In Paris 2015 at the United Nations Climate Change Conference, nearly 200 nations agreed to tackle climate change by cutting their greenhouse gas emissions. The effects of global warming include rises in sea levels which could lead to widespread flooding; a decline in Arctic sea ice to such an extent that Arctic summers could be ice free as early as 2025; an increase in the frequency and severity of heatwaves causing droughts to become more frequent; and ocean acidification, a growing threat to coral reefs and fisheries. As well as this, higher global temperatures and carbon dioxide levels have affected global ecosystems, resulting in reduced biodiversity and species extinctions. Governments worldwide are now taking steps to reduce their carbon emissions in an attempt to slow down the effects of global warming on our planet, in order to conserve what is left.
However, a recent study published in Nature measuring the biggest threats to wildlife has shown that rather than climate change, the greatest threats to biodiversity are over-exploitation and agriculture. Measuring 11 threats (over-exploitation, agriculture, urban development, invasion and disease, pollution, ecosystem changes, climate change, human disturbance, transport and energy production) against over 8000 species on the IUCN Red List, 72% (6,241 species) are at threat due to over-exploitation and 62% (5,407 species) threatened by agriculture alone. Climate change on the other hand only affects 19% (1,688) of the species measured in the study, 7th on the list of threats.
Over-exploitation and Agriculture
Over-exploitation is defined as the unsustainable harvest of species from the wild; including logging, hunting and fishing. The trade in wildlife is worth $10 billion a year, which has caused many species to be hunted for sale in the bushmeat, Chinese traditional medicine and fur trades. As human populations has increased, so too has demand, and this has caused a depletion of natural stocks to the point where they are unable to recover quickly enough. This can have huge effects on ecosystems, particularly if an apex predator is eradicated. For example, the sea otter was hunted from the 17th century to 1911 for their pelts, to the point that only 32 remained. This caused their main prey of sea urchins to multiply and over-exploit their own food source, kelp. As kelp ran out, sea urchins became locally extinct and it wasn’t until sea otter numbers recovered that the depleted areas started to repopulate.
Out of the 6,241 species affected by over-exploitation, 4,000 are at risk from unsustainable logging, including the orangutan; 1,600 are threatened by hunting, including the Sumatran rhinoceros, poached for its horn which is in demand for its supposed medicinal properties; and excessive fishing affects over 1,000 species including the southern bluefin tuna, which will have a population of less than 500 mature fish in 100 years if excessive fishing continues.
Agriculture has itself contributed to the effects of climate change, through its production of greenhouse and use of pesticides. As well as this, deforestation to make way for plantations is causing the loss of habitat of millions of species worldwide. Over 5,300 species have been affected by land changes for crops and timber plantations, including the far eastern curlew, which has suffered massive habitat losses due to growing human populations around its home range. Livestock farming is also a huge problem due to a growth in human populations. This is particularly affecting African predators. Cheetahs and African wild dogs require large areas of land to survive but due to their habitat being lost to livestock farmers, they increasingly come into conflict with humans. Of all species that have gone extinct in the last 500 years, 75% have died out due to over-exploitation, agriculture, or both.
Climate change has been at the forefront of international environmental policy since the Kyoto Protocol in 1997, when UN member states committed to reduce greenhouse gas emissions in order to limit the effects of global warming. Climate change is having a major effect on the environment, and will become more problematic in the coming decades as the global temperature rises, alongside rising sea levels.
Increasing temperatures affect numerous species, including the leatherback turtle. The temperature of the sand where turtles lay their eggs determine the sex of the hatchlings, so rising temperatures are affecting the sex ratios of turtle hatchlings. In the Arctic, sea ice has declined massively over the last few decades, causing a 90% decline in hooded seals due to a lack in availability of sites to raise their pups.
What Should Happen Now?
It is just a month before the annual IUCN World Conservation Congress in Hawaii, where there is no doubt that the agenda will be fully set on implementing the recommendations of the 2015 Paris agreement but the efforts to prevent climate change should not overshadow other priorities that are perceived to be greater threats to biodiversity. Although the balance of threats will change over the next few decades when climate change will become an increasingly dominant problem, the impacts of over-exploitation and agriculture will continue to increase as long as human development and populations increase.
Therefore, in order to protect threatened species, many precautions need to be taken. To prevent over-exploitation, sustainable harvesting should be encouraged, hunting of species should be regulated, and marine protected areas should be established where fishing is forbidden. Alongside these regulations, there should be a continuation of international policy (CITES) and programmes of education to reduce demand. Protecting ecosystems from exploitation will also slow down the effects of climate change, as allowing biodiversity to flourish, species will be able to adapt to the changes in climate.
Conservationists may be more attracted to new problems facing wildlife, but we must not forget the persistence of old problems and the damages they can cause.
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