Hit & Run

Kill Yourself to Protect Biodiversity

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Giant Moa
New Zealand Post

All right, the headline not exactly what a new study, "Social-Ecological Predictors of Global Invasions and Extinctions," in the journal Ecology and Society recommends. The study, however, does claim that longer human lives is a significant factor in falling global biodiversity. From the study:

As human life expectancy increases, the percentage of invasive and endangered birds and mammals within a country increases…

We found a positive relationship between life expectancy and the percentage of endangered and invasive species in a country… The overall trend in high-income countries with improvements to the Human Development Index, which includes human life expectancy as one of its variables, is toward a disproportionately larger negative impact on a country's ecological footprint…. Increased life expectancy means that people live longer and affect the planet longer; each year is another year of carbon footprint, ecological footprint, use of natural resources, etc. The magnitude of this impact is increased as more people live longer.

So on this analysis, one could logically conclude that shortening human lives might be one way to preserve species.

I further note that the study focuses a lot on the biodiversity trends in New Zealand:

New Zealand has had a massive invasion by nonindigenous species since its human colonization in the past 700 to 800 years, and this has resulted in catastrophic biodiversity loss. New Zealand's invasive species crisis may be due in large part to its isolation, high endemism, and recent human colonization. Island ecosystems are often the most invaded and consequently the most threatened worldwide.

Catastrophic biodiversity loss? It is true that lots of local species have gone extinct in New Zealand, e.g., giant moas that ended their days in Maori cooking pots. However, one measure of biodiversity is "species richness" defined as the number of different species represented in an ecological community, landscape or region. By that measure, modern humans have been dramatically increasing biodiversity nearly everywhere including New Zealand.

Consider that in California an additional 1,000 new species of vascular plants have joined the 6,000 native species in the Golden State, and so far as is known, only 40 species have gone extinct. Similar increases in plant diversity can be seen around the globe. For example, New Zealand's 2,000 native plant species have been joined by 2,000 from elsewhere, doubling the plant biodiversity of its islands. Meanwhile only 3 species of native plants have gone extinct. Similarly, the number of plant species living on the landscape in Hawaii has increased from 1,300 to 2,300.

For more background on the trend toward increasing local biodiversity see my article, "Invasion of the Invasive Species."