Researchers have found that over half of all human infectious diseases can be worsened by climate change
Will we have enough food for a growing global population? How will we take care of more people in case there is another pandemic? What will heat do to millions with hypertension? Will countries wage water wars because of increasing droughts?
These risks all have three things in common: health, climate change and a growing population which, according to the United Nations, passed 8 billion people on November 15, 2022 — twice as much from just 48 years ago.
Researchers have found that over half of all human infectious diseases can be worsened by climate change.
Flooding, for example, can affect water quality and the habitats where dangerous bacteria and vectors like mosquitoes can breed and transmit infectious diseases to people.
Dengue, a painful mosquito-borne viral disease that sickens about 100 million people every year becomes more common in warm, wet environments. Its R0, or basic reproduction number — a gauge of how quickly it spreads — increased by about 12% from the 1950s to the average in 2012-2021, according to the 2022 Lancet Countdown report. Malaria’s season expanded by 31% in highland areas of Latin America and nearly 14% in Africa’s highlands as temperatures rose over the same period.
The floods in Pakistan have destroyed 10% of Pakistan’s health facilities. In the three-month period between mid-June and September this year, at least 539,500 cases of malaria were reported, compared to fewer than 400,000 cases for the whole of 2021.
Droughts, too, can degrade drinking water quality. As a result, more rodent populations enter into human communities in search of food, increasing the potential to spread hantavirus. The Horn of Africa and California are facing an unprecedented drought. Rising temperatures also affect fresh water supplies through evaporation and by shrinking mountain glaciers and snowpack that historically have kept water flowing through the summer months.
Water scarcity and drought have the potential to displace almost 700 million people by 2030, according to UN estimates. Combined with population growth and growing energy needs, they can also fuel geopolitical conflicts as countries face food shortages and compete for water.
Heat also affects food security for a growing population. The Lancet review found that high temperatures in 2021 shortened the growing season by about 9.3 days on average for corn, or maize, and six days for wheat compared with the 1981-2020 average. Warming oceans, meanwhile, can kill shellfish and shift fisheries that coastal communities rely on. Heatwaves in 2020 alone resulted in 98 million more people facing food insecurity compared with the 1981-2010 average.
Pakistan is missing its wheat production target for the last three years due to the climate change effects.
Floods can surge all year round, in every region of the world. But discerning the relationship between any given flood and climate change is no small feat — made difficult by limited historical records, particularly for the most extreme floods, which occur infrequently. Pakistan experienced catastrophic floods between June and August of this year, triggered by climate change-induced torrential rains.
The flooding drenched one-third of Pakistan’s territory, affected 33 million people and killed more than 1,700. It cost the country an estimated $40 billion in damages and economic losses.