This comprehensive review appraises the state-of-the-art in direct air capture materials, processes, economics, sustainability, and policy, to inform, challenge and inspire a broad audience of researchers, practitioners, and policymakers.

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Does democratization help countries mitigate climate change? On the one hand, by increasing the value placed on quality of life, creating more opportunity for environmental actors to influence policymaking and holding elected politicians accountable, an increase in democratic institution and process should promote emissions reduction. On the other hand, the desire to safeguard individual freedom presumably brings with it an aversion to intervene in lifestyle and market decisions, thereby raising the risk of climate inaction. This outcome is further encouraged by the political need to balance (conflicting) environmental and energy interests.This article evaluates the thesis that democratization promotes mitigation in light of national emissions levels from 1990 to 2012. Using data from the Freedom House, Polity IV and V-Dem indices, World Bank World Development Indicators and the World Resources Institute Climate Data Explorer it conducts a large-N investigation of the emissions levels of 147 countries. Although several quantitative studies have found that domestic political regimes affect emissions levels, this article goes beyond existing research by building a more sophisticatedmultilevel-research design to determine whether democracy: (a) continues to be an important driver of emissions when country-level clustering is accounted for and (b) has uniform effects across countries. The results indicate that, even after controlling for country-level clustering and holding constant the other confounding factors, democracy is indeed a significant driver. More strikingly, they reveal that while democracies tend to have lower emissions than non-democracies, democratization spells within the same country do not have the same kind of inhibitory effects as they do between countries. This article also finds tentative evidence that the type of electoral system plays a critical role in shaping the effect of democratization on individual countries. Key policy insights. Democracies tend to perform better in terms of emission levels than nondemocracies. . Democratization has non-uniform effects across different countries, with the type of electoral system playing a key role in determining the effect that democratization has on national emissions. . Further research is needed to develop our understanding of how the political context influences emissions, especially with regard to the influence of pro and anti-decarbonisation actors.ARTICLE HISTORY

The analysis of ideology at the vernacular level requires access to peer-to-peer political discussions amongst non-specialists. It is in these discursive exchanges that political views are articulated, refined, and revised. Such exchanges are, however, difficult for the researcher to capture. Here we take c.25,000 learner comments (along with several hundred image uploads) from a Massive Open Online Course, run in conjunction between the University of Nottingham and the British Library, as a source of such peer-to-peer political discussions. Learners discussed five topics, of which we have selected 'Freedom', 'Justice', and 'Community' for close analysis. We find that the idea of 'freedom' generated by far the most learner discourse, and in both the comments and image uploads this concept was both positively appraised and highly personalised. 'Justice' was generally seen as something to be delivered by political institutions, although accounts of injustice were frequently appraised through either personal experience or the experiences of others. Accounts of 'community' often focused on the trappings of nationhood, but some comments, and many images in particular, highlighted moments of ephemeral and more personal, self-chosen communities such as music concerts or hobbyist conventions. Overall, both comments and images show that, in their interpretation of the conceptual vocabulary of politics, people frequently frame their understanding through personal experience in a very direct manner. It is not only true that the 'personal is political', but also, for many, that the 'political is personal'.

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