Seems like the weather’s been extreme in
recent years; heat waves, ice storms, floods, etc. How is this related to
climate change? The answer is: indirectly. Weather events are not a good tool
for assessing the climate, since climate is made up of weather patterns over many
decades. There are ups and downs within seasons, but the trends over time are what
counts. They include both temperature and precipitation patterns, and these
affect environmental conditions, which in turn affect plants, animals and ecosystems.
Research conducted by the University of
New Hampshire makes it pretty clear that the climate in our region is changing.
Scientists analyzed data collected by hundreds of weather stations and found
that the Northeast’s average annual temperature increased by 1.8 degrees F. from
1899-2000. Winters in particular have gotten warmer, with the average
temperature from December through February warming by 2.8 degrees. It may not
sound like a lot, but these changes have had significant effects on the
environment, and therefore on farming.
For example, the Northeast frost-free
growing season is 8 days longer than it was 100 years ago; the number of
extreme precipitation events (more than 2 inches of rain in 48 hours) has
increased from about 3 to 5 per year; there were, on average, 16 fewer days
with snow on ground in 2001 than in 1970; apple and grape bloom dates were
about two days earlier per decade from 1965 through 2001; and the maple
sugaring begins 8 days earlier and ends 11 days earlier than it did 40 years
Climate changes have been documented not
just here but all over the globe, which means that farmers everywhere will be
affected. The U.N. Intergovernmental Panel on Climate Change concluded in 2007 that
the increased frequency of heat waves, droughts and floods will negatively
affect crop yields and livestock, especially for subsistence farmers at low
In places like Bangladesh, rising sea
level is the climate change effect that outweighs all others in importance,
since it is a low-lying country. In Vermont, climate change impacts are
diverse, and they will have some positive as well as negative effects on
farming. For example, a longer growing season can help the production of annual
crops. In recent years we’ve seen mild autumns that allowed pumpkin and squash
growers get higher yields, and let fall raspberry growers harvest fruit that
would otherwise be lost to earlier frost.
But there are serious downsides to our
changing climate, too. For example, studies suggest that two very important crops
in Vermont– apples and maple syrup – may be negatively affected. Warmer winters
could reduce apple fruit yields, and sugar maples in our area are likely to decline
in health as the climate warms. The dairy industry will also face challenges,
especially from an increase in summer temperatures since milk production drops
off when cows are exposed to hot, humid weather.
Farmers will be able to cope with some
climate changes more easily than to others, and this will depend on what they
produce, where they’re located, and the extent of the change. (For a series of
fact sheets about climate change impacts on agriculture in the Northeast, see: www.climateandfarming.org/clr-cc.php.)
For example, it’s likely that cool season crops won’t do as well in areas that
warm up significantly, but farmers who grow potatoes or crucifers can fairly
easily switch to varieties that are more heat-tolerant, or change the types of annual
crops they grow. Maintaining the comfort of heat-sensitive livestock such as dairy
cows is also feasible with practices such as improved barn design to promote ventilation,
or misting systems to provide evaporative cooling. Other problems will be harder
to cope with, such as the gradual decline of perennial crop species, or the
greater aggressiveness of weeds.
Rising CO2 levels may promote
photosynthesis and thus the growth of crops, but the weeds in those crops may
grow even better. Some fast-growing weeds are especially well adapted to
utilizing extra CO2 because their photosynthetic system differs from
most crops. Certain perennial weeds such as thistles and quackgrass that can
store extra energy underground may become harder to control. Integrated weed
management systems that combine tactics such as crop rotation, cover crops,
cultivation, no-till production and mulching will become more important in the
Climate change will also alter pest populations,
though exactly how is not clear. It‘s likely that new pests will arrive and
some existing pests will become more abundant while others decline. For
example, insect pests of crops that travel here on storm fronts from southern
areas, such as leafhoppers, corn earworm and armyworms could become more
abundant as summer storm frequency increases. Other pests that overwinter here,
such as the European corn borer, flea beetle and tarnished plant bug could
become more abundant if milder winters encourage their survival, although
reduced snow cover might lower overwintering populations. Changes in rainfall
patterns will affect crop diseases, since most of them require moisture to
proliferate. The likelihood of changes in pest pressure, plus the uncertainty
about it, will make frequent monitoring for pests an even more important
activity on farms than it already is now. Farmers will want to avoid being
taken by surprise.
Greater variability in precipitation
patterns will have a big impact on agriculture. Farmers will need to take steps
to deal with more intense rainfall events in order to avoid soil erosion. This
could include putting in drainage systems or establishing strips of permanent
sod in or around fields. Dealing with longer periods of drought will call for
more investment in irrigation and water storage.
Besides planning to adapt to climate
change, farmers can also help mitigate the problem by reducing their greenhouse
gas (GHG) emissions. Although agriculture generates only a small part of the
nation’s GHG output—about 6% of the 2009 total—Vermont farmers, like everyone
else, should do what they can to address the problem. The good news is that
many agricultural actions that reduce GHG emissions can also enhance farm profitability.
For example, renewable energy systems can reduce fossil fuel use and CO2 emissions
while lowering energy costs.
In order to understand how farmers can
help mitigate climate change, one needs to understand something about the
greenhouse gases involved. While much of the focus on GHG reduction is on CO2,
nitrous oxide (N20) and methane (CH4) are other gases
that contribute to climate change. Although they are generated in smaller
amounts by human activity than C02, they are far more potent in
terms of their warming effect. However, compared to most other industries,
agriculture produces proportionally more N2O and CH4 than
carbon dioxide. (In general, methane from agriculture is released by livestock
and manure, and nitrous oxide is released when excess nitrogen fertilizer is
applied under certain soil conditions.)
Given the information above, there are a
several key steps that farmers can take to reduce GHG emissions, including:
- Using nitrogen fertilizer more efficiently in order to avoid N2O emissions. This involves proper timing, placement and application rates.
- Taking CO2 from the atmosphere and sequestering (storing) it in plant biomass and soils. This can be done through increased use of cover crops, permanent
pastures and reduced tillage systems that ‘tie up’ atmospheric carbon while building soil organic matter.
- Increasing the efficiency of farm inputs such as fuel, fertilizers, and pesticides, thus reducing consumption of fossil energy that is required to produce them.
- Increasing production of biological-based energy to replace fossil energy. Vermont farms already offer many examples of this, from anaerobic digesters that make electricity
from dairy manure, to on-farm biodiesel production using oil from canola and sunflower crops.
- Switching to non-carbon energy sources such as wind and solar; and using energy efficient equipment for heating, cooling and tillage;
With the support of consumers, Vermont farmers can also use the marketplace to combat climate change. Growing the
demand for local food products can improve the efficiency of food distribution and
thereby reduce the energy consumed by storage and transportation. Eating fresh
foods purchased from local farms can also avoid the need for packaging and
refrigeration, further reducing fossil fuel use and GHG emissions. Of course, this assumes that local food is
aggregated at roadside stands, farmers’ markets, food coops, cafeterias and the
like. Driving from place to place to purchase small quantities of local food is
Although the effects of climate change
are daunting and somewhat uncertain, it makes sense to take steps to protect
our agricultural landscape for generations to come. These steps include
planning ahead to prepare for likely changes while working to reduce greenhouse
gas emissions. Many farmers are already taking the initiative in these areas with
innovative on-farm practices. Consumers can take action by continuing to buy
local food, adding climate change to the list of reasons for doing so.