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Showing papers by "International Institute for Applied Systems Analysis published in 2010"


Journal ArticleDOI
11 Feb 2010-Nature
TL;DR: A new process for creating plausible scenarios to investigate some of the most challenging and important questions about climate change confronting the global community is described.
Abstract: Advances in the science and observation of climate change are providing a clearer understanding of the inherent variability of Earth's climate system and its likely response to human and natural influences. The implications of climate change for the environment and society will depend not only on the response of the Earth system to changes in radiative forcings, but also on how humankind responds through changes in technology, economies, lifestyle and policy. Extensive uncertainties exist in future forcings of and responses to climate change, necessitating the use of scenarios of the future to explore the potential consequences of different response options. To date, such scenarios have not adequately examined crucial possibilities, such as climate change mitigation and adaptation, and have relied on research processes that slowed the exchange of information among physical, biological and social scientists. Here we describe a new process for creating plausible scenarios to investigate some of the most challenging and important questions about climate change confronting the global community.

5,670 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a new dataset of gridded emissions covering the historical period (1850-2000) in decadal increments at a horizontal resolution of 0.5° in latitude and longitude.
Abstract: We present and discuss a new dataset of gridded emissions covering the historical period (1850–2000) in decadal increments at a horizontal resolution of 0.5° in latitude and longitude. The primary purpose of this inventory is to provide consistent gridded emissions of reactive gases and aerosols for use in chemistry model simulations needed by climate models for the Climate Model Intercomparison Program #5 (CMIP5) in support of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). Our best estimate for the year 2000 inventory represents a combination of existing regional and global inventories to capture the best information available at this point; 40 regions and 12 sectors are used to combine the various sources. The historical reconstruction of each emitted compound, for each region and sector, is then forced to agree with our 2000 estimate, ensuring continuity between past and 2000 emissions. Simulations from two chemistry-climate models is used to test the ability of the emission dataset described here to capture long-term changes in atmospheric ozone, carbon monoxide and aerosol distributions. The simulated long-term change in the Northern mid-latitudes surface and mid-troposphere ozone is not quite as rapid as observed. However, stations outside this latitude band show much better agreement in both present-day and long-term trend. The model simulations indicate that the concentration of carbon monoxide is underestimated at the Mace Head station; however, the long-term trend over the limited observational period seems to be reasonably well captured. The simulated sulfate and black carbon deposition over Greenland is in very good agreement with the ice-core observations spanning the simulation period. Finally, aerosol optical depth and additional aerosol diagnostics are shown to be in good agreement with previously published estimates and observations.

1,953 citations


Journal ArticleDOI
TL;DR: Results indicated there were significant cross-regional differences in the ideal female figure and body dissatisfaction, but effect sizes were small across high-socioeconomic-status (SES) sites.
Abstract: This study reports results from the first International Body Project (IBP-I), which surveyed 7,434 individuals in 10 major world regions about body weight ideals and body dissatisfaction. Participants completed the female Contour Drawing Figure Rating Scale (CDFRS) and self-reported their exposure to Western and local media. Results indicated there were significant cross-regional differences in the ideal female figure and body dissatisfaction, but effect sizes were small across high-socioeconomic-status (SES) sites. Within cultures, heavier bodies were preferred in low-SES sites compared to high-SES sites in Malaysia and South Africa (ds = 1.94-2.49) but not in Austria. Participant age, body mass index (BMI), and Western media exposure predicted body weight ideals. BMI and Western media exposure predicted body dissatisfaction among women. Our results show that body dissatisfaction and desire for thinness is commonplace in high-SES settings across world regions, highlighting the need for international attention to this problem.

