What LCA indicators actually indicate

In my previous post I referenced an analysis of life cycle assessment studies which looked at the impacts of different foods across five different indicators. The first of these – greenhouse gas emissions – was probably pretty familiar. But what are the others and why are they important too?

Greenhouse gas emissions

What is it?
Greenhouse gases are gases that absorb infrared radiation and trap heat in the Earth’s atmosphere. These include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone (O3), and synthetic gases, such as chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs). This indicator is a measure of how much of these gases are emitted to the atmosphere.
Why is it important?
​Human activities such as burning fossil fuels and changing the way land is used (deforestation, agriculture) are releasing greenhouse gases into the atmosphere at a far greater rate than would otherwise naturally occur. This is leading to what is known as anthropogenic climate change (and I doubt this is the first time you are reading about that one…).
What is it measured in?
This indicator is measured in units of carbon dioxide equivalent (kg CO2eq). It is a measure of the equivalent global warming potential of all greenhouse gases relative to that of carbon dioxide. For example, over 100 years a molecule of methane will have 28 times the global warming impact of a molecule of carbon dioxide.

Land use

What is it?
​This indicator considers the occupation of land to produce food. For this study it includes the following types of land associated with food production – seed, on- and off-farm arable and permanent crops, fallow land, temporary pasture and permanent pasture.
Why is it important?
For products like food, land use is a very important indicator. ‘Ecological footprint‘ is often used as a measurement to indicate the area that is required to support each human, and it is currently about 1.7 times the area actually available on Earth! Expanding agricultural land threatens other land uses such as ancient rainforests and other fragile ecosystems.
What is it measured in?
This indicator is measured in m2.year, which is a measure of the area occupied (in square metres) with consideration of the time that it is occupied for (for example, if there are two harvests per year, twice as much food can be produced on the same area compared to if there is one harvest per year – all other things being equal).

Acidification

What is it?
Some gases that are emitted to the atmosphere combine with water to form an acid, which fall back to the ground as ‘acid rain’ (also called acid deposition). These gases, such as sulphur and nitrogen oxides, are released from fossil fuel burning and resultant acidic compounds can travel pretty far in the atmosphere before falling as acid rain.
Why is it important?
Some areas of the world are more or less susceptible to acidification. In Australia acid rain levels are low compared to the rest of the world because our coal has low levels of sulphur (uh, yay?) and the population is so widely distributed. However in places like Europe acid rain has resulted in devastating effects. It enters waterways and is toxic to aquatic life, and also damages forests and crops.
What is it measured in?
This indicator is measured in units of grams of sulphur dioxide equivalent (g SO2eq). The impacts of other gases such as ammonia and nitrogen oxides can be expressed in terms of sulphur dioxide equivalence.

Eutrophication

What is it?
Eutrophication occurs when excessive amounts of nutrients, such as phosphorus or nitrogen, enter a body of water. Usually plant growth is limited by the availability of nutrients, so when extra nutrients are available plants and algae start growing at a crazy rate which has all sorts of impacts on the ecosystem.
Why is it important?
Excessive amounts of nutrients enter water bodies through industrial and agricultural activities. One of the main sources of excessive nutrients is fertilisers on agricultural land that are washed into nearby waterways (fertilisers have high concentrations of nutrients on purpose, to help the plants that we want to eat grow). Eutrophication can lead to algal blooms and decreased water quality. When the algae dies and decomposes, the microbial activity can deplete the oxygen dissolved in the water and create a ‘dead zone’ where other organisms can’t survive.
What is it measured in?
This indicator is measured in units of grams of phosphate equivalent (g PO4eq). The impacts of other nutrients such as ammonia and nitrates can be expressed in terms of phosphate equivalence.

Freshwater withdrawals

What is it?
This indicator considers the water required to produce food. For this study it includes irrigation withdrawals, irrigation withdrawals embedded in feed, drinking water for livestock, water for aquaculture ponds and processing water.
Why is it important?
Many areas of the world are facing water scarcity – the recent crisis in Cape Town highlighted this issue. Growing up during the Millenium drought in Australia I remember reading many stories about farmers struggling to keep their crops and livestock alive, not to mention controversy about allocation to agricultural, environmental and other uses. And climate change is just going to exacerbate the issue.
What is it measured in?
This indicator is measures in kilolitres of water. A factor was also applied to weight the water consumption depending on water scarcity in the particular region (for example, consuming water in Australia is given a higher weight as there isn’t so much of it there, whereas it would have a lower weighting in Wales because it is a very wet place!).
Hopefully that gave a little more insight into the indicators that were discussed in the Science paper and subsequent media reports (such as here and here). These indicators cut across a range of critical environmental issues that the world is facing from climate change to land use to water scarcity.

Want to learn more about life cycle assessments?

  • The Life Cycle Initiative has put together a wonderful online course about life cycle thinking. It doesn’t go too much into the technical aspects of life cycle assessment, but rather discusses the importance of considering whole-of-life impacts in achieving sustainable development.
Photo credits: Unsplash
Back to Top