Yemen and South Sudan are, in many ways, worlds apart. But, despite vast differences in history, tradition, and culture, both countries share one painful feature: their people are now bearing the brunt of two of the most devastating manmade crises: violent conflict and climate change.
South Sudan has been mired in conflict for nearly a decade. In the last five years alone, tens of thousands have died, and nearly a quarter of the population has been displaced, with many having little choice but to flee to neighboring Kenya, Uganda, or Sudan.
Yemen, for its part, has emerged as a major front in the ongoing struggle for regional influence between Saudi Arabia, which has ties to Yemen's government, and Iran, which supports the Houthi rebel group. In recent years, Saudi Arabia, in particular, has been carrying out devastating air strikes that have killed countless civilians and reduced Yemen's infrastructure - including roads, schools, hospitals, apartment complexes, and markets - to rubble, leaving the country's people without access to essential services. With water and sanitation facilities knocked out, the country is now facing the worst cholera outbreak in modern history.
The effects of violent conflict are being exacerbated by climate change. This year's Climate Change Vulnerability Index ranks South Sudan among the world's five most vulnerable countries, with the increase in temperature expected to be nearly two and a half times larger than the global average. This will devastate an already-desperate country, where the livelihoods of 95% of the population depend on climate-related services, from agriculture to animal husbandry and fisheries.
Yemen, for its part, is considered among the clearest examples of the tangible consequences of climate change. According to the World Bank, since 1970, irrigation in Yemen has increased by a factor of 15, as rain-fed agriculture has declined by nearly 30%. The country faces both heavy rains and deadly floods - in 2008, floods in southeastern Yemen resulted in losses equivalent to 6% of GDP - and, at the other extreme, devastating droughts.
The global health community is now increasingly recognizing the extent to which the traditional consequences of war - such as injury, trauma, and displacement - are being compounded by the effects of climate change, which undermines nutrition and development. For example, conflict can, as in Yemen, result in the contamination of water resources, which are already being depleted by climate change.
Similarly, malnutrition, rooted in the loss of crops and livelihoods from climate change, undermines people's ability to recover from injuries sustained in violent conflict or endure the challenges of migration - a situation exacerbated by the destruction of health-care infrastructure. The list goes on.
None of this is a matter of coincidence. In fact, researchers are now concerned that conflict and climate change are mutually reinforcing, with economic and agricultural losses, as well as water shortages, triggering conflicts that then undermine health and livelihoods further. In such an environment, outbreaks of an old disease (such as cholera) or a new one may lead to new regional and global pandemics.
The situation is further complicated by political calculations, including geostrategic considerations, like those behind Saudi Arabia's actions in Yemen, and the rejection of scientific evidence in order to pander to constituents, as in the United States. In fact, the withdrawal of US President Donald Trump's administration from the Paris climate agreement is set to weaken the world's collective ability to respond to climate change. Cuts in aid funding for women's health - another Trump administration policy - will not help matters.
The reality is that confronting the interconnected challenges associated with conflict and climate change demands comprehensive solutions. Of course, influential countries - including China, France, and Germany - have a role to play in filling the gap left by the Trump administration's retreat from global leadership. But the scientific and public-health communities must also step up and rethink how to manage diseases and handle water shortages in conflict environments.
We have already seen what happens in the absence of systems-level solutions. Consider the 2014 Ebola outbreak in West Africa: despite ample support programs and infrastructure focused on confronting malaria, countries were not even remotely prepared to handle a new health challenge. When Ebola emerged, the system simply broke down - with overwhelming human and economic consequences.
That is why the scientific and public-health communities must work urgently to deepen their understanding of the integrated challenges of conflict and climate change, finding and filling gaps in knowledge. The first step is a clear-eyed assessment of the current state of affairs, which will surely produce a harsh reality check regarding the resilience and effectiveness of existing solutions.
It is time to recognize the speed at which the combined threat of conflict and climate change is spreading and intensifying, and that addressing it requires new multidisciplinary, evidence-based tools and solutions. It is within our collective capacity to control, limit, and potentially even reverse the effects of the climate-conflict nexus. But we have to do the work.
Muhammad Hamid Zaman is a professor in the Department of Biomedical Engineering and International Health at Boston University.