<P> Global assessments of biodiversity indicate that the current epoch, the Holocene (or Anthropocene) is a sixth mass extinction . Species loss is accelerating at 100--1000 times faster than average background rates in the fossil record . The field of conservation biology involves ecologists that are researching, confronting, and searching for solutions to sustain the planet's ecosystems for future generations . </P> <P> "Human activities are associated directly or indirectly with nearly every aspect of the current extinction spasm ." </P> <P> Nature is a resilient system . Ecosystems regenerate, withstand, and are forever adapting to fluctuating environments . Ecological resilience is an important conceptual framework in conservation management and it is defined as the preservation of biological relations in ecosystems that persevere and regenerate in response to disturbance over time . However, persistent, systematic, large and nonrandom disturbance caused by the niche constructing behavior of human beings, habitat conversion and land development, has pushed many of the Earth's ecosystems to the extent of their resilient thresholds . Three planetary thresholds have already been crossed, including biodiversity loss, climate change, and nitrogen cycles . These biophysical systems are ecologically interrelated and naturally resilient, but human civilization has transitioned the planet to an Anthropocene epoch, where the threshold for planetary scale resilience has been crossed and the ecological state of the Earth is deteriorating rapidly to the detriment of humanity . The world's fisheries and oceans, for example, are facing dire challenges as the threat of global collapse appears imminent, with serious ramifications for the well - being of humanity; while the Anthropocene is yet to be classified as an official epoch, current evidence suggest that "an epoch - scale boundary has been crossed within the last two centuries ." The ecology of the planet is further threatened by global warming, but investments in nature conservation can provide a regulatory feedback to store and regulate carbon and other greenhouse gases . </P> <P> In 1992, William Rees developed the ecological footprint concept . The ecological footprint and its close analog the water footprint has become a popular way of accounting for the level of impact that human society is imparting on the Earth's ecosystems . All indications are that the human enterprise is unsustainable as the footprint of society is placing too much stress on the ecology of the planet . The WWF 2008 living planet report and other researchers report that human civilization has exceeded the bio-regenerative capacity of the planet . This means that the footprint of human consumption is extracting more natural resources than can be replenished by ecosystems around the world . </P>

Who introduced the concept of relationship of environment with human health