Rising atmospheric carbon dioxide concentrations are anticipated to decrease the zinc and iron concentrations of crops. The associated disease burden and optimal mitigation strategies remain unknown. We sought to understand where and to what extent increasing carbon dioxide concentrations may increase the global burden of nutritional deficiencies through changes in crop nutrient concentrations, and the effects of potential mitigation strategies.
Poor air quality is thought to be an important mortality risk factor globally1,2,3, but there is little direct evidence from the developing world on how mortality risk varies with changing exposure to ambient particulate matter. Current global estimates apply exposure–response relationships that have been derived mostly from wealthy, mid-latitude countries to spatial population data4, and these estimates remain unvalidated across large portions of the globe. Here we combine household survey-based information on the location and timing of nearly 1 million births across sub-Saharan Africa with satellite-based estimates5 of exposure to ambient respirable particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) to estimate the impact of air quality on mortality rates among infants in Africa. We find that a 10 μg m−3 increase in PM2.5 concentration is associated with a 9% (95% confidence interval, 4–14%) rise in infant mortality across the dataset. This effect has not declined over the last 15 years and does not diminish with higher levels of household wealth. Our estimates suggest that PM2.5 concentrations above minimum exposure levels were responsible for 22% (95% confidence interval, 9–35%) of infant deaths in our 30 study countries and led to 449,000 (95% confidence interval, 194,000–709,000) additional deaths of infants in 2015, an estimate that is more than three times higher than existing estimates that attribute death of infants to poor air quality for these countries2,6. Upward revision of disease-burden estimates in the studied countries in Africa alone would result in a doubling of current estimates of global deaths of infants that are associated with air pollution, and modest reductions in African PM2.5 exposures are predicted to have health benefits to infants that are larger than most known health interventions.
Stanford scientists found that the global economy is likely to benefit from ambitious global warming limits agreed to in the United Nations Paris Agreement.
Failing to meet climate mitigation goals laid out in the U.N. Paris Agreement could cost the global economy tens of trillions of dollars over the next century, according to new Stanford research. The study, published in Nature, is one of the first to quantify the economic benefits of limiting global warming to levels set in the accord.
The agreement commits 195 countries to the goal of holding this century’s average temperature to 2 degrees Celsius above levels in the pre-industrial era. It also includes an aspirational goal of pursuing an even more stringent target of limiting temperature rise to 1.5 degrees. To date, the economic benefits of achieving these temperature targets have not been well understood.
“Over the past century we have already experienced a 1-degree increase in global temperature, so achieving the ambitious targets laid out in the Paris Agreement will not be easy or cheap. We need a clear understanding of how much economic benefit we’re going to get from meeting these different targets,” said Marshall Burke, assistant professor of Earth system science in the School of Earth, Energy & Environmental Sciencesand lead author of the study.
To develop this understanding, a team of Stanford researchers studied how economic performance over the past half-century correlated with changes in temperature around the world. Then, using climate model projections of how temperatures could change in the future, they calculated how overall economic output is likely to change as temperatures warm to different levels.
The researchers found a large majority of countries – containing close to 90 percent of the world’s population – benefit economically from limiting global warming to 1.5 degrees instead of 2 degrees. This includes the United States, China and Japan – the three largest economies in the world. It is also true in some of the world’s poorest regions, where even small reductions in future warming generate a notable increase in per capita gross domestic product.
“The countries likely to benefit the most are already relatively hot today,” said Burke. “The historical record tells us that additional warming will be very harmful to these countries’ economies, and so even small reductions in future warming could have large benefits for most countries.”
The projected costs from higher temperatures come from factors such as increases in spending to deal with extreme events, lower agricultural productivity and worse health, the scientists said.
Previous research has shown that the actual climate commitments each country has made as part of the Paris Agreement add up to close to 3 degrees of global warming, instead of the 1.5–2 degrees warming goals.
Given this discrepancy, the researchers also calculated the economic consequences of countries meeting their individual Paris commitments, but failing to meet the overall global warming goals of 1.5–2 degrees. They found that failing to achieve the 1.5–2 degrees goals is likely to substantially reduce global economic growth.
Percentage gain in GDP per capita in 2100 from achieving 1.5 degrees Celsius global warming instead of 2 degrees.
Percentage gain in GDP per capita in 2100 from achieving 1.5 degrees Celsius global warming instead of 2 degrees. (Image credit: Marshall Burke)
“It is clear from our analysis that achieving the more ambitious Paris goals is highly likely to benefit most countries – and the global economy overall – by avoiding more severe economic damages,” said Noah Diffenbaugh, professor of Earth system science and paper co-author.
The authors note the study may underestimate the total costs of higher levels of global warming. That’s especially true if catastrophic changes such as rapid melting of the ice on Greenland or Antarctica come to pass, or if extreme weather events such as heatwaves and floods intensify well beyond the range seen in historical observations. A recent studyby Diffenbaugh and his colleagues showed that even with reduced levels of global warming, unprecedented extreme events are likely to become more prevalent.