584 citations


Journal ArticleDOI
12 Aug 2010-Nature
TL;DR: Neither other-regarding tendencies or preferences for reciprocity and equity, nor group selection or prescriptions from higher authorities, are necessary for the emergence and stability of rudimentary forms of sanctioning institutions regulating common pool resources and enforcing collaborative efforts.
Abstract: Cooperation in evolutionary games can be stabilized through punishment of non-cooperators, at a cost to those who do the punishing. Punishment can take different forms, in particular peer-punishment, in which individuals punish free-riders after the event, and pool-punishment, in which a fund for sanctioning is set up beforehand. These authors show that pool-punishment is superior to peer-punishment in dealing with second-order free-riders, who cooperate in the main game but refuse to contribute to punishment. Cooperation in evolutionary games can be stabilized by the punishment of non-cooperators, at a cost to those doing the punishing. It can take various forms, including peer punishment, where individuals punish free-riders after the event, and pool punishment, where a fund for sanctioning is set up beforehand. The former can be summed up as 'taking the law into your own hands', the latter as having police to do the job. Using a computational model, Sigmund et al. show that pool punishment has the edge over peer punishment in dealing with second-order free-riders — those who cooperate in the main game but refuse to contribute to punishment. The model shows that individuals can spontaneously adopt a self-governing institution to monitor contributions and sanction free-riders. It needs no top-down prescriptions or planning. Trial and error, and the imitation of successful examples, suffice to produce a social contract between individuals guided by self-interest. Theoretical and empirical research highlights the role of punishment in promoting collaborative efforts1,2,3,4,5. However, both the emergence and the stability of costly punishment are problematic issues. It is not clear how punishers can invade a society of defectors by social learning or natural selection, or how second-order free-riders (who contribute to the joint effort but not to the sanctions) can be prevented from drifting into a coercion-based regime and subverting cooperation. Here we compare the prevailing model of peer-punishment6,7,8 with pool-punishment, which consists in committing resources, before the collaborative effort, to prepare sanctions against free-riders. Pool-punishment facilitates the sanctioning of second-order free-riders, because these are exposed even if everyone contributes to the common good. In the absence of such second-order punishment, peer-punishers do better than pool-punishers; but with second-order punishment, the situation is reversed. Efficiency is traded for stability. Neither other-regarding tendencies or preferences for reciprocity and equity, nor group selection or prescriptions from higher authorities, are necessary for the emergence and stability of rudimentary forms of sanctioning institutions regulating common pool resources and enforcing collaborative efforts.

504 citations


Journal ArticleDOI
TL;DR: The paper provides a detailed discussion of different relevant dimensions in population projections and an evaluation of the methods and assumptions used in current global population projections, in particular those produced by the United Nations and by IIASA.
Abstract: The total size of the world population is likely to increase from its current 7 billion to 8–10 billion by 2050. This uncertainty is because of unknown future fertility and mortality trends in different parts of the world. But the young age structure of the population and the fact that in much of Africa and Western Asia, fertility is still very high makes an increase by at least one more billion almost certain. Virtually, all the increase will happen in the developing world. For the second half of the century, population stabilization and the onset of a decline are likely. In addition to the future size of the population, its distribution by age, sex, level of educational attainment and place of residence are of specific importance for studying future food security. The paper provides a detailed discussion of different relevant dimensions in population projections and an evaluation of the methods and assumptions used in current global population projections and in particular those produced by the United Nations and by IIASA.

330 citations


Journal ArticleDOI
TL;DR: This paper reviewed the history and economics of the French PWR program and revealed for the first time both absolute as well as yearly and specific reactor costs and their evolution over time, concluding that even the most successful nuclear scale-up was characterized by a substantial escalation of real-term construction costs.

312 citations


Journal ArticleDOI
TL;DR: In this paper, a food first paradigm was applied in the estimations of land potentially available for the production of biofuel feedstocks, without putting at risk food supply or nature conservation.
Abstract: Europe's agricultural land (including Ukraine) comprise of 164 million hectares of cultivated land and 76 million hectares of permanent pasture. A "food first" paradigm was applied in the estimations of land potentially available for the production of biofuel feedstocks, without putting at risk food supply or nature conservation. Three land conversion scenarios were formulated: (i) A base scenario, that reflects developments under current policy settings and respects current trends in nature conservation and organic farming practices, by assuming moderate overall yield increases; (ii) an environment oriented scenario with higher emphasis on sustainable farming practices and maintenance of biodiversity; and (iii) an energy oriented scenario considering more substantial land use conversions including the use of pasture land. By 2030 some 44-53 million hectares of cultivated land could be used for bioenergy feed-stock production. The energy oriented scenario includes an extra 19 million hectares pasture land for feedstocks for second-generation biofuel production chains. Available land is foremost to be found in Eastern Europe, where substantial cultivated areas can be freed up through sustainable gains in yield in the food and feed sector. Agricultural residues of food and feed crops may provide an additional source for biofuel production. When assuming that up to 50% of crop residues can be used without risks for agricultural sustainability, we estimate that up to 246 Mt agricultural residues could be available for biofuel production, comparable to feedstock plantations of some 15-20 million hectares.

