Sunday, March 3, 2024

Rotation turns forestry reckoning around

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Parliamentary Commissioner for the Environment Simon Upton says there are good reasons to allow forestry offsets for methane rather than for fossil fuels.

In his role as Parliamentary Commissioner for the Environment, Upton has produced a new “note” for Parliament exploring the possibilities of using carbon sequestration from forestry to offset methane emissions. It is an interesting and some might say provocative paper. 

Upton was an MP for close on 20 years and a minister in the Bolger and Shipley Cabinets, including more than six years as minister for the environment. Then he headed overseas, working for the OECD. In 2017 he was appointed in the last year of the National Government to an initial five-year term as Parliamentary Commissioner for the Environment. 

In that current role, Upton reports to Parliament itself and not to any minister. This distinction is important because his role is intended to be non-political. In this role, he has the freedom to roam widely, exploring issues he thinks are of fundamental importance, without ministerial direction.

The MPs of all political parties are the first audience for his reports. This means there is a need to write for people who have no science training but who, one hopes, are keen to get to the essence of issues that are important to New Zealand’s future. 

This particular “note” (as he calls it) makes no recommendations. Instead, the focus is on educating people as to the issues. The terminology of a “note” relates to the idea that it is intended to inform and generate debate rather than to make specific recommendations. Despite the terminology suggesting it might be a short document, it is still 49 pages long and not an easy read. 

There is a shorter version of nine pages, but readers of the short version should be wary of thinking they have the issues nailed down.

I have a particular interest in this note in that I was one of three people invited to review an earlier draft. As external reviewers, our task was to identify weaknesses and make constructive suggestions for improvement, and our names are publicly acknowledged at the start of the note. But none of us had responsibility for the final content. It is Upton’s paper, supported by his internal professional team.

In the first two introductory paragraphs, Upton puts forward a fundamental philosophical issue that others have failed to address.

“New Zealand’s emissions reduction targets for 2050 were enshrined in legislation in 2019. When setting these targets, the Government decided that forestry offsets would be counted towards the target for fossil carbon dioxide and other long-lived greenhouse gases (net zero by 2050), but not the emissions reduction targets for biogenic methane (a 10% reduction by 2030 and a 24–47% reduction by 2050, relative to the 2017 level). The rationale behind the important and far-reaching decision to have a net target for long-lived greenhouse gases but a gross target for biogenic methane was never satisfactorily explained. 

“Why should emitters of carbon dioxide in the fossil-fuel-based economy have access to New Zealand’s limited supply of forestry offsets to assist them in meeting their emissions reduction target, but not emitters of livestock methane in the land-based economy?”

A key point here is that the 2050 net zero for carbon dioxide still allows a large volume of carbon dioxide emissions to be emitted. Further on in the report, Upton says: “In the Climate Change Commission’s ‘current policy reference’ scenario, gross carbon dioxide emissions are reduced by 11% by 2030 and 37% by 2050.”

This illustrates that the “net zero” figure for carbon dioxide bandied about so much by politicians and the media only sounds impressive because sequestration from forests is assumed to offset all of the very substantial remaining carbon dioxide emissions, primarily from the energy and transport sectors. In contrast, the lack of offsets available for methane makes the methane figure look bad in comparison.

The alternative perspective that Upton has been putting forward, both here and previously in 2019 in a 189-page report called Farms, Forestry and Fossil Fuels, is that the land-based economy should be considered as an entity. Given that forestry and farming compete for the same land, there is a logic to that. In contrast, it seems unreasonable that the rest of the community should be able to offset its emissions by singling out forestry from the overall land-based economy, to make it look good in relative terms.

Upton writes in the note about the contribution of New Zealand agricultural emissions to global warming. He makes the point that the best estimates – which, I add here, does not necessarily mean they are correct, because there are lots of uncertainties – are that NZ’s historical agricultural emissions have added 0.0015degC to the current global climate. 

“My own conclusion is somewhat different. This is because Upton’s starting point has been to assume production forestry with approximately 28-year rotations, for which the average sequestration over multiple cycles is equivalent to only 16 years of initial growth.”

At one level this figure seems totally trivial, but that is influenced by the world being big but New Zealand being small. NZ also makes up less than 0.1% of the world’s population, and on a per capita basis our emissions are certainly not small.  

Upton then points out that even if methane emissions decrease, with this leading in time to a reduction in the level of agriculturally sourced methane in the atmosphere, there would still be ongoing warming effects due to lags in the temperature response function.  

In the second part of the paper, Upton explores how much forestry would be needed to take the total emissions from the land-based sector, from both short-term and long-term gases, down to net zero. The answers are daunting. But before discussing that, it is important to acknowledge an assumption made by Upton that all of the new forests will be approximately 28-year production forests. I will return to that assumption later.

Upton looks at the net-zero question using two different metrics, both focusing on 2050 as the initial target date. The first is the GWP100 measure of emissions, which is the official international method used for comparing short- and long-lived gases. The second measure focuses on the amount of further warming, which is not the same as the level of emissions, to ensure that the land-based sector is not adding to warming after 2050. That second analysis uses the principles that underpin the alternative GWP* metric.

Using the GWP100 measure, Upton reports that NZ would need to plant approximately 4 million hectares of new pine forests progressively over the next 100 years to balance current methane emissions. Using a warming metric based on principles set out in the alternative GWP* metric, NZ would need to plant slightly less at 3.9 million hectares, but with all of this occurring by 2050 and none thereafter.

Not surprisingly, Upton then concludes in his final paragraph: “This work shows that very large areas of forest would need to be planted to make any significant dent in the marginal warming effect of New Zealand’s livestock methane emissions. For that reason, if forest planting were to be used to offset livestock methane, it would have to be in addition to – not instead of – reducing national gross emissions of biogenic methane by 24–47% by 2050. We cannot simply plant our way out of this problem.”

My own conclusion is somewhat different. This is because Upton’s starting point has been to assume production forestry with approximately 28-year rotations, for which the average sequestration over multiple cycles is equivalent to only 16 years of initial growth. This short-rotation assumption leads inevitably to his results and conclusion.

The conclusion would be different using long-rotation forests or so-called permanent exotic forests, possibly transitioning eventually to native forests.  For example, with permanent forests the sequestered carbon can be five times that of the average under short-rotation forests. Accordingly, his conclusion should have been that we cannot plant our way out of this problem with short-rotation forests.

My second conclusion reflects Upton’s long-held perspective that there is a logic associated with using forestry to balance emissions within the land-based sector instead of as a get-out-of-jail card for the energy and transport sectors. If we accept that proposition, which has considerable merit and is worthy of consideration, then there is a lot more analysis needed as to alternative pathways forward and their effects on all sectors of the economy. I hope that Upton takes up those challenges.

In seeking out those alternative pathways, we should never forget that more than 80% of New Zealand’s merchandise exports derive from the primary industries, and approximately half of those total exports derive from methane-emitting ruminants. Without vibrant export industries, as a nation we are in big trouble. 

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