Volume 4 Issue 7, July 2014

Governments and businesses are beginning to account for natural capital, but must collaborate to promote sustainability, combat climate change and improve decision-making.

Embracing an 'evidence-informed' rather than 'evidence-based' attitude to policy-making should result in more effective action on climate change, recognizing that evidence must be used in such a way as to interact persuasively with other factors.

Net energy analysis should be a critical energy policy tool. We identify five critical themes for realizing a low-carbon, sustainable energy future and highlight the key perspective that net energy analysis provides.

Stratospheric injection of sulphate aerosols has been advocated as an emergency geoengineering measure to tackle dangerous climate change, or as a stop-gap until atmospheric carbon dioxide levels are reduced. But it may not prove to be the game-changer that some imagine.

Through modern media, Africa is now in people's living rooms and offices, so Africans need to report their experience of climate change.

Cost–benefit analysis and risk assessment approaches inform global climate change mitigation policy-making processes. Now, a development in the former shows that optimal carbon tax levels have previously been underestimated by a factor of two.

Agriculture-focused integrated assessment models may be overstating the ability of poor countries to adapt to climate change. Empirical research can elucidate limits of adaptation in agricultural systems and help models better represent them.

Arctic warming has reduced cold-season temperature variability in the northern mid- to high-latitudes. Thus, the coldest autumn and winter days have warmed more than the warmest days, contrary to recent speculations.

Sugar cane ethanol replaces fossil fuels, but changes in soil carbon could offset some of the benefit. Now, a study shows minor loss of soil carbon when pastures and croplands are converted to cane, but larger losses when converting native savannahs.

Atmospheric CO₂ fertilization may go some way to compensating the negative impact of climatic changes on crop yields, but it comes at the expense of a deterioration of the current nutritional value of food.

Global demand for wheat is projected to increase significantly with continuing population growth. Currently, Europe reliably produces about 29% of global wheat supply. However, this might be under threat from climate change if adaptive measures are not taken now.

2014 is a critical year for preparing for the 2015 deadline to settle a new international agreement on measures to tackle climate change. This Perspective offers a number of compromises designed to help overcome the present impasse in global climate negotiations.

Climate change mitigation and adaptation are human-mediated processes but global modelling tools currently take no account of human responses to environmental change. In this Perspective the authors propose the agent functional type approach to advance the representation of these processes.

Purposeful action leading to significant structural and/or functional changes — known as transformational adaptation — may be required to adapt agriculture to the changing climate. Now, research shows that strong access to knowledge and weak social ties (social capital) empowers individuals to plan and implement novel farming strategies and options.

Climate variability in the Southern Hemisphere is dominanted by the Southern Annular Mode, which influences temperatures and latitudinal rainfall distribution. This work reconstructs its annual variability since the year 1000. The authors find that a positive trend since the 1940s is reproduced by climate model simulations with representative greenhouse gas forcings and ozone depletion. Early trends indicate a teleconnection to tropical Pacific climate, which may need to be considered in projections under climate change.

Changes in precipitation extremes are occurring under climate change, but how they will manifest on sub-daily timescales is uncertain. This study used a high-resolution model, typically used for weather forecasting, to simulate hourly rainfall in the UK in the year 2100. The results confirmed previous findings of winter rainfall intensification and found that short-duration rainfall intensified in summer, increasing the risk of flash flooding.

Arctic amplification is thought to be altering the polar jet stream and increasing Northern Hemisphere mid-latitude temperature variability. This study investigates cold extremes in the mid-latitudes and shows that subseasonal cold-season variability has significantly decreased in recent decades. The reduction in variability is partly due to more rapid warming of northerly winds and associated cold days, relative to southerly winds and warm days.

Increased surface temperatures are expected to cause less precipitation in the form of snow. The impact of decreased snowfall has previously been assumed to not influence streamflow significantly. This work applies a water-balance framework to catchments in the United States and finds a greater percentage of precipitation as snowfall is associated with greater mean streamflow.

The impact of climate change on the water resources and hydrology of High Asia is uncertain. This work uses a cryospheric hydrological model to quantify the hydrology of five major rivers in the region and project future water availability. Runoff is expected to increase until at least 2050 due to an increase in precipitation in the upper catchment of four rivers and increased melt entering the fifth river.

Carbon dioxide seeps in marine environments act as ‘natural labs’ for studying the impact of ocean acidification on benthic calcifiers. Focusing on the effects of an increased CO₂ concentration on population density and biomineralization, this study helps explain species-specific responses to ocean acidification, and reveals some evidence of phenotypic plasticity that may improve the persistence of marine species in low pH conditions.

The timing of life-history events has a strong impact on ecosystems. Now, analysis of the phenology of temperate forests in the eastern US indicates that in the case of an earlier spring and a later autumn, carbon uptake (photosynthesis) increases considerably more than carbon release (respiration).

Sugar cane is increasingly cultivated for bioenergy. This work looks at the effects on the soil-carbon balance of converting native vegetation, pastures or existing cropland, to sugar-cane plantations in Brazil, the world’s largest producer. The findings of the study should help shape policies aimed at achieving more sustainable sugar-cane production in Brazil as demand for biofuels grows.

On-farm adaptations could play an important role in moderating the adverse effects of climate change on agriculture. Here, a statistical approach is applied to assess the adaptation potential of agriculture in Europe, focusing on three major crops—maize, wheat and barley.

To meet growing food demands without expanding cropland area, much of the North China Plain has moved from single to double annual cropping. Now, research shows that this change in agricultural management alters biophysical feedbacks to the climate in such a way that they can amplify summertime climate changes over East Asia.

Cross-breeding between invasive and native species (hybridization) is one of the potential ways that climate change can impact biodiversity; unfortunately there is little data on this phenomenon. Now, research shows that rapid climate-warming has exacerbated interactions between native trout (Oncorhynchus clarkii lewisi) and the non-native species (Oncorhynchus mykiss) through invasive hybridization in western North America.

Climate is assumed to be the predominant control on the decomposition rates of organic matter in Earth-system models. Now, research investigating the sensitivity of this relationship to spatial scale reveals the important role of local-scale factors in controlling regional decomposition dynamics.

Most integrated assessment models used to estimate the long-term economic loss from current carbon emissions, and to evaluate climate policy, are deterministic. By including the risk of damage in these models, research now shows that estimates of the optimal rate of emissions abatement and carbon taxation are double the levels obtained by using the standard formulation.

Studies into the effects of climate change on crop yields have tended to focus on the average state of the climate. Now, research into the effects of adverse weather events on wheat yields in Europe suggests that the probability of single and multiple adverse events occurring within a season is expected to increase substantially by the year 2060.

Climate change fundamentally alters the way that farmers need to plan and manage their operations. This is necessary to avoid the worst impacts of climate change while reducing greenhouse gas emissions and meeting growing demand for food, fuel and fibre. This is a grand challenge for farmers and has the potential to touch the lives of everyone that uses farmed produce; in short, all of us. In this focus, Nature Climate Changepresents a variety of original research and opinion pieces that highlight important themes in our understanding of the effects of climate change on agriculture, agriculture's influence on the climate and our capacity to adapt to better face these challenges.