DELY : Disabled Earth Life Years

We can develop beautiful so-called scientific methods to calculate all the effects of our impact, but in the end only two data are relevant: energy and material use, and the rest is derived from that: all emissions, to air or water, pollution, disappearance of forests, , and climate warming and desiccation, etc., are side effects of this. So we only have to look at energy and material, and then we immediately see that as long as we use renewable or organic, or ‘flowing’, resources there is little to worry about, because we live parallel and participate in natural processes, As soon as we deviate from those, and use resources that are not regenerated, we’re in trouble, especially if we over-consume those resources and don’t restore supplies. Ergo, it turns out that we have to switch mainly to renewable energy and renewable materials. In that case it is mainly important to measure the extent to which we apply renewables, and although the side effects of direct use are small, if we surpass the annual potential , ‘the budget’, side effects and problems also arise for renewable sources.

(for the record: there is also an annual budget for metals and other non-renewed raw materials, these also ‘flow’, but in such low quantities that they are no longer interesting for us in 2021 – MAXergy 3.0) [1].

There is also a different way to look at this. A colleague from France, Bruno Peuportier, asked himself , and us, in a meeting more or less the same kind of question, and wondered if it would not be enough to work with 2 indicators. One for ‘human health’ and one for ‘systemic (ecological) health’.

Interesting thought. That certainly sounds logical, so I was very curious. And he wondered if that could be these two indicators: .DALY and PDF. The first I knew, the second not really. But as follows:

DALY stands for Dissability Ajusted Life Years. In other words: lost years of life due to external factors, such as air pollution (and also increasingly due to heat waves and the like). It is a common way of expressing the severity of an effect in terms of health.

The second turned out to stand for Potentially Disappeared Fraction of species. In other words: the ecosystem quality is not expressed in soil quality, or depletion of sources (loss or effect), but in biodiversity loss. I hadn’t looked at it that way, but it’s an interesting view. After all, if biodiversity remains healthy and at the right level, then so is the air, the soil, the variety of vegetation, the forest area. And most probably this will be a society without the use of pesticides, no depletion of land due to overexploitation, clear-cutting of forests, etc.

The unit for ‘PDF’ is in numbers per m2-year… Interesting, m2-year (ha-year) is also the unit in which I calculate in MAXergy, with “Embodied Land” use: how much land is involved in producing or compensating for resource use. If that is in balance, reversely argued, biodiversity will also do well (because renewable resources are used within maximum potential, no overexploitation). With PDF, things are viewed coming from the other side: if biodiversity is doing well, resources and their use will be ok as well, probably.

The combination of DALY with PDF, is in fact again a representation of the balance between people and planet, or people and resources (as supplied by the planet) P/R as I derived it in my book People vs Resources [2]. Interesting! Or in this case reframed as : people (health) versus biodiversity (health) …!

However to make this concrete is still quite difficult. For example take as a measure the number of lost years of life. Lost compared to what? To what level of expectation? After all, many (average and absolute) years of life have been added in the past 2 centuries, and these are largely the result of exhausting that other side of the coin: healthier and more consistent nutrition, enormous investments in health care and education, which required money and time, that came available as a result of economic growth, or increased and accelerated use of (fossil) energy and raw materials. It could well be that the optimal level of life expectation is lower or, in other words, that the balance between human health and system health requires that we have to die 10 years earlier as the current average life expectancy. After all, the longer we live as humans, the more we consume per person, ie energy and material devour, with all the annoying side effects, and moreover , if we live longer we are with more people at the same time on earth , increasing the pressure on the system. So we could die six months earlier due to air pollution, for example, but we may have already lived 5 or 10  years too long because of over-exploitation of resources. I don’t know, I just want to say it’s a very difficult question and/or calculation.

The question is, however, whether we (can) have any influence on this ourselves. So far, no species has been able to control its own success. It is usually boom and bust, one species explodes at the expense of another, and when the food or prey runs out, the species collapses again. To start all over again.

But well, here I actually wanted to talk about the other indicator in particular; ecological health. Biodiversity actually doesn’t seem like such a bad choice for an indicator. Because the success of one species is the downfall of another, which is exactly what we see happening: biodiversity is decreasing, with 1 species flourishing. Which however automatically means that we as the flourishing species will also collapse at some point: Since when biodiversity populations decrease, or that there are fewer animal species, this will also imply that plants are less fertilized and inseminated, and therefore plant-food yields decrease. We exist thanks to the activity of worms at the bottom on one side, and bees at the top of the land on the other side, creating the interaction we have to live from on the land we walk on. When those interactions disappear, and they do (who still sees worms regularly?), then it becomes very annoying and inconvenient. So biodiversity should definitely be considered Per hectare.

Although I can’t help to dig a bit deeper: What if we don’t measure the decline of biodiversity, but measure whether we are staying within the potential of that hectare? That’s a little more proactive maybe. Sustainable land use then, the measure with which I in any case measure the physical balance: land as the interaction platform between the ultimate energy source, the sun, and the (bio) mass on which we live. Land that is needed to keep the cycles closed, cycles that also depend on the worms and the bees that act on them. Healthy land use is the essence here.

Or, elaborating on DALY: the DELY: Disabled Earth Life Years: Due to overproduction and excessive depletion of the soil, lost production years of the soil arise: It is already assumed that the soil in northern Europe can only handle a maximum of 60 harvests, before being completely exhausted. In fact, every hectare of current agriculture requires at least 7.7 hectares of resources as input. [3] In other words, 7.7 years of production are lost by 1 year of production.

The number of years of ecological growth that we have already used up as an advance, years that actually would have been needed to compensate for our impact. Think of CO2: it requires a certain amount forest, for a certain time, to capture that CO2 again, and possibly even to form oil, gas  and coal again as inert storage. As Dukes calculated , somewhere around 1888 we crossed the barrier, when we started using more as the system could compensate in new formed stocks. [4] Or calculated differently by Dukes: “that to generate the fossil fuels burned (in 1997), it required ( in original biomass) 422 times the amount of carbon that is fixed globally each year! “.

So we now live on the credit of the future: we in fact consume already (ref 1997) the land yield (system potential) of the year 2419…. That is like the man in the Pub who drinks a few liquors every evening, and declares: The doctor allows me one drink a day, this one is from Wednesday 14 May 2024….

And DALY? For the time being, life expectancy is growing faster than the reduced years. Until biodiversity collapses completely, and life suddenly stops, of course.




[1] Maxergy 3.0



[2] Book:

NL: Gebroken Kringlopen. Naar een volhoudbaar gebruik van bronnen, Ronald Rovers, Uitg Eburon, isbn 9789463012034

and UK version: People vs Resources – restoring a world out of balance, Ronald Rovers, Publ. Eburon, isbn 9789463012553

[3] blog with references:



[4] Dukes: Dukes, J.S. 2003. Burning buried Sunshine: Human consumption of ancient solar energy, Climatic Change 61:31-44 Zie:

Author: ronald rovers