Every few weeks it seems another company, country, or organization is making a big announcement about their pledge to go net zero at some point in the future. It all sounds well and good for the environment, but what does “net zero” actually mean? When even oil companies like BP are pledging to go net zero, has the term lost all its meaning?

Let’s take a look at where “net zero” comes from and why it’s become so widely used. We’ll see that there’s a big difference between zero and net zero, especially in terms of what it means to achieve the latter.

History of “Net Zero”

In 1920 the Noble Prize-winning chemist Frederick Soddy proposed that economics could learn a lot from the laws of thermodynamics. Soddy thought that these laws of physics that govern how energy flows in chemical reactions were a good model for analyzing the flows of capital and creation of wealth in societies.

While Soddy’s thoughts on economics were mostly ignored, they were an early example of applying this view of energy flows to larger systems. As the twentieth century progressed, many ecologists began thinking this way about nature’s own systems. They explored how energy is created and used in a system like a forest or wetland, and then wondered what the total energy impact of the whole ecological system is after everything had been netted out.

The term “net zero” itself began to appear in the 1930s according to Merriam-Webster. It describes situations or systems where the total of all the gains & losses when summed up together equal zero. That same decade Vannevar Bush, Dean of MIT’s School of Engineering, began exploring the potential of solar energy and how it could be used to create net zero houses—houses whose heating and cooling systems would be powered by the sun and thus would have no net impact in energy or fuel consumption. The first of what would ultimately be several of these concept houses, Solar 1, was built in 1939, but none ever truly achieved net zero energy use.

So in the early 20th century the term net zero arose and was most often used to describe systems, like a building or biome, where their overall energy consumption netted out to zero. But soon we’ll see this term grow to be applied to many more types of systems and simultaneously narrow to describe these systems’ carbon impact rather than their overall energy impact.

Growing Popularity and Evolving Use

After World War II there appears to have been not much talk about net zero for the next few decades. The concept wasn’t really catching on or being discussed much outside small academic circles.

This changed in the 1970s. The oil crisis and growing environmental awareness brought net zero as a design concept for buildings back into relevance. During this decade Professor Vagn Korsgaard of the Technical University of Denmark built one of the first “net zero” houses, setting the stage for future developments in the field. Korsgaard’s house was equipped with highly insulated construction materials, a 42 square meter flat-plate solar collector, and a seasonal water storage tank with a capacity of 30 cubic meters.

A second, smaller oil crisis in the 1990s precipitated by the Gulf War further fueled the growth in sustainable practices and net zero building designs.

This continued even through the Great Recession and its aftermath. The green building segment was one of the only parts of the construction industry that continued to grow as evidenced by increasing LEED project registrations, even as building projects overall were in decline.

As the world entered the second decade of the 2000s the idea of net zero buildings became more widely known. Concern over climate change and carbon emissions continued to grow, resulting more and more in the idea of ‘net zero’ being applied not just to energy consumption in general but to carbon emissions in particular. Simultaneously, the concept was increasingly used to describe not just buildings but a whole host of concepts and systems, including supply chains, whole companies, and entire countries.

In the Google Ngram chart below you can see the emergence of the term “net zero” around the 1930s, its slow increase in use, and then a spike in the 1970s and subsequent reemergence starting again in the 1990s.

The Paris Climate Accord: Net Zero’s Big Moment

After the perceived failure of the 2009 climate talks at Copenhagen, it wasn’t clear how the United Nations would proceed with addressing greenhouse gases. The UN’s Framework Convention on Climate Change came into being in the early 1990’s and resulted in the famous Kyoto Protocol committing countries to reduce their greenhouse emissions, including CO2. 

But figuring out how to coordinate addressing climate change was still far from resolved. In the leadup to what would become the 2015 Paris Climate Accord, it was widely recognized that any agreement would need to limit global warming’s impact to no more than a 2° C increase in the Earth’s temperature. Yet it wasn’t clear how to translate that into greenhouse gas emission targets.

Should each country have its own target? How would accountability be handled? Was there any way to easily and understandably state a goal that could apply to every country?

A group of roughly 30 women including UN diplomats, lawyers, World Bank financiers, and activists had been tackling these questions together since 2013. And after much discussion they ultimately agreed to and became advocates for setting a target of net zero carbon emissions by 2050. This goal had the benefit of being simple and applicable to all countries.

How Do We Achieve Net Zero?

On a global level, achieving net zero carbon emissions requires (1) reducing the amount of carbon emitted by human activities as much as possible and (2) removing enough carbon from the atmosphere to make up for any amount of carbon still being emitted.

