Counter-intuitive LCA results

June 27, 2019 by Bo Weidema

Bio-based plastics with larger effect on global warming than their fossil derived counterparts? Certified forest products that unintendedly are more harmful to biodiversity than the corresponding products from plantation forestry? No environmental effect of demanding recycled paper? All these are examples of LCA results that are not immediately intuitive. Does that mean that they are wrong? Not necessarily.

We are often met by a demand that our results should be immediately understandable and make intuitive sense. And there is no doubt that it is easier to communicate results when they are intuitive. Then they are immediately accepted, although often with a condescending “Ah, that’s typical, science just confirms what we knew already”. But it is when our results are not intuitive, as in the above examples, that there is a chance to learn something new. And this is where real change begins.

Counter-intuitive results are not wrong, they are just harder to communicate. Our common sense – just another word for prejudice – is challenged. Intuition is simply not capable of capturing the results of complex systems – at least not without a deeper explanation. But when that explanation is provided, the counter-intuitive results become intuitively right. Let me demonstrate how that works for the above examples:

Bio-based plastics with larger global warming impact than their fossil derived counterparts? Intuitively, one may think of bio-based plastics as being CO2-neutral due to the uptake of carbon from the air during biomass growth. However, that bio-based plastics have a larger effect on global warming than their fossil derived counterparts moves from being counter-intuitive to be intuitive when we understand that agriculture is not CO2 neutral (due to the need for fuel and fuel-based inputs, such as fertilisers) and even more importantly that up to half of the total greenhouse gas emission from growing biomass can come from the indirect land-use effects (iLUC), see e.g. the data for our life cycle assessments of milk.

Certified forest products that are more harmful to biodiversity than the corresponding products from plantation forestry? Intuitively, we would expect the certification to lead to lower impacts on biodiversity, since that should be one of the main reasons for the certification. And the biodiversity in the specific certified forest may indeed be higher than in non-certified forests. However, that the certification may unintendedly lead to an overall reduction in biodiversity compared to plantation forests moves from being counter-intuitive to be intuitive when we understand that the overall impact on biodiversity needs to be measured per unit of wood produced. Plantation forests have a high impact on biodiversity per area, but a low area per cubic metre of wood. This means that more area can be left untouched, with no biodiversity impact. If you have a lower output per area than plantation forests, you will need more area to produce the same – and thus impact the biodiversity on a larger area. The challenge is then to have a biodiversity impact that is so low per area that it also becomes lower per cubic metre of wood. This is what we call “biodiversity-managed forests”. However, in practice, it is very difficult to have low impact on biodiversity when you harvest even rather small amounts the wood that would otherwise be “food” for a large share of this biodiversity (“deadwood”). Therefore, most certified forests have higher biodiversity impacts per unit of produced wood than a plantation forest, i.e. they lie above the iso-biodiversity line in the figure below, taken from our criteria for good biodiversity indicators for forest management.

No environmental effect of demanding recycled paper? When we know that the production of recycled paper has lower impacts than virgin paper, we intuitively think that it must be beneficial for the environment to buy recycled paper. And companies that use recycled paper want to be credited for this and brag about it on their product labels. However, that there is in practice no beneficial effect moves from being counter-intuitive to be intuitive when we understand that the amount of recycled paper is not driven by demand but by supply. The market for recycled paper is constrained by the availability of waste paper. So, an increase in recycling can only come about by throwing more paper in the recycling bins, not by demanding more recycled paper. This is so for all materials where there is a well-functioning collection system. For other materials, such as plastics, there may still be situations where the market is driven by demand. And the market situation can change over time, which has caused a lot of confusion about how to apportion the burdens and credits for recycling as described in one of our previous blog-posts.

Improving dairy products for a carbon-net-zero future

March 13, 2019 by Randi Dalgaard

Yesterday marked the release of a new strategy from Arla Foods launching their targets to accelerate the transition to sustainable dairy production.

The new strategy has an increased focus on the farms and we are pleased to see how our climate tool has now been applied to 5000 individual farms. The tool calculates climate footprints for the milk from each farm and thus demonstrates to the farmer where the CO2 emissions originate.

The numbers are a motivation in themselves, and often climate ’savings’ may also entail cost savings according to Jan Toft Nørgaard, a milk producer himself and chairman of Arla Foods.

In the project for Arla we have calculated climate footprint since 1990 and the Arla farmers have reduced their emissions per kilogram of milk by 24 %. The current average for the Arla farmers in the study is an emission intensity of 1.15 kg COper kilogram of milk, which is approx. half of the global average, which is 2.5 kg CO2 (according to FAO).

Links to more information:

Arla press release (in Danish):

Our project with ARLA is described in more detail here:

Is there a future for plastics?

August 30, 2018 by Jannick Schmidt

Plastic is a ubiquitous material with many benefits such as low price and weight and an extreme functional versatility. Plastics are pervasively used in modern society.

However, the uses of petro-based plastics present us with some serious problems. First of all, we are talking about huge amounts of plastics. The approximate global production is around 480 mio tonnes of plastics produced every year (2011 data[1]) and is expected to double within the next 20 years. Currently the production of plastics accounts for around 3% of global GHG emissions[1].

