Research articles

Has the frequency of ‘extreme weather events’ changed with climate warming over the last century? Using hourly precipitation records from thirteen sites, this study finds no evidence for significant changes in mean ‘storminess’ across the United States.

Estimating the probable magnitude of future sea-level rise under global warming is complicated by a limited understanding of long-term ice-sheet dynamics. This study presents a probabilistic approach for assessing upper bounds on twenty-first-century Antarctic ice-sheet loss, and its effect on sea level.

Pronounced increases in winter temperature result in lower seasonal temperature differences, with implications for vegetation seasonality and productivity. Research now indicates that temperature and vegetation seasonality in northern ecosystems have diminished to an extent equivalent to a southerly shift of 4°– 7° in latitude, and may reach the equivalent of up to 20° over the twenty-first century.

The Walker circulation is a large overturning cell that spans the tropical Pacific Ocean. Fluctuations in this circulation reflect changes in tropical heating, and have global impacts on temperature and precipitation. Analysis of trends in sea-level pressure from ten data sets reveals strengthening of the Walker circulation in line with increasing global temperature, which is counter to current model predictions.

Biomaterial function depends on biological, chemical and environmental factors during formation and subsequent use. Ocean acidification has been shown to affect secreted calcium carbonate, but effects on other biomaterials are less well known. Research now reveals that proteinaceous byssal threads—used to anchor mytilid mussels to hard substrates—exhibited reduced mechanical performance when secreted under elevated $p_{{\text{CO}}_2}$ conditions.

Current thinking on the causes of anthropogenic radiative forcing in the lower atmosphere is misleading. This study finds tropospheric ozone-precursor emissions have contributed more to positive forcing, and halocarbons more to negative forcing, than previously thought.

Climate change has the potential to disrupt marine habitats and food webs. Targeted multidisciplinary research reveals how this is likely to affect the contributions of fisheries and aquaculture to the food security and economies of Pacific islands.

Statistical analysis of maize yields in the United States reveals a strong negative response to very high temperatures, and a relatively weak response to seasonal rainfall. Now simulations using a process-based model suggest that the most important effects of extreme heat are associated with increased vapour-pressure deficit—which contributes to water stress—rather than direct heat stress on reproductive organs.

The influence of relatively slow changes in sea surface temperature on regional climate variability can provide a basis for medium-term (seasonal to decadal) prediction of many environmental factors. Research now shows that the sea surface temperature in the tropical South Atlantic can act as a dominant driver of rainfall variability, and hence outbreaks of malaria in northwest India.

Individual labour capacity has reduced to 90% in peak months owing to environmental heat stress over the past few decades. Under the highest climate change scenario considered, model projections indicate a reduction in labour capacity to less than 40% by 2200 in peak months, with most tropical and mid-latitude regions experiencing extreme heat stress.

As the Earth continues to warm over the coming decades, spatially extensive or ‘mass’ coral bleaching events—induced by persistently high water temperature—are expected to threaten the survival of coral reef ecosystems. Bleaching ‘hazard’ maps based on ensembles of the latest climate models and emissions pathways quantify the potential for mitigation activities to buy these ecosystems a temporary respite from this threat.

A study that couples a barrier-island model with an agent-based model of real-estate markets shows that, relative to people with little belief in model predictions on climate change, informed property owners invest heavily in defensive measures in the short term. They then abandon coastal real estate when price volatility becomes significant.

There is a widespread assumption that changes in reported anthropogenic global CO₂ emissions are indicative of changes in climate and ocean chemistry. However, examination of atmospheric CO₂ measurements from the past two decades challenges this idea. A new study develops and advocates use of CO₂ measurement practices that reduce uncertainty in atmospheric verification of emissions, and identifies modelling inadequacies.

Seamless quantification of past and present climate variability is needed to understand the Earth’s climate well enough to make accurate predictions for the future. This study addresses whether tree-ring-dominated proxy data properly represent the frequency spectrum of true climate variability. The results challenge the validity of detection and attribution investigations based on these data.

Research shows that incorporating energy consumption in a global climate model can explain past surface temperature changes of as much as 1 K in mid and high latitudes in winter and autumn over most part of North America and Eurasia. This study concludes that energy use should be considered as an additional forcing in simulations to project future climate change.

Soils are the largest repository of organic carbon in the terrestrial biosphere. Nevertheless, relatively little is known about the factors controlling the efficiency with which microbial communities utilize carbon, and its effect on soil–atmosphere CO₂ exchange. Now research using long-term experimental plots suggests that climate warming could alter the decay dynamics of more stable organic-matter compounds with implications for carbon storage in soils and ultimately climate warming.

Changing wind-wave climate has the potential to exacerbate, or negate, the impacts of sea-level rise in coastal zones. Results from the first community-derived multi-model ensemble of wind-wave climate projections show agreement over extended regions of the global ocean. Large uncertainty in available wave-climate projections is found to be due to downscaling methods.

Climate mitigation policies are rarely assessed in terms of the proportion of climate impacts they can avoid both regionally and globally. Research shows that policies with a 50% chance of remaining below a 2 °C rise in temperature may reduce the impacts of climate change by 20–65% by 2100, relative to pathways with a temperature rise of 4 °C.

Many plant species used for biofuel emit more isoprene—an ozone precursor—than the traditional crops they are replacing. A modelling study now indicates the potential for significant human mortality and crop losses due to changes in ground-level ozone concentrations that could arise from large-scale biofuel cultivation in Europe. These findings suggest that biofuel policies could have adverse consequences that should be evaluated alongside carbon-budgeting considerations before large-scale policies are implemented.

Climate models struggle to reproduce the amplitude of polar temperature change observed in palaeoclimatic archives. A synthesis of observational and model data was used to reconstruct atmospheric dust concentrations in the Holocene and Last Glacial Maximum. The impact of aerosols in polar areas is underestimated in simulations for dustier-than-modern conditions; the inclusion of the amplified response to aerosols at high latitudes would improve model predictions.