News about global climate impacts that elevate mortality, wreak weather havoc, and create massive displacement is inescapable. And those are just the stories that make the headlines. Droughts in Africa are estimated to impact 250 million people and displace 700 million more by 2030. Climate impacts brought on by El Niño are devastating the food supply chain, exacerbating Guatemala’s struggle to reduce childhood malnutrition.

Since climate change affects health and wellbeing on a global basis, why is there a hesitancy among global advocates to talk about links between climate and population dynamics? One reason may be that while greenhouse gas (GHG) emissions increase as populations grow, not all people contribute equally to these increases. In fact, the countries with the highest per capita carbon dioxide emissions are not the ones with the largest populations or highest fertility levels.

So, a focus on fertility doesn’t adequately address the links between climate and population dynamics. Forging an adequate response to climate change—and mitigating its impacts—requires consideration of the intersection of climate change, health impacts, and population dynamics from a systematic, equitable perspective.

Looking at the 2022 floods in Pakistan offers an interesting example of how population dynamics can be used to better understand and respond to climate catastrophes. Specifically, we need to consider where impacted people live, who is impacted, and how they are impacted to better understand the relationship between climate, health, and population.

Mapping Out Affected Populations

Where impacted people live (i.e., population distribution) helps identify the geographies where climate change results in adverse health outcomes and the size of the population impacted. It can also help with planning responses to predictable climate impacts.

While climate change is often viewed as a homogeneous phenomenon, its underlying causes—rising temperatures, more extreme weather, rising sea levels, and increases in CO2 levels—play out differently across geographies. The ability to predict where and when adverse events will happen puts governments and communities in a better position to mobilize relief efforts.

Anticipating diverse human health needs is a critical element of an effective response. The 2022 flooding in Pakistan followed annual monsoon patterns that were worsened by a severe heatwave that caused glaciers in the mountains to melt, while warmer water in the Indian Ocean contributed to heavier-than-normal rain. Climate scientist Friederike Otto notes that in vulnerable regions, such as the southern part of the Indus River valley, a small change in a risk factor can have a big impact. As waters flowed downstream and were paired with heavy rains in the regions, the low-lying, arid areas of Sindh and Balochistan provinces were overwhelmed by flooding.

Engaging those who live in climate-affected areas early with data from early warning systems can help vulnerable communities anticipate difficulties and mobilize a locally-based response that includes both the public and private sectors, as outlined in Pakistan’s post-disaster assessment. Planning ahead helps engage the right people and instill public confidence that situations will be effectively managed. 

Who Bears the Brunt?

Discovering who is impacted (i.e., population composition) by climate change—and the characteristics of those most vulnerable to it—are also critical steps to creating an effective response.

Are certain ethnic groups that live in vulnerable areas more likely to be impacted? In some cases, climate catastrophes may only impact vulnerable groups; other times, they cut across an entire population, leaving everyone devastated. Children often bear the brunt of these events—either through illness, leaving school, or being orphaned. Minority and ethnic groups that live in vulnerable geographies—especially those located in coastal and remote areas—may need champions to advocate for an effective response to a disaster.

In Pakistan’s 2022 floods, an estimated 33 million people were affected, and more than 1,500 people died. Yet, information on which populations were affected by the floods does not paint a clear portrait of who was especially impacted by this catastrophe. Areas where flooding occurred were largely rural and used for farming. Large numbers of children in these areas with acute malnutrition (estimated at 1.6 million) and stunting (6 million) were made worse off by flooding. Women were also disproportionately affected, as they largely work in farming and the informal sector, where they are either unpaid or underpaid. Because of inequitable gender norms, these women have limited access to the capital needed to support recovery.

While not offering a full portrait of the affected, what information is available provides insight into who was—and continues to be—affected by the flooding. Understanding who is (and will be) impacted by climate change is critical to an effective response. In addition to promoting health, any responses must also address the social, food security, housing, and other key needs of affected people.

Tracking Climate Impacts

How people are impacted, either directly or indirectly, is also critical to planning a response. Climate change can drive disease vectors into new habitats—and bring human populations in close contact with vectors of malaria, dengue, or West Nile virus. Draught can force people to migrate to new areas, and the use of overland routes can expose them to additional risks, such as extreme heat that contributes to increases in cardiovascular deaths. Increased rains and flooding can increase the risk of malnutrition and diarrheal disease—a leading cause of childhood death.

The recent flooding in Pakistan brought about a variety of adverse health impacts. Stagnant water contributed to increases in water-borne diseases, including dysentery, shigella, E coli, and amebiasis, which are characterized by diarrhea, fevers, abdominal cramps, and dehydration. A rise in malaria and dengue also originates in stagnant water that serves as breeding grounds for mosquitoes. Breakdowns in the medical supply chain led to increases in measles and polio, as well as shortages of medicines needed to treat the ill through community- and facility-based care. Destruction or damage to approximately 10 percent of the country’s health facilities created additional strain on the health system.

In addition to health issues, Pakistan’s flooding polluted drinking water, caused food insecurity as millions of acres of crops were destroyed, and put increased strain on the country’s insufficient energy infrastructure. These challenges further exacerbate the country’s political and economic difficulties. 

Examining Pakistan’s devastating floods shines a spotlight on the intersection of population and climate change and reveals this interplay to be both complex and multifaceted. It is simplistic to think about only the most basic demographic characteristics when considering these relationships, but fertility, mortality, and migration all evolve in response to climate change.

For some, the temptation is to focus on slowing population growth, which could result in heavy-handed measures to slow fertility. However, instead of framing these critical relationships from a perspective of blame, we should focus on solutions and how we can better use knowledge about population characteristics and climate to predict and mitigate the adverse impacts that leave much of the planet struggling with challenges beyond their control.