Science Snippets: Differential Responses to Climate Change Illustrated by Rats, Ants

Draft script:

As I have indicated previously in this space, the responses of different organisms vary considerably due to environmental changes. Relying upon two articles in National Geographic and an article in the peer-reviewed journal Science Advances, this video indicates the differential responses of rats and ants to climate change.

First up, the good news, if you’re a rat. An article published on 31 January 2025 in National Geographic is titled Climate change is amazing—if you’re a rat. The subhead: “In the first study of its kind, scientists found a correlation between climate change and a rise in urban rat populations.”

Here’s the lede, followed by a single sentence to complete the first paragraph and another paragraph marked by a single sentence: “Scientists have already linked climate change to more severe weather, rising sea levels, and melting polar ice caps. And now, a new study offers more bad news.

Urban rat populations appear to be rising with the mercury.”

The article in National Geographic explains the economic importance of rats: “Rats already cost the United States approximately $27 billion each year in damage to infrastructure, crops, and contaminated food supplies. At the same time, media reports tend to suggest that rat populations are skyrocketing. And yet, when scientists started looking into the supposed rodent boom, they hit a wall.”

A Professor of urban ecology at the University of Richmond is the first author of the peer-reviewed paper in the renowned Science Advances. Also published on 31 January 2025, the peer-reviewed, open-access paper in Science Advances is titled Increasing rat numbers in cities are linked to climate warming, urbanization, and human population. The peer-reviewed paper was written by 19 scholars. The first author is again quoted in the article in National Geographic: “It seemed like that data would be pretty easy to get. But we were wrong about that.” He explained that pest control departments in most cities are underfunded and understaffed. Wait, what? People don’t want to work in pest control? Citizens and their representatives don’t want to spend a lot of money to eliminate pests?

I’m kidding, of course. Most of us would rather have pests disappear without cost to us. Among the many expectations of privileged people is that of a pest-free existence. As with many other issues, we simply want this problem to go away without even thinking about it. After all, pests are called pests for a reason. The Merriam-Webster online dictionary defines a pest as “a living thing that is a nuisance or harmful to humans, their belongings, or the environment.” I don’t know about you, but I want a pest-free existence, preferably at no cost to me.

After explaining that the peer-reviewed paper is based on data from 16 cities with at least 7 years of calls made to 311 numbers, the first author of the peer-reviewed paper is again quoted in the National Geographic article: “We found that, yes, rat numbers are generally increasing in cities around the world. And cities that are warming faster have larger increases in rats over time.”

Based on the 16 cities that had at least 7 years of calls—some of which had 17 years of calls—the peer-reviewed paper used this information as a proxy for rodent populations. In 11 of the 16 cities, rat numbers rose significantly during the time of study. Washington, D.C. led the way, which surely is no surprise to those of us who have occupied or visited the U.S. capital. After only a few months during the year I lived in Washington, D.C., I realized that disgusting, furry mammals of all kinds were abundant.

Not surprisingly, the article in National Geographic quoted the peer-reviewed paper in Science Advances in pointing out that cities with more dense human populations and more urbanization exhibited larger increases in the number of rats. Specifically, the Abstract of the peer-reviewed paper includes this information: “Warming temperatures and more people living in cities may be expanding the seasonal periods and food availability for urban rats.”

Yes, that’s correct: More people means more wasted food. And what we call waste, rats call dinner. And lunch. And breakfast. And the occasional snack.

I turn now to the second paper published in National Geographic. Published 14 January 2025, it is titled These ants are saving our forests—by spraying acid everywhere. That’s right: I have a rare bit of good news.

I have mentioned the power of mighty ants previously in the space. The subhead in this latter National Geographic article supplies further information about the positive effects of ants: “The engineering and defensive skills of red wood ants help the endangered species transcend its small stature in the natural world.”

Red wood ants are classified as belonging to the genus Formica. They are one of the tiniest of all species referred to as keystone species. Keystone species, including elephants and sharks, have tremendous impacts on ecosystems. As their numbers change, the entire ecosystem changes disproportionately. What seems like just another species among dozens or hundreds of species within an ecosystem becomes apparent when the entire ecosystem responds negatively.

According to the latter article in National Geographic, red wood ants generate formic acid in a venom gland. As they build a nest, the ants gather tree resin, which is antimicrobial. They spray the tree resin with their formic acid, which has its own antimicrobial properties. The result is a particularly potent chemical that the ants place throughout their nest as a means of fighting bacterial and fungal pathogens.

Formic acid is also used to kill other insects. The ants bite other species, such as wood-boring beetles that weaken and kill trees. In so doing, the ants promote the continued existence of the trees, which are otherwise susceptible to death from the wood-boring beetles.

As I have pointed out many times in this space, we are one. The positive power of ants is a trenchant reminder of our dependence on other species.

The negative impacts of climate change on rats is no surprise to those of us paying attention. Just when you believe the negative impacts of climate change have been fully described, another bit of bad news appears.