Biodiversity, biocapacity and better choices

What does “ecological overshoot” mean?Humanity’s annual demand on the natural world has exceededwhat the Earth can renew in a year since the 1970s. This “ecologicalovershoot” has continued to grow over the years, reaching a 50 percent deficit in 2008. This means that it takes 1.5 years for the Earthto regenerate the renewable resources that people use, and absorbthe CO2 waste they produce, in that same year.How can this be possible when there is only one Earth?Just as it is possible to withdraw money from a bank accountfaster than to wait for the interest this money generates, renewableresources can be harvested faster than they can be re-grown. Butjust like overdrawing from a bank account, eventually the resourcewill be depleted. At present, people are often able to shift theirsourcing when this happens; however at current consumptionrates, these sources will eventually run out of resources too –and some ecosystems will collapse even before the resource iscompletely gone.The consequences of excess greenhouse gases that cannotbe absorbed by vegetation are already being seen, with risinglevels of atmospheric CO2 causing increased global temperatures,climate change and ocean acidification. These impacts in turn placeadditional stresses on biodiversity and ecosystems and the veryresources on which people depend.Global hectares per capita3.532.521.510.50BIOCAPACITY =(SUPPLY)ECOLOGICAL FOOTPRINT =(DEMAND)Area x BioproductivityPopulation xConsumption xper personFootprintintensity1961 1970 1980 1990 2000 2008YearFigure 23: Trends in Ecological Footprint and biocapacity per personbetween 1961 and 2008The decline in biocapacity per capita is primarily due to an increase in globalpopulation. More people have to share the Earth’s resources. The increase in theEarth’s productivity is not enough to compensate for the demands of this growingpopulation (Global Footprint Network, 2011).1.5 yearsto generatethe renewableresources usedin 2008OVERSHOOTFigure 24: Factorsdriving EcologicalFootprint andbiocapacity (GlobalFootprint Network, 2011)Biocapacity factorsBioproductive area: The area availableof cropland, grazing land, fishing groundsand forests.Bioproductivity per hectare: Anarea’s productivity can vary each year anddepends on factors such as ecosystemtype, management and health, agriculturalpractices and weather. Productivity canbe enhanced to achieve more biocapacity,however this often comes at the costof a larger Ecological Footprint. Forexample, energy-intensive agriculture andheavy reliance on fertilizer may increaseyields, but requires increased inputs andgenerates higher CO2 emissions.Biocapacity and Ecological Footprint trendsThe Ecological Footprint is driven by consumer habits and theefficiency with which goods and services can be provided. Thegrowing biocapacity deficit – defined as when a population usesmore biocapacity than can be supplied and regenerated in a year– is driven by the combination of high consumption rates that areincreasing more rapidly than improvements in efficiency (increasingpeople’s footprint); and populations growing faster than thebiosphere’s capacity (driving down biocapacity per person).Ecological Footprint driversPopulation growth: The growingnumber of consumers is a strong driverbehind the increasing global footprint.The human population is forecast to reach7.8-10.9 billion people by 2050, with amedium estimate of just over 9.3 billion(UN, 2010). Population size also affectsthe biocapacity available to each person.Consumption of goods and servicesper person: Different populationsconsume different quantities of goodsand services, primarily based on theirincome level.Footprint Intensity: The efficiency withwhich natural resources are convertedinto goods and services affects the size ofthe footprint of every product consumed.This varies between countries.WWF Living Planet Report 2012 page 40 Chapter 1: The state of the planet page 41