Paying off Earth's ecological debt

Blog Post by Luc Sidebotham 20 November 2015

I’m always keeping an eye out for interesting environmental stories and ideas that I’m not familiar with, but one that’s passed me by (until now) is the ominous-sounding ‘Ecological Debt Day’.

The article I read said Ecological Debt Day was on 9th August this year and August 19th in 2014; back in 1970 Ecological Debt Day was December 23rd. That meant we’d lost 10 days in the space of a year and months in a few decades: it seemed worrying, but I was mostly confused. Here’s what I learned about Ecological Debt Day.

Ecological Debt Day (also known as Earth Overshoot Day) is an annual occurrence marking the day in the calendar year that our resource use exceeds the amount of resource that the planet can regenerate in that calendar year, i.e. the point at which we start consuming things that we really shouldn’t be (from a sustainability perspective). As the example dates above suggest, the EDD is creeping forward every year because, as a whole, humanity’s overconsumption of resources is accelerating.

In economic terms, EDD represents the day of the year in which humanity enters ‘deficit spending’.

If you prefer a mathematical formula (no, me neither!) it looks like this:

(World Biocapacity / World Ecological Footprint) * 365 = Ecological Debt Day

The world’s ‘Biocapacity’ is the ability of the planet to produce useful biological materials and to absorb carbon dioxide emissions. It’s calculated according to the amount of biologically productive land and sea available (this includes forests, grazing lands, cropland, fishing grounds and built-up land).

The world’s ‘Ecological Footprint’ is a measure of the global demand for biological resources, including plant-based food and fibre (e.g. cotton), livestock, fish, timber, space for infrastructure and carbon sinks such as forests.

The resulting EDD illustrates how far beyond our planetary means we’re living and also which direction we’re moving in. The consequences of this ecological debt are climate change (because greenhouse gases are emitted faster than they can be absorbed by forests and oceans), shrinking forests, species loss, fisheries collapse, higher commodity prices and civil unrest.

One of the interesting things about the EDD is that the figures and footprints can be calculated country by country, showing individual countries’ deficits and surpluses. As you might expect the UK, as an industrialised, relatively small nation, runs an ecological deficit of around 200%. However, we are by no means the worst: Singapore has the world’s biggest deficit (an eyewatering 15,000%) and Japan’s deficit is 450%. This compares with China (170%), India (100%) and France (41%). Countries with big biocapacities or small footprints are those in surplus, such as Congo with 1,000% surplus, Brazil 220% and Canada 120%. The figures show that in total we’ll consume 1.6 Earth’s worth of resources this year. For more info and data interpretation, go to

As a measure EDD has its flaws but for me, it’s an interesting and accessible, non-scientific way of demonstrating how our consumption of resources is escalating. On my lookout for interesting environmental stuff I’ll be keeping an eye out for Ecological Debt Day 2016 but hopefully not seeing it before 9th August.


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