climate Change (IPCC) 2007 report cited up to 1 meter in global mean sea level rise by 2100, a mean increase of as much as 5C (9F) in global surface level temperature, disappearance of northern hemisphere September sea ice by about 2060, and a decrease in global ocean surface pH from about 8.1 now to below 7.8 – if we continue with business as usual. Predictions by IPCC have been conservative in the past, said Aber. (Regarding sea ice, Koehler later forwarded an article that states, "It is reasonable to conclude that Arctic sea ice loss is very likely to occur in the first rather than the second half of the 21st century, with a possibility of loss within a decade or two." Source: "When will the summer Arctic be nearly sea ice free?" by James E. Overland and Muyin Wang, Geophysical Research Letters, May 21, 2013, Vol. 40, 2097–2101,

Forest cover, Aber continued, decreased in New England from the 1600s until the mid-1800s, so New England was a huge source of atmospheric CO2 then. But as forest cover rebounded, New England became a locally significant sink for CO2. More recently forest cover has been declining slowly.

The primary driver for increased CO2 in the atmosphere is industrial activity and burning of fossil fuels. Agriculture (including energy use on farms) produces about 10 percent of U.S. greenhouse gas (GHG) emissions, based on CO2 equivalents. Residential and commercial uses are about twice that, and industry and transportation about three times that percentage.

That 10 percent produced by agriculture comes from these sources:

30 percent cropland soils (basically nitrous oxide – nitrogen fertilization escaping to the atmosphere)
enteric fermentation (digestion of carbohydrates by bacteria in ruminant animals. Beef and dairy cattle – primarily feedlot animals – are the largest source of enteric methane.)
15 energy use
14 manure management
12 grassland soils (basically nitrous oxide)
1 rice cultivation

Aber noted that eastern North America is the only place that has been extremely cold in the last three years. He gave a possible explanation: Normally, cold Arctic air is contained by the polar jet stream in a span of about 620 miles (the polar vortex). But warmer temperatures led to less Arctic ice and sudden stratospheric warming (SSW; 25C in a week) in 2013 and 2014. Less Arctic ice meant more moisture for precipitation in Siberia and a smaller temperature gradient between the equator and the poles. That de-energized the polar jet stream, enabling Arctic air to be drawn southward. In the eastern United States, the Greenland block is an upper-air weather pattern partly responsible for delivering prolonged Arctic cold here. When the jet stream is de-energized, the Greenland block persists, delivering more Arctic air here for longer periods.

The Challenge and Opportunity for New England Agriculture

New England, said Aber, will be challenged by increased weather variability, increased extreme events and possibly increased incidences of the Greenland block. But California and Florida farmers may face even greater challenges – presenting possible opportunities for us.

Aber noticed, when he visited Tyrol and Bavaria, how much they look like New England, but with a more intense, small-scale, high-value agriculture, and with sustainability ingrained in the culture – so we can change the food system, he said.

Our issues include the fact that New England is 75 percent forested, has rocky, shallow soils, has gone through a cycle of clearing and abandonment, has a high population density and high land and labor costs.

On the other hand, we have high consumer demand for local, organic and sustainable food and a huge increase in the number of farmers' markets; a land conservation ethic; historic and cultural values and our ingenuity.

Aber asked whether alternative visions for our future might create land use challenges. For example, Wildlands and Woodlands, an organization that works to conserve New England's natural heritage, envisions a future with 70 percent woods, 5 percent water and wetlands and 25 percent developed and agricultural lands. A New England Food Vision, on the other hand, looks at ways to raise 40, 50 or 70 percent of our calories here – which would require increasing New England's 2 million agricultural acres to 6 or 7 million (out of 46 million acres).

Intensifying agricultural production may help meet this demand, he said. He cited work toward this goal at UNH, including high tunnel work; variety trials; enhancing energy efficiency in greenhouses with heat pumps, especially during the shoulder seasons; heating with compost; extending the grazing season; increasing pasture productivity with novel species mixtures; and improving organic dairy nutrition.

Aber asked whether high-density fruit plantings, as he saw in Tyrol, might work here. Glen Koehler told The MOF&G later that a specific system of high-density planting called "tall spindle" is becoming popularized by Terrence Robinson of Cornell University. It costs more to establish, said Koehler, but provides earlier and higher crop yields per acre. The system is being used in new Maine plantings, often with some modifications. Dr. Renae Moran, UMaine Cooperative Extension tree fruit specialist, has information on the topic.

John Aber's research involves integrating woodland resources with dairy farming. Illustration from 09-Climate-Change.jpg

The UNH Organic Dairy Research Farm, Aber continued, is looking at ways to increase sustainable production. The farm has 100 acres of certified organic pasture and 160 acres of typical old-field New England woodland. When UNH researchers asked organic milk producers what the biggest challenges are in New England, they cited financial viability (especially with costs for bedding, energy and grains) and their environmental impact (GHG emissions, runoff and water quality, and manure management). Respondents also said that the most successful farms have diversified income and/or value-added processing. So Aber and his co-workers decided to research a closed-system, energy independent organic dairy. This work is being supported by the USDA Northeastern Sustainable Agriculture Research and Education (SARE) program and the New Hampshire Agricultural Experiment Station (NHAES).

