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The blue marble

Human overpopulation:
The Ocean is our Plan(et) B

The Royal Society of the UK has released a new report, People and the Planet, addressing the problem of human overpopulation and the depletion of key resources.

As always, the report is well written, although, in my opinion it lacks novelty, in that the trajectory toward exhaustion of key resources, including water, arable land and essential elements, such as phosphorus or iron, have been well understood and remarkably forecasted since the publication forty years ago of “The Limits to Growth”, by Donella H. Meadows and coworkers (1972).

In brief, we are aiming at 9.3 billion people on Earth by 2050, reaching the median of 23 independent estimates of the maximum human population on Earth (Cohen 1995), imposed largely by freshwater and arable land available to produce sufficient food to feed them.

Key recommendations of the report include a request to alleviate poverty and reduce inequality, the need to reduce per capita consumption in the most developed nations, implement voluntary programs for family planning, and integrate economic development and environmental conservation.

Really no surprises there, as we have known what we should do for over 40 years, yet we seem unable to implement these recommendations and continue to march toward a grim future, among increasing symptoms of overshoot.

Whereas the plan outlined in the “People and the Planet” report should continue to be our priority, as the most responsible plan, we must move onto considering a Plan B. This, in the opinion of some, such as Stephen Hawking and others (e.g. Bainbridge 2009), must include the search of an Earth-like exoplanet in our galaxy, an argument that is often used as one of the drivers for the search of exoplanets (Bainbridge 2009).

But rather than looking to space for a Plan(et) B, I suggest we should look from space, and consider our own planet, an unique blue marble, whose blue colour derives from the abundance of water, covering 72% of its surface down to a mean depth of 3800 m. If we were aliens in search for exoplanets to carry on with our lives, we would consider planet Earth to be a perfect candidate, unparallelled among the 500 plus known planets for the abundance of water. Yet, we insist in using water in the dry parts of our planet, the continents, where water is increasingly scarce.

Indeed, humans are, without fully realizing the significance of these developments, taming the oceans and starting to deliver significant amounts of water, food, energy and other resources from the oceans.

Estimates of the potential of the oceans to deliver these critical resources indicates that this is well in excess of those required to satisfy the livelihoods of 9.3 billion people (Duarte et al. 2009). The challenge, and not a difficult one, is to do so sustainably.

So we do already have our Plan(et) B, and this is called the Ocean. The Ocean has the capacity to safely and sustainably deliver resources to face the gran challenges of humanity. Indeed, the the motto of the UWA Oceans Institute, which I lead, is “Ocean Solutions for Humanity’s Grand Challenges”, as we are committed to deliver the knowledge to pursue this Plan(et) B.

Sunset over the Equatorial Pacific during the Malaspina 2010 Expedition. Photo Carlos Duarte.

I will devote the next series of blogs to present you with our Plan(et) B: Oceans.


Bainbridge, W.S. 2009. Motivations for space exploration. Futures 41: 514–522

Cohen J.E. 1995. How many people can the earth support? WW Norton & Company

Duarte, C.M., M. Holmer, Y. Olsen, D. Soto, N. Marbà, J. Guiu, K. Black and I. Karakassis. 2009. Will the Oceans Help Feed Humanity? BioScience 59: 967–976.

Meadows, D.H., D.L. Meadows,J. Randers and W.W. Behrens III. 1972. The limits to growth. Universe Books.

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