Imagine an entire country enacts a law that requires the use of a more energy-efficient LED lightbulbs. Sounds good right? But what if I told you that in every country this law has been passed energy consumption went up?

The reason why could be a bit of a mystery, but it's exactly why using green technology to solve problems can be incredibly difficult. It all boils down to two main reasons: The first is that a lot of what we consider to be the sustainable option, is only sustainable if a product is used in a certain way. The second is that people's behavioral changes that come from introducing new technology are hard to predict. That's what we call "rebound effects". But what does that mean?

Like many people today, you might feel guilty about going to your favorite café because every time you buy a coffee, it comes in a disposable plastic cup that you know will somehow, someway, end up in a landfill and slowly make its way into the ocean where it may sit for decades or even centuries. What do you do? The easy answer for many of us is to purchase a reusable coffee mug that we take with us every day to fill up our coffee. Voila! You've circumvented the need for a single-use paper cup with a plastic lid. The purchase feels good knowing that we've done our small part to help save the planet. Problem solved… right?

A Woman Holding A Takeout Coffee Getty Images

But is any of this really true- that a reusable mug is "greener" than a disposable cup? As it turns out, it depends on how you use your reusable coffee container. This is because, in part, it requires more CO₂ emissions to produce than a disposable cup. Just to make up for emissions, it might need to be used up to 100 times in order to balance the emissions of a disposable cup. And it gets even trickier: "Sustainability" doesn't just mean reducing CO₂ emissions, right?

All the materials that combined make up everything we buy come at an environmental cost. If we take into account the materials used in a reusable coffee mug, the water it takes to wash it after each use, the soap and more - it may take over a thousand uses compared to a disposable mug to balance the overall environmental impacts. If you're anything like me and you tend to lose reusable mugs every now and then, this really calls into question whether it's an environmentally friendly purchase.

Nowadays, this is why researchers are trying to understand the lifecycle of products - the environmental impacts starting from the extraction of materials from the Earth, through manufacturing, to the transportation to stores - all for increased understanding of the conditions under which a product might actually be considered "sustainable".

The second, even more tricky issue, is that day-to-day human behavior may change when we exposed people to a new piece of technology. Going back to the coffee mug, for example, a consumer may drink 50% more coffee, simply because the volume of the mug is larger compared to a single-use cup. At first, it may seem like a small change, but on a large scale, an increase in coffee demand, simply from using a bigger mug, could easily lead to a huge number of unintended consequences: Increased coffee demand, for example, has long been linked to deforestation and economic inequality. These types of changes are known as direct rebound effects.

On the other side of that same coin are indirect rebound effects. Indirect rebound effects are even more difficult to quantify, and there can be many of them associated with a single new product or technology. In our coffee cup scenario, it could be that with your new purchase you start drinking more milk with your coffee - another driver of deforestation. It might mean you make more frequent trips to a café and increase your time driving which increases your annual CO2 emissions. You might start purchasing more snacks alongside each new coffee, increasing your net consumption of goods that were likely imported from all over the world. As you can imagine, those indirect rebound effects are extremely hard to track and basically impossible to predict in advance.

It's amazing that even the example of the reusable coffee mug above can have so many unintended consequences on a global scale. It's also important to note that these may be particularly prevalent in technological products that are individually owned, rather than something that is publicly owned. This is exactly why the problem gets even more precarious with initiatives like promoting an entire rehaul of the transportation system by electric vehicles (EV). Other options like making public transit and biking more accessible is more likely to have a net positive effect since both are options that are less materially intensive than an EV.

Electric car charging. Getty Images

The lifecycle of electric vehicles already requires rare earth metals that are more environmentally destructive than a comparable fossil-fuel-powered vehicle when being mined. In many places, they also have thin margins in terms of how much they actually reduce emissions compared to fossil-fuel-powered vehicles. This gets tricky because when people buy an EV, their behavior may change. In their excitement of driving a new, "sustainable" vehicle, they may end up driving it more often and actually emitting more carbon dioxide than the average diesel-powered vehicle - a direct rebound effect commonly associated with electric cars. Electric vehicle owners may also make other decisions differently: to use less public transport, car share less with others, or to use the tax rebate issued to promote electric cars (such as in California) to buy other products that, in the end, all contribute to increased emissions and environmental destruction. Of course, none of this means we should keep using huge amounts of fossil fuels in the face of climate change- it just means that the solutions to these problems may be even more difficult than we initially expected.

Pollution Getty Images

While the idea of rebound effects applies most commonly to topics related to energy use, it's conceptual framework can apply to almost any new integrated technology or product. As of now, all that researchers and policy-makers can do is monitor the impacts in the aftermath of introducing new "green" technology. In the face of these rebound effects, more and more people have been asking themselves whether or not the current technological solutions to climate change are the way to go, especially for individually owned products. Given the urgency of climate change mitigation, the environmental destruction many types of green technology causes because of their lifecycle is precarious. Added is the uncertainty of how rebound effects might actually reduce emissions benefits of EVs in the real world compared to theory. And, in the end, it's why we can mysteriously advocate for energy-efficient lightbulbs and see energy consumption go up. Sometimes, "green" energy may be anything but.

Related articles:

The Guardian - Could the rebound effect undermine climate efforts?

World Economic Forum - Do fuel-efficient cars make us drive more?