Warming Trends: Best-Smelling Vegan Burgers, the Benefits of Short Buildings and Better Habitats for Pollinators

A column highlighting climate-related studies, innovations, books, cultural events and other developments from the global warming frontier.

A couple look at Paris skyline from the Montmartre area in Paris, on March 15, 2020. Credit: Stefano Rellandini/AFP via Getty Images
A couple look at Paris skyline from the Montmartre area in Paris, on March 15, 2020. Credit: Stefano Rellandini/AFP via Getty Images

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Hmmm. Smells Like Burgers

Which brand of plant-based meat alternative best imitates the fatty aroma of cooked beef? A new study tested it out. 

The research, conducted by scientists at Eastern Kentucky University and presented this week at an American Chemical Society meeting, found that the aroma from cooking a Beyond Burger was closest to the aroma of a beef hamburger, compared to other plant-based burger brands, including Impossible Foods’ Impossible Burger and Morningstar Farms’ Incogmeato burger. Both companies did not respond to requests for comment by the time of publication.

LiLi Zyzak, an assistant professor in the Department of Chemistry at Eastern Kentucky University, led the research, using a gas chromatography/mass spectrometry device, which detects the dozens of compounds that combine to form a scent, and an olfactometer, which allows the researchers to smell and characterize a scent. A food’s aroma combined with taste creates its flavor, Zyzak said, so the smell of a plant-based burger is important in simulating a hamburger flavor.

The plant-based meat industry has been growing quickly and is projected to continue to grow,  as demand for more environmentally friendly protein options keeps rising. Cattle account for 62 percent of the greenhouse gas emissions from the livestock sector, according to the United Nations Food and Agriculture Organization. 


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The Beyond Burger not only was closest in aroma to the beef hamburger, but also had some of the same compounds that led to a meaty, grilled flavor. 

The key to mimicking the beef flavor is to focus the flavor profile, Zyzak said, rather than trying to mask the plant’s flavor with excessive spices. 

“Beyond has done a pretty good job at it in terms of mimicking the profile,” she said. “But it’s not quite the aroma yet. There’s still some work to be done on it.”


Reconsidering the Climate-Friendly City Building

It has long been thought that cities with tall buildings that are densely packed are the most efficient and best for the environment. But a new study that looked at density and height separately found that dense cities packed with low-rise buildings are actually the most efficient and climate-friendly.

Francesco Pomponi, lead author of the study and head of the Resource Efficient Built Environment Lab at Edinburgh Napier University, said he realized that building dense and tall was seen as the most sustainable way to construct homes, offices, stores and other buildings in urban areas. But as he started to think through he math, he began to question this notion. 

“I think unless you stop for a second, it makes sense. Being closer to one another and going up seems to make sense,” he said. “But then actually doing research in structural engineering, I’ve realized we need a lot more structural materials when we build tall.”

In the study, published in the Nature Partner Journal Urban Sustainability, Pomponi and other researchers at Edinburgh Napier University modeled four types of cities—high-rise, high-density; low-rise, high-density; high-rise, low-density; and low-rise, low-density. The researchers simulated 5,000 urban environments under two scenarios—a fixed population with varying land area, and a fixed land area with varying population.

In each scenario, they conducted a cradle-to-grave life cycle analysis of each building’s carbon footprint, including emissions from the extraction and manufacturing of the materials, the energy used during the 60 years on average a building is used, the transportation of people to and from the building, the land on which the building is constructed and the deconstruction and disposal of the building materials at the end of the structure’s life. 

The researchers found that buildings in low-rise, high-density cities, similar to Paris or Vienna, had a lower carbon impact than buildings in high-rise, high-density cities, similar to Manhattan. 

This is because taller buildings use more materials and they need to be built further apart, Pomponi said. High-rise buildings are bulkier, with a larger foundation that requires more materials, each with its own carbon footprint. Plus, taller buildings need to be constructed with more space between them than shorter buildings for privacy, lighting and ventilation, Pomponi said. 

Pomponi hopes these insights will help inform future development in places like China and some countries in Africa, where new cities are appearing quickly, and even in places like the United States and Europe that have already developed cities but are building new neighborhoods from the perspective of lifecycle carbon emissions. 

“We’re dispelling the myth that there’s one way only to accommodate a growing urban population,” he said. “This is not true, and we’ve been able to prove it mathematically, with numbers.”


