Volume 8 Issue 5, May 2018

Ambition regarding climate change at the national level is critical but is often calibrated with the projected costs — as estimated by a small suite of energy–economic models. Weaknesses in several key areas in these models will continue to distort policy design unless collectively addressed by a diversity of researchers.

Sometimes policymakers have backed the wrong technologies, lacked ambition or simply not engaged with potential emissions reductions. Sonja van Renssen explores climate policies that have not delivered and why.

There is large geographic variation in the public's views about climate change in the United States. Research now shows that climate messages can influence public beliefs about the scientific consensus on climate change, particularly in the places that are initially more skeptical.

For integrated climate change research, the Scenario Matrix Architecture provides a tractable menu of possible emissions trajectories, socio-economic futures and policy environments. However, the future of decision support may lie in searchable databases.

In the Paris Agreement, nations committed to a more ambitious climate policy target, aiming to limit global warming to 1.5 °C rather than 2 °C above pre-industrial levels. Climate models now show that achieving the 1.5 °C goal would make a big difference for Arctic sea ice.

Low soil moisture conditions can induce drought but also elevate temperatures. Detailed modelling of the drought–temperature link now shows that rising global temperature will bring drier soils and higher heatwave temperatures in Europe.

The African continent is one of the most vulnerable regions to future climate change. Research now demonstrates that constraining anthropogenic warming to 1.5 °C instead of 2 °C will significantly lower the risk of heatwaves to inhabitants.

Deforestation often increases land-surface and near-surface temperatures, but climate models struggle to simulate this effect. Research now shows that deforestation has increased the severity of extreme heat in temperate regions of North America and Europe. This points to opportunities to mitigate extreme heat.

Geographic variation in social, economic, political and climatic factors may influence public responsiveness to climate change messaging. This study shows that messages about scientific consensus have a greater influence in more conservative US states.

The record hot year of 2015 in Africa had devastating impacts. The likelihood of future annual temperature extremes over Africa exceeding those of 2015 are 91% and 100% in 1.5 °C and 2 °C worlds, respectively, stressing the benefits of limiting future anthropogenic warming.

The 2010 Russia heatwave had devastating impacts, including loss of life, wildfire and drought. Model simulations reveal similar heatwaves may be amplified by up to 8 °C in the future as soil moisture becomes less able to suppress maximum temperatures.

Deforestation in the northern mid-latitudes has generally been considered to cause biogeophysical changes that drive mean annual cooling in the region. Research now suggests that historical deforestation has led to substantial local warming of hot days.

Scenarios that constrain warming to 1.5 °C currently place a large emphasis on CO₂ removal. Alternative pathways involving lifestyle change, rapid electrification and reduction of non-CO₂ gases could reduce the need for such negative emission technologies.

The co-benefits of carbon pricing in China are investigated by a cross-scale modelling approach. The health benefits from reduced emissions and improved air quality could offset the climate policy costs.

Nations are currently pursuing efforts to constrain anthropogenic warming to 1.5 °C. In such a world, model projections suggest the Arctic will be ice-free every one in forty years, compared to one in every five under stabilized 2 °C warming.

Arctic sea ice cover has declined significantly in recent years. Model simulations suggest the probability of an ice-free Arctic will be 100% under 2 °C, but 30% under 1.5 °C, motivating efforts to constrain anthropogenic warming.

Heat waves have become increasingly frequent in the United States, but their occurrence is largely linked to natural variability. Model simulations reveal anthropogenically forced signals will first emerge in the western United States and Great Lakes regions by ~2030.

Severe drought plagued Europe in 2003, amplifying heatwave conditions that killed more than 30,000 people. Assuming business as usual, such soil moisture deficits will become twice as frequent in the future and affect up to two-thirds of the European population.

California recently experienced a rapid shift from multi-year drought to abundant rainfall. A large ensemble of climate model simulations suggests that the frequency of extreme wet-to-dry precipitation events will increase by 25% to 100% across California due to anthropogenic forcing.

Increasing zonal asymmetry in tropical precipitation is projected by 2100, with increases over Asian and African forests and decreases over South American forests. Plant physiological responses to increasing CO₂ are now identified as a primary driving mechanism.