Reviews & Analysis

Climate change has reached the level of a 'scientific consensus', but is not yet a 'social consensus'. New analysis highlights that a growing divide between liberals and conservatives in the American public is a major obstacle to achieving this end.

The causes of the severe drought in the Sahel in the 1970s and 1980s are uncertain. Now a study provides the firmest evidence so far that emissions of aerosols from industrialized countries played a significant role, but other forcings cannot be ruled out yet.

The inability to verify nations' reported progress towards emission-reduction commitments is a stumbling block in climate change negotiations. Narrowing uncertainties in the global carbon cycle could help overcome this obstacle.

A lack of buy-in by the United States arguably represents the greatest obstacle to tackling climate change. A major new report urges America to take action to cut emissions and begin adapting to climate change.

The processes of abstraction, conveyance and treatment of fresh water and wastewater are all energy-intensive processes. This systematic review shows that the growing energy use and greenhouse-gas emissions from the water sector are under-recognized, suggesting the need for energy use to be further quantified and integrated into water resources management.

Climate change is known to affect the carbon balance of Arctic tundra ecosystems by influencing plant growth and decomposition. Less predictable climate-driven biotic events, such as disease outbreaks, are now shown to potentially shift these ecosystems from net carbon sinks to sources.

A tipping point occurs when an external forcing causes a qualitative change in a system. Human-induced climate change could push several large elements of the climate system, such as the Greenland ice sheet, past a tipping point. Given the severity of the potential impacts, early warning of these changes would be advantageous. This Review discusses the most promising approaches to early warning of tipping points.

The production of traded goods accounts for a significant proportion of global greenhouse-gas emissions. Now analysis reveals that emissions embodied in imports from developing countries have out-stripped emission reductions made by developed countries at home over the past 20 years.

Over half of all anthropogenic carbon dioxide emissions into the atmosphere are removed naturally by land and ocean carbon sinks. New analysis indicates that the land sink is increasing in some surprising places.

The roles that microorganisms play in carbon storage are not fully understood. Now modelling results show that the activity of a single group of soil fungi may significantly enhance ecosystem carbon-storage capacity.

The impacts of climate change on human organizations depend not only on the level of emissions but also on the social and economic structures in place. A study identifies three dimensions on which to build a new set of scenarios to assess climate change effects on human systems.

Current policies to reduce emissions from forest loss could mean that rising demand for food is not met. A new approach to forest conservation that reduces emissions while meeting demand for agricultural products may be feasible, but more expensive.

Carbon capture and storage demonstration projects are focused on learning about technologies through conventional 'learning by doing'. Analysis of three case studies indicates that including other types of learning could bring significant rewards.

The timing of seasonal events such as flowering and migration is changing as the climate warms, reshuffling the order in which such events take place each year. Now research sheds light on the causes of changes in the timing of butterfly emergence.

Instrumental records show that El Niño is highly variable in space and time. Now a thousand-year-long record from trees in the southwestern United States reveals even greater extremes, and a possible link between El Niño activity and climate warming.

Comparing changes in temperature and solar radiation on centennial timescales can help to constrain the Sun's impact on climate. New findings regarding the minimum activity level of the Sun reveal that comparisons made so far may have been too simplistic.

Mounting evidence that climate change will impact food security demonstrates the need to adapt food systems to future conditions. New work sheds light on the measures that will be needed to do so, and what the gains of implementing them might be.

Laboratory studies indicate that warming can eventually push cold-blooded organisms past their physiological limits, with detrimental effects on growth. Now evidence from the field indicates that this phenomenon is occurring in the Tasman Sea.