The new research helps shed light on the overall economic value of the Paris Agreement, as well as on the Trump administration’s decision to withdraw the U.S. from the accord because of concerns that it is too costly to the U.S. economy. The researchers calculated that the overall global benefits of keeping future temperature increases to 1.5 degrees are likely in the tens of trillions of dollars, with substantial likely benefits in the U.S. as well. They note that these benefits are more than 30 times greater than the most recent estimates of what it will cost to achieve the more ambitious 1.5 degrees goal.
“For most countries in the world, including the U.S., we find strong evidence that the benefits of achieving the ambitious Paris targets are likely to vastly outweigh the costs,” said Burke.
Burke is also a fellow at the Center on Food Security and the Environment, the Stanford Woods Institute for the Environmentand the Freeman Spogli Institute for International Studies. Diffenbaugh is also the Kara J Foundation Professor, the Kimmelman Family Senior Fellow in the Stanford Woods Institute for the Environment and an affiliate of the Precourt Institute for Energy. Additional co-authors include W. Matt Davis, a former researcher at the Center on Food Security and the Environment. The research was supported by the Erol Foundation.
Media Contacts
Marshall Burke, School of Earth, Energy & Environmental Sciences: mburke@stanford.edu, (650) 721-2203 Noah Diffenbaugh, School of Earth, Energy & Environmental Sciences: diffenbaugh@stanford.edu, (650) 223-9425 Michelle Horton, Center on Food Security and the Environment: mjhorton@stanford.edu, (650) 498-4129
Stanford welcomes Cousin, a global hunger expert, to the Center on Food Security and the Environment.
The Freeman Spogli Institute for International Studies (FSI) at Stanford University is pleased to announce that former U.S. Ambassador and World Food Programme (WFP) Director Ertharin Cousin will serve as this year’s Frank E. and Arthur W. Payne Distinguished Lecturer and Visiting Fellow at the Center on Food Security and the Environment (FSE).
Cousin brings over 25 years of experience addressing hunger and food security strategies on both a national and international scale. As U.S. Ambassador to the United Nations Agencies for Food and Agriculture, she focused on advocating for longer-term solutions to food insecurity and hunger, and at WFP she addressed the challenges of food insecurity in conflict situations.
“Dr. Cousin’s outstanding leadership at the WFP and extensive experience in public service exemplifies the attributes we seek for Payne Lecturers,” says FSI Director Michael McFaul. The Payne Distinguished Lectureship is awarded to scholars with international reputations as leaders, with an emphasis on visionary thinking, practical problem solving, and the capacity to clearly articulate an important perspective on the global political and social situation. Past Payne Lecturers include Bill Gates, Nobel Laureate Mohamed El Baradei, UNAIDS Executive Director Peter Piot, and novelist Ian McEwan.
As a visiting fellow with FSE, Cousin will be working to further her research focus on global food security and humanitarian efforts. In November 2015, FSE welcomed Cousin as the featured speaker in their Food and Nutrition Symposium series, where she presented her paper “Achieving food security and nutrition for the furthest behind in an era of conflict and climate change.” FSE Director, Roz Naylor, sees Cousin’s appointment as a pivotal opportunity for FSE and FSI to advance a global agenda on food security and human rights. “Ertharin Cousin is one of the most inspirational leaders we could ever hope to attract to Stanford as a year-long visitor,” Naylor says.
“This is a truly humbling, yet exciting prospect,” says Cousin. “This position provides an opportunity for scholarly work and dialogue with distinguished academics across Stanford's schools and policy institutes. I also look forward to the opportunity to convene thought leaders from a broad variety of backgrounds, who can help us explore some of the intractable issues plaguing humanitarian and development practitioners today.”
Following the completion of her term with the WFP, Cousin accepted an appointment as a Distinguished Fellow with The Chicago Council on Global Affairs, which conducts research on food and agriculture, global cities, economics, energy, immigration, security, public opinion, and water. Cousin hopes her appointments can provide a unique collaborative opportunity to expand her work on food security and nutrition issues.
“In my career I have never before been given the opportunity of pursuing intellectual inspiration. Just thinking about the ‘what’s possible’ gives me genuine pleasure,” Cousin said.
About FSE
The Center on Food Security and the Environment (FSE) is a research center at Stanford University, jointly funded by the Freeman Spogli Institute for International Studies and the Stanford Woods Institute for the Environment.
Using agricultural and economic characteristics in African nations as test cases, new research by David Lobell and Marshall Burke demonstrates the use of satellite data to address the long-standing problem of accurate data collection in developing countries. An often cited challenge in achieving development goals aimed at poverty and hunger reduction is the lack of reliable on-the-ground data. Limited or insuffiient data makes it difficult to establish baseline conditions and to assess effectiveness of various aid programs. In the past, researchers and policymakers had to rely on ground surveys, which are expensive, time-consuming, and rarely conducted. This has led to large data gaps in mapping sustainable development goal progress, such as in agricultural and poverty statistics.
