SCIENCE

Underestimating Heat Indexes 

In the midst of a heat wave, your weather app will not only tell you how hot it is, but also how hot it feels, combining heat, humidity and your body’s ability to respond into a metric known as the heat index.

But scientists from the University of California, Berkeley say that at high temperatures and relative humidities, the heat index is way underestimated, in some cases by as much as 20 degrees Fahrenheit.

In a paper earlier this year, Yi-Chuan Lu and David Romps updated a model from 1979 that estimated the heat index at temperatures up to about 88 degrees Fahrenheit for a high relative humidity of 80 percent. Beyond that, the mathematical model broke and could not calculate an accurate heat index. 

Since then, the index has been extrapolated by the National Weather Service into the undefined area beyond where the 1979 model could calculate, and that’s the number you likely see on your weather app, if it relies on the agency’s heat index. At the time, these extreme conditions were so rare that this was not much of a concern. But now, a warming climate regularly drives up temperature and humidity into deadly zones. 

For a temperature of 96 degrees and 70 percent relative humidity, the “feels like” temperature was calculated as 126 degrees based on the extrapolated National Weather Service heat index. With the updated model by Lu and Romps, that would now be 20 degrees higher at 146 degrees.

“We’re just on this path to potentially pushing the heat index in places around the world into conditions that just are not livable and workable,” said Romps, an earth and planetary science professor at Berkeley. “We’ll start to see real tightening of the number of hours and when people can work outside, when our children can be outside.”

The updated model found that the National Weather Service heat index far underestimates how the human body truly perceives extremely hot and humid conditions. Humid air interferes with the body’s ability to cool off using sweat, since the moisture does not readily evaporate in humid conditions. At a heat index of 161 degrees, Romps said, the human body hits a point where it “runs out of tricks” to keep its core temperature at 98.6 degrees, and careens into a danger zone. That may seem outrageously hot, but with the updated model, a temperature of just 97 degrees can combine with 80 percent humidity to hit that dangerous point.

In a new paper out this month, Romps and Lu take this new model and look back at significant heat waves that hit the United States in the last several decades. They found that the highest heat indexes occurred in the Midwest, not in the Southeast, as Romps said he expected. In a 1995 heat wave, which killed over 400 people in Chicago, the heat index reported at Midway Airport was 124 degrees. The updated model puts that now at 141 degrees. That signals a huge difference in the body’s physiological response, Romps said. 

“That has implications for how stressful these heat waves were, because each value in the heat index corresponds to a unique behavioral and physiological state of a person,” he said. “These differences do indeed matter.”

CULTURE

The Demise of Freya the Walrus

Many are outraged after officials in Norway decided to kill a walrus known as Freya that had become a media darling and a happy sight in the Oslo fjord, but was also deemed a potential threat to humans by Norwegian officials.

The 1,300-pound walrus had been spotted dozens of times on the coasts of Norway and other North Sea nations in the last year and a half. Often she was seen sunning herself on dinghies and motorboats in populated harbors. 

Norway’s Directorate of Fisheries said in a statement this week that Freya was euthanized “in a humane fashion” on Sunday morning. People were disregarding warnings to stay away from the animal, the statement said, and “potential harm to people was high and animal welfare was not being maintained.” The officials considered moving Freya, the statement said, but determined it would be too complex and impossible to conduct.

“We have sympathies for the fact that the decision can cause reactions with the public, but I am firm that this was the right call,” said Director General of Fisheries Frank Bakke-Jensen in the statement. “We have great regard for animal welfare, but human life and safety must take precedence.”

Much like polar bears, walruses depend on sea ice for survival, which is becoming less available with a warming climate, so the animals are seeking out terrestrial habitats.

Rune Aae, who created and maintained a map of Freya sightings, wrote on Facebook that officials were too hasty in their decision to euthanize the walrus, given that the summer holiday is coming to an end and the Oslo harbor won’t be as populated once school is back in session.

“Killing her was, in my view, completely unnecessary,” he wrote. 

Others posted about their anger on a Facebook group dedicated to tracking Freya’s movements. Many were frustrated not only by the government’s choice to kill her, but also by the people who did not heed warnings to stay away from the wild creature. 

