Typically, environmental health is defined in terms of what is not present: It’s an absence of contaminants, pesticides, and toxic waste. We need to expand that definition, though, to include man-made alterations to entire ecosystems. Such transformations of the natural environment have had many unintended consequences, potentially harming the health of current and future generations. But before such effects can be mitigated, more research will be required, along with a more concerted effort by governments and international organizations.

In the earliest years of the environmental movement, activists focused on pollution. Rachel Carson’s groundbreaking book Silent Spring, published in 1962, highlighted the dangers of pesticide use, in particular DDT. With her descriptions of dying birds and trees, she heightened public concern about pollution and environmental contamination—and sparked a revolution. On the first Earth Day, April 22, 1970, millions of people took to the streets to peacefully demonstrate against oil spills, toxic waste dumping, indiscriminate pesticide use, and polluting factories. Eight months later, President Richard Nixon established the Environmental Protection Agency (EPA) with the mission of protecting human health and the environment. Its strategic goals include improving air quality, protecting waterways, cleaning up communities, preventing pollution, ensuring chemical safety, and enforcing environmental laws. These remain vitally important.

They should no longer be the only goals, though. More than seven billion humans are not merely putting toxins into the land, sea, and air, but also transforming nearly all of the planet’s ecosystems in dramatic ways. They’re doing so to meet an ever-increasing demand for food, clean water, manufactured products, and energy, all of which require natural resources. This monumental transformation of the planet has prompted scientists to rename the current geological epoch the Anthropocene. The full brunt of humans’ impact on the natural world remains to be seen, but some political leaders are worried.

An inadequate response. In 2000, United Nations Secretary-General Kofi Annan called for a Millennium Ecosystem Assessment, with the objective of evaluating the impact of ecosystem change on human well being, as well as developing a scientific basis for action. The assessment involved more than 1,360 experts from 95 countries and cost $24 million.

They found that humans had changed ecosystems more extensively and rapidly in the previous 50 years than at any other time in human history. Many of these changes improved human well-being and economic development, but came at a huge cost: extensive and largely irreversible biodiversity loss.

While some people might not care that frog, bird, fish, or mammalian species have gone extinct, these losses could be early warning signals of a looming environmental catastrophe. Ecosystems perform important functions that are largely taken for granted or ignored. For instance, deforestation can unleash deadly emerging diseases, often by displacing wildlife or arthropod vectors (insects) so that they come into closer contact with humans. Yellow fever, dengue fever, Rocky Mountain spotted fever, and Lyme disease are all associated with deforestation. A new field called “disease ecology” studies how biodiversity, population dynamics, and altered ecosystems affect the risk of infection. There is much we don’t know and, unfortunately, little funding for research.

We do know that ecosystems provide clean water, control floods, absorb carbon dioxide, and protect human health. For example, watersheds and forest wetlands filter contaminants and pathogens from rainwater before it passes into rivers and seas, and coastal barriers such as mangroves, coral reefs, and marshes protect millions of people living near shores from storm surges and flooding. But we don’t understand all the dynamics at play.

No one is in charge. Ecosystems should be thought of as natural resources that need to be understood and protected. Unfortunately, there is no global, coordinated effort and no single international body in charge of environmental protection. Instead, responsibility for environmental issues is fragmented among many entities. The United Nations has the Environment Programme, which was established in 1972 with the mission of assessing global trends and promoting wise use of the environment. Its budget is approximately $250 million, which comes primarily from voluntary contributions by member states. The European Union has proposed upgrading it as a separate UN organization, but a debate is ongoing as to how this restructured entity would perform better than the existing Environment Programme.

The World Health Organization (WHO), a UN body, does have an environmental health section that focuses on air and water pollution as well as sanitation. Out of a total WHO budget of approximately $3.9 billion, though, only $86.8 million is targeted at the environment, with a focus on strengthening countries’ abilities to deal with health problems caused by climate change, promoting better responses to weather emergencies such as tsunamis, and providing occupational health services, among other goals. These are important, but they are reactive measures that do not get at the heart of understanding humanity’s impact on the environment. Neither the UN Environment Programme nor the WHO has the resources to do what’s needed: comprehend the root causes and effects of ecosystem alterations, so that the world community can develop better strategies to prevent and mitigate the resulting health threats.

For example, the spread of farms and suburban lawns and other factors have contributed to decimating not only monarch butterfly populations, but also the number of bees, which pollinate food crops. Without bees, humanity would lose about 80 percent of the plants (especially fruits and nuts) required for a healthy diet. Scientists and policy-makers should have studied the impact of such environmental alterations long before the decimation of these essential populations was occurring.

Next steps. The international community needs to think creatively and comprehensively about how Earth’s resources are being used. The haphazard alteration of ecosystems is not sustainable and threatens the lives of future generations. So what should be done?

First, the definition of environmental health should be expanded to include understanding ecosystem alterations, as Samuel S. Myers of the Harvard School of Public Health and his colleagues have suggested. Schools of medicine, public health, urban planning, and public administration should include this subject in their curriculums. Currently, courses in environmental health focus on environmental contaminants and exposures, primarily in occupational settings. We need a cadre of professionals who can understand and address a growing and broader challenge.

Second, government entities like the EPA and the US Fish and Wildlife Service should work together to conduct ecosystem alteration assessments. These should be integrated with the health impact assessments that governments and the WHO already conduct to examine the impact of public policies.

Third, governments should expand the funds allotted to studying and dealing with ecosystem alterations. With origins dating back to 1871, the Fish and Wildlife Service has primary responsibility for managing biological resources and enforcing laws like the Endangered Species Act and the Marine Mammal Protection Act. But while Fish and Wildlife Service experts play an important role in monitoring the status of flora and fauna, they are severely underfunded. In fiscal 2012, the service’s budget was $1.48 billion, which represented a 2 percent decrease from the previous year.

The EPA’s budget isn’t so large either. Its fiscal 2013 budget was $7.9 billion, a 23 percent decrease from fiscal 2010—a drop that required it to cut its workforce to fewer than 16,000 people. To put these budgets in perspective, the US Defense Department’s fiscal 2013 budget was $525.4 billion. Because environmental change has such a profound effect on human health and well-being, Washington must find ways to expand the budgets of the agencies grappling with it.

Finally, international organizations need to consolidate the array of bodies dealing with environmental health and give the subject the priority, funding, and other resources it deserves.

Fortunately, in the United States and around the world, concern about the effects of ecosystem alteration has spread beyond academia and government to ordinary citizens. The corporate world, too, has begun to show more readiness to address its role in the problem, for instance through the World Forum on Natural Capital held in Edinburgh in November 2013. That’s good news, because everyone’s effort is crucial to this global endeavor. Ultimately, we need to work together to make sure the planet remains habitable—for our own sake and for future generations.