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The central objective of the is to limit Earth's warming to well below 2 C above pre-industrial levels, but preferably 1.5 C.

This challenging task will require policies and tools to enable every sector of society to drastically reduce greenhouse gas (GHG) emissions to eventually reach net-zero.

Enacting the most effective and efficient strategies to reduce emissions starts with knowing in detail where, when and how much of these greenhouse gases we are emitting, followed by implementing emission reduction policies and tracking our progress.

Is it possible to track carbon dioxide (CO₂) emissions and emission reductions from space? shows that it is.

Why CO₂ matters

CO₂ is the . Burning fossil fuels for electricity generation, heating buildings, industry and transportation has elevated the CO₂ in our atmosphere well beyond natural levels.

Currently, CO₂ emission reporting is mainly done by accounting for the mass of fossil fuels purchased and used, then calculating the expected emissions—not actual atmospheric CO₂ measurements. The finer details about exactly when and where the emissions occurred are often not available, but more transparent monitoring of CO₂ emissions could help track the effectiveness of policies to reduce emissions.

Today help us to get around, track weather systems and communication satellites relay TV, internet and telephone signals. It is time we use satellites to help tackle the biggest challenge that humanity has ever faced—climate change.

Satellites for measuring CO₂

A global network of and now consists of . Accurate and precise measurements from these stations have revealed a lot about changes in global atmospheric CO₂ and Earth's overall carbon cycle, but we can't place these stations everywhere on Earth.

Satellites can observe the entire planet. Those that measure CO₂ in the lower atmosphere near Earth's surface (where CO₂ emissions and CO₂ uptake by plants happens) first began making measurements in 2002. Since then, they have been getting better and better at doing it, but there have been setbacks along the way.

About a decade of effort by NASA went into developing the satellite to make precise measurements of atmospheric CO₂ across the Earth.

In 2009, OCO was lost due to a launch problem. After sustained advocacy for a rebuild of this important climate mission, NASA secured new funding to launch the satellite in 2014 and to the International Space Station in 2019.

The OCO missions were designed to improve our understanding of vegetation's CO₂ absorption, also known as . But what about fossil fuel CO₂ emissions?

A new way to verify CO₂ emissions

In 2017, I led a research team that published the .

Since OCO-2 was not designed for this purpose, its coverage and infrequent visits were inadequate for operational global CO₂ emission monitoring, but we can still quantify emissions in .

OCO-3 is very similar to OCO-2, but has an additional pointing mirror that enables it to better map CO₂ around targets of interest like the in Poland, Europe's largest fossil fuel burning power plant and CO₂ source.

With ten clear views of CO₂ emission plumes from BeÅ‚chatów imaged by OCO-2 and OCO-3 from 2017-2022 analyzed in our , we were able to determine emissions on those days.

European power plants report but only annual CO₂ emissions. Power generation fluctuates with electricity demand and generating unit shutdowns (for maintenance or decommissioning) and CO₂ emissions are expected to exhibit proportional fluctuations.

We confirmed this using OCO-2 and OCO-3 in , which showed that satellite observations can track changes in facility-level CO₂ emissions. This means that satellites can be used to verify (or refute) reported CO₂ emission reductions that result from climate change mitigation—like mandated efficiency improvements, carbon capture and storage technology, etc.

Emissions monitoring for the Paris Agreement

Our approach can be applied to more power plants or modified for CO₂ emissions from . We can also try integrating the satellite observations with CO₂ monitoring from the ground or aircraft.

While we are already working on this, advances will only be incremental until the launch of the European Commission-funded . CO2M is comprised of two satellites, aiming to launch in late 2025.

These satellites will provide about 50 times as much coverage as OCO-2 and OCO-3 combined and will form the .

CO2M will be a major advance, but just like successful global climate action, requires contributions from many countries. The long-term robust operational global monitoring of GHG emissions will need a .

Hopefully, with new, more detailed and transparent tracking of human-caused greenhouse gas emissions to assess and guide us toward the most effective policies, society can achieve the emission reductions needed to reach .

This article is republished from under a Creative Commons license. Read the .