Poison ivy will likely become both larger and more resilient due to climate change.

Scientists testing how climate change affects plants found, in a years-long simulation study, that poison ivy grew 70% faster with the resulting extra carbon dioxide.

Scientists testing how climate change affected plants found in a years-long simulation study that poison ivy grew 70% faster than it did without extra carbon dioxide

The experiments in the 1990s were designed to simulate potential 2050 conditions, using carefully controlled circular forest plots with gas pumped into them.

Poison ivy's rash-causing compound is found in the plant's roots, stem, and leaves—so coming into contact with any part of the plant can lead to rashes for the 85% of people who are allergic to it.

Poison ivy's rash-causing compound is found in the plant's roots, stem, and leaves—so coming into contact with any part of the plant can lead to rashes for the 85% of people who are allergic to it

Once sold as an ornamental plant, poison ivy can actually look varied—its colors change seasonally from reddish to green to yellow. It typically has three broad, shiny, tear-shaped leaves. But it sometimes may have a different number of leaves, and its edges can be serrated.

Poison ivy can cause rashes year-round since all parts of the plant contain urushiol, the oil that triggers our allergic response.

Urushiol, the oily toxin in poison ivy, can remain allergenic on clothing for years.

Poison ivy can cause rashes any time of the year

This myth-busting article about poison ivy notes that all parts of the plant contain urushiol, the oil that triggers our allergic response, so if you are in the woods in winter you may be still encounter the plant—and urushiol.

Poison ivy's characteristic rash is caused by an allergic response to an oily compound in the plant called urushiol.

Urushiol, the oily toxin in poison ivy, can remain allergenic on clothing for years

The substance can still cause rashes even after being on shoelaces, clothing, sleeping bags, boots, or other clothing for multiple years—some reports say five years on surfaces—so they all need to be washed after outdoor adventures with the plants.

This poison ivy knowledge quiz—accompanied by photos of the plant's varied forms—may help you identify this common rash-inducing growth.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak each year.

Poison ivy is in the same family as mangoes, cashews, and pistachios—and they all produce oily urushiol in their raw, unprocessed state—but they are typically prepared in ways to avoid causing human discomfort.

Poison ivy was sent to Europe in the 1600s as an exotic, ornamental oddity, where it was purposefully grown in the English royal gardens at Kew, the Faculty of Medicine in Paris, and a few other locations.

Poison ivy was sent to Europe in the 1600s as an exotic, ornamental oddity

The plants were grown in the English royal gardens at Kew, the Faculty of Medicine in Paris, and a few other locations.

Climate change creates conditions for more invasive species

Increasing temperatures shift the conditions native organisms are accustomed to, allowing those from warmer climates to move in with a greater chance of survival. Drought stress can cause invasive plants to absorb less herbicide, limiting the effectiveness of the control method, while melting ice can open new Arctic shipping routes, expanding the transport of species.

Increases in atmospheric carbon dioxide lead plants to produce more pollen

Pollen issues are emerging earlier in the year and lasting longer as rising levels of carbon dioxide in the atmosphere boost plants’ pollen production and also simultaneously extend warmer, pollen-producing seasons.

A third of Americans now live in wildfire risk zones

Climate change and human development into fire-prone regions have extended the wildfire season, with some areas experiencing fire conditions year-round. Extreme conditions, poor compensation, and exposure to carcinogens have complicated firefighter recruitment, further exacerbating wildfire risks.

Environmental conditions, shifting immunity, and viral strain could help explain 2025 spike

The surge in HFMD in the summer and early fall of 2025 in the mid-Atlantic could be the result of a confluence of factors, including a more virulent strain of disease-causing virus, good environmental conditions for the virus to spread—hot, humd—and a potential immunity gap among kids due to milder HFMD outbreaks the previous year.

The ‘humongous fungus’ may be the largest organism on Earth at more than 2,300 acres

Discovered in 1988, when it was only covering 400 acres, this massive colony of Armillaria ostoyae, based in Oregon, has taken hold among the tree roots of the Malheur National Forest. It consists of a vast network of unique long black filaments of fungal tissue called rhizomorphs that grow under the soil and infect tree roots, nourishing the fungus but killing the trees. Researchers believe this fungal growth dates back more than 8,000 years and currently weighs approximately 35,000 tons.

Wildfires have seriously affected Napa's winemaking

If there’s a single thing that has defined the last decade of California winemaking, it’s the effects of climate change, particularly wildfires. To avoid the threats of wildfires, some vineyards have pivoted to more heat-tolerant grapes.

Plants use physical and chemical defenses to protect themselves

Tree bark is difficult to chew and resistant to pathogens, while the waxy cuticle on the surface of leaves deters insects and microbes. Some plants possess thorns, spines, and prickles to discourage predators. Plant cells can also produce antimicrobial toxins or release compounds to alert parasitic wasps to lay eggs in attacking insects.