Tales From Mongolian Trees

An analysis of tree rings in living and dead Siberian larch trees in Mongolia has allowed scientists to create a 750-year record of summer temperatures in the remote region, which is rapidly warming. 

Researchers at Columbia University’s Lamont-Doherty Earth Observatory used a relatively new method of tree ring analysis called delta blue intensity, which uses blue light reflectivity to measure the density of tree rings and determine what the temperature was when they formed. 

The tree samples were collected in 1998 and 2005 from living trees, which can be 400 to 500 years old, and from dead, “subfossil” trees that can be preserved for 1,000 years in cold, dry conditions. But for years, the tree samples could not be processed with existing technology. Nicole Davi, an adjunct senior research scientist at Columbia, picked up the research and led a reprocessing of the tree rings with the new delta blue intensity technology and published the findings last month in the journal Geophysical Research Letters

The analysis compiled temperature data stretching back to 1269, and was verified by records of climatic events like cooling after known volcanic eruptions and by observational data collected in the region since 1950.

Central Asia is an important area for studying temperature change, Davi said, because of how quickly it is warming. Summer temperatures in Mongolia are increasing at a rate three times higher than the global average, the researchers wrote in the study, and the region is experiencing longer and more intense droughts, affecting the livelihoods of farmers and ranchers there.

Davi compared what is happening in Mongolia to the southwestern United States, where a decades-long drought has led to low water levels in reservoirs like Lake Mead. 

“There are similar climate impacts happening in Central Asia. We just aren’t hearing about them as much,” Davi said. “This is another point of reference in a place where we have very limited points of reference for what’s happening in the climate system.”


Building Back Better—For Pollinators

A new computer program puts the intricate knowledge that scientists have developed about bee needs and behavior into the hands of farmers and land managers, who can use that information to make smarter decisions for their local pollinator populations. 

Bee-Steward, a user-friendly software tool developed by researchers at the University of Exeter, allows landowners to see a map of their own farms, detailed down to every flower and tree. With this tool, landowners can test and see ways they can improve their pollinator habitat. For example, the software may point out a specific area where a farmer could plant a particular species of flower that would improve bee populations by a certain percentage. 

“These tools basically take the really complex mechanisms behind honeybee or bumblebee growth and survival,” said Grace Twiston-Davies, a research fellow at the University of Exeter who helped develop the software. “Then from that we can work out some management recommendations in the real world to help pollinators thrive.”

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These models have existed for a few years and have been used by academics studying bees, but the software allows it to be used on the ground by the people who are actually making decisions on landscapes. 

“A farmer knows his land better than anybody else, he knows where the best place is for trees or plants and wildflowers, because that’s his job, every single day he’s out there,” Twiston-Davies said. “So, actually putting it back into the hands of the farmers and the land managers is really, really valuable in engaging and then incentivizing those actions that the model might suggest.”


Three Cities Aim for Zero Diesel Emissions

Three American cities are receiving $100,000 and a year of support to help transition commercial vehicles away from diesel fuels.

Chicago, San Diego and San Jose have been selected from a pool of 25 cities to receive a year of funding and technical support from the Delivering Zero Emissions Communities program managed through the Natural Resources Defense Council to help each city transition towards zero emissions vehicles in commercial fleets and freight transportation.

Transportation is the largest source of greenhouse gas emissions, according to the EPA. About one-third of vehicles on U.S. roads are powered by diesel, which can lead to poor air quality, increasing the risk of heart and lung diseases and other adverse health effects. 

“Our freeways and our freight hubs are disproportionately located in communities of color, and low income communities, meaning that those communities are facing the most direct and constant pollution,” said Amanda Eaken, the transportation director of the Bloomberg Philanthropies American Cities Climate Challenge at NRDC.

Each of the three cities is using the funding differently, Eaken said. Chicago will use it to fund its Drive Clean Chicago program to roll out zero emissions commercial vehicles in specific communities and invest in a cargo e-bike pilot program to displace delivery trucks. San Diego plans to put the decision-making power around zero emissions commercial vehicles in the hands of the communities that are most affected. And San Jose will create groups to partner with community members and private sector stakeholders to spearhead the transition.

“Each city takes its own unique pathway towards the goal of zero emissions commercial vehicles, and we feel that’s a real strength of the program,” Eaken said. “Part of the idea is to model different pathways that then may each be successful in different ways and also may each be relevant and replicable to other cities.”