Climate & Human Disease

We’re all becoming more familiar with the climate-caused problems of flooding and drought, wildfires, and with the more intense heat … and even increases in utility bills to pay for the air conditioning we need.  But – might we also be in for suffering from an increase in infectious diseases just because of climate change?  Here’s a research report.  Comments afterwards.


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Climate impacts have worsened

vast range of human diseases


More than half of human diseases caused by pathogens have been

aggravated by hazards associated with climate change, study finds


Oliver Milman


The Guardian

Mon 8 Aug 2022


More than half of the human diseases caused by pathogens have been worsened at some point by the sort of impacts associated with the climate crisis, a new and exhaustive study of the link between disease and climatic hazards has found diseases such as Zika, malaria, dengue, chikungunya and even Covid-19 have been aggravated by climate impacts such as heatwaves, wildfires, extreme rainfall and floods, the paper found.

In all, there are more than 1,000 different pathways for these various impacts to worsen the spread of disease, a cavalcade of threats “too numerous for comprehensive societal adaptations”, the researchers wrote.

Global heating and changed rainfall patterns are expanding the range of disease vectors such as mosquitoes, ticks and fleas, resulting in the spread of malaria, Lyme disease, West Nile virus and other conditions.

Storms and flooding have displaced people, bringing them closer to pathogens that cause outbreaks of gastroenteritis and cholera, while climate impacts have weakened humans’ ability to cope with certain pathogens – drought, for example, can lead to poor sanitation, resulting in dysentery, typhoid fever and other diseases. Camilo Mora, a geographer at the University of Hawaii who led the research, said …


“We are opening a Pandora’s Box of dis-

ease. Because of climate change, we have

all these triggers all over the world, over

1,000 of them. There are diseases out there

just waiting to be unleashed. It’s like we

are poking a stick at a lion – at some point

the lion will come and bite us in the ass.”


The researchers combed through more than 70,000 scientific papers that analysed the links between different climatic hazards and infectious disease. Some of these papers look at evidence stretching back 700 years, before the advent of the human-caused climate crisis. Of the 375 different infectious diseases mentioned in these papers, the researchers found that 218, more than half, have been aggravated by climatic impacts now being made more common by global heating.

A smaller proportion of infectious diseases, about 16%, were diminished by climate impacts, according to the paper, published in Nature Climate Change. Kira Webster, co-author of the study, said that as the database of disease grew …


“We became both fascinated and distressed

by the overwhelming number of available

case studies that already show how vul-

nerable we are becoming to our ongoing

growing emissions of greenhouse gases”.


Mora said there were probably multiple ways that the climate crisis worsened the spread of Covid, such as habitat disturbances by fire and flood that dislodge wildlife, such as disease-carrying bats, into new areas closer to humans. Mora said he has himself suffered from chronic aches in his joints after contracting chikungunya during an outbreak in Colombia a few years ago after a period of intense rainfall caused a boom in mosquito numbers.  He said …


“If there are pathogens that cause us

harm, climate change is trying to get

to every single one of them. For me, it’s

shocking we don’t take this more seriously.”


The World Health Organization has warned that the climate crisis “threatens to undo the last 50 years of progress in development, global health, and poverty reduction” and has estimated that an additional 250,000 people will die each year from 2030 to 2050 due to proliferating diseases such as malaria and diarrhea, as well as malnutrition and heat stress.

The new research is an “impressive mining of what’s been studied to demonstrate that climate shocks, on balance, make our already daunting task of combating microbes harder”, said Aaron Bernstein, director of the center for climate, health, and the global environment at Harvard University, who was not involved in the study.  Bernstein added …


“Climate science has shown that

climate change makes more parts

of the world too hot, too dry, too wet

and, ultimately, too unsuitable for

people to sustain their livelihoods.


“Mass migrations of people may spur

infectious outbreaks of all kinds, from

meningitis to HIV. In short, an unstable

climate creates fertile ground for infectious

disease to establish roots in and spread.”


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For reader recommendations on what seems an extremely serious problem not remotely in my area of expertise, I began by D for comments …


“This problem has the potential to be quite nasty.  As an example, Covid spread more easily in warm places.  And “long Covid” seriously deteriorates the quality-of-life experience – often for life.  This is another really good example as to why each individual on Earth needs to change their behavior in relationship to fossil fuels. 

“There is not much one can do to avoid some of these diseases.  But here are a few thoughts: 


“Learn through the CDC which countries have outbreaks in various diseases before traveling to them.  If you still so choose to travel, find the best ways to avoid getting the disease, such as mosquito-netting when sleeping, to avoid mosquitoes.

“Second, when you come back in, after having gone outside, and, be sure to do a tick check.  And remember that some ticks are extremely tiny, so try to have someone help you. 

“Third, do put on creams or sprays to avoid bites. 

“Fourth, learn where massive tick infestations are; then wear insect repellent and continue to be careful to check afterwards. 

“And fifth, you probably need to only drink filtered water outside the U.S.” 

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