thCrichton Conversation, 5 February 2008
“It never rains but it pours”
Professor Bill McKelvey, Chief Executive & Principal, SAC
Notes to Slides
Two Key Quotes from IPPC (2007)
Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.”
“Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely* due to the observed increase in anthropogenic greenhouse gas concentrations.”
*In IPCC parlance, „very likely‟ is >90% chance
Sustainable Flood Management may involve allowing agricultural land to flood – blocking field drains and holding the water up river. This may also be extended to considering coastal defences. The UK population is set to increase by further 10 million – competing
pressures on agricultural land and for water resources. Could migration as a result of Climate change increase these numbers. In Scotland the areas most likely to have population growth are on the East coast where prime agricultural land is so could be increased pressure from Development
Figures for predicted soil moisture in England indicate a shift northwestwards in terms of optimum conditions for traditional cereal production. In the SE of England we will see new crops developed as a result. But this may be to the advantage of Scottish growers. The generally warmer weather and longer growing seasons present opportunities to introduce new or novel crops and increase the geographical range of more conventional ones. The north west of England and Scotland may become more suitable for arable crops, especially as it is unlikely that lack of water will be a limiting factor as it may become elsewhere. The south, east and south west may become more suitable for crops such as soya, sunflowers, peaches, apricots and grapes.
Longer growing seasons will also offer opportunities for livestock farmers to alter lambing and calving patterns in line with grass growth to enable longer market supply. As with arable production, the areas most suited to particular enterprises may change. For example, upland areas may become more productive. There may be less need to house livestock during the winter – reducing costs of production.
Governments are setting increasingly higher targets for reductions in emissions; often , it seems, without the scientific modelling information to predict whether or not such targets are realistic and achievable.
This is particularly so with respect to agriculture where a balance needs to be struck between the need to reduce emissions, and the need to produce ever greater quantities of cheap food.
Last week the Scottish Government published its consultation paper on its proposals to reduce GHG emissions in Scotland. Changes in land management practices do not feature significantly in the proposals. Yet land managers have the capacity to significantly impact on Scottish emissions. The real question is the relative cost 250945482.doc 2
benefit of land use changes relative to other major emitters such as power stations and transport.
As I will discuss later in this presentation the cost of mitigation procedures must not exceed the savings that can be expected to ensue. If the social cost of one tonne of CO2 equivalent is currently reckoned to be about ?25 per tonne , then whatever mitigation measures are adopted must cost less than that.
LEAST COST MITIGATION IN AGRICULTURE
How much regulatory pressure should we expect agricultural emissions to come under? Aside the political aversion to introducing further regulation, the answer should depend partly on the cost to mitigate emissions from agriculture relative to any other industry.
Industry wide estimates of the marginal cost of emission abatement are in fact difficult to derive, but recent evidence compiled by Hanley (2007) suggests a range that suggests agricultural abatement measures lying below the benchmark set by the social cost of carbon.
Analysis by Nera (2007) suggests that these measures include the use of maize silage, reducing some livestock stocking rates, afforestation, improving milk yields and larger centralised anaerobic digestion.
However, given that the size of enterprises are relatively small, the rewards to participants as benchmarked by the social cost of carbon may mean that incentives to participate in any voluntary schemes
Agriculture contributes ? of all N20 emissions and ? of all methane emissions in Scotland.
Emissions from Scottish agriculture in 1990 were 2.44 MtC To meet 2010 target SG are seeking a reduction of 0.6 MtC in agricultural emissions (22%)
By 2003 a 15% reduction had been achieved (largely due to fewer livestock and less N application)
Agricultural emissions arise mostly as CO2 from the conversion of land to cropping (nearly 1/2 of total agricultural emissions), N2O from the application of fertiliser and manure to soils (1/4), and CH4 from enteric fermentation in ruminant digestion (1/5). Against this, agriculture also represents a GHG sink, with sufficient CO2 being sequestered by crop and grassland to offset nearly 1/5 of agricultural emissions – bringing its net contribution to Scottish emissions closer to 1/5 than 1/4.
In the UK, agricultural emissions are currently outside any regulation, although as government signals an intention for all sectors to take responsibility, with a preference for introducing market based mechanisms for affecting cost-effective reductions.
Emissions sources Sinks
Cropped land : 48% Grassland : 22% Agricultural soils : 26% Forestry land : 77% Ruminants : 19%
NO and NOx are short-lived greenhouse gases produced in
agriculture which can produce ozone in the troposphere. NO and NH3 are precursors in the production of nitric acid. NH3 can be deposited on soil, leading to the production of N2O and NO.
Ammonia NH4 – acts on atmosphere, not GHG as such, and affects mostly poultry
Most of the emissions lie in N application, enteric fermentation and manure/slurry disposal.
NiTox is a simple scaling framework to bring together field measurements with soil, land use and climate maps to quantify how much nitrous oxide is emitted from different soil:land use combinations in Scotland.
We consider that there is potential to use mitigation strategies to reduce field-scale emissions and that these will be most effective in areas with highest emissions.
Grasslands are main sources of nitrous oxide.
Soil wetness (combination of drainage and heavy rainfall) and temperature are the driving factors.
Researchers in various European countries applied 300kg of N/ha under similar conditions and measured N flux…with very variable
results. Warmth and wetness significantly affect N2O flux. The message here is that the emissions recorded vary very significantly between various climatic regions in Europe, making comparisons extremely difficult to make.
Inputs of N are:
Bush marginal 128 kg/ha, Bush Mixed 249 kg/ha, Crichton beef 205 kg/ha and Crichton dairy 288 kg/ha
Temperature and wetness significantly affect N2O flux.
NitroEurope will also tackle uncertainties and gap areas in GHG emissions for farm system budgeting. These include GHG losses from feed stores and conservation and harvesting of feed crops. Also, for grazing, spillage and trampling losses.
