New Zealand’s Parliamentary Commissioner for the Environment has released a report exploring how much and over what timescale the climate is affected by methane emissions from livestock. It focused on two questions. First,if methane emissions from livestock were held at current levels or followed business-as-usual trajectories, what would their contribution to future warming be? Second, what reduction in methane emissions from livestock would be needed so that they cause no additional contribution to warming?

A recent paper uses data from volcanic eruptions to estimate the effects that geoengineering with sulphate aerosols would have on agricultural production. It concludes that the damage that geoengineering would do to maize, soy, rice and wheat outputs (because of reduction in sunlight reaching the crops) would have roughly the same magnitude as the benefits of the cooling it would provide.

A carbon tax applied across the whole economy, including agriculture, could put more people at risk of hunger (in terms of dietary energy availability) than climate change itself, according to a recent paper.

Researchers have warned that a cascade of positive feedback loops could push global temperatures into a “Hothouse Earth” state for millennia, even if human greenhouse gas emissions are reduced. Some systems, such as ice sheets, forests and permafrost, could pass a temperature tipping point beyond which they rapidly become net contributors to climate change. If one is set off, the warming produced could trigger the remaining tipping points, like a line of dominoes.

Farmers in Britain and other European countries have been affected by the ongoing heatwave and dry weather. Oxfordshire farmer Lesley Chandler told the Guardian, “It’s like a tinderbox out here… Just a spark could set it all alight” (read more here). Combine harvesters can create sparks if their blades hit a stone.

The FAO has released a report on the current state of knowledge on how climate change will affect fisheries and aquaculture, including mitigation and adaptation options. The report finds that “climate change will lead to significant changes in the availability and trade of fish products”. Marine catches could decrease by 2050 in the tropics and rise in some high latitude regions, with a global decrease in Exclusive Economic Zones of 3% to 12%. Inland fisheries in Pakistan, Iraq, Morocco and Spain may come under greater stress, while those in Myanmar, Cambodia, the Congo, the Central African Republic and Colombia may remain under low stress in the future.

Researchers from the University of Oxford’s Environmental Change Institute (of which the FCRN is part) have created a new tool - the “temperature of equivalence” - to map the impacts of varying degrees of climate change in different areas. They find that people living in low-income countries will, on average, experience heat extremes at 1.5°C of (global average) warming that people living high-income countries will not encounter until 3°C. This result is based on combining a map of predicted heat extremes with information on where people actually live within these areas. The paper also finds that, on average, people in high-income countries would experience the same increase in extreme rainfall after 1.0°C of warming that people in low-income countries would experience at 1.5°C of warming.

As global mean temperature rises due to climate change, the chance of multiple shocks in maize production occurring at the same time rises, due to greater variability in yields. The top four maize-producing countries are United States, China, Brazil, and Argentina. The chance of all four suffering a yield loss of more than 10% in the same year is presently almost zero, but rises to 6% for 2°C of warming and 87% for 4°C of warming. The study does not account for changing variability in temperature (only the increase in mean temperature), nor any gains from breeding heat-tolerant maize varieties.

The Centre for Ecoliteracy, a Californian non-profit, has produced a free interactive guide to understanding food and climate change, covering both how climate change affects the food system and how the food system contributes to climate change.