Cooling Demand is Heating Up
As both incomes and average temperatures increase worldwide, so does air-conditioning use. In a paper published in Nature Sustainability last December, Berkeley researchers warn that global demand for cooling could drive huge increases in electricity usage.
Using daily temperature data from more than 14,500 weather stations, the group ranked 1,692 cities and 219 countries by “total cooling degree day (CDD) exposure,” a common metric for cooling demand. Their results pinpoint eight countries with higher CDD exposure than the United States: India, Indonesia, Brazil, China, Pakistan, Bangladesh, Nigeria, and the Philippines.
Currently, the U.S. leads in electricity use for cooling. Some 400 terawatt-hours of electricity go to U.S. air-conditioning annually, representing 1.5 percent of all electricity consumption worldwide. But as middle classes in developing countries expand, significantly more people are expected to buy air conditioners.
Two factors that influence CDD exposure are population size and temperature. Although the population of the Philippines is just one-third that of the U.S., for example, the island nation’s CDD is four times as high, owing to its hotter climate. Populous India leads with 28 percent of global CDD exposure, and Mumbai alone has a CDD exposure equivalent to 25 percent of the United States’.
Virtually everywhere on the planet is hotter than just two decades ago. Along a horizontal band through northern Africa, the Middle East, and southern Asia, vast areas are exposed to 3,000-plus and even 4,000-plus CDDs annually; by comparison, sweltering Phoenix, Arizona, has 2,700 CDDs.
“Increasing cooling demand will likely cause significant electricity-usage spikes worldwide,” said co-author Léopold Biardeau, a PhD student in agricultural and resource economics. “But adaptation strategies may help mitigate the need for air-conditioning. For instance, architecture can play a critical part in controlling temperatures inside buildings.”
– Adapted from a Haas Energy Institute Blog by study co-author Lucas Davis
A Homey Atmosphere
Photo by Callie Richmond.
Scientists who study air pollution have traditionally taken measurements outdoors, in urban areas with industrial smokestacks and spewing tailpipes. But people stay inside 90 percent of the time, so some curious researchers have begun to focus on indoor environments as well.
One of these scientists is Allen Goldstein, a professor in the Department of Environmental Science, Policy, and Management. Using cutting-edge instruments to test for volatile and semivolatile organic compounds (VOCs and SVOCs) indoors, Goldstein and his collaborators have found surprisingly high and dynamic concentrations of chemicals from sources such as cooking, cleaning, building materials, personal care products, and even people.
In one study, they took hourly measurements of VOCs and SVOCs in two Northern California homes over several months. The results showed hundreds of different VOCs, with at least 50 percent at concentrations 10 times higher than outdoors and 80 percent at concentrations at least double those outdoors. HOMEChem, another study in which Goldstein’s research group participated, used a test house to study emissions from specific activities like cooking and cleaning.
Measuring air chemistry indoors has proved extremely complex and is intriguing to researchers, as well as garnering a lot of broader interest.
Not only do everyday activities and indoor materials contribute chemicals to the interior atmosphere; some indoor emissions react with each other, resulting in new compounds. Heat, light, moisture, and interactions with surfaces can further alter chemical compositions and affect how they change over time.
Most studies are still in the early stages of understanding the emissions and the behavior of many of these organic chemicals, so it’s too soon to draw meaningful conclusions about the consequences for public health.
“Most of our exposure to organic chemicals is happening in indoor air, and most of that is happening in residences,” Goldstein told Chemical & Engineering News in November. “It’s relevant to try to understand these things, but we certainly aren’t trying to make a claim that we know a specific health effect that people should worry about from these chemistries.”
– Jacob Shea
How the Monkeyflower Gets Its Spots
Photo by Srinidhi Holalu.
The intricate spotted patterns dappling the bright blooms of the monkeyflower plant may be a delight to humans, but they also serve a key function for the plant. These patterns act as “bee landing pads,” attracting nearby pollinators to the flower and signaling the best approach toward the sweet nectar inside.
“They are like runway landing lights, helping the bees orient so they come in right side up instead of upside down,” said Benjamin Blackman, an assistant professor in the Department of Plant and Microbial Biology.
Using CRISPR-Cas9 gene editing, researchers produced monkeyflowers with altered red pigments. In a new paper, Blackman and his group at UC Berkeley, in collaboration with researchers at the University of Connecticut, reveal for the first time the genetic programming that helps monkeyflowers—and likely other patterned flowers—achieve their spotted glory. The team used CRISPR-Cas9 gene editing to re-create the monkeyflower patterns found in nature.
The study, which is the first reported use of CRISPR-Cas9 editing to research the biology of monkeyflowers, was published in February in the journal Current Biology.
– Kara Manke
What Killed Off the Neanderthals?
Photo: Wikimedia
For tens of thousands of years, modern humans and Neanderthals lived side by side. Neanderthals inhabited Europe and southwest Asia, while our ancestors lived in Africa. In the Levant—an area now containing Israel, Lebanon, and Syria— the ranges of the two groups overlapped. Then, some 40,000 years ago, Neanderthals suddenly went extinct, leaving Homo sapiens as the surviving human species on Earth.
The abrupt disappearance of the Neanderthals has remained a mystery to scientists. But a new study co-authored by researchers at UC Berkeley, Stanford University, and the Hebrew University of Jerusalem suggests that deadly diseases carried by modern humans may have been the cause.
Because Neanderthals and modern humans first evolved in separate ranges, the researchers hypothesized, each group would have harbored its own unique set of pathogens and immunities. Through mathematical modeling of disease transmission and gene flow, the researchers showed that when two species with unique diseases and immunities start to intermingle, a period of “stasis” often precedes the collapse of one species—which is precisely what happened in this case.
“There was this period where the two species coexisted, and then, relatively quickly, modern humans triumphed over the Neanderthals,” said Wayne Getz, a professor emeritus in the Department of Environmental Science, Policy, and Management and a co-author of the study, which appeared in Nature Communications in November.
“We wanted to know whether Neanderthal extinction could be explained by their having a less virulent, less diverse disease load that they brought with them when they met modern humans, compared with the disease load and the virulence of the pathogens that modern humans were bringing with them,” Getz said. “And it turns out that it could.”
– Adapted from an article by Kara Manke
Student-Led Course Focuses on Sustainable Action For students
Photo by Irene Yi.
For students seeking to apply academics to environmental action, one UC Berkeley course stands out: Zero Waste: Solutions for a Sustainable Future, taught by fourth-year conservation and resource studies major Sage Lenier.
Part of the DeCal program—in which students create, teach, and facilitate classes with faculty oversight—Lenier’s course educates students on how to incorporate environmental solutions into their lifestyles.
Lenier got her inspiration for the DeCal during her first year on campus. “We’d learn about huge problems like rising greenhouse gas emissions or topsoil collapse, but there wasn’t much focus on what we could actually do about it,” she said recently in a New York Times article about the course.
Lenier structured the class as a comprehensive environmental education for nonspecialists, starting with the relationship between consumerism and natural resources, climate change, and human rights. The class then covers such topics as the circular economy, industrialized food and agriculture, sustainable cities, and decarbonization.
“This course is an explanation of, and a call to action for, the necessary changes we must make as a society to not only avoid complete ecological catastrophe, but hopefully create a future that is more sustainable and equitable than today,” Lenier said.
Since its inception, her DeCal has become exceedingly popular. When it was first offered in 2017, around 25 students enrolled. This spring, three years later, nearly 300 students signed up. In 2018, Lenier won an award for her curriculum at the annual California Higher Education Sustainability Conference.
– Jacob Shea