Domestic production / Import
Imports may benefit
Transport is rarely a dominant contribution – with the general
exception of air-freighting
Other issues MAY counterbalance local production benefits
From increased use of renewables
From greater rates of primary production
Domestic producers may have better data and a greater
commitment to footprint reduction
Plants are Globeflower and Parsley Fern
Ecologists based at SACs Hill and Mountain Research Centre have a main interest its impact on biodiversity
It is likely to cause significant changes in the distribution and abundance of some species and the loss of habitats and species. It is the uplands that are most susceptible, where montane habitats and species such as snow bed vegetation and alpine plants and invertebrates are most at risk.
Phenological changes (earlier Spring and later autumns) Spread of non-native species, both by natural migration and through accidental or deliberate introduction
DEBATE : Is this good or bad??
WE have a particular interest is alpine plant communities and many of these species in Scotland are likely to suffer under changing climatic conditions. Alpines do not like mild, wet winter conditions, so an increase in winter rainfall, warmer winter temperatures, reduced snow cover and shorter cold periods are all bad for alpine plants like 250945482.doc 6
the alpine bartsia here, a red data book species with a very restricted distribution. Here it is growing on a cliff ledge at SACs Kirkton Farm.
The Mountain ringlet is Britain‟s only truly alpine butterfly only occurring above about 400m.
It is one of the species most often highlighted as at serious risk of decline or extinction in Britain due to global warming.
What needs to be done?
Increase pest forecasting and monitoring to detect and eradicate any sporadic introductions of pests and diseases
Identify key pests and diseases that are likely to benefit from climate change
Assess the changes in crops and crop agronomy under climate change
Integrate pest and disease management programmes with the increased need for irrigation
Probable increase in aphids in potatoes, brown rust in cereals. Grass weeds especially challenging (eg Blackgrass). More herbicide application may lead to increasing resistance.
Reduction in duration of herbicide effectiveness due to warmer winters (more frequent applications). Herbicides applied in autumn no longer effective until springtime.
Lack of frost means fewer pests and weeds killed.
Soil water logging in winter could become an issue locally. Possible increase in cabbage stem flea beetle and foma (fungus) in oil seed rape.
Challenge to Scotland as source of seed potatoes ?
Likely increase in many pest and disease problems (including „aliens‟) due to less „winter kill‟, earlier appearance in the spring and summer, and more generations
Some pests and diseases will become less of a problem
Drought stressed crops more at risk from pests and diseases Crop adaptation and plant breeding may circumvent problems to some extent, but pests and diseases are already adapting to CO2 and temperature changes
Will be changes in use of pesticides on crops through earlier use, and dry summer conditions will limit efficacy
Recent upsurge in liver fluke linked to warm wet conditions and less drainage. Could be mixed with increased resistance.
Midge vector for Blue Tongue virus viable in Scotland
Foot and mouth virus spreads more easily in warm wet weather. Increased transmission rates for Haemonchus nematodes (sheep). Warmer winters means earlier ticks affecting lambs (February) Warmer winters lead to increased leatherjacket densities (2007 is fourth high year in a row, with densities third highest in last 30 years of data)
Poaching, soil erosion, overtopping of slurry stores
Flooding in estuaries due to storm events and tides.
Less risk of generalised coastal plain loss due to isostatic rise in Scotland.
Severe autumn rainfall causes lower lambing rates (absorption of embryos in stressed ewes)
Need clear framework for irrigation (permits, pricing, trading rights ?) and link to Water Framework Directive during droughts
Mitigation is an issue which must be tackled on a global scale. This carbon cycle shows the storage and annual exchange of C between the atmosphere, hydrosphere and geosphere in gigatons –
or billions of tons of carbon (GtC). Burning fossil fuels by people adds about 6 GtC per year to the atmosphere, itself a small sink. What is just as important as release is sequestration of Carbon Agriculture is virtually unique as is both a source and sink for Carbon Agriculture accounts for seven percent of carbon emissions in UK (20 per cent in Scotland)
68% of Scottish methane emissions and 83% of Scottish nitrous oxide emissions
Currently no specific requirements on agriculture
Opportunities or threats?
Agriculture provides significant possibilities for sequestering carbon. This arises because conventional agricultural techniques have led to a large loss of carbon from soils and changes in tillage and management practices can replenish this carbon.
There is some uncertainty surrounding the role of soil sinks. Some debate around the amount of carbon that can be sequestered, how the gain is measured and how permanent the sequestration will be. The actual contribution that agriculture can make depends on the economics of soil sequestration and this is complicated by the problems with market failure due to the existence of external costs and benefits from land use and management changes.
1 MT = 10^12 g = 1 Tg
A key point is that agricultural soils provide a short-term solution for reducing greenhouse gases.
They are finite in scale and require no technological change to make them operational.
Greatest utility lies in an immediate focus on carbon sequestration while effective and efficient renewable energy sources that do not emit GHG are developed.
When undisturbed soil is brought into cultivation the result is a loss of between 20 and 50 per cent of soil C over a period of around 50 years with the amount varying by soil type, agricultural practices and other site-specific conditions.
Therefore in most cultivated soils there is the potential to rebuild the soil C stock.
Cropping changes 0.5 – 1.5 t C ha/year
Woodland regeneration 3.3 t C ha/year SRC 6.62 t C ha/year But we need food
Increase productivity per animal
more milk from fewer animals (?milk yield and longevity)
reduce time to slaughter (?lean tissue growth rate) –
Modify Feed :
Increase the diversion of H2 to other compounds such as propionate
Feed more starchy concentrates, increase level of feeding, process roughages
Use previously fermented feeds (distillery by-products) 250945482.doc 10