Research articles

Future changes in the Indian monsoon could affect millions of people, yet even the ways in which it might have changed over recent years remain uncertain. Statistical analysis indicates that during the second half of the twentieth century there were no spatially uniform changes in the frequency or intensity of heavy rainfall events over India, but there was an increase in the spatial variability of these characteristics.

A study based on a long-term manipulation experiment in a grassland ecosystem describes the microbial mechanisms controlling feedbacks to carbon and nutrient cycling under warming. The findings suggest that ecosystem models should more explicitly consider microbial feedbacks to climate change.

An analysis shows that the coral endosymbiont Symbiodinium—a dinoflagellate genus underpinning the ecological and evolutionary success of reef corals—can adapt to local thermal regimes, thereby shaping the fitness of coral hosts. This may explain why many corals show fidelity for single Symbiodinium types over wide thermal ranges.

Perturbed-physics climate modelling experiments simulate past and future climate scenarios using a wide combination of model parameters consistent with past climate. Using such an approach, a study examines variations in the response of climate to solar-radiation management under different climate sensitivities.

Adult fish seem relatively resilient to increased carbon dioxide levels, but how early-life-stage fish fare remains less clear. In a study, the estuarine fish Menidia beryllina experienced severely reduced survival and growth rates in its early life stages under levels of ocean acidification expected later this century. This suggests that ocean acidification may affect fish populations, because small changes in early-life survival can generate large fluctuations in adult-fish abundance.

Biofuels are often promoted as a way of mitigating climate change, but their impacts on climate and air quality remain uncertain. Estimates of air-pollutant emissions from the production and use of sugar-cane ethanol in Brazil indicate that this biofuel may have larger impacts on regional climate and human health than previously thought.

Ocean acidification—resulting from anthropogenic carbon dioxide emissions to the atmosphere—has been shown to affect fish growth rates and reproduction. Now research shows detrimental effects of ocean acidification on the development of Atlantic cod larvae—a mass-spawning fish species of high commercial importance—suggesting that ocean acidification could cause additional larval mortality, affecting populations of already exploited cod stocks.

Tropical species are considered especially sensitive to climate change, but research now shows that a tropical reef fish can rapidly acclimate over multiple generations. Acute exposure to a 1.5 °C and 3.0 °C temperature rise decreased an individual’s ability to perform aerobic activities such as swimming or foraging by 15% and 30% respectively, but this did not occur when both parents and offspring were reared at the higher temperature.

One of the impacts of ocean warming is a decrease in dissolved oxygen, with implications for valuable pelagic fish species. A study shows that the oxygenated upper ocean layer in the tropical northeast Atlantic thinned at a rate of around one metre per year between 1960 and 2010, and, by tracking individually tagged fish, demonstrates that this contraction in the oxygenated layer limited the movement of blue marlin.

Drought-induced forest dieback has emerged as a global concern and is expected to increase worldwide under projected future climate change. A study using long-term forest plots now provides a quantitative estimate of drought-induced increase in tree mortality across Canada's boreal forests—one of the most important terrestrial carbon sinks.

A significant proportion of the US public believe that climate scientists widely disagree about climate change. Now a survey-based study investigates whether this misperception is important and finds that individuals who believe there is broad scientific disagreement tend to feel less certain that global warming is occurring and show less support for climate policy.

Decisions about how soon, how quickly and by how much carbon dioxide emissions are reduced will determine whether the climate target of limiting warming to 2 °C can be met. Research reveals that it will probably only be possible if ambitious reductions are implemented within the next two decades and emissions eventually fall to zero.

Both greenhouse gas emissions and changes in land use and cover have modified the Earth’s climate since preindustrial times. A modelling study now shows that the impact of land-cover change on regional climate depends critically on how snow cover and rainfall change under increased greenhouse gases.

Global climate models have a well-known bias in the position and strength of the Southern Hemisphere westerly winds. Research reveals that this bias increases carbon uptake by the ocean, reducing atmospheric carbon dioxide concentrations, in climate model simulations—a result that should help constrain uncertainties in climate model projections.

The ‘pathway’ the world needs to follow to limit global temperature rise to 2 °C remains uncertain. Analysis that takes technical and economic constraints on reducing emissions into account indicates that emissions need to peak in the next decade and then fall rapidly to have a good chance of achieving this goal.

Substituting fossil fuels with bioenergy from forests, as well as thinning forests to reduce wildfire emissions, has been proposed as a means of cutting carbon dioxide emissions. A study based on inventory data for US West Coast forests now challenges this proposal, and finds that it could lead to 2–14% higher emissions than current management practices over the next 20 years.

The West Antarctic Peninsula has experienced rapid warming in recent decades. One of the effects has been a loss of the ‘fast-ice’ skin, or frozen layer, that forms on the sea surface each winter and reduces seabed scouring. A study now links increased seabed scouring over the past 25 years to higher benthic mortality, with implications for the region’s biodiversity.

Little information exists to guide conservation planning under climate change uncertainty. Now a study combines ecological predictions with an economic decision framework to investigate strategies to minimize extinction risk in one of the world’s most threatened ecosystems—the South African fynbos. The research finds that the best conservation options vary nonlinearly with available budget.

In some decades, such as 2000–2009, the observed globally averaged surface-temperature time series has shown a flat or slightly negative trend. A modelling study provides evidence that heat uptake by the deep ocean may cause these hiatus periods and may be linked to La Niña-like conditions.

Climate impacts on biodiversity are usually assessed at the morphospecies level. An analysis of the distribution and mitochondrial DNA variability of nine montane aquatic insect species in Europe suggests range contractions will be accompanied by severe loss of genetic diversity. These results imply that morphospecies-scale assessments may greatly underestimate potential biodiversity losses from climate change.