2 Apr 2019
‘Climate change and agriculture: all you need to know in a day’, held on March 6 at SCI HQ, London, and organised by the SCI Agri-Food Hub, brought to the fore some important issues facing the agricultural and food industries.
Bruce Knight (SCI Agrisciences group), Sebastian Eves-van den Akker (SCI Horticulture group) and Craig Duckham (SCI Food group)
At SCI, interests in food and agriculture, and how climate change affects these, are central to the work of the Agri-Food Hub. This event, and other climate-related events in 2019 and beyond, are seen as a way of bringing together different communities from academia, the private sector, NGOs and government, to discuss and raise awareness of this important issue in technical and non-technical audiences, catalysing action to address it.
Agriculture and climate change
The first speaker of the day was Professor Ian Crute CBE, who is a former chief scientist at the Agriculture and Horticulture Development Board (AHDB). He outlined the predicted impact of climate change in the UK. There will be more weather extremes, heavier rain storms resulting in increased river water flow and flooding, warmer drier summers resulting in heat stress on crops and livestock, arrival of new pests and generally fewer frosts.
Mitigation proposals were covered in the UK Environment Agency report published in November 2018. The report, a contribution for the UK government’s Committee on Climate Change, concluded that for England to reduce greenhouse gas (GHG) emissions by 80% – the global target if the average rise in temperature is kept to 1.5°C – then land use has to change. The report advocates a significant reduction of grassland area, an increase in the area of trees and more planting of energy crops.
Professor Crute pointed out that the report only focused on GHG reduction strategies. If the 80% reduction is to be achieved, it will mean that England will effectively be reducing domestic food production and relying more on imported food. In effect, it will be exporting the GHG emissions to other food producing countries. He called for the impact on agricultural and food production to be factored into these policies. Although climate change is a global problem there is a strong case for the UK to demonstrate to the rest of the world how successful approaches can be adopted based on the country’s reputation in innovation and scientific skills.
Next to speak was Dr Marc Metzger from Edinburgh University, who also stressed how agriculture in the UK will have to change, but that this will be down to societal choice taking into consideration food and diet, job creation and environmental impact. There will always be trade-offs because fixing one problem can exacerbate another, he said.
Dr Alison Foster, a freelance horticulturist and Chair of SCI’s Horticulture group, described how UK horticultural crop production will be affected with flooding and highlighted the need for developing salt tolerant varieties to offset the impact of increased soil salinity in important horticultural crop areas.
It is also becoming clear that insect life cycles may be changing such that pollinators are out of synchronisation with crop flowering times. In the UK, around 10% of land surface is non-productive sphagnum peat mainly on moorland. Globally, the figure is 3%. Dr Foster described a case study in which the use of gel beads is being examined to help improve the productivity potential of peaty land. Effective peatland management can contribute to their maintenance as a carbon sink.
Water use efficiency is clearly a key issue in maintaining crop and livestock productivity under increasing pressures brought about by climate change. Professor Tim Hess from Cranfield University explained that 70% of freshwater withdrawals globally are used to support agriculture. Although the demand for water is much lower in the UK, imported food from low rainfall countries, such as Spain, relies on access to irrigation water to support agricultural production. 40% of global food production and 20% of agricultural land relies on irrigation. Therefore, an important objective under the increased impact of global warming is to maximise the efficiency of irrigation systems.
He made it clear that technological solutions cannot be addressed in isolation and that management solutions are equally important. Losses of irrigation water can occur through its conveyance and its application. Better linings for irrigation channels can substantially reduce losses, while losses for sprinkler and boom pivots irrigators are generally affected by evaporation and winds.
Professor Hess indicated that boom pivot water wastage can be reduced by 75%, and sprinkler and drip irrigation by as much as 85% through improved timing and management, particularly by avoiding over irrigation. However, the most efficient systems in terms of water use, such as delivery of water from drip pipes, may also require more energy to operate – another example of a trade-off.
Dr Simon Bowen, of the British Beet Research Organisation (BBRO), described approaches being examined for the production of UK sugar beet in response to climate change. Three methods are under consideration by BBRO: improving soil resilience by increasing organic matter through the use of cover crops; a greater focus on trait improvement such as pest resistance and drought tolerance rather than just yield enhancement; and exploiting warmer and more variable growing seasons with the possibility of autumn sowing.
Most of the conference proceedings centred on crops, however, Dr Sokratis Stergiadis from Reading University explained that the most significant source of GHGs from agriculture was from enteric fermentation from ruminants. Furthermore, current global trends are for demand for livestock products to increase. There is much that can, and needs to, be done to address the issue in the short term. This includes improvement in forage quality, precision feeding, more use of manure for anaerobic digesters, enhanced animal health and more efficient animal production. These factors can all help to reduce the need for land use change.
Management and sociological solutions
The next speaker, Professor Tim Benton from the University of Leeds, addressed the climate change problem from a different angle. He said: ‘We have to change the way we eat then we will need to change how we farm.’
With GHGs still rising, it is food production that is a major driver of climate change. The expectation is that extreme weather that will be the main determinant of change. In the worst situation, the global population could reach 11bn but we will only have enough food for 7-8 bn people.
The prognosis is dramatic; yields will be more variable, diseases will change, most wet regions will become warmer and wetter, whereas dry areas will be drier and hotter. There will be more extreme storms and the impact of such storms on critical supply routes, such as the English Channel, will be another risk.
Professor Benton commented that the only way to achieve the objective of keeping global warming to acceptable limits is through a major change in human diet towards plant-based food. He considers that the proposal to rely on the planting of more trees is flawed. On current trends an additional 8m square kilometres will be needed – twice the area of India. He added that dietary change needs to be systemic not just marginal and that we have only two decades to make the dietary and food production changes required.
Caroline Drummond, of LEAF (Linking Environment and Farming), stressed that UK farmers generally are capable and show a ‘can do’ approach. However, they will need to be shown how and why changes need to be made. The use of integrated farm management and modern technologies such as robotics and artificial intelligence in order to improve production sustainably can be demonstrated and the use of social media will play an important part. Bringing about change through legislation should be a last resort.
Martin Collison from Collison and Associates said that the pressure on land use could be substantially reduced if food waste was minimised. Currently, it is estimated that 30% of food is wasted worldwide. The use of co-products and by-products in agricultural production is a major way to maximise land utilisation and reduce waste. The sugar beet crop is a good example as it can be a source of sugar, livestock feed and energy. How much we eat and what we eat are the big factors.
However, bringing about change in diet through legislation does not generally work, he said. In Britain, the idea of a sugar tax has not taken off and in Denmark the introduction of a ‘fat tax’ failed. Collison believes that a concerted approach from across the food chain – from farmer to retailer – is called for, rather than through government intervention.
The conference certainly proved that the subject of climate change and agriculture is complicated. Professor Benton said that the current model of agricultural and food production cannot be left for more than a decade if serious risks to the global economy and health of the population are to be avoided. For future food systems to deliver healthy food sustainably the research agenda should reflect on the different models of adaptation that are possible. The underlying message from the day is that our current diet and production strategies must change and that change must start now.