Letters in 2014

Widespread forest die-back due to the increasing frequency and intensity of drought in many parts of the planet is focusing attention on the mechanisms of tree drought resistance. This study provides direct experimental evidence that greater non-structural carbohydrate concentrations before drought help maintain hydraulic function and thereby prolong drought tolerance in seedlings of ten tropical tree species.

The criteria used to classify species as being at risk of extinction are based on global population estimates, making global-scale analysis important for conservation. Now, a study projecting population dynamics of all 45 known emperor penguin (Aptenodytes forsteri) colonies indicates long-term decline, primarily due to altered Antarctic sea ice conditions.

An increase in extreme weather events in the Northern Hemisphere mid-latitudes has been proposed as a result of amplification of atmospheric planetary waves in the region. This study finds months of extreme weather are associated with amplified planetary waves, with different types of extreme events associated to differing degrees.

Atmospheric stagnation can have serious health implications due to increased pollution exposure. This study investigates how global warming will alter atmospheric circulation and the resulting changes in the frequency and persistence of stagnation events. The authors find an overall increase in the size of the population exposed to these events and highlight the need to evaluate air pollution management.

Linkages between neighbouring ecosystems are rarely considered when seeking to predict ecological responses to climate change. However, the finding that the impact of climate change on seagrass beds is mediated by the response of neighbouring coral reef habitats highlights the need for a broader-scale view of climate change impacts on ecosystems.

Intermittency is often cited as the single greatest hurdle to making a transition from a fossil-based power system to one based on renewables. This study shows that a network of solar power plants, located in deserts, could provide significant baseload in four world regions, suggesting that decarbonization of the power system may be possible and affordable, even if no new technologies come online.

Crustose coralline algae (CCA) are potential ‘poster children’ of ocean acidification stress, yet their stress responses have been poorly studied in a natural or ecological context. Now, a comparison of historical and modern specimens from a site with a declining pH trend over a 30-year period reveals trade-offs in skeletal traits tied to calcium carbonate use in response to ocean acidification in four CCA species.

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.

The increased use of wind turbines for power generation could play an important role in climate change mitigation efforts. This study shows that, assuming greenhouse gas emissions are kept in check and energy-use efficiency increases, crossing the 2 °C warming threshold could be significantly delayed or even avoided altogether depending on how aggressively wind energy is taken up over coming decades.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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.

Representative Concentration Pathways (RCPs) play a central role in assessments conducted by the climate modelling community. This study comprehensively assesses air pollution emissions in the RCPs and provides projections for air pollutants over the 21st century. Such projections should increase understanding of the range of possible impacts of air pollutants on the climate.