297 citations


Journal ArticleDOI
TL;DR: This article used three global energy system models to investigate the technological and economic attainability of meeting CO2 concentration targets below current levels and showed that negative emission technologies (e.g., biomass energy with carbon capture and storage) significantly enhances the possibility to meet low concentration targets (at around 350 ppm CO2).
Abstract: The United Nations Framework Convention on Climate Change (UNFCCC 1992) calls for stabilization of atmospheric greenhouse gas (GHG) concentrations at a level that would prevent dangerous anthropogenic interference with the climate system. We use three global energy system models to investigate the technological and economic attainability of meeting CO2 concentration targets below current levels. Our scenario studies reveal that while energy portfolios from a broad range of energy technologies are needed to attain low concentrations, negative emission technologies-e.g., biomass energy with carbon capture and storage (BECCS)-significantly enhances the possibility to meet low concentration targets (at around 350 ppm CO2).

288 citations


Journal ArticleDOI
TL;DR: A number of existing and potential approaches for terrorism risk analysis are explored, focusing particularly on recent discussions regarding the applicability of probabilistic and decision analytic approaches to bioterrorism risks and the Bioterrorism Risk Assessment methodology used by the DHS and criticized by the National Academies and others.
Abstract: Since the terrorist attacks of September 11, 2001, and the subsequent establishment of the U.S. Department of Homeland Security (DHS), considerable efforts have been made to estimate the risks of terrorism and the cost effectiveness of security policies to reduce these risks. DHS, industry, and the academic risk analysis communities have all invested heavily in the development of tools and approaches that can assist decisionmakers in effectively allocating limited resources across the vast array of potential investments that could mitigate risks from terrorism and other threats to the homeland. Decisionmakers demand models, analyses, and decision support that are useful for this task and based on the state of the art. Since terrorism risk analysis is new, no single method is likely to meet this challenge. In this article we explore a number of existing and potential approaches for terrorism risk analysis, focusing particularly on recent discussions regarding the applicability of probabilistic and decision analytic approaches to bioterrorism risks and the Bioterrorism Risk Assessment methodology used by the DHS and criticized by the National Academies and others.

253 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a new generic modelling approach, with a focus on cooking fuel choices, and explore response strategies for energy poverty eradication in India, which analyzes the determinants of fuel consumption choices for heterogeneous household groups, incorporating the effect of income distributions and traditionally more intangible factors such as preferences and private discount rates.

253 citations


Journal ArticleDOI
TL;DR: In this article, a GIS-based version of the EPIC model, GEPIC, is used for the estimation of consumptive water use in cropland on a global scale with a spatial resolution of 30 arc-minutes.

Journal ArticleDOI
01 Apr 2010-Energy
TL;DR: In this paper, the authors re-examine the energy-GDP relationship for the US for the period 1946-2000 by redefining energy in terms of exergy (the amount of energy available for useful work) and the amount of useful work provided from energy inputs.

Journal ArticleDOI
TL;DR: Although Beijing's mutualism indices remained generally stable, the ecological relationships among compartments changed greatly, and ways to further optimize this system and the relationships amongcompartments are revealed, thereby optimizing future urban water resources development.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the extent to which electricity access can be investigated using night-time light satellite data and spatially explicit population datasets to compare electricity access between 1990 and 2000.

Journal ArticleDOI
TL;DR: In many areas of the world, recreational fisheries are not managed sustainably as mentioned in this paper, which might be related to the omission or oversimplification of angler behaviour and angler heterogeneity in fisheries.
Abstract: In many areas of the world, recreational fisheries are not managed sustainably. This might be related to the omission or oversimplification of angler behaviour and angler heterogeneity in fisheries...

Journal ArticleDOI
TL;DR: The evolution of opportunism (the readiness to be swayed by incentives) and the evolution of trust (the propensity to cooperate in the absence of information on the co-players) are studied.
Abstract: Cooperation in public good games is greatly promoted by positive and negative incentives. In this paper, we use evolutionary game dynamics to study the evolution of opportunism (the readiness to be swayed by incentives) and the evolution of trust (the propensity to cooperate in the absence of information on the co-players). If both positive and negative incentives are available, evolution leads to a population where defectors are punished and players cooperate, except when they can get away with defection. Rewarding behaviour does not become fixed, but can play an essential role in catalysing the emergence of cooperation, especially if the information level is low.