Bedding is a significant cost for dairy and equine facilities at UNH, hence the idea to use shavings from inferior trees in University woodlot for bedding. Then the bedding and dairy manure would be composted. Heat and CO2 from the composting could be used in a greenhouse, and the compost would be spread on fields. Harvesting 1 acre per year of the UNH farm's 100-acre woodlot would provide enough shavings for the organic dairy. One cord of wood (about 4 cubic meters) produces about 3 cords of shavings.

For the research project, a large, mobile, $65,000, self-contained, planer-like shaving machine that runs on diesel produced the shavings. Less expensive alternatives for commercial farms include a $45,000 model that runs off a tractor. This particular machine is large enough to supply more than one dairy of typical size in New England,  so sharing through a co-op, or establishing a stand-alone business producing shavings, is possible, said Aber.

The bedding/manure mix is composted aerobically in, and energy is captured from, a $500,000 research facility built with funds from a private donor. Aber estimates that half that amount would be needed for a commercial operation. The static compost pile is not turned. The floor of the composting facility has perforated PVC pipes embedded in the concrete under marine plywood strips. A blower pulls air through the compost and from the pipes into a manifold and into an isobar (heat exchanger) assembly in a bulk water tank. The farm now uses some of this energy to pre-heat water for cleaning in the milk house. Other uses to be tested in the ongoing research funded by USDA-SARE and the NHAES include drying shavings produced by the shaving machine and characterizing the flow of warm, CO2- and ammonia-rich air emitted from the heat exchanger as possible input to a high tunnel greenhouse. In a commercial farm setting, the heat could be used to warm buildings as well. Aber suggested unbundling this process so that some businesses produce the wood shavings, while others may make compost (a rapidly growing business in New England) and use its heat in a greenhouse operation. For more information, see

Maine's Climate Future

Dr. Ivan Fernandez, a UMaine professor of soil science, highlighted the report "Maine's Climate Future, 2015 Update" (posted at Since the last century, Fernandez summarized, Maine has gained two weeks of growing season, 3-degree F warmer temperatures and 13 percent more precipitation. In the last decade, we've had two to three times more intense precipitation events. The Gulf of Maine is warming faster than 99 percent of the oceans in the world, and sea level rise is accelerating. Those projections will continue and probably accelerate – with such effects in Maine as a rising incidence of Lyme Disease, more soil erosion, a longer growing season, new pests and more difficulty harvesting forests (due to shorter periods of frozen ground).

Regarding the 2015 update of "Maine's Climate Future," Fernandez noted critical differences in public perceptions evident today compared with five years ago when the first report was released:

1. The U.S. Senate voted that climate change is real.

2. Adaptation (not just mitigation) is part of the narrative now.

3. Climate change is a business concern.

4. Climate change is a security concern – from the melting Arctic to the impact of drought on the price of wheat in Syria and the Syrian uprising.

5. We really recognize ocean acidification. Even if nothing else was happening, the acidifying of oceans would be a crisis, because they are fundamental to our global ecology.

Glen Koehler (center) of the University of Maine knows apples – and climate change and its possible effects on agriculture in our state. English photo

Glen Koehler  of the University of Maine Cooperative Extension, Pest Management Office, detailed observed and predicted climate changes for Maine. He emphasized that the risk to a farm is a combination of the environment, the farm's vulnerability and its resilience (how well it recovers from challenges). Reducing vulnerability and building resilience can reduce risk – and may even create opportunities.

Over the last two decades, the weather has become warmer – but unevenly among locations (even within Maine, which has as much climate variation across 4 degrees of latitude as western Europe has across 20 degrees), between decades, among seasons and between day and night.

Temperature effects are more pronounced at higher latitudes in the northern hemisphere. Maine warmed more than most other states from about 1930 to about 2001. Between about 1980 and 2010, daily average temperatures increased in Maine by 0 to 4F, depending on the season and the location. (Koehler used midpoint dates for multiple-year spans. So in this case, 1980 represents the midpoint of the 1970-1990 span. This article will use those midpoints.) Koehler cited the following observations:

Warming has been greater in fall and winter (1 to 4F) than in spring and summer (0 to 2F) and has accelerated since 2000.

The daily low temperature has warmed more than the daily high temperature.

The greatest change is in the most recent 10-year comparison: 1985 vs. 1995.

Northern Maine has warmed more than southern, and winter low temperatures have changed the most.

Maine has fewer very cold nights, and northern Maine is predicted to have 44 fewer days below -4F in 2020 than in 1975.

Parts of Maine are one hardiness zone warmer, according to the USDA plant hardiness zone map.

The National Weather Service divides Maine into northern, southern interior and coastal climates. The difference between northern and southern interior in average annual temperature is 3.8F, and between southern interior and coastal is 1.2F. The difference is greatest in winter.

By 2005, we had a longer melt season and a shorter freeze season than in 1885. While the start of the freeze season (when the average air temperature is below 32F) in Orono was Nov. 21, it is now Dec. 4; and the end has moved from March 29 to March 19. So the freeze season decreased from 128 to 105 days. Classic Maine winters are history, said Koehler. Penobscot Bay commonly froze over during the 19th century, froze only in 1904, 1905, 1918, 1923 and 1934 in the 20th century and has not frozen in the last 80 years.