The ongoing decline in under-5 mortality ranks among the most significant public and population health successes of the past 30 years. Deaths of children under the age of 5 years have fallen from nearly 13 million per year in 1990 to less than 6 million per year in 2015, even as the world's under-5 population grew by nearly 100 million children. However, the amount of variability underlying this broad global progress is substantial. On a regional level, east Asia and the Pacific have surpassed the Millennium Development Goal target of a two-thirds reduction in under-5 mortality rate between 1990 and 2015, whereas sub-Saharan Africa has had only a 24% decline over the same period. Large differences in progress are also evident within sub-Saharan Africa, where mortality rates have declined by more than 70% from 1990 to 2015 in some countries and increased in others; in 2015, the mortality rate in some countries was more than three times that in others.
What explains this remarkable variation in progress against under-5 mortality? Answering this question requires understanding of where the main sources of variation in mortality lie. One view that is implicit in the way that mortality rates are tracked and targeted is that national policies and conditions drive first-order changes in under-5 mortality. This country-level focus is justified by research that emphasises the role of institutional factors in explaining variation in mortality—factors such as universal health coverage, women's education, and the effectiveness of national health systems. It is argued that these factors, which vary measurably at the country level, fundamentally shape the ability of individuals and communities to affect more proximate causes of child death such as malaria and diarrhoeal disease.
An alternate view has focused on exploring the importance of subnational variation in the distribution of disease. In the USA, studies on the geographical distribution of health care and mortality have been influential for targeting of resources and policy design. Similar studies in developing regions have shown the substantial variability in the distribution and changes of important health outcomes such HIV, malaria, and schistosomiasis—information that can then be used to improve the targeting of interventions. Nevertheless, the relative contribution of within-country and between-country differences in explaining under-5 mortality remains unknown. Improved understanding of the relative contribution of national and sub-national factors could provide insight into the drivers of mortality levels and declines in mortality, as well as improve the targeting of interventions to the areas where they are most needed.
Stanford researchers have determined that more than 15 million children are living in high-mortality hotspots across 28 Sub-Saharan African countries, where death rates remain stubbornly high despite progress elsewhere within those countries.
The study, published online Oct. 25 in The Lancet Global Health, is the first to record and analyze local-level mortality variations across a large swath of Sub-Saharan Africa.
These hotspots may remain hidden even as many countries are on track to achieve one of the U.N. Sustainable Development Goals: reducing the mortality rate of children under 5 to 25 per 1,000 by 2030. National averages are typically used for tracking child mortality trends, allowing left-behind regions within countries to remain out of sight — until now.
The authors note that the ongoing decline in under-5 mortality worldwide ranks among the most significant public and population health successes of the past 30 years. Deaths of children under the age of 5 years have fallen from nearly 13 million a year in 1990 to fewer than 6 million a year in 2015, even as the world’s under-5 population grew by nearly 100 million children, according to the Institute for Health Metrics and Evaluation.
“However, the amount of variability underlying this broad global progress is substantial,” the authors wrote.
“Mortality numbers are typically tracked at the national level, with the assumption that national differences between countries, such as government spending on health, are what determine progress against mortality,” Bendavid said. “The goal of our work was to understand whether national-level mortality statistics were hiding important variation at the more local level — and then to use this information to shed light on broader mortality trends.”
The authors used data from 82 U.S. Agency for International Development surveys in 28 Sub-Saharan African countries, including information on the location and timing of 3.24 million births and 393,685 deaths of children under 5, to develop high-resolution spatial maps of under-5 mortality from the 1980s through the 2000s.
Using this database, the authors found that local-level factors, such as climate and malaria exposure, were predictive of overall patterns, while national-level factors were relatively poor predictors of child mortality.
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Temperature, malaria exposure, civil conflict
“We didn’t see jumps in mortality at country borders, which is what you’d expect if national differences really determined mortality,” said co-author Sam Heft-Neal, PhD, a postdoctoral scholar in Earth System Science. “But we saw a strong relationship between local-level factors and mortality.”
For example, he said, one standard deviation increase in temperature above the local average was related to a 16-percent higher child mortality rate. Local malaria exposure and recent civil conflict were also predictive of mortality.
The authors found that 23 percent of the children in their study countries live in mortality hotspots — places where mortality rates are not declining fast enough to meet the targets of the U.N. Sustainable Development Goals. The majority of these live in just two countries: Nigeria and the Democratic Republic of Congo. In only three countries do fewer than 5 percent of children live in hotspots: Benin, Namibia and Tanzania.
As part of the research, the authors have established a high-resolution mortality database with local-level mortality data spanning the last three decades to provide “new opportunities for a deeper understanding of the role that environmental, economic, or political conditions play in shaping mortality outcomes.” The database, available at http://fsedata.stanford.edu, is an open-source tool for health and environmental researchers, child-health experts and policymakers.
“Our hope is that the creation of a high-resolution mortality database will provide other researchers new opportunities for deeper understanding of the role that environmental, economic or political conditions play in shaping mortality outcomes,” said Bendavid. “These data could also improve the targeting of aid to areas where it is most needed.”
Percentage gain in GDP per capita in 2100 from achieving 1.5 degrees Celsius global warming instead of 2 degrees.
