12/28/2012 01:02 pm ET Updated Feb 27, 2013

2012: A Farewell to Creatures Great (and Small)

Nothing is for certain, but in an 80-100 year timeframe, the prognosis is not good for large mammals, large fish and even large trees. Many young people will likely witness in their lifetime the virtual extinction of elephants, rhinos, lions, tigers and many other large mammals. With their numbers steadily shrinking and many of their species already extinct, there is little reason to believe that conservation's effort will stave off their ultimate demise. As human numbers and habitats expand and as poaching becomes ever more lucrative, it is hard to see how their species could survive in the wild. The news in 2012, almost without exception, was grim.

Jane Goodall, the world-renowned conservationist, warned earlier this month that the world's ivory trade is wiping out elephants in Africa, where an estimated 30,000 were killed this year. Goodall told the Guardian, that "We believe that Tanzania has lost half its elephants in the last three years. Ugandan military planes have been seen over the Democratic Republic of the Congo shooting elephants from the air. Armed militia are now shooting the elephants." The World Conservation Society estimates that the elephant population in southern Sudan has crashed from 130,000 in 1986 to a mere 5,000 today. Unless a global ban on ivory sales is implemented soon, the African elephant will be virtually extinct before we know it.

The ivory trade is also threatening rhinos. The World Wildlife Fund just reported that 2011 was another record year for poaching, with an estimated 448 rhinos in southern Africa killed for their tusks. Last year the International Union for Conservation of Nature declared that the Western Black Rhino is now extinct in the wild. Now, a year later, still more species are edging ever closer to extinction.

The lion kingdom is in steep decline. In 1960, there were 400,000 lions living in the wild. Today, there are, by some estimates, only 20,000. Experts predict that lions could be extinct in the wild within 10 to 15 years. Tanzania has a viable lion conservation program, but continent-wide the lion population has fallen by two-thirds in the past 40 years because of shrinking African savannahs. In many African countries the lion population is now gone.

Tigers, too, are in mortal danger. Despite efforts to curb poaching and preserve remaining habitats, the odds of extinction are growing. Wildlife conservationists estimate that there are only 2,500 breeding adult tigers left in the wild. The population of the Sumatran tiger, the only remaining tiger species in Indonesia, has shrunk to 500, just half of what it was 40 years ago.

But it's not just large mammals that are vanishing; the populations of large fish, including tuna, marlins, cod and sharks are in rapid decline. As recently as a decade ago, research indicated that large fish populations had declined by 90 percent since 1950. Today, as the world's appetite for shark fin soup soars, the populations of many shark species are in free fall. An estimated 25 million sharks were killed this year for their fins.

And it's not just the large animals that are under assault. A study released earlier this month indicates that big trees are in peril. Around the world, climate change and deforestation are accelerating the loss of pines, evergreens, cedars, eucalyptus and other large trees. Droughts and rising temperatures are fueling fires and infestations that are destroying whole forests and the habitats the provide. Many of the dying trees are 100-300 years old.

When large animals, big fish and old trees die off, their rapid demise affects entire eco-systems, imperiling creatures both great and small. Some species may benefit, as the lobster population did after the Atlantic cod fishery collapsed, but the overall effect is highly disruptive. When large animals or fish die off, the population of their natural prey may soar, but unsustainably so, leading to overgrazing or the extinction of other species in the food chain. In the case of large trees, the canopies they provide are essential habitats for birds and small animals.

In the end, of course, the disruption of entire eco-systems is harmful to the people who depend upon them for their economic survival. Poaching in developing countries may temporarily enrich the poachers, but posterity is inevitably impoverished.

For better or worse, we are now stewards of the Earth and all the life that it sustains. If the elephants, rhinos, lions and tigers vanish from the Earth, if large fish populations are extinguished, if all the great trees are felled, and if the seas are overtaken by algae and jellyfish and the land by rodents and cockroaches, we will have no one to blame but ourselves.