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What's the Best Kind of Car for the Climate?

Climate
What's the Best Kind of Car for the Climate?

By Sara Peach

Dear Sara,

I live in a city that does not have great transportation options, and I live far enough from my work that I am not able to walk or ride a bike. I have a 15-year-old car that I am looking to replace.


My husband and I are open to buying a hybrid or electric car. We live in Michigan, and the gentleman at the dealership told us that in our climate, we would not get maximum efficiency out of a hybrid due to cold temperatures in the winter. Additionally, I understand that hybrid and electric cars have less of a footprint on the road, but require greater resources to create, thus negating the benefit. Is that true? – Christina in Michigan

Dear Christina,

One of the claims you've heard is true – but it's not the whole picture. And the other is false. As I'll explain, Michigan is an imperfect place to drive hybrid or electric vehicles. But overall, their benefits to the climate outweigh the drawbacks, so these vehicles can make solid choices even in your cold Midwestern state.

Why Hybrids Can Be Better for the Climate

Most cars and trucks run by burning diesel or gasoline in internal combustion engines. They contribute to climate change by releasing heat-trapping carbon dioxide from their tailpipes.

Hybrid vehicles, by contrast, contain both an electric motor and an internal combustion engine. The electric motor assists the gasoline engine and in some cases propels the car on its own, boosting the vehicle's efficiency. Hybrids also take advantage of several fuel-saving features, such as powering off automatically at stoplights to prevent idling. As a result, they typically boast better fuel economy – and therefore a smaller climate impact – than vehicles running on conventional engines alone.

But be sure to compare mileage ratings: A hybrid SUV may get fewer miles to the gallon than a compact car running on a conventional engine alone.

The Climate Benefits of Electric Cars

Fueling and driving an electric vehicle generally produces far less carbon dioxide than a car with a conventional engine. That's because across much of the U.S., generating the electricity to charge the car produces less heat-trapping pollution than burning gasoline or diesel.

That said, the mix of fuels powering the electricity grid makes a big difference to the climate impact. For example, California generates less than half of its electricity from fossil fuels. As a result, the average electric car charged in the Golden State is responsible for the same amount of carbon dioxide as a gasoline car getting 109 miles per gallon, according to a Union of Concerned Scientists analysis. In Michigan's Lower Peninsula – where a larger share of electricity is generated from fossil fuels – an average electric car pollutes as much as a gasoline car getting 49 mpg. That's worse for the climate than an electric car fueled in California, but still better than the average new car with an internal combustion engine.

In fact, most U.S. residents now live in a place where electric cars get at least the equivalent of 46 mpg, and often much higher. You can see the mileage estimate for your region here.

When it comes to climate change, an electric car holds another advantage over vehicles with conventional engines: the opportunity to improve if and when the grid reduces its reliance on fossil fuels.

"If you buy a gasoline car, you know, the efficiency is set," said David Reichmuth, an engineer who studies vehicles at the Union of Concerned Scientists. "If anything, it gets a little less efficient, you know, as the car gets older – whereas the electric car could effectively become cleaner over time, not because it becomes more efficient, but because the electricity going into it will become cleaner over time."

How Does Cold Weather Affect Vehicle Efficiency?

Your dealer was correct to say that cold weather reduces the efficiency of hybrid vehicles. But that's not the whole picture. In fact, cold weather causes efficiency to decline in all three kinds of vehicles – hybrid, electric and internal combustion engine. In icy temperatures, vehicle batteries and engines simply don't perform as well as they do in warmer weather, among other factors that drag down efficiency.

According to FuelEconomy.gov, a gasoline car's mileage is 12 to 22% lower at 20 degrees Fahrenheit than at 77 degrees. For hybrids, fuel economy falls by 31 to 34% in cold weather.

But that need not deter you from purchasing a hybrid vehicle – provided you choose one with a high mileage rating. Top-performing hybrids, such as the 2019 Hyundai Ioniq hybrid (58 mpg) and the 2019 Toyota Prius (56 mpg), will likely contribute less to climate change than vehicles with conventional engines, even accounting for cold-weather efficiency declines.

As for electric vehicles, a 2015 paper by Carnegie Mellon researchers found that the range of the Nissan Leaf can drop by as much as 36% in cold climates. Test drives of several electric vehicle models by AAA and Consumer Reports have also found substantial range losses in cold temperatures. So don't miss these tips from Consumer Reports, which advises those living in cold climates to purchase a car with twice the range they expect to use.

But despite Michigan's cold climate, the Carnegie Mellon researchers found that an electric vehicle will still likely pollute less than one with a conventional engine. Taking into account the carbon impact of the regional electricity grid and the diminished performance of electric vehicles in a cold climate, the researchers calculated that a Nissan Leaf driven in Michigan's Lower Peninsula is responsible for roughly 200 grams of carbon dioxide per mile driven. That's about half as much as the average new vehicle, according to this greenhouse gas emissions calculator from the U.S. Department of Energy and the Environmental Protection Agency.

How Manufacturing Affects the Climate Impact of Hybrid and Electric Vehicles

Christina, you've heard that hybrid and electric vehicles consume more resources to manufacture than vehicles with internal combustion engines. It's true that producing hybrid and electric vehicles requires more energy – and associated greenhouse gases – than those with only internal combustion engines. Manufacturing batteries for electric vehicles, in particular, consumes a lot of energy.

However, that does not negate the climate benefits of the vehicles. Calculating the lifetime impact of the vehicles is complex, but various studies suggest that after they hit the road, hybrid and electric vehicles more than make up for their energy-intensive beginnings.

Reichmuth of the Union of Concerned Scientists, an author of one such analysis, said that excess emissions from manufacturing electric vehicles are offset quickly: "As long as the car's driving for more than a couple years, there'd be a net emissions benefit," he said.

The bottom line: Either a hybrid or electric vehicle is likely a better choice for the climate than a vehicle with an internal combustion engine, even in chilly Michigan. But nothing beats avoiding unneeded car trips in the first place, so don't neglect to let your leaders know your thoughts on improving local options for walking, biking and public transit.

– Sara

Wondering how climate change could affect you or your loved ones? Send your questions to sara@yaleclimateconnections.org. Questions may be edited for length and clarity.

Sara Peach is the senior editor of Yale Climate Connections.

Reposted with permission from our media associate Yale Climate Connections.

A net-casting ogre-faced spider. CBG Photography Group, Centre for Biodiversity Genomics / CC BY-SA 3.0

Just in time for Halloween, scientists at Cornell University have published some frightening research, especially if you're an insect!

The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.

"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."

The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.

They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.

They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.

But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.

"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.

What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.

It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.

To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.

First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.

Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.

University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.

"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."

Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.

Hoy agreed.

"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.

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