As more of the greenhouse gas carbon dioxide enters the atmosphere, leading to climate change, crops might carry fewer nutrients, like zinc and iron. Stanford researchers explored this trend and regions most likely to be hurt by it.

The way we treat the planet has direct consequences on human health. This series of stories explores some of those consequences and what we can do to lessen the risks.

In warmer temperatures suicide rates increase, leading to concerns about an uptick in suicides as the globe continues to warm. But researchers offer some hope if greenhouse gases get under control.

As global temperatures rise, climate change’s impacts on mental health are becoming increasingly evident. Recent research has linked elevated temperatures to an increase in violence, stress and decreased cognitive function leading to impacts such as reduced test scores, lowered worker productivity and impaired decision-making.

Adding to the concern, a Stanford study led by economist Marshall Burke also finds a link between increased temperatures and suicide rates. The research, published in Nature Climate Change, concluded that up to 21,000 additional suicides will occur by 2050 within the United States and Mexico if unmitigated climate change continues to warm the Earth at the current projected rates.

Suicide is one of the top 10 causes of death in the United States. Unlike other leading causes – which include heart disease, cancer, homicide and unintentional injury – suicide rates have increased rather than fallen over time. And, while there has been a noticeable trend of rising suicide rates in warmer months, up to this point it has been difficult to attribute these changes to temperature, as other factors like day length and social patterns also vary.

Burke and team overcame these obstacles by assembling and examining decades worth of temperature and suicide data across thousands of U.S. counties and Mexican municipalities. To complement the data, they also scanned over half a billion Twitter updates or tweets and looked for language signaling a negative state of mind.

They found that hotter than average temperatures increase both suicide rates and the use of depressive language on Twitter. They also concluded that socioeconomic status had little to no impact, meaning wealth does not help insulate populations from suicide risk.

“One claim you often hear is that it’s the socioeconomically disadvantaged that are going to be affected by climate change. Our results suggest that at least in the case of mental health, impacts are going to cut across the income distribution and could affect any of us,” Burke said.

He and his team then used global climate model projections to predict how future temperatures could affect suicide rates. They found climate change could increase suicide rates by 1.4 percent in the United States and 2.3 percent in Mexico by 2050.Excess suicides by 2050 caused by warmer temperatures if greenhouse gas emissions stabilize consistent with Paris Agreement goals (move the slider to the right), or if emissions continue unabated (move the slider to the left). (Image credit: Sam Heft-Neal)

Experts gathered to discuss the linkages between climate change and health at a Stanford-led event at the Global Climate Action Summit.

When it comes to food security, health and poverty, the impacts of climate change already are evident. That’s the message FSE Fellows David Lobell and Marshall Burke delivered last week at Global Climate Action Summit events held by Stanford in San Francisco. Attendees from across the globe gathered at the summit aimed to mobilize commitments and action from local governments, corporations and NGO’s to mitigate climate change and reach the goals of the Paris Agreement. 

Lobell and Burke – a professor and assistant professor (respectively) in Earth system science in Stanford’s School of Earth, Energy & Environmental Sciences participated in the Stanford Woods Institute for the Environment sponsored panel on Sept. 14  “The 2009 EPA ENDANGERMENT FINDING: EVEN STRONGER EVIDENCE in 2018.” Moderated by Stanford Woods Institute Director Chris Field, the panel examined how new research bolsters the original report’s findings that greenhouse gases pose a threat to human health and welfare.

Read the full story.

More children die from the indirect impact of armed conflict in Africa than those killed in the crossfire and on the battlefields, according to a new study by Stanford researchers. 

The study is the first comprehensive analysis of the large and lingering effects of armed conflicts — civil wars, rebellions and interstate conflicts — on the health of noncombatants.

The numbers are sobering: 3.1 to 3.5 million infants born within 30 miles of armed conflict died from indirect consequences of battle zones between 1995 and 2005. That number jumps to 5 million deaths of children under 5 in those same conflict zones.

“The indirect effects on children are so much greater than the direct deaths from conflict,” said Stanford Health Policy's Eran Bendavid, senior author of the study published today in The Lancet.

The authors also found evidence of increased mortality risk from armed conflict as far as 60 miles away and for eight years after conflicts. Being born in the same year as a nearby armed conflict is riskiest for young infants, the authors found, with the lingering effects raising the risk of death for infants by over 30 percent.

On the entire continent, the authors wrote, the number of infant deaths related to conflict from 1995 to 2015 were more than three times the number of direct deaths from armed conflict. Further, they demonstrated a strong and stable increase of 7.7 percent in the risk of dying before age 1 among babies born within 30 miles of an armed conflict.

The authors recognize it is not surprising that African children are vulnerable to nearby armed conflict. But they show that this burden is substantially higher than previously indicated. 

“We wanted to understands the effects of war and conflict, and discovered that this was surprisingly poorly understood,” said Bendavid, an associate professor of medicine at Stanford Medicine.  “The most authoritative source, the Global Burden of Disease, only counts the direct deaths from conflict, and those estimates suggest that conflicts are a minuscule cause of death.”

Paul Wise, a professor of pediatrics at Stanford Medicine and a senior fellow at the Freeman Spogli Institute for International Studies, has long argued that lack of health care, vaccines, food, water and shelter kills more civilians than combatants from bombs and bullets. 

This study has now put data behind the theory when it comes to children.

“We hope to redefine what conflict means for civilian populations by showing how enduring and how far-reaching the destructive effects of conflict have on child health,” said Bendavid, an infectious disease physician whose co-authors include Marshall Burke, PhD, an assistant professor of earth systems science and fellow at the Center on Food Security and the Environment.

“Lack of access to key health services or to adequate nutrition are the standard explanations for stubbornly high infant mortality rates in parts of Africa,” said Burke. “But our data suggest that conflict can itself be a key driver of these outcomes, affecting health services and nutritional outcomes hundreds of kilometers away and for nearly a decade after the conflict event”. 

The results suggest efforts to reduce conflict could lead to large health benefits for children.

The Data

The authors matched data on 15,441 armed-conflict events with data on 1.99 million births and subsequent child survival across 35 African countries. Their primary conflict data came from the Uppsala Conflict Data Program Georeferenced Events Dataset, which includes detailed information about the time, location, type and intensity of conflict events from 1946 to 2016. 

The researchers also used all available data from the Demographic and Health Surveys conducted in 35 African countries from 1995 to 2015 as the primary data sources on child mortality in their analysis.

The data, they said, shows that the indirect toll of armed conflict among children is three-to-five times greater than the estimated number of direct casualties in conflict. The indirect toll is likely even higher when considering the effects on women and other vulnerable populations.

Zachary Wagner, a health economist at RAND Corporation and first author of the study, said he knows few are surprised that conflict is bad for child health.

“However, this work shows that the relationship between conflict and child mortality is stronger than previously thought and children in conflict zones remain at risk for many years after the conflict ends.” 

He notes that nearly 7 percent of child deaths in Africa are related to conflict and reiterated the grim fact that child deaths greatly outnumber direct combatant deaths.

“We hope our findings lead to enhanced efforts to reach children in conflict zones with humanitarian interventions,” Wagner said. “But we need more research that studies the reasons for why children in conflict zones have worse outcomes in order to effectively intervene.” 

Another author, Sam Heft-Neal, PhD, is a research fellow at the Center for Food Security and the Environment and in the Department of Earth Systems Science. He, Burke and Bendavid have been working together to identify the impacts of extreme climate events on infant mortality in Africa.