Journal ArticleDOI
TL;DR: In this article, a preliminary attempt towards the technical and economic assessment of concentrating solar power (CSP) technologies in India has been made, which can be used as preliminary indicators for identifying niche areas for immediate/short-term utilization of solar energy for concentrating solar PV generation in India.

Journal ArticleDOI
TL;DR: In this paper, the IIASA's agro-ecological zones modelling framework has been extended for biofuel productivity assessment distinguishing five main groups of feedstocks covering a wide range of agronomic conditions and energy production pathways, namely: woody lignocellulosic plants, herbaceous lignosynthetic plants, oil crops, starch crops and sugar crops.
Abstract: IIASA's agro-ecological zones modelling framework has been extended for biofuel productivity assessments distinguishing five main groups of feedstocks covering a wide range of agronomic conditions and energy production pathways, namely: woody lignocellulosic plants, herbaceous lignocellulosic plants, oil crops, starch crops and sugar crops. A uniform Pan-European land resources database was compiled at the spatial resolution of 1 km2. Suitability and productivity assessments were carried out by matching climate characteristics with plant requirements, calculating annual biomass increments or yields including consideration of soil and terrain characteristics of each grid-cell. Potential biomass productivity and associated energy yields were calculated for each grid-cell. Spatial distributions of suitabilities of biofuel feedstocks in Europe were generated for each individual feedstock as well as for the five biofuel feedstock groups. Estimated agronomical attainable yields, both in terms of biomass (kg ha-1) as well as biofuel energy equivalent (GJ ha-1), were mapped and tabulated by agriculture and pasture land cover classes as derived from the CORINE land cover database. Results have been further aggregated by administrative units at NUTS 2 level.

Journal ArticleDOI
TL;DR: In this paper, the impacts of increased demand for food due to population growth and economic development on potential land and water use until 2030 were quantified with a global forest and agricultural model.
Abstract: Fertile land and freshwater constitute two of the most fundamental resources for food production. These resources are affected by environmental, political, economic, and technical developments. Regional impacts may transmit to the world through increased trade. With a global forest and agricultural model, we quantify the impacts of increased demand for food due to population growth and economic development on potential land and water use until 2030. In particular, we investigate producer adaptation regarding crop and irrigation choice, agricultural market adjustments, and changes in the values of land and water. In the context of resource sustainability and food security, this study accounts for the spatial and operational heterogeneity of irrigation management to globally assess agricultural land and water use. Agricultural responses to population and economic growth include considerable increases in irrigated area and water use but reductions in the average water intensity. Different irrigation systems are preferred under different exogenous biophysical and socioeconomic conditions. Negligence of these adaptations would bias the burden of development on land and water scarcity. Without technical progress, substantial price adjustments for land, water, and food would be required to equilibrate supply and demand.

Journal ArticleDOI
TL;DR: In this article, a societal level exergy analysis approach was developed to analyse transitions in the way that energy is supplied and contributes to economic growth in the UK, the US, Austria and Japan, throughout the last century.

Journal ArticleDOI
TL;DR: Novel disturbance by timber harvest and insect outbreaks may greatly reduce the aboveground living biomass of Siberian forests and may significantly alter ecosystem dynamics and wildlife populations by increasing forest fragmentation.
Abstract: Multiple global changes such as timber harvesting in areas not previously disturbed by cutting and climate change will undoubtedly affect the composition and spatial distribution of boreal forests, which will, in turn, affect the ability of these forests to retain carbon and maintain biodiversity. To predict future states of the boreal forest reliably, it is necessary to understand the complex interactions among forest regenerative processes (succession), natural disturbances (e.g., fire, wind, and insects), and anthropogenic disturbances (e.g., timber harvest). We used a landscape succession and disturbance model (LANDIS-II) to study the relative effects of climate change, timber harvesting, and insect outbreaks on forest composition, biomass (carbon), and landscape pattern in south-central Siberia. We found that most response variables were more strongly influenced by timber harvest and insect outbreaks than by the direct effects of climate change. Direct climate effects generally increased tree productivity and modified probability of establishment, but indirect effects on the fire regime generally counteracted the direct effects of climate on forest composition. Harvest and insects significantly changed forest composition, reduced living aboveground biomass, and increased forest fragmentation. We concluded that: (1) Global change is likely to significantly change forest composition of south-central Siberian landscapes, with some changes taking ecosystems outside the historic range of variability. (2) The direct effects of climate change in the study area are not as significant as the exploitation of virgin forest by timber harvest and the potential increased outbreaks of the Siberian silk moth. (3) Novel disturbance by timber harvest and insect outbreaks may greatly reduce the aboveground living biomass of Siberian forests and may significantly alter ecosystem dynamics and wildlife populations by increasing forest fragmentation.

