Mainstream economists are trying to kill us. They don't think of it that way, but they should. The standard policies promoting endless economic growth of the conventional sort are destroying the ecosystem. Converging and interacting with other threats such as population growth, peak oil, and excessive per capita consumption, such policies and the economic growth they promote are hastening a looming global ecological collapse. And when influential economists push ecocidal policies when they could instead play a central role in protecting the ecosystem, how is that not homicide?
Cue the white hats
A ray of hope, though, comes from that transdisciplinary group of economists, ecologists, and others whose work falls under the heading, "ecological economics." Those concerned with the environment today need to understand how this group compares to their mainstream counterparts. Herman Daly, one time economist for the World Bank and now one of the most influential ecological economists, has argued persuasively that the mainstream or neoclassical model sees the economy as "everything," with the ecosystem being merely one element within it. Because this acknowledges no physical limits, it allows for the irrational notion of endless growth.
The ecological economics camp pushes for a fundamental revamp of economic theory to account for the limits of the ecosystem and the economy's being a part of it, as dependent upon it as any other aspect of human culture. They want an acknowledgment that economic growth, as it's typically understood, cannot continue indefinitely on a finite earth. They want it understood that such growth is unsustainable and destructive to our natural life support system. 
In a confusing twist, a subset of neoclassical economics is known as "environmental economics." Its practitioners are often pitted in theoretical debates against ecological economists. Environmental economists retain the fundamentals of neoclassical theory, including its failure to acknowledge the limits of the ecosystem. They attempt, however, to apply minor tweaks to the theory in an effort to account for environmental impacts, ultimately trusting the market to wield its "invisible hand" to make everything right. Most other neoclassical economists do little at all to to account realistically for the ecosystem.
Ecological economists thus find themselves at odds with a range of neoclassical economists ranging from traditionalists who see no need for any special considerations for the environment, to the "environmental" group which acknowledges it may be wise to include environment considerations in calculations and measurements, but insists the traditional model is up to the task. 
Ecological economics has so far found only minimal acceptance among mainstream economists. Most mainstream economists will say they simply disagree with the ideas of ecological economics to such an extent that they refuse to incorporate them. But what do they disagree with? The fundamental differences between the two camps seem to boil down to a few issues on which the ecological economics camp's arguments are essentially irrefutable or, at worst, eminently more reasonable than those of the mainstreamers: The ecosystem is finite. All human activities and cultural entities, including our economy, are a part of it, dependent on it, and subject to its limits. And the physical throughput associated with ongoing economic growth is degrading it.
The concerns of ecological economists reflect those of of natural scientists who point to the risks we face in allowing our actions to degrade our planet's biodiversity. Our actions have damaged the web of life, that system of millions of interdependent species on which all life, including our own, depends. The extraction of oil, burning of fossil fuels, and resulting climate change has teamed, for example with the use of land as a resource for activities such as ranching to drive deforestation, a major driver of species loss. As a result, extinctions are now occurring at 100 to 1000 times the normal background rate. Scientists such as E.O Wilson and Richard Leaky are calling it a "mass extinction event," the sixth such event and the the heaviest loss of species since the disappearance of the dinosaurs.
Do we, as one species, as dependent on the web of life as any other, think we are exempt from the risk of extinction as a result of the loss of ecosystem services provided by other species? It's a question paralleling the ecological economists' question, "Does our species really believe our economy, one of our cultural creations, sits apart from or is greater than the ecosystem which supports us?"