The Northeast as a whole had 10 to 14 more frost-free days in 2000 than in 1930. Koehler estimated that southern interior Maine went from about 110 to about 160 frost-free days between 1850 and 2000 – "a huge change!" he said.

Maine has become wetter, with precipitation changing unevenly among locations, seasons, decades and intensity of rain events. Average precipitation changed by about 5 to 15 percent between about 1930 and 2000, with more change in northern Maine. We had about an inch more precipitation (using the water equivalent for snow) in winter and spring between 1980 and 2010, and 1 to 5 more inches in summer and fall.

The change appears to have accelerated since 2000 – as has the increase in the number of "very heavy" precipitation events (the top 1 percent of all daily events from 1901 to 2012). By 2012, the Northeast had 71 percent more precipitation in intense events than in 1958 – the largest increase in the nation. The number of rainfall events with more than 2 inches per day has increased 50 to 100 percent in the last 10 years at weather stations across Maine, according to the UMaine Climate Change Institute, and long-term rain records from central Maine show that storms producing 3.5 inches of rain used to occur once every 50 years but now occur about every 12 years, according to Maine Climate News.

On average, snowfall in Maine has been decreasing (2014-2015 excepted!). Between 1970 and 2000, the Northeast had a mean of 16 fewer days per year with snow on the ground.

By 2050, coastal Maine is expected to warm by 1.9 to 2.2F, southern interior by 2.2 to 2.5F, and most of northern Maine by 2.5 to 2.8F. In Kennebec County, the average January minimum temperature is expected to increase by 2.9F by 2045. Augusta is expected to have 20 fewer days per year below 10F than it did in 1990 and is expected to be in USDA plant hardiness zone 6 rather than 5 by 2045.

A 3F change in annual average temperature would mean that by 2045, Waterville could have about the same average annual temperature as Sanford had for 1981-2010, when Sanford averaged almost 250 more corn growing degree days than Waterville. But the +28F frost-free growing season in Sanford averaged only two days longer in Waterville (173 vs. 171). Frost-free growing season length involves site-specific characteristics, such as local air drainage and proximity to water bodies, Koehler noted. It is not directly defined by average annual temperature.

In Kennebec County, the average April minimum temperature is expected to be 2.2F warmer in 2045, the average July and October maximum temperatures 2.8F and 2.9F warmer, respectively. Augusta could add 25 days per year with temperatures above 32F.

Between 2000-2004 and 2050-2054, the average number of days with a heat index (a combination of temperature and humidity) over 95F is expected to increase – from 4.5 to 13 days in Sanford, from 3 to 10.5 in Bangor and from 0 to 1.5 in Fort Kent.

These changes could affect fruit tree productivity, as fewer chilling hours occur. The percent of years expected to provide 1,000 chilling hours below 45F, under a high emissions scenario, is expected to decrease, so that by 2055, the number of cumulative chilling hours in southern New England (even parts of southern Maine and New Hampshire) could resemble that of 2020 in Maryland and southern New Jersey.

The Northeast growing season for 2045 is forecast to be 10 to 17 days longer than in 2000 (primarily because of the earlier date of the last spring freeze), and apple bud break and bloom dates three to six days earlier. The frequency of "1 in 20-year" extreme temperature events is likely to increase to "1 in 3" by 2055.

The "new climate" – when the annual average temperature is always above that of any year before 2000 – is predicted to occur in Maine by 2040 to 2050. Precipitation will increase, from a 1 to 2 percent increase along the Down East coast to a 6 to 7 percent increase in parts of northern Maine. Augusta could see 15 to 18 more days per year with 1+ inches of rain. The Northeast could see an additional 8 percent increase in the frequency of intense rain events (2+ inches in 48 hours) by 2055. The frequency of what was "1 in 20" years of extreme precipitation events almost doubles to "1 in 11 years" during 2046-2065.

The midcentury drought forecast for Maine is unclear: More rain is expected, but so are higher temperatures, greater evaporation and earlier snow melt. Texas has more than an 80 percent chance of a 10-year-or-longer drought during 2050 to 2100. Maine and New England have a 0 to 10 percent chance. Still, water demand is expected to increase by more than 50 percent in Maine by 2060 (relative to 2005) due to changes in climate, population and the economy. The water supply risk index for Maine counties in 2050 is low for all counties except Franklin, which has a moderate rating. Predicting drought, said Koehler, is more difficult than predicting temperature or precipitation alone, because it requires estimating multiple factors including temperature and precipitation simultaneously.

Snowfall is expected to decline by 2045 (relative to 2005) by more than 40 percent along the coast, 20 to 40 percent in southern interior Maine, and less than 20 percent in northern Maine.

Predicting impacts is difficult for temperatures that exceed anything in our records, said Koehler, but yields of major grain crops, given a 2C (about 3.5F) increase by 2050 without adaptation, are expected to increase in Maine – if temperature and rainfall are the only weather elements to change.

– Jean English