Journal ArticleDOI
TL;DR: This article showed that the presence of adults during early development influences the social behaviour of juveniles later on in the cooperatively breeding cichlid Neolamprologus pulcher, and that the social rearing conditions persistently affect the economy and adequacy of individual reactions to social challenges.

Journal ArticleDOI
TL;DR: In this article, the authors developed an ecological network model for the system, and used four Chinese cities as examples of how this approach provides insights into the flows within the system at both high and low levels of detail.

Journal ArticleDOI
TL;DR: This work analyzes how modelers have chosen to describe adaptation within an integrated framework, and suggests many ways they could improve the treatment of adaptation by considering more of its bottom-up characteristics.
Abstract: Adaptation is an important element on the climate change policy agenda. Integrated assessment models, which are key tools to assess climate change policies, have begun to address adaptation, either by including it implicitly in damage cost estimates, or by making it an explicit control variable. We analyze how modelers have chosen to describe adaptation within an integrated framework, and suggest many ways they could improve the treatment of adaptation by considering more of its bottom-up characteristics. Until this happens, we suggest, models may be too optimistic about the net benefits adaptation can provide, and therefore may underestimate the amount of mitigation they judge to be socially optimal. Under some conditions, better modeling of adaptation costs and benefits could have important implications for defining mitigation targets.

Journal ArticleDOI
TL;DR: Fritz et al. as mentioned in this paper compared four sources of land cover data to determine which product is the most suitable for agricultural monitoring and for the subsequent development of a crop mask, using a user-defined fuzzy logic approach to comparing global land cover products.
Abstract: Achieving food security in particular in Africa continues to pose a major challenge to humankind. It is clear that the future agricultural potential of Africa plays a critical role in meeting this challenge. Although crop yield can be estimated with a degree of reliability using a limited sample of ground observations, the exact crop acreage and the spatial distribution are rarely available. Even though remote sensing offers the ability to produce a rapid and up-to-date land use and land cover database for agricultural monitoring, there are only a few countries in Africa where higher resolution satellite data such as Landsat have been used for land cover map production at the national level. However a number of global products have been produced which contain information on cropland extent. This paper will outline a comparison of four sources of land cover data to determine which product is the most suitable for agricultural monitoring and for the subsequent development of a crop mask. The land cover products used are the Global Land Cover Map (GLC-2000), the Moderate Resolution Imaging Spectroradiometer (MODIS) land cover product (MOD12V1), the SAGE (Center for Sustainability and the Global Environment) and the AFRICOVER dataset from the Food and Agriculture Organisation (FAO). Both the GLC-2000 and MODIS land cover products are at a resolution of 1 km2 while AFRICOVER, based on visual interpretation of 30-m resolution Landsat images, is available at a much finer resolution. The four land cover products are first aggregated to the same resolution so that they can be compared. The legend categories of the four land cover products in this study are reconciled using the method developed in Fritz and See [Fritz, S. and See, L., 2005, Comparison of land cover maps using fuzzy agreement. International Journal of Geographic Information Science, 19, pp. 787-807.] and See and Fritz [See, L.M. and Fritz, S., 2005, A user-defined fuzzy logic approach to comparing global land cover products. In 14th European Colloquium on Theoretical and Quantitative Geography, 9-12 September 2005, Lisbon, Portugal.] that allows overlap between legend definitions to be taken into account. Once the legend definitions between the different land cover products are reconciled, the maps are then compared with national and sub-national statistics. Analysis is undertaken at both continental and national scales as well as sub-national for Sudan and Eritrea. The study generally concludes that MODIS has the tendency to underestimate cropland cover when compared with FAO statistics or AFRICOVER data, whereas GLC-2000 tends to overestimate cropland cover in those countries that are located at the northern transition zone of subtropical shrubland and semi-desert areas. In this area MODIS and SAGE show a relatively similar cropland distribution. Even though the SAGE database has been calibrated with national statistics, it does not perform better than the other two datasets overall, and has highlighted the fact that the SAGE data show regional weaknesses and should be replaced in certain regions by more recent datasets such as GLC-2000 and MODIS, or ideally by a hybrid product that combines the best of the three products, depending upon the region and country.

