More mold and mildew in a warming world

Climate change increases mold and mildew and their concomitant problems

We live in a warming world. And because of that greater warmth and the increased precipitation it can cause, we are living, more and more, in a moldy, mildewy world. While most of us think of mold as an occasionally bothersome fact of life, the increasing molds and mildew have ramifications for human health and agriculture.

What are mold and mildew?

A mold is any species of microscopic fungi that grow as long, branching multicellular filaments called hyphae. We’ve all seen mold. It’s that stuff growing on the jelly you forgot at the back of the fridge. And I’m always finding it when I open up that container of sour cream I bought a couple weeks ago. If there is organic material—paper, clothing, leather, etc.—and moisture, there will be mold. That dark stuff on your unused gloves and mechanic’s manual you keep in the garage? That’s mold. Mold will grow on floors, walls, and ceilings of houses where moisture is a problem.

Mildew is a type of mold. One difference is that mildew will appear whitish in its early stages. The black stuff that crops up on your windowsills and shower stalls, that’s mildew. Mildew affects living plants. Where I work as a gardener, there is a tree in a shady spot underneath an eave. The tree is shielded from winds and receives water runoff from the roof during storms. I am often fighting mildew that grows on the tree’s leaves.

Mold and health

Mold is pretty ubiquitous. Even in clean, dry homes and buildings, mold spores enter from the outdoors, blown in by the wind or hitching rides on clothing or pets. Besides being some of the ugliest stuff around, molds emit toxins and can be a source of health problems. Everyone is exposed to molds all the time, and most folks don’t have much problem with them. But for some folks, being around molds can cause them to have a stuffy nose, sore throat, burning eyes, coughing and wheezing, or burning eyes.

Mold and mildew [SOURCE?]

People who are asthmatic or allergic to molds can have more severe reactions. And people with compromised immune systems or chronic lung disease, such as COPD, can get infections in their lungs from mold, causing fever and shortness of breath.

Mold and agriculture

You don’t have to be a farmer to know how mold can affect crops. We have all reached into the refrigerator for the grapes or strawberries that we bought just yesterday, only to find them engulfed in whitish, fuzzy mold.

That white mold is Sclerotinia sclerotiorum. It attacks hundreds of plant species and can ruin beans, potatoes, tomatoes, cabbage, and other crops. It can sometimes ruin an entire crop yield.

Mold can also affect grain crops, mostly during storage. The U.N. estimates that about 14 percent of the world’s grain production, valued at an estimated $400 billion U.S. dollars is lost to mold every year.

Grain and hay contaminated with mold loses nutritional value for feedlots and can sometimes lead to health problems when fed to cattle. Ranchers and farm workers who breathe in mold spores can develop a disease known as farmer’s lung, with symptoms that include chronic cough and a general feeling of tiredness and depression.

Grains contaminated with mold can sometimes make it into the food system. Eating such tainted foods can be very serious, causing kidney and liver failure. Mold-tainted foods have been associated with liver cancer and birth defects.

Climate change brings more mold

Extreme weather, drenching houses for long periods or downpours, are increasing indoor mold growth. And damp conditions in flooded buildings—an increasing occurrence due to climate change—also greatly increase mold growth, which can start just days after a storm. Examining levels from 2002 to 2019, scientists reported an increase in mold spores in San Francisco. New York and other cities are reporting similar problems.

For decades, climate change has been spreading molds that live in warmer environments into more temperate regions. As far back as 2003, a fungus that had been little known in Italy spread throughout the peninsula and ruined crops during a spell of unusually hot, dry weather. A similar outbreak hit France in 2015.

If current climate scenarios work out, scientists predict that within the next 100 years, Aspergillus flavus, a fungus that thrives in hot, humid climates, could threaten food safety throughout southern Europe. Other tropical fungi are infecting barley, grapes, and coffee as temperatures increase. The science suggests that, overall, fungal infestations of crops will increase because of climate change.

Valley fever, a fungal disease that infects humans and animals when they breathe in dust containing the spores, causes cough, fever, chest pains, and fatigue. The fungus lives in the soil of hot, dry regions. It has commonly occurred in the American Southwest and parts of Mexico and Central America. Climate change may be spreading and increasing the disease. From 2014 to 2018, valley fever cases tripled in California. From 2018 to 2022, between 7,000 and 9,000 cases were reported each year in the Golden State. The scientific consensus blames increased droughts for driving the increased infections. Climate change may be spreading the disease as well; a case was reported in Washington State in 2015.

Staying healthy

Folks may feel safe because their homes or workplaces are air conditioned, but mold has a way of working itself into buildings from the outside. Though you may not find molds in your shower stall, they may lurk in air ducts, crawl spaces, and basements. Regular building inspections that include mold observations can preclude these problems.