As a businessperson Barnes' solution to this problem is to charge for the "use"/ misuse of the sky, something akin to a carbon tax on atmospheric use/pollution. Whatever the logistical difficulties this is an appealing suggestion. But it is inadequate to its ambition because it essentially risks reducing essentials like the sky to tradeable commodities and thus fails what we may call the philosophical test. The sky is not a commodity; if we think it is we can trade it away. A better answer and one that imposes a barrier on misuse is that the sky, indeed the whole universe is a common trust. As such exchange is an inappropriate way of regulating its use. Neither the use-, nor the exchange-, value of the sky or rivers or forests can, or should be, quantified. A better model for their economic role is that of the commons. Once intentionally allocated to the garage-bin of history by "non-commoners" the commons is back in popular discourse for a good reason: the fragility of our eco-system. A better economic concept for our "use" of the common earth than that of the commodity the loan. The world and all therein must be seen as a temporary loan which, as in a library it is. It is our responsibility to return it as un-reduced as possible.
In fact the largely informal social contract of the loan/trust is the key concept that has historically restrained us from destroying what we cannot live without. Inscribed in indigenous beliefs it was rejected by western economics. Time to re-learn it, if indeed there still is time. We have to learn to loan more and restrain the habit of ownership that was normalized when the agricultural commons were enclosed in the 18th century. If what is in the world is becoming scarce then, as Barnes and Nobel prize-winner Elinor Ostrom understood, the commons model of universal group ownership must be championed if we are to survive as a species. And to achieve this we must loan more and own less, in that ownership is a form of separation of something that is integral - the earth.
Extending commons of various forms is the challenge of the 21st century. Unless we do this we are doomed, socially and existentially. We must loan or, in the term used by libraries we must circulate what we have instead of consuming it. In so doing we will be closer to nature as circulation is what nature does. And before the predictable response of "get real" to this principle is heard the reality is that in fact the new economics is already happening in several places, including Mondragon and Chiappas, and with the library model being extended in recent years to knowledge (influenced by the success of the Internet) and material items like seeds, cars, bikes and tools. Will it be long before we are impressing our neighbours by how much we loan rather than how much we own. For survival's sake it must be sooner rather than later.
As for Barnes' book you can buy it from our worker co-op (much better than corporate predator Amazon) . But much better than owning of course is borrowing it from your local branch of the Toronto Public Library.