Declining crop yields and increasing agricultural emissions

ID-100148476Alongside the recent release of the UN IPCC Fifth Assessment Report, a new study, published in Nature, provides evidence that global increases in temperature of only 2°C will reduce crop yields in temperate and tropical regions from the 2030s onward.

The meta-analysis, collated and analysed by researchers at the University of Leeds, combined 1,700 published data sets for wheat, rice and maize, the largest dataset on crop responses to climate change yet. The research, taking into account currently practiced adaptation activities such as changing planting dates and using improved varieties, as well as uncertainty and the timing of impacts, found that the variability between crop yields in different places and at different times is also likely to increase with climate change, which could have a profound impact on the security of food supply.

Beyond 2050 declines in crop yields will be greater in magnitude, reductions of 25% are expected to be widespread with median crop yields to drop by 2% each decade for the rest of the century. Although crop productivity has previously been predicted to improve in Northern Europe, crop yields even under moderate future warming may decline in many places. Coupled with increasing demand for food (expected to increase 14% per decade until 2050), future food security without significant intervention looks bleak.

The clear message from the paper and the IPCC Fifth Assessment Report is the urgent need for farmers to adapt to a changing climate and for all countries to seriously engage in mitigating climate change. The UN Food and Agriculture Organisation recently released figures showing that greenhouse gas emissions from the agricultural, forestry and fisheries sector have doubled over the last 50 years and could grow by over 30% by 2050. The majority of this increase is being seen in developing countries, with the expansion of agricultural production.

Between 2001 and 2010 emissions from crop and livestock agriculture increased 14% while emissions from land use change and deforestation declined 10%, yet more evidence that agriculture needs to be part of climate discussions. Within agriculture, enteric fermentation (methane from livestock) accounts for the largest proportion of emissions (39%) and increased 11% between 2001 and 2010. The FAO, in 2012, launched the FAOSTAT emissions database, which details the GHG emissions of agriculture, forestry and other land use activities.

With crop yields expected to decline (and already declining in many countries) and agricultural emissions appearing to be on an upwards trajectory, the former perhaps incentivising the latter, we need smarter agriculture, that is resilient to future climate change while also reducing GHG emissions, the very goal of sustainable intensification.

ID-100144969A recent paper in the Proceedings of the National Academy of Sciences, Climate change mitigation through livestock system transitions, discusses how climate mitigation policies can reduce emissions from the livestock sector. Authors identify much potential to mitigate climate change in livestock production systems, namely the transition from extensive to more productive systems, reducing the livestock sector’s impact on land use change. The paper also recommends emissions reductions should be targeted to the supply (rather than demand) side. Aside from this rather controversial recommendation, this paper, as with many others, identifies significant opportunities to mitigate climate change and increase food supply within the agricultural sector. Serious action on implementing the variety of adaptation and mitigation strategies at the global and local level appears to be the limiting factor in progress.

Making livestock farming more sustainable

ID-1005418The livestock sector is important as a source of protein and income, and some one billion people rely on livestock for their livelihood but it is generally accepted that the world’s livestock systems place a huge burden on the environment, for example, contributing 14.5% of all human-induced greenhouse gas emissions. Some 45% of these emissions originate from the production of feed. The one billion tons of cereals produced for feed each year could feed an estimated 3.5 billion humans. The health impacts of a diet high in meat have also been widely reported.  It is clear that the world’s livestock systems are not sustainable but how can we change this? Two new reports address this challenge.

A Nature commentary piece authored by Eisler et al, discusses the need for the sustainable intensification of livestock. They highlight eight strategies to cut the environmental and economic costs of livestock farming while increasing the quantity and quality of the food they produce.

1)      Feed animals less human food. Of the third or more of cereal grains going to livestock feed, 40% goes to ruminants. But ruminants, such as cattle, can survive on food inedible to humans, such as hay, silage and high-fibre crop residues. They can also graze in marginal areas leaving prime agricultural land for growing human food.

2)      Raise regionally appropriate animals. Highly productive livestock breeds such as Holstein cattle have been introduced around the world in the pursuit of increased productivity. Given that they are a temperate breed, however, they are often expensive and labour-intensive to manage in other climates, and yields can be less than a third of normal yields under these conditions. Working with breeds adapted to local conditions such as those resistant to local pests and diseases may be a less risky option, particularly for poor households.

3)      Keep animals healthy. Improving hygiene, quarantine and disease surveillance practices can help avoid animal diseases being transmitted to humans. 13 livestock-related zoonoses cause 2.4 billion cases of human illness and 2.2 million deaths each year. Improving husbandry practices and animal welfare, for example keeping livestock at lower densities, can improve the health of livestock and the quantity and quality of livestock products.

4)      Adopt smart supplements. Specific plant extracts can help microbial populations in the rumen to grow faster, using nitrogen and energy more efficiently and boosting yields without significantly increasing GHG emissions. And smart supplements don’t have to be expensive: a water fern in India is a source of extra protein for cattle and goats. [Read more…]

What we’ve been reading this week

This week’s summary on the news stories, reports and blogs that have grabbed our attention. We welcome your thoughts and comments on these articles.

The amazing, surprising, Africa-driven demographic future of the Earth, in 9 charts, The Washington Post

Driving Agricultural Innovations to Improve Nutrition, Feed the Future

GM crops: Public fears over ‘Frankenstein food’ may be easing, Independent poll reveals, The Independent

Costs of Arctic methane release could approach value of global economy – study, Thomson Reuters Foundation

Can We Trust Monsanto with Our Food?, Scientific American

Climate Forecasts Shown to Warn of Crop Failures, Science Daily

Better evidence, better programmes, better outcomes, IFAD

Zimbabwe: Smallholders Feed a Nation As Land Reform Fails, Africa Agriculture News, IPS

Partnerships bear fruit in drive for Africa to feed Africa, Thomson Reuters Foundation

How (and why) Africa should solve its own problems, The Christian Science Monitor

The era of cheap food is over. Are we ready for that?, The Telegraph

Commentary – Who feeds Africa? It is the woman, Global Food for Thought

The ‘invisible’ farmer and the global hunger debate, Aljazeera

How To Prevent Hunger In Upcoming Decades? Try Precision Agriculture, Huffington Post