Land use changes in Connecticut may have helped to enable Lyme's leap into humans

Forest clearing and fragmentation, alongside suburban development, may have contributed to the emergence of Lyme disease in humans in the 1970s. Those changes brought mice, carriers of the disease, into greater contact with people. Climate change is also facilitating Lyme's spread as tick populations survive milder winters and move northward.

Even in recent history, adaptations to the environment drove human evolution

Through genetics, environmental pressures, and cultural influences, humans have evolved to tolerate lactose, develop varying skin pigmentation, and acquire genetic resistance to diseases like bubonic plague. The metabolic and digestive systems of Indigenous peoples have adapted to their diet, which is influenced by the availability of food and water.

Inhalers, antihistamines, immunotherapy, and more have made allergies a multimillion-dollar market

Market research suggests that the allergies market will continue to grow in the years ahead as the number of allergy diagnoses increases, identifying new patients. Areas of growth include the increasing interest in immunotherapies designed to retrain the immune system through regular exposure to potential allergens via injections and under-the-tongue medical formulations, among other approaches.

Lightning may kill as many as 320 million trees each year

Ignoring the effects of tree loss resulting from lightning-induced wildfires, researchers at the Technical University of Munich developed a quantitative model to estimate the loss of these organisms due to cloud-to-ground strikes, based on global lightning data and forest structure. They expect the estimate to rise due to increased strikes resulting from climate change.

The fragility of the alpine tundra

This article takes readers into Rocky Mountain National Park's Alpine Tundra, an area above the tree line where only specially adapted plants can survive. One such plant is the cushion plant, which avoids strong winds by growing close to the ground...

Heatstroke can reprogram your DNA, putting survivors at risk of future health problems

Severe illness from extreme heat exposure can alter DNA through epigenetics—turning genes "on" or "off" to shape disease risk. These changes can place an organism at greater risk of future health complications—unlike the epigenetic changes produced by moderate, repeated heat exposures.

The Chernobyl exclusion zone has become a unique wildlife refuge

Within the area—roughly the size of Yosemite National Park—animals such as wolves, bears, and feral dogs descended from the pets left behind have gradually adapted to low-level radiation. Eastern tree frogs in the area have darker skin than usual, which may have helped protect them from ionizing radiation.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Women typically have more robust immune responses than men

This difference helps women better combat infectious diseases, but this more turbo-charged response may also make women more vulnerable to autoimmune diseases by potentially priming their immune systems to overreact to their own cells and tissues and label them as invaders that must be destroyed. Roughly 80% of American women have autoimmune conditions.

Aerial photos of red tide off the Gulf Coast

The toxic algae grows naturally in warmer oceans in small amounts and is typically harmless. With extended warm periods and unusually-high additions of nutrients from run-off, the algae blooms extensively, posing health risks to wildlife and humans...

Why Earth will be made uninhabitable by the sun far sooner than when the sun dies

The star has enough fuel to continue fusing hydrogen into helium for another 5 billion years, but the gradual increase in core temperature from these reactions will brighten the sun by 10% every billion years. Some models predict that the increased radiation will be enough to vaporize all of Earth's surface water about 1 billion years from now, long before the sun becomes a red giant and disintegrates the planet.

Tick bites can fuel an allergy to a sugar molecule in red meat

Alpha-gal syndrome is on the rise globally as ticks spread due to climate shifts. Bites from some ticks can trigger a sensitivity to a sugar molecule called alpha-gal found in mammal meat, which can lead to allergic responses to hamburgers and steak, among other products. Listen to an expert’s tips for avoiding this allergy, including quickly removing any ticks to limit exposure to their saliva or vomit.

How bedbugs have evolved immunity against pesticides

Bedbugs, once nearly eradicated in the United States due to the use of pesticides like DDT, have made a resurgence, with New York being declared the most bedbug-infested city. The primary reason for the return is the evolution of resistance in...

Air pollution in war-torn Iran unleashes invisible toxic threats

Burning oil depots and bombed buildings are endangering the health of millions of people during the 2026 attacks. Heavy metals from munitions and other damaged materials are going airborne, but the exact health implications depends on dose, wind currents, and other factors including preexisting health conditions.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

Watch how viruses like Ebola can spill over from animals to humans—and vice-versa.

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

Louisiana's 'Cancer Alley' is infamous for having some of the highest industrial pollution, toxic air emissions, and cancer risks in the US.

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

Tattoos remain visible on your skin thanks to immune cells called macrophages

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

Fireworks-related ER visits are on the rise—in 2024, they increased by 52% as compared to the prior year.

The deadliest aspect of volcanic eruptions is often not lava, but pyroclastic flows—avalanches of ash, gas, and rock that can move more than half the speed of sound.

The power and influence of the American presidency have expanded significantly over time—far beyond what the founders envisioned.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in casualties, forces mobilized, and displacement of civilians.

In recent years a child anxiety expert has created and tested a novel phobia and anxiety treatment approach for children, focused on changing how parents respond to the fears.