Volume 8 Issue 7, July 2018

The atmospheric concentration of CO₂ at the time of passing 1.5 °C or 2 °C is unknown due to uncertainties in climate sensitivity and the concentrations of other GHGs. Impacts studies must account for a wide range of concentrations to avoid either over- or underestimating changes in crop yields and land and marine biodiversity.

The benefits of limiting global warming to the lower Paris Agreement target of 1.5 °C are substantial with respect to population exposure to heat, and should impel countries to strive towards greater emissions reductions.

In key European cities, stabilizing climate warming at 1.5 °C would decrease extreme heat-related mortality by 15–22% per summer compared with stabilization at 2 °C.

A global effort is underway to restore more than 350 million hectares of deforested and degraded land by bringing together reforestation commitments under the Bonn Challenge. Molly Hawes investigates the benefits and complexities of returning land to forest.

The race against time to mitigate climate change has increasingly focused on the development and deployment of bioenergy with carbon capture and storage. New research shows that negative-emissions hydrogen production is potentially a cost-effective alternative.

Floods are one of the most devastating disasters and their intensity and severity is expected to increase in the future. New research shows how regional floods can cause global impacts through propagation within the global trade and supply network.

Plant transpiration is the largest continental water flux. Research now shows that climate and water availability projections are highly sensitive to the ways that plant responses to changing atmospheric conditions are represented.

Action needs to be taken to limit the impacts of climate change, however, human rights and the right to development need to be preserved. This Perspective weighs the risks of action and inaction on achieving a just transition to a low-carbon world.

This Perspective provides a comparative analysis of how well six cities and regions with different coastal and social characteristics and adaptation constraints will be able to adapt to sea-level rise, considering technological, economic, financial, and social factors.

A press–pulse framework is used to understand the interactive ecological effects of gradual climate trends and extreme weather events. Australian case studies include population collapses, loss of relictual communities and novel ecosystems.

New fossil fuel investments may become stranded if demand for fossil fuel declines due to technological change. This could amount to a discounted global wealth loss of US$1–4 trillion, with the negative impact for producer countries amplified by climate mitigation policies of consumer countries.

Economic losses due to river floods are expected to increase globally in the next 20 years. Direct local losses and indirect losses propagated through a global supply network are derived.

Projections of Arctic sea-ice loss vary significantly between global circulation models. Analysis of the CMIP5 ensemble reveals that these differences can be related to background ice thickness and corresponding growth/melt processes, and not variations in the sea-ice model used.

A 1.5 °C temperature target can have varying atmospheric CO₂ concentrations associated with it. GCM simulations reveal CO₂ increases have a direct impact on climate extremes, highlighting the need for climate policy to complement temperature goals with CO₂ targets.

A reasonable interpretation of the Paris Agreement may well still be technically achievable without the need for net negative emissions or excessively stringent policies according to climate–carbon-cycle modelling.

This study shows that relationships between climate scepticism and indices of conspirational and conservative ideology are stronger and more consistent in the United States than in 24 other nations, with the majority of nations showing weak relationships.

Combining saline water electrolysis with mineral weathering powered by non-fossil electricity could produce low-cost, negative-CO₂-emissions energy.

Residual CO₂ emissions from fossil fuels limit the likelihood of meeting the goals of the Paris Agreement. A sector-level assessment of residual emissions using an ensemble of IAMs indicates that 640–950 GtCO₂ removal will be required to constrain warming to 1.5 °C.

The northern Barents Sea has warmed rapidly in recent decades. Hydrographic observations suggest increases in ocean temperature—particularly after the mid-2000s—can be linked to reduced sea-ice import, freshwater loss, weakened stratification and increased upward heat fluxes from the deep Atlantic layer.

The ratio of plant transpiration to total terrestrial evapotranspiration (T/ET) captures the role of vegetation in surface–atmosphere interactions. An emergent constraint approach strongly increases existing model T/ET estimates with implications for river flows.