Human impact on nature Plan: Human impact on nature

Overconsumption[edit]
Main article: Overconsumption
Chart published by NASA depicting CO₂ levels from the past 400,000 years.^[26]
Overconsumption is a situation where resource use has outpaced the sustainable capacity of the ecosystem. It can be measured by the ecological footprint, a resource accounting approach which compares human demand on ecosystems with the amount of planet matter ecosystems can renew. Estimates^{[by whom?]} indicate that humanity's current demand is 70%^[27] higher than the regeneration rate of all of the planet's ecosystems combined. A prolonged pattern of overconsumption leads to environmental degradation and the eventual loss of resource bases.
Humanity's overall impact on the planet is affected by many factors, not just the raw number of people. Their lifestyle (including overall affluence and resource use) and the pollution they generate (including carbon footprint) are equally important. In 2008, The New York Times stated that the inhabitants of the developed nations of the world consume resources like oil and metals at a rate almost 32 times greater than those of the developing world, who make up the majority of the human population.^[28]
Reduction of one's carbon footprint for various actions.
Human civilization has caused the loss of 83% of all wild mammals and half of plants.^[29] The world's chickens are triple the weight of all the wild birds, while domesticated cattle and pigs outweigh all wild mammals by 14 to 1.^[30][31] Global meat consumption is projected to more than double by 2050, perhaps as much as 76%, as the global population rises to more than 9 billion, which will be a significant driver of further biodiversity loss and increased Greenhouse gas emissions.^[32][33]
Population growth and size[edit]
Human population from 10000 BCE to 2000 CE, increasing sevenfold after the eighteenth century.^[34][35]
Main article: Human overpopulation
Some scholars, environmentalists and advocates have linked human population growth or population size as a driver of environmental issues, including some suggesting this indicates an overpopulation scenario.^[11] In 2017, over 15,000 scientists around the world issued a second warning to humanity which asserted that rapid human population growth is the "primary driver behind many ecological and even societal threats."^[36] According to the Global Assessment Report on Biodiversity and Ecosystem Services, released by the United Nations' Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services in 2019, human population growth is a significant factor in contemporary biodiversity loss.^[37] A 2021 report in Frontiers in Conservation Science proposed that population size and growth are significant factors in biodiversity loss, soil degradation and pollution.^[38][39]
Some scientists and environmentalists, including Pentti Linkola,^[40] Jared Diamond and E. O. Wilson, posit that human population growth is devastating to biodiversity. Wilson for example, has expressed concern when Homo sapiens reached a population of six billion their biomass exceeded that of any other large land dwelling animal species that had ever existed by over 100 times.^[41]
However, attributing overpopulation as a cause of environmental issues is controversial. Demographic projections indicate that population growth is slowing and world population will peak in the 21st century,^[34] and many experts believe that global resources can meet this increased demand, suggesting a global overpopulation scenario is unlikely. Other projections have the population continuing to grow into the next century.^[42] While some studies, including the British government's 2021 Economics of Biodiversity review, posit that population growth and overconsumption are interdependent,^[43][44][45] critics suggest blaming overpopulation for environmental issues can unduly blame poor populations in the Global South or oversimplify more complex drivers, leading some to treat overconsumption as a separate issue.^[46][47][48]
Advocates for further reducing fertility rates, among them Rodolfo Dirzo and Paul R. Ehrlich, argue that this reduction should primarily affect the "overconsuming wealthy and middle classes," with the ultimate goal being to shrink "the scale of the human enterprise" and reverse the "growthmania" which they say threatens biodiversity and the "life-support systems of humanity."^[49]
Fishing and farming[edit]
Main article: Environmental impact of agriculture
The environmental impact of agriculture varies based on the wide variety of agricultural practices employed around the world. Ultimately, the environmental impact depends on the production practices of the system used by farmers. The connection between emissions into the environment and the farming system is indirect, as it also depends on other climate variables such as rainfall and temperature.
Lacanja burn
There are two types of indicators of environmental impact: "means-based", which is based on the farmer's production methods, and "effect-based", which is the impact that farming methods have on the farming system or on emissions to the environment. An example of a means-based indicator would be the quality of groundwater that is affected by the amount of nitrogen applied to the soil. An indicator reflecting the loss of nitrate to groundwater would be effect-based.^[50]
The environmental impact of agriculture involves a variety of factors from the soil, to water, the air, animal and soil diversity, plants, and the food itself. Some of the environmental issues that are related to agriculture are climate change, deforestation, genetic engineering, irrigation problems, pollutants, soil degradation, and waste.
Fishing[edit]
Main article: Environmental impact of fishing
Fishing down the foodweb
The environmental impact of fishing can be divided into issues that involve the availability of fish to be caught, such as overfishing, sustainable fisheries, and fisheries management; and issues that involve the impact of fishing on other elements of the environment, such as by-catch and destruction of habitat such as coral reefs.^[51] According to the 2019 Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services report, overfishing is the main driver of mass species extinction in the oceans.^[52]
These conservation issues are part of marine conservation, and are addressed in fisheries science programs. There is a growing gap between how many fish are available to be caught and humanity's desire to catch them, a problem that gets worse as the world population grows.^{[citation needed]}
Similar to other environmental issues, there can be conflict between the fishermen who depend on fishing for their livelihoods and fishery scientists who realize that if future fish populations are to be sustainable then some fisheries must reduce or even close.^[53]
The journal Science published a four-year study in November 2006, which predicted that, at prevailing trends, the world would run out of wild-caught seafood in 2048.^[54] The scientists stated that the decline was a result of overfishing, pollution and other environmental factors that were reducing the population of fisheries at the same time as their ecosystems were being degraded. Yet again the analysis has met criticism as being fundamentally flawed, and many fishery management officials, industry representatives and scientists challenge the findings, although the debate continues. Many countries, such as Tonga, the United States, Australia and New Zealand, and international management bodies have taken steps to appropriately manage marine resources.^[55][56]
The UN's Food and Agriculture Organization (FAO) released their biennial State of World Fisheries and Aquaculture in 2018^[57] noting that capture fishery production has remained constant for the last two decades but unsustainable overfishing has increased to 33% of the world's fisheries. They also noted that aquaculture, the production of farmed fish, has increased from 120 million tonnes per year in 1990 to over 170 million tonnes in 2018.^[58]
Populations of oceanic sharks and rays have been reduced by 71% since 1970, largely due to overfishing. More than three-quarters of the species comprising this group are now threatened with extinction.^[59][60]