The second part is important because it’s very likely human activity will still involve some carbon emissions in the future. And if that’s the case, the only way to reach net zero will involve actively removing carbon from the atmosphere.

Yet how individual countries and companies achieve net zero also involves carbon offsetting, which can be controversial. Rather than achieving net zero purely by reducing their own emissions and directly removing carbon, these entities can instead pay someone else to do it for them.

For example, Norway has announced its intention to get to net zero by 2030, but a key part of getting there will be paying other countries to reduce their carbon emissions. Many people question carbon offsets because they can incentivize delaying tough decisions about reducing one’s own footprint.

On the other hand, many encourage carbon offsetting because it can effectively create a market for carbon reduction and direct dollars to invest in the most effective carbon reduction and removal methods. These methods can include capturing carbon by planting forests, sequestering CO2 in soil, directly removing it from the air, and hopefully even better methods that have yet to be developed.

What Are Companies Doing?

Last December it was announced that 177 companies had now committed to achieving net zero carbon emissions by 2050. Together these companies’ combined direct emissions equal that of France.

But people are right to be skeptical. What will these companies actually do? How exactly are they defining their own carbon footprint? Do they only care about the emissions of their own operations or are they also considering the carbon footprint of their suppliers and the actual use of their products?

For example, a car company may only focus on reducing emissions from its own manufacturing plants while ignoring the carbon footprints of its engine suppliers, dealership network, and the cars themselves once they’re driven.

Let’s take a look at what’s behind a few companies sustainability commitments.

Amazon

Last fall the Everything Store announced its plans to have net zero carbon emissions by 2040 and use 100% renewable power by 2030. Current efforts to achieve this include switching to electric delivery vehicles, purchasing solar and wind electricity, and funding reforestation projects.

It’s impressive and ambitious, but it will be years before we know if it will be achievable. If every company starts paying for reforestation projects instead of cutting their own emissions, well, we’ll run out of space eventually. Then we’ll have to double down on reducing emissions or developing other carbon removal technologies that maybe we should have been investing in earlier.

Coca-Cola

Perhaps understanding how much their business relies on carbon-intensive global manufacturing and distribution, Coca-Cola hasn’t committed to net zero emissions. (I don’t see the term net zero anywhere in their recent sustainability reports.)

While they’ve pledged to reduce their carbon emissions by 25% by 2020, the lack of any net zero commitments likely indicates how tough it will be for its industry to achieve this goal. 2050 is still decades away, and only time will tell if today’s net zero commitments will actually be achieved.

We could see lots of progress in the beginning when lots of “low-hanging fruit” carbon reductions methods are put in place. However we could still find ourselves a decade down the road with less time and even more difficult choices ahead of us that have been deferred.

Patagonia

It’s no surprise that eco-friendly Patagonia has committed to net zero carbon emissions—by 2025 no less! In addition to switching to renewable energy sources, the company is focusing on its supply chain, using more recycled materials and developing low-emission dying and production methods.

But even a company as environmentally ambitious as Patagonia can’t do it alone and is investing in carbon sequestration to get them to net zero.

And Finally, BP

When BP announced its intention to get to net zero carbon emissions by 2050, there was a lot of head scratching. How can an oil company achieve this? Will they be switching completely to renewable energy?

But the devil is in the details. And there are many details in BP’s promise.

Part of their promise is to get to net zero direct emissions from their own operations. But BP’s own operations only represent part of its overall carbon footprint, the vast majority of which comes from the use of the hydrocarbon products it sells rather than their own operations.

However, BP also has committed to achieving net zero carbon emissions on the actual consumption of the oil it extracts (so-called Scope 3 emissions). Now this is a big deal and unusual among oil companies. But it’s a bit less impressive once you realize it only applies to the oil BP itself extracts. The company also refines and sells a lot of oil it didn’t actually take out of the ground itself.

Net Zero Problems

One of the problems with net zero is also one of its strengths. While it’s easy to summarize and conceptually understand, the term can also be defined in seemingly misleading ways.

The other main issue is that committing to net zero is much easier to say now. Many worry that the word ‘net’ functions as a giant loophole that may enable us to defer hard decisions. Perhaps we’re just holding out hope that before 2050 there will be a revolution in carbon removal technologies that does the work of netting out to zero for us.

Despite its shortcomings, net zero is becoming a useful tool for thinking about and planning how to address carbon emissions and climate change.

A key part of all this work is measuring and accounting for all the carbon being emitted. And for any environmental efforts getting good data and measurements of your work is key, something that Temboo enables for a wide range of projects.