As the world continues to battle the rising cases of Covid-19 caused by zoonotic virus, a study by a team of researchers has found that over 50 per cent (that is, 218 out of 375) of infectious diseases, from common waterborne pathogen to life-threatening diseases like plague have been at some point aggravated by climatic hazards.
The team of environment and health scientists had reviewed decades of scientific papers on all known pathogenic disease to create a map of the human risks aggravated by climate-related hazards. The outcome was shocking, said the scientists.
Flooding, for example, can spread hepatitis. Rising temperatures can expand the life of mosquitoes carrying malaria. Droughts can bring rodents infected with hantavirus into communities as they search for food, said the lead author, Camilo Mora from Department of Geography and Environment, University of Hawai,USA, of the study published in the journal Nature Climate Change.
With climate change influencing more than 1,000 transmission pathways like those and climate hazards increasingly globally, the team concluded that expecting societies to successfully adapt to all of them isn’t a realistic option. The world will need to reduce the greenhouse gas emissions that are driving climate change to reduce these risks.
To be able to prevent global health crises, humanity needs a comprehensive understanding of the pathways and the magnitude with which climate change might affect pathogenic diseases.
“We focused on 10 climate-related hazards linked to rising greenhouse gas emissions: atmospheric warming, heat waves, drought, wildfires, heavy precipitation, flooding, storms, sea-level rise, ocean warming and land cover change. Then we looked for studies discussing specific and quantifiable observations of human disease occurrences linked to those hazards,” said the researchers.
In total, 77,000 scientific papers were reviewed. Of those, 830 papers had a climatic hazard affecting a specific disease in an explicit place and/or time, allowing us to create a database of climatic hazards, transmission pathways, pathogens and diseases.
The largest number of diseases aggravated by climate change involved vector-borne transmission, such as those spread by mosquitoes, bats or rodents. Looking at the type of climate hazard, the majority were associated with atmospheric warming (160 diseases), heavy precipitation (122) and flooding (121).
The study found four key ways climatic hazards interact with pathogens and humans: These are climate-related hazards that bring pathogens closer to people; In some cases, climate-related hazards are shifting the ranges of animals and organisms that can act as vectors for dangerous pathogenic diseases.
For example, warming or changes in precipitation patterns can alter the distribution of mosquitoes, which are vectors of numerous human pathogenic diseases. In recent decades, geographic changes in outbreaks of mosquito-borne diseases such as malaria and dengue have been linked to these climatic hazards, the study said.