Volume 3 Issue 5, May 2013

At a time of stagnant international climate negotiations, national legislation on climate continues to progress apace. So what can these policy developments deliver?

Europe should take action to prevent contamination of blood products by emerging infectious diseases as the climate warms.

Obama entered his first presidential term promising action on climate change, but the main climate bill disintegrated. What can be done during his second term?

A clear European Union policy on shale gas is yet to emerge and opinions remain sharply divided, explains Sonja van Renssen.

Climate change is amplified in polar regions compared with the rest of the globe. A study now describes how dust particles and other aerosols may contribute to this phenomenon.

The Earth is getting hotter as carbon dioxide, predominantly from the burning of fossil fuels, continues to accumulate in the atmosphere. It is widely recognized that increasing temperatures pose a threat to coral reefs, but just how large a risk are these reefs facing?

Climate change studies rarely yield consensus on the probability distribution of exposure, vulnerability, or possible outcomes, and therefore the evaluation of alternative policy strategies is difficult. This Perspective highlights the importance of decision-making tools designed for situations where generally agreed-upon probability distributions are not available and stakeholders show different degrees of risk tolerance.

The first public engagement study on the acceptability of stratospheric aerosol technology and a proposed field trial of an aerosol deployment mechanism shows that almost all participants were willing to allow the trial to proceed. However, very few were comfortable with using stratospheric aerosols.

Reliable measurements of changes in wetland surface elevation are necessary to understand and predict the probable impact of sea-level rise on vulnerable coastal ecosystems and for science-informed management, adaptation and mitigation. A simple, inexpensive and low-technology device called the 'rod surface elevation table' could be used to monitor threatened coastal wetlands around the world.

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.

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.

Sea-level rise brings the risk of coastal flooding from marine waters. This study looks at how rising sea level will affect groundwater balance, which may also cause coastal plain flooding. Taking groundwater into consideration shows that sea-level rise may cause twice the flooding expected from marine waters alone.

Under global warming, arid subtropical regions are expected to get drier and expand polewards. This study uses model simulations to examine changes in hydrological parameters for the southwestern United States. The predictions for 2021–2040 show declines in surface-water availability, resulting in reduced soil moisture and runoff.

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.

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.

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.

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.

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.

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.