It is more than a generation since the appearance of Barry Lopez’s classic Arctic Dreams. That book’s effortless integration of history, anthropology and ecology, mediated through its author’s radiant prose, introduced a global audience to the frozen north. It freed the frigid ice world from much historical polar literature, conjuring instead landscapes of delicate beauty and extraordinary natural abundance. Lopez also revealed the Arctic as a place of remarkable human achievement, as expressed in the survival skills and spiritual endurance of the indigenous Inuit.

A follow-up has long been anticipated and now, 33 years later, Horizon has finally arrived. It is vast in both scope and size; comprising more than 200,000 words, the book is divided into six geographical sketches, the shortest of which is nearly 60 pages long. The normally reticent Lopez begins his story with a lengthy preamble about his childhood, which offers insights into his career as a global nomad. It seems significant that he grew up in the 1940s and 1950s, close to both America’s Atlantic and Pacific coastlines, and all but one of his six sections are set by the sea.

The first, Cape Foulweather, is on the shores of his adopted home state, Oregon. The second and third are off Ellesmere Island, in the Canadian Arctic Circle, and on Ecuador’s Galápagos archipelago. His quest for the remains of early hominids in the Rift Valley of Kenya provides the one inland anomaly. Sections five and six are set largely on the Pacific shores of Australia and the frozen edge of Antarctica, where Lopez joined a scientific expedition in search of meteorites.

These locations supply the backdrop for some of the author’s favourite themes, most notably the adaptation of life to its surrounding environment, and especially the spiritual and physical armouries developed by non-industrial peoples living in the most arduous conditions. His participation in archaeological digs in the Canadian Arctic and the Turkana territories of Kenya also gives rise to essays on human origins.

In addition to these underlying intellectual fields there is a recurrent concern to set out an ethical position. Given that Horizon is largely a book about ‘New Worlds’,  where Europeans undertook the political and spiritual displacement of the original pre-industrial communities — the Bantu tribes of Kenya, the aborigines of New South Wales, the eskimos of Ellesmere Island — the issues of imperialism and its legacy are constant.

Lopez is now 74, and it seems natural that he should be nostalgic. In his life he has seen human population triple to 7.5 billion, with all its catastrophic impact on the rest of life. In Horizon, he addresses himself to the moral implications of society’s capitalist consumerism and the threat of climate change.

For all his pronouncements on this pressing matter, however, the ambiguities entailed in his own status as both global wanderer-cum-witness and tireless consumer of fossil fuel never enter his moral sphere. Yet, given his multiple expeditions to both poles and a canon of work centred on inaccessible places (many of which can be reached only by helicopter, land-cruiser, ice-breaker or private charter), it is hard to think of a major modern writer whose life has involved the burning of more oil.

It is not just this ethical lacuna which creates a curious absence at the heart of the book. Its structure is also fragmented and faltering. What distinguishes Lopez’s earlier masterworks — especially Of Wolves and Men and Arctic Dreams — is that they possess a unity of place and subject matter. In those books his imagination illuminates a thematic kernel, whose ideas radiate outwards towards larger and grander implications. Here the reverse seems the case.

Horizon looks from the outset to be striving for some kind of universal recapitulation. The geography moves from pole to pole and, thematically, from Chilean poetry to quantum physics. Lopez tries to track the story of humankind from its Pleistocene origins towards its Anthropocene future, while giving us his thoughts on the inner workings of DNA and the role of dark matter in outer space.

Don’t get me wrong: there are superb essays that reveal the author’s remarkable technical mastery of very diverse subjects, and these are rewarding. More-over, the examples of Captain Cook and Charles Darwin are on hand as historical proxies and inspirations for Lopez’s own quest for global inclusivity. Finally there is, as distraction almost on every page, the sonorous cadence of his prose. But despite such consolations, I could not avoid a nagging sensation of some fundamental incoherence — and the conclusion thatthe whole was somehow less than the sum of its parts.