The Australian Carbon Emissions Reduction Scheme—and specifically the methodologies that measure emissions reduction or sequestration in the form of ACCUs (Australian Carbon Credit Units)—has been rated by several respected international groups as the best system currently available.

Philip Mulvey

Yet despite that, there is a persistent effort by some within the industry—particularly a handful of government scientists and academics—to undermine the scheme in the media. Their criticism seems rooted less in empirical flaws and more in the fact that the method isn’t perfectly aligned with their expectations. Whether intentional or not, these public attacks, in my opinion, pose the greatest threat to the credibility of the ACCU system—especially the Soil Carbon Method.

As someone who sat on the technical advisory group for the Soil Carbon Method, let me be clear: the method represents a compromise between the best available science and the realities of commercial delivery. That’s how most functional systems are built. The method was developed over five years with input from CSIRO, university soil departments, commercial practitioners, and government representatives. It launched in 2018 and was updated in 2021 after industry testing.

At the time, it used the most current science available for sampling and statistics.

It includes mechanisms for reversals, conservative accounting, and safeguards that account for variability, including how and when additional sampling is conducted. We knew from the outset that the method would be improved over time—and we acknowledged that soil sequestration below 150mm under new practice regimes was poorly studied. That’s precisely why the review date was set for 2031. But early in 2025, a small number of critics made enough noise to prompt an early review.

Earlier this year, a paper co-authored by government and academic representatives criticised the Soil Carbon Method because the evidence collected as per the Method didn’t match their expectations. But evidence is data—and data is derived from measurement and observation. In this case, the measurements and on-ground farmer observations are telling a consistent story: soil carbon is increasing.

Rather than engaging with that reality, the authors developed an uncalibrated model using remote sensing as a proxy—ignoring the actual data.

Remote sensing might give you a ballpark view of plant behaviour, but it’s imprecise beyond 100mm depth and completely inadequate for measuring soil carbon changes down to 300 or 1000mm. Their model disregarded both practice-specific calibration and site context—two pillars of the current Method—and would not have passed the Method’s own standards. Ironically, their proposed “solutions” already exist within the current protocol or fall under the commercial risk that landholders knowingly accept.

So, I was more than a little annoyed to read a recent social media post from another prominent critic claiming that the ACCU system is “allergic to evidence.” On one hand, we’re told the method ignores models; on the other, we’re told it ignores evidence. Which is it? The Australian Government can’t win.

There’s a pattern here: if critics aren’t directly involved—or if the data doesn’t support their worldview—they attack the process.

Here’s what’s often overlooked: this is the first time anyone has studied what happens to soil carbon at depth over time following meaningful changes in practice. Legacy data and models built on conventional systems may not apply to these new conditions. It seems, to me, that some academics are struggling with a changing paradigm they didn’t initiate—and instead of adjusting their thinking or at least being open to the fact the paradigm may not be relvant, they’re attacking the emerging data.

Some of these attacks have been aggressive—even personal. I know of one outstanding scientist who defended early empirical measurements, only to be hounded out of the industry. He retired early.

It’s time to ask the critics to hold their fire. Let’s wait for enough data to draw proper conclusions. That might take another five years. In the meantime, yes, some projects might be over- or under-credited. But those issues will be resolved through ongoing data collection, method refinement, and transparency.

We can’t let the pursuit of perfection block meaningful progress. Many farmers are already benefiting—financially and environmentally—from the practices that build soil carbon. They’re improving their drought resilience and the stability of their farming systems.

No system is perfect. That’s why the Australian Government built a framework for method updates.

Constructive criticism backed by evidence is essential—but let’s channel it toward improvement, not obstruction.

About the author: Phil Mulvey is a soil and water specialist with more than 40 years’ experience in soil sciences. He has played a major role in the development of both Australia’s regenerative farming and soil carbon industries, running a company called Ryzo which uses a web platform to guide farmers in the journey of regenerative farming and in soil carbon projects. He is also part of the Soil Carbon Industry Group.