Amazon’s carbon emissions decreased slightly in 2023 after the company ramped up renewable energy purchases and cut down on pollution from construction, hardware, and equipment, according to its latest sustainability report.

Back in 2019, Amazon pledged to reach net zero carbon emissions by 2040. Despite that goal, its carbon emissions actually ballooned soon after — climbing from around 51 million metric tons of CO2 in 2019 to more than 71 million metric tons in 2021. Now it seems that the company’s carbon footprint has shrunk a bit over the past couple years, decreasing 3 percent in 2023 to just under 69 million metric tons of CO2.

To put it in context, Amazon’s carbon footprint last year was roughly equivalent to the annual CO2 emissions from 184 gas-fired power plants. And the company is still pumping out around 34 percent more carbon pollution than it did when it made its climate pledge in 2019. But it’s notable that Amazon’s emissions fell slightly in a year when other tech giants’ pollution shot up with the explosion of new AI tools.

Amazon says the drop is mostly thanks to cleaning up carbon pollution from its electricity use and indirect supply chains emissions, which fell 11 percent and 5 percent, respectively. It also announced that it reached its goal of matching 100 percent of its electricity consumption with renewable energy in 2023, seven years ahead of its 2030 deadline.

Breaking down what “matching” means gets a little tricky, but it’s important for understanding any company’s clean energy goals. Simply put, there isn’t enough renewable energy online yet to meet global climate goals, and siphoning off what’s available to meet a single giant company’s clean energy targets would be pretty unfeasible. Plus, when a company plugs into the grid, it doesn’t control whether the electricity it uses comes from a solar farm or fossil fuel power plant. Instead, companies typically pay to “match” their energy use with Renewable Energy Certificates (RECs) meant to support renewable energy projects.

The quality of those RECs makes a difference. RECs can get so cheap that they’re no longer enough of a revenue source to incentivize new clean energy projects. As a result, many companies have overestimated reductions in carbon emissions through RECs, research published in 2022 found. And what’s really needed to stop climate change are new, additional sources of renewable energy.

To try to achieve this, other companies, including Microsoft and Google, have set goals to match their electricity use with locally generated clean energy on an hourly basis (rather than on an annual basis). That’s supposed to support a future where there’s enough renewable energy to rely on 24/7 on any grid a company plugs into.

Another alternative is to enter into a Power Purchase Agreement (PPA), a long-term contract to support the development of a clean energy project and / or purchase electricity from it. Amazon is the biggest corporate purchaser of renewable energy, buying more solar and wind power through PPAs than Google and Microsoft combined, according to BloombergNEF.

In comparison, Google and Microsoft saw their greenhouse gas emissions climb roughly 13 and 20 percent, respectively, last year as they infused AI into their products and services. Like Amazon, they’ve seen larger increases since setting climate goals several years ago. Microsoft’s carbon footprint was 30 percent larger in its 2023 fiscal year than it was in 2020, according to its latest sustainability report. Google’s carbon emissions, were 48 percent higher in 2023 compared to 2019. Amazon is also bringing AI to Alexa and other services but is reportedly scrambling to catch up with other big players in the AI race.

Amazon also saw a 13 percent drop in emissions stemming from capital goods last year, as noticed by Bloomberg. That includes things like building construction and new servers, vehicles, and other equipment. The company’s capital expenditures dropped by around $10 billion in 2023, Bloomberg reports. The company grew during the covid pandemic, which sent its carbon emissions skyrocketing at the time. But after cutting down on warehouse and data center costs, its carbon emissions are also sliding.