Journal ArticleDOI
TL;DR: It is suggested to conceptualize the urban ecosystem health as a process, which impels us to focus more studies on the dynamic trends of health status and projecting possible development scenarios.

Journal ArticleDOI
TL;DR: In this article, the authors proposed to adjust design floods using a "climate change factor" approach, which is based on the prediction of flood hazard in Europe based on climatic and hydrological models.
Abstract: Flood damages have exhibited a rapid upward trend, both globally and in Europe, faster than population and economic growth. Hence, vigorous attempts of attribution of changes have been made. Flood risk and vulnerability tend to change over many areas, due to a range of climatic and nonclimatic impacts whose relative importance is site-specific. Flooding is a complex phenomenon and there are several generating mechanisms, among others intense and/or long-lasting precipitation, snowmelt, ice jam. Projected climate-driven changes in future flood frequency are complex, depending on the generating mechanism, e.g., increasing flood magnitudes where floods result of heavy rainfall and possibly decreasing magnitudes where floods are generated by spring snowmelt. Climate change is likely to cause an increase of the risk of riverine flooding across much of Europe. Projections of flood hazard in Europe based on climatic and hydrological models, reviewed in this paper, illustrate possible changes of recurrence of a 100-year flood (with probability of exceedance being 1-in-100 years) in Europe. What used to be a 100-year flood in the control period is projected to become either more frequent or less frequent in the future time horizon of concern. For a large part of the continent, large flooding is projected to become more commonplace in future, warmer climate. Due to the large uncertainty of climate projections, it is currently not possible to devise a scientifically-sound procedure for redefining design floods (e.g. 100-year flood) in order to adjust flood defenses. For the time being, we recommend to adjust design floods using a “climate change factor” approach.

Journal ArticleDOI
TL;DR: In this article, the authors investigate the effect of role-playing games on the understanding of basic insurance concepts and find that better understanding correlates with greater willingness to purchase it. But, they also suggest that roleplaying games may be an important tool for improving understanding, but that they do not necessarily outperform more conventional training practices.
Abstract: Innovative micro-insurance schemes can be one tool to help African small-holder farmers cope with climate variability and change. A critical challenge for implementing such risk transfer programs, however, is helping participants understand how insurance operates, and there is evidence that farmers with a poor understanding of insurance are less likely to use it. One of the proposed tools to help farmers understand insurance is a simulation game, through which farmers can gain first-hand experience with a functioning insurance market. This paper reports on the results of experiments in Ethiopia and Malawi, investigating farmers’ understanding and the effectiveness of a role-playing game at improving that understanding. Our results suggest a generally poor understanding of basic insurance concepts, and are consistent with past results in suggesting that better understanding correlates with greater willingness to purchase it. Our results also suggest that role-playing games may be an important tool for improving understanding, but that they do not necessarily out-perform more conventional training practices.

Journal ArticleDOI
TL;DR: In this paper, the authors used a longitudinal study to compare the direct and indirect emissions of an urban scale economy and found that direct emissions account for only about 20% of the overall upstream emissions necessary to sustain the input side of the economic production process (domestic emissions plus indirect emissions embodied in imported goods).

Journal ArticleDOI
TL;DR: Societal support for families and for couples trying to conceive improves the lives of families but makes no substantial contribution to increased fertility rates.
Abstract: INTRODUCTION: Although fertility rates are falling in many countries, Europe is the continent with the lowest total fertility rate (TFR). This review assesses trends in fertility rates, explores possible health and social factors and reviews the impact of health and social interventions designed to increase fertility rates. METHODS: Searches were done in medical and social science databases for the most recent evidence on relevant subject headings such as TFR, contraception, migration, employment policy and family benefits. Priorities, omissions and disagreements were resolved by discussion. RESULTS: The average TFR in Europe is down to 1.5 children per woman and the perceived ideal family size is also declining. This low fertility rate does not seem directly caused by contraception since in Northern and Western Europe the fertility decline started in the second half of the 1960s. Factors impacting on lower fertility include the instability of modern partnerships and value changes. Government support of assisted human reproduction is beneficial for families, but the effect on TFR is extremely small. Government policies that transfer cash to families for pregnancy and child support also have small effects on the TFR. CONCLUSIONS: Societal support for families and for couples trying to conceive improves the lives of families but makes no substantial contribution to increased fertility rates.