Massive slums have become major features of cities in many low-income and middle-income countries. Here, in the first in a Series of two papers, we discuss why slums are unhealthy places with especially high risks of infection and injury. We show that children are especially vulnerable, and that the combination of malnutrition and recurrent diarrhoea leads to stunted growth and longer-term effects on cognitive development. We find that the scientific literature on slum health is underdeveloped in comparison to urban health, and poverty and health. This shortcoming is important because health is affected by factors arising from the shared physical and social environment, which have effects beyond those of poverty alone. In the second paper we will consider what can be done to improve health and make recommendations for the development of slum health as a field of study.

This paper discusses the influences on food and farming of an increasingly urbanized world and a declining ratio of food producers to food consumers. Urbanization has been underpinned by the rapid growth in the world economy and in the proportion of gross world product and of workers in industrial and service enterprises. Globally, agriculture has met the demands from this rapidly growing urban population, including food that is more energy-, land-, water- and greenhouse gas emission-intensive. But hundreds of millions of urban dwellers suffer under-nutrition. So the key issues with regard to agriculture and urbanization are whether the growing and changing demands for agricultural products from growing urban populations can be sustained while at the same time underpinning agricultural prosperity and reducing rural and urban poverty. To this are added the need to reduce greenhouse gas emissions and to build resilience in agriculture and urban development to climate change impacts. The paper gives particular attention to low- and middle-income nations since these have more than three-quarters of the world's urban population and most of its largest cities and these include nations where issues of food security are most pressing.

This paper suggests that the contribution of cities to global anthropogenic greenhouse gas emissions is often overstated. Many sources suggest that cities are responsible for 75-80 per cent of all such emissions. But as statistics drawn from the IPCC's Fourth Assessment show, this considerably understates the contributions from agriculture and deforestation and from heavy industries, fossilfuelled power stations and high-consumption households that are not located in cities. It is likely that, worldwide, less than half of all anthropogenic greenhouse gas emissions are generated within city boundaries. However, if greenhouse gas emissions from power stations and industries are assigned to the location of the person or institution who consumes them (rather than where they are produced), cities would account for a higher proportion of total emissions. But it would be misleading to attribute this to "cities" in general, since these emissions would be heavily concentrated in cities in high-income nations and they should be ascribed to the individuals and institutions whose consumption generates them, not to the places where they are located.

This paper highlights the major challenges and considerations for addressing COVID-19 in informal settlements. It discusses what is known about vulnerabilities and how to support local protective action. There is heightened concern about informal urban settlements because of the combination of population density and inadequate access to water and sanitation, which makes standard advice about social distancing and washing hands implausible. There are further challenges to do with the lack of reliable data and the social, political and economic contexts in each setting that will influence vulnerability and possibilities for action. The potential health impacts of COVID-19 are immense in informal settlements, but if control measures are poorly executed these could also have severe negative impacts. Public health interventions must be balanced with social and economic interventions, especially in relation to the informal economy upon which many poor urban residents depend. Local residents, leaders and community-based groups must be engaged and resourced to develop locally appropriate control strategies, in partnership with local governments and authorities. Historically, informal settlements and their residents have been stigmatized, blamed, and subjected to rules and regulations that are unaffordable or unfeasible to adhere to. Responses to COVID-19 should not repeat these mistakes. Priorities for enabling effective control measures include: collaborating with local residents who have unsurpassed knowledge of relevant spatial and social infrastructures, strengthening coordination with local governments, and investing in improved data for monitoring the response in informal settlements.

The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription.

This paper outlines a framework for assessing the environmental performance of cities in regard to the meeting of sustainable development goals. It also considers how the environmental goals fit with the social, economic and political goals of sustainable development and the kinds of national framework and international context needed to encourage city-based consumers, enterprises and governments to progress towards their achievement. In a final section, it considers the extent to which the recommendations of the Habitat II Conference helped to encourage national governments and city and municipal authorities in this direction.

This paper considers the implications of population growth and urbanization for climate change. It emphasizes that it is not the growth in (urban or rural) populations that drives the growth in greenhouse gas (GHG) emissions but rather, the growth in consumers and in their levels of consumption. A signifi cant proportion of the world's urban (and rural) populations have consumption levels that are so low that they contribute little or nothing to such emissions. If the lifetime contribution to GHG emissions of a person added to the world's population varies by a factor of more than 1,000 depending on the circumstances into which they are born and their life choices, it is misleading to see population growth as the driver of climate change. A review of carbon dioxide (CO 2 ) emissions levels for nations, and how they changed between 1980 and 2005 (and also between 1950 and 1980), shows little association between nations with rapid population growth and nations with high GHG emissions and rapid GHG emissions growth; indeed, it is mostly nations with very low emissions per person (and often only slowly growing emissions) that have had the highest population growth rates. The paper also discusses how in the much-needed planning for global emissions reduction, provision must be made to allow low-income, low-consumption households with GHG emissions per person below the global "fair share" level to increase their consumption.

Approximately 1 billion people currently live in informal settlements, primarily in urban areas in low-and middle-income countries. Informal settlements are defined by poor-quality houses or shacks built outside formal laws and regulations. Most informal settlements lack piped water or adequate provision for sanitation, drainage, and public services. Many are on dangerous sites because their inhabitants have a higher chance of avoiding eviction. This paper considers how to build resilience to the impacts of climate change in informal settlements. It focuses on informal settlements in cities in low-and middle-income countries and how these concentrate at-risk populations. This paper also reviews what is being done to address climate resilience in informal settlements. In particular, community-and city-government-led measures to upgrade settlements can enhance resilience to climate-change risks and serve vulnerable groups. It also discusses how the barriers to greater scale and effectiveness can be overcome, including with synergies with the Sustainable Development Goals. Rapid Urbanization and Growth of Informal SettlementsThe current urban population is approximately 4.4 billion people globally. About 3.4 billion people currently live in urban centers in what the United Nations (UN) terms ''less developed regions.'' 1 UN projections suggest that urban population growth in ''less developed regions'' will be over 2 billion people by 2050 and that close to 90% of this increase will be in Asia and Africa. This means that another 2 billion urban dwellers will require housing, basic services, and resilience to climate-change impacts. 1 At present, approximately 1 billion urban dwellers live in what are termed informal settlements in poor-quality houses or shacks. 2 Informal settlements fall outside formal laws and regulations on land ownership, land use, and buildings. Their illegality makes government agencies unable or unwilling to work with them. These are settlements to which city governments have not extended what the UN Intergovernmental Panel on Climate Change (IPCC) terms risk-reducing infrastructure (paved roads, storm and surface drainage, piped water, etc.) and services relevant to resilience (including healthcare, emergency services, and rules of law). 2 Many informal settlements are ill prepared for climate change and face particularly high risks of floods and landslides as a result of poor-quality buildings and a lack of infrastructure to prevent flooding, withstand heavy storms, and cope with heat waves. 2 In the absence of more effective policies, most of the world's growth in urban population will be accommodated in informal settlements. Given the projected rates and regions of urban population growth by 2050, there is an urgent need to build resilience to climate change in these settlements and to do so at scale. There is also an urgent need to vastly expand the supply and reduce the cost of ''formal'' (i.e., legal) housing that provides low-income groups with safer and more accessible alternatives to...