A fundraiser was shared in the group asking for donations to construct a statue in Freya’s memory. Over 240,000 Norwegian krone, or about $25,000 had been raised by the time of publication. If the funds do not go toward a statue, the fundraiser description says, they will be given to the country’s World Wildlife Fund organization, which also shared their disapproval of the choice to euthanize Freya. 

“Let the legacy of Freya be that Norway reaches its climate goals, so that we do our part to take care of the nature that is the habitat of the walrus,” said WWF Norway’s Oceans Team Leader Fredrik Myhre in a statement translated from Norwegian.

SCIENCE

A Blue Tit, Only Less

The blue tit is a common bird found widely across Europe. It’s easily recognizable with its bright blue crown and sunny yellow chest. Yet climate change may be connected to those colors becoming more dull, a new study shows, with implications for mating and sexual selection. 

Both females and males exhibit the striking blue and yellow colors, and both use the colors to choose a mate, said study lead author David López-Idiáquez. He and others from the Center for Functional and Evolutionary Ecology in France looked at 15 years of data on blue tit coloration in two locations, mainland France near Montpellier and the Mediterranean island of Corsica. They found that from 2005 to 2019, the colors in both populations became more muted, and in the Corsica population, the color loss was correlated with a rise in temperature of 1.2 degrees Celsius and a decrease in precipitation of 0.6 millimeters during the annual molting, when birds shed their old feathers and grow new ones. 

López-Idiáquez said they are not able to determine if or how these climatic changes caused the color changes in blue tits in Corsica by just looking at this data, but future experiments could help figure that out, and determine if indirect effects of climate changes, like food quality or availability, are to blame. 

“It’s difficult to say which is the specific mechanism explaining the change that we found,” López-Idiáquez said, “because it is probably multifactorial and there are many things behind this.”

The trend toward duller coloration is not due to a genetic change, he said, but a phenotype change, indicating that the cause is environmental, not evolutionary. He compared this to the human experience of our skin getting darker when exposed to the sun. That’s not because our genes have changed, but because our environment has changed our appearance. 

The birds use coloration to select a suitable mate—more vibrant color means a more suitable partner. But if the trend of lost coloration and decreasing variation between individuals continues, López-Idiáquez said that the effect of sexual selection could be diminished and mating may become simply random.

“This potentially has a lot of implications in terms of population viability,” he said. 

SOLUTIONS

A Vice President for Carbon Strategy 

Hines, a giant real estate firm with over $90 billion in assets in 28 countries, appointed its first vice president of carbon strategy last fall. The role could become more common as carbon emissions associated with buildings contribute to nearly 40 percent of greenhouse gas emissions globally and cities like New York are focusing on buildings for big emissions cuts.

Michael Izzo, the executive serving in this novel position, said his job requires him to keep an open mind to meet the needs of stakeholders from finance to engineering, while focusing on ways to eliminate carbon in Hines’ buildings. 

Buildings are such a dominant source of carbon emissions because of the carbon emitted to create and transport the materials used to build them and the carbon emitted to power and maintain the buildings. Plus, buildings stick around for decades after they are constructed, so the way they are built has important implications for their future carbon footprint. 

“Fossil fuels within buildings are the problem, if you talk about it from an operational point of view,” Izzo said. The solution is to electrify buildings and create systems that reduce waste and recycle energy to improve efficiency, he added.

The firm recently announced its intention to have net-zero carbon emissions from building operations by 2040 without buying carbon offsets. Instead, they plan to electrify buildings, increase efficiency and invest in renewable energy to eliminate the need for carbon-based energy sources. 

That vision is currently in the works at 555 Greenwich Street in Manhattan, a project that Izzo has been involved with since before he took on this new role. The 16-story building will be constructed to radiate warm and cool air back into the building to reduce the need for energy-intensive climate control. The building will also be fully electric and is expected to reduce carbon emissions by 45 percent, exceeding New York City’s 2030 carbon reduction goals for buildings. The city attributes about two-thirds of its carbon emissions to buildings and their operations. 

Izzo expects that other real estate companies will follow Hines’ lead in dedicating resources to carbon reduction. “It’s a complex problem, but it’s not complicated,” he said. “But the complexity is what we really have to navigate and it takes quite a long time.”