Research articles

Urban climate policies interact with socio–economic policy goals. These interactions can lead to trade-offs or synergies, but have been rarely analysed. Now research provides a quantification of these trade-offs and synergies, and suggests that stand-alone adaptation and mitigation policies are unlikely to be politically acceptable, emphasizing the need to mainstream climate policy within urban planning.

This study documents the effects of warming on cyanobacterial mats from the Arctic and Antarctica. It describes toxin production in such mats and provides experimental evidence that increased temperatures could shift mat cyanobacterial species diversity from cold-loving species towards predominance of cold-tolerant and toxin-producing species.

Trends in phenological phases associated with climate change are widely reported, yet attribution remains rare. Attribution analysis of trends in wine-grape maturity in Australia indicates that two climate variables—warming and declines in soil water content—are driving a major portion of the earlier-ripening trend. Crop-yield reductions and evolving management practices have also contributed.

This modelling study shows that chemical weathering of continental surfaces—which removes carbon dioxide from the atmosphere—is highly sensitive to a carbon dioxide doubling for the Mackenzie River Basin, the most important Arctic watershed. The findings highlight the potential role of chemical weathering processes in mitigating global warming.

There are concerns that sea-level rise resulting from climate change could lead to saltwater intrusion into coastal aquifers. However, a study shows that groundwater extraction is the main driver of saltwater intrusion in the United States, highlighting the importance of sustainable water management.

A comparison of specimens collected from the same locations but nearly a century apart shows that an alpine chipmunk has suffered reduced genetic diversity and gene flow as a result of climate-driven habitat loss in Yosemite National Park, USA. This study highlights one important impact of climate change on biodiversity

There has been concern that climate change may cause increases in harmful algal blooms (HABs). Research now shows that previously abundant HAB and non-HAB dinoflagellates have decreased since 2006, whereas common diatoms, including both HAB and non-HAB species, have recently increased in abundance.

It is unclear how global warming will affect the El Niño/Southern Oscillation (ENSO), in part because the instrumental record is too short to understand how ENSO has changed in the past. Now a 700-year-long tree-ring record indicates that ENSO-related climate variability may increase in New Zealand with continued warming.

A study shows that regional atmospheric change driven by land-cover change contributes little to glacier mass loss on Tanzania’s Mount Kilimanjaro. More generally, this finding suggests that local land-cover change may have limited impact on mountain glaciers in the tropics and elsewhere, compared with that of global climate change.

Reducing Emissions from Deforestation and forest Degradation (REDD) has been widely discussed as a way of mitigating climate change while concurrently benefitting biodiversity. This study combines a global land-use model and spatial data on species distributions to quantify the potential impacts of REDD in avoiding global species extinctions.

Models and scenarios on which climate projection are based vary between IPCC reports. To facilitate meaningful comparison, this study provides probabilistic climate projections for different scenarios in a single consistent framework, incorporating the overall consensus understanding of the uncertainty in climate sensitivity, and constrained by the observed historical warming.

Deforestation contributes 6–17% of anthropogenic carbon dioxide emissions. However, much uncertainty in the calculation of deforestation emissions stems from the inadequacy of forest carbon-density and deforestation data. Now an analysis provides the most-detailed estimate so far of the carbon density of vegetation and the associated carbon dioxide emissions from deforestation for ecosystems across the tropics.

One difficulty in anticipating the effects of climate change on agriculture is accounting for crop responses to extremely high temperatures. Now a remote-sensing study demonstrates accelerated ageing of wheat in northern India in response to extreme heat (>34 °C); an effect that reduces crop yields but is underestimated in most crop models.

A study shows that soil food webs directly help mitigate the effects of drought on soil nutrients. The fungal-based food webs of grassland were more resistant to bouts of drought than the bacterial-based food webs of intensively managed wheat, and retained more carbon and nitrogen in the soil.

An analysis indicates that the warm, powerful currents that flow along the western edges of ocean basins warmed more than twice as quickly than the global ocean as a whole over the past century. This enhanced warming could have important effects on climate because these currents affect the air–sea exchange of heat, moisture and carbon dioxide.

A study advocates the efficient production of cellulosic biofuel using waste nitrogen through wastewater treatment with constructed wetlands in China. The analysis suggests that the net life-cycle energy output of constructed wetlands is higher than many other biofuel production systems.

Increasing carbon dioxide emissions since the beginning of the industrial revolution have caused widespread ocean acidification and concomitant changes in ocean chemistry, with potential ramifications for major marine ecosystems. A study shows that recent trends in ocean acidification are detectable against natural variability with virtual certainty, even on regional scales.

Quality of life improves with economic growth and hence requires increasing greenhouse-gas emissions. Little is known, however, about the role of international trade. Now research shows that most socio-economic benefits are actually accruing to carbon-importing countries. It also finds that high life expectancy is compatible with low carbon emissions, but high incomes are not.

Deflection of sunlight could compensate for the warming induced by increased greenhouse gases. However, the effects of such geoengineering on food security are highly uncertain. Now research using high-carbon-dioxide, geoengineering and control climate simulations suggests that solar-radiation management in a high-carbon-dioxide world generally causes crop yields to increase.

Previous research has examined temperature-related excess deaths or mortality risks. A study now uses years of life lost to provide a new measure of the impact of temperature on mortality, and finds an increase in the years of life lost for cold and hot temperatures. The loss will greatly increase further if future temperature rise goes beyond 2 °C above pre-industrial levels.