Research from the past decade has demonstrated plastic contamination from micro-plastics being washed out as products are produced and used[2]. Microplastics are now routinely found in marine food chains[3], and the situation in terrestrial and freshwater ecosystems might be the same, as recent research demonstrates[4]. Furthermore most of us have seen troubling pictures of ‘macroplastics’ contaminating oceans, landscapes or cities around the world. Plastics in the environment cause serious ecological problems, but also represent a substantial economic challenge, as materials are wasted and fisheries and tourism are negatively affected.

In January 2018 a strategy to turn the ‘plastics economy’ into a circular economy was put forward by the European Commission as one of the solutions to the environmental problems of the production and use of plastics[5]. In a circular economy, focus is on keeping the values in the economy for as long as possible by keeping them in the ‘loop’ by reuse and recycle initiatives, as well as to minimise the materials (waste) that goes out of the loop[6].

For plastics, special attention is on reducing the waste component, as around 95% of plastics are only used once. Improving designs and options for consumer sorting and recycling can be an important part of the solution. Similarly there is a potential to improve the economy of post-use plastics as the market lacks unified standards and infrastructure for reprocessing[7]. A final approach that is often mentioned is to innovate various non-petro plastic systems, leading to products that are bio-degradable.

While the circular economy thinking intuitively makes sense to consumers and decisions makers, there are quite a few pitfalls seen from the life cycle assessment (LCA) perspective. When real life causalities are not appropriately investigated and considered, I am left with such questions as: Is recycling always a good idea? How do we compare single use vs. multiple use solutions? Are the alternatives to plastic really better for the environment?

Unfortunately, these questions are often not addressed. In the supermarkets, I begin to see bio products being labelled with blatantly incorrect claims, such as being 100% CO2 neutral. Let us remind ourselves that the old adage ‘there is no such thing as a free lunch’ is true here as well – producing and using bio plastics has environmental implications just as the petro plastics have.

Luckily, we have the tools to arrive at a more balanced view of the pros and cons by applying LCA that provide answers to the above question (and more). Some of my rules of thumbs are:

  • Always consider the trade offs (What is being replaced? Pick the solution that is actually best for the environment, avoiding suboptimisation)
  • For recycling, consider what is replaced (i.e., can reuse replace equal materials or products – avoiding down-cycling?).
  • Biomaterials or products are not inherently free of GHG implications, land use effects, or biodiversity concerns (look at the full picture).
  • Be critical – find the relation between causes and effects (e.g., marine litter is not caused by plastic production, but a missing waste management)
  • Realize that sometimes more investigations are needed to reveal the true consequences of product choices.

As sustainability professionals, we need to support the decision makers and consumers to ask for truly sustainable designs and material choices. Sometimes this implies saying something that goes a bit against the grain.

It is important to distinguish between micro-plastic and “macro-plastic”. Micro-plastics, e.g., micro-beads used as scrubbers and micro-fibres from washing of synthetic textiles, pass unaltered through most waste treatment systems, and end up in the environment. Micro-beads have no options for recycling, and biodegradable alternatives are available. Thus, there are obvious reasons for banning such products, as has already been done for their use in cosmetics and personal care products in a number of countries.

For synthetic textiles and macro-plastics, the picture is quite different. When considering the alternatives, petro-plastic based products often turn out to be better for the environment, as long as it is collected and properly treated after use, so that it does not end up to decompose in nature. Capturing micro-fibres directly from the washing process therefore appears a necessity. When suggesting designs for recycling we need to make sure that fractions are clean or can be easily separated, so that downcycling is avoided as far as possible. In some situations switching to selling ‘a service’ though rental, instead of selling ‘a product’ can be a game changer, as rental comes with built-in repeated use of the product. Take-back systems also need to be investigated further, and those that actually work for the environment should be chosen over those that miss the point.

I believe there is a sustainable future for plastics, when we seriously consider the facts that we have at hand.



[2] Law K L 2017. Plastics in the Marine Environment. Annu. Rev. Mar. Sci. 9:205–29.

[3] Cole M, Lindeque P, Halsband C, Galloway T S 2011. Microplastics as contaminants in the marine environment: A review. Marine Pollution Bulletin 62(12): 588-2597

[4] Rochman C M 2018. Microplastics research—from sink to source. Science April:28-29.

[5] Communication from the Commission to the European Parliament, the Concil the European Economic and Social Committee and the Committee of the Regions. A European Strategy for Plastics in a Circular Economy.

COM/2018/028 final

[6] Ellen MacArthur Foundation 2016. The new plastics economy –rethinking the future of plastics

[7] Ellen MacArthur Foundation 2016. The new plastics economy –rethinking the future of plastics

Kick-off for the linking of SDGs to LCA

July 31, 2018 by Bo Weidema

My blog-post last October announced our SDG club – a crowd-funded project to place each of the 169 targets of the 17 UN Sustainable Development Goals (SDGs) into a comprehensive, quantified and operational impact pathway framework, as we know it from Life Cycle Impact Assessment.

Now, with co-financing from the UN Environment Life Cycle Initiative, we have added an elaborate stakeholder consultation to run parallel with the development work, and expanded the project by teaming up with PRé Consultants to cover also the more qualitative approach known from their Roundtable for Product Social Metrics.
To mark the start of this collaboration, we published yesterday a joint, free, 13-page report entitled “Making the SDGs relevant to business”, summarising the existing knowledge on the linking of SDGs to business needs and outlining the role of LCA in meeting the needs and filling the gaps.

We are now looking for businesses that are interested in taking part in the stakeholder consultations and industry case studies. Contact if you want to take part or know more.