Download What`s the Earth`s biggest threat to biodiversity

What's the Earth's biggest threat to biodiversity?
by Jonathan Atteberry
Slash and burn deforestation in the Amazon Basin circa June 2001. A decade later, Brazilian rates of
deforestation have dropped sharply. Marcus Lyon/Getty Images
What's the Earth's biggest threat to biodiversity?
Earth is a planet of unfathomable biodiversity. Scientists have already identified nearly 2 million individual species,
and even conservative estimates state that more than 9 million more remain undiscovered [source: O'Loughlin].
The planet's amazing variety of life is more than just an academic curiosity; humans depend on it. For instance,
farmers rely on worms, bacteria and other organisms to break down organic waste and keep soil rich in nitrogen,
processes vital to modern agriculture. Pharmaceutical companies use a wide array of plants and animals to
synthesize medications, and we can only guess how many medicinal breakthroughs reside in Earth's undiscovered
species.
A stable food supply and a source for pharmaceuticals are only a couple of the benefits Earth's biodiversity
provides. Earth's plant life mitigates the effect of global warming by absorbing carbon dioxide, yet 90 percent of
those plants (and nearly two-thirds of all food crops) depend on the nearly 190,000 species of pollinating insects
[sources: New York Times, U.S. Forest Service]. Scientists from Cornell even went so far as to add up the value of
the different services Earth's plants and animals provide, and after factoring everything from ecotourism to
biological pest control, they arrived at a grand total of $2.9 trillion -- and that was back in 1997 [source: Science
Daily].
Clearly, the planet would be a much different place without its rich and diverse ecosystems, and while it's hard to
imagine what that place would look like, we may not have to if we can't protect the planet from the looming threats
to biodiversity. Climate change is increasingly forcing species away from their habitats in search of more favorable
temperatures, and scientists fear not all species will survive the change. Overhunting, which famously led to the
extinction of the passenger pigeon, continues to endanger animals like the rhino. Invasive species like kudzu and
the brown tree snake, introduced by humans to non-native environments, can rapidly drive native species to
extinction. In the United States, invasive species cause between $125 and $140 billion in damage every year, and
they are thought to have played a part in nearly half of all extinctions worldwide since the 1600s
[sources: Thomas, University of Michigan].
The greatest of all threats to Earth's biodiversity, however, is deforestation. While deforestation threatens
ecosystems across the globe, it's particularly destructive to tropical rainforests. In terms of Earth's biodiversity,
rainforests are hugely important; though they cover only 7 percent of the Earth, they house more than half the
world's species [sources: NASA, University of Michigan]. Through logging, mining and farming, humans destroy
approximately 2 percent of the Earth's rainforestsevery year, often damaging the soil so badly in the process that
the forest has a difficult time recovering [source: University of Michigan]. As their habitats disappear, plants and
animals are forced to compete with one another for the remaining space, and those that can't go extinct. In recent
history, deforestation has led to approximately 36 percent of all extinctions, and as the habitat loss accelerates, that
number is bound to increase [source: University of Michigan].
Deforestation is particularly difficult to stop because it has so many causes. While it's easy to blame irresponsible
logging and mining companies for the devastation, their reckless practices are in some ways a symptom of larger
problems. For instance, many rainforests are located in developing countries that lack the resources to enforce
environmental regulations. These countries also benefit greatly from the economic activity that the companies
generate, giving them even less incentive to discourage deforestation. What's more, the indigenous people who
make their homes in the rainforests regularly clear the land to make room for plantations and cattle pastures, and
efforts to stop this activity directly impair the livelihoods of those people.
Fortunately, hope remains for the Earth's rainforests. In Brazil, satellite imagery revealed that the rate of
deforestation fell by 49 percent compared to the previous year, thanks in part to stricter environmental regulations
and increased enforcement. Recent studies have also shown that as a country's economic conditions improve, its
deforestation rate slows considerably as the indigenous populations rely less on the rainforest's resources for
survival. Finally, nonprofit groups like the World Wildlife Fund and the Sierra Club continue to raise awareness
about the importance of Earth's rainforests. One such nonprofit, the Nature Conservancy, has even started working
with local Brazilian municipalities to help land owners register their plots of the rainforest, a practice that will help
hold them accountable to Brazil's environmental regulations. The collective efforts of governments, nonprofits and
the indigenous peoples may be enough stop the destruction before it's too late.
Questions for “What are Earth’s Biggest Threats to Biodiversity?”
1. The article stated that there are likely 9 million undiscovered species. What are your thoughts on
this? Where do you think they are? Do you think they will be discovered before they go extinct?
2. How do we depend on biodiversity?
3. How does climate change affect biodiversity?
4. How does overhunting/overharvesting affect biodiversity?
5. Why would invasive species threaten biodiversity? What is an example of an invasive species in
our area?
6. According to this article, what is the greatest threat to biodiversity? Why?
7. Why is it difficult to stop deforestation?
8. What is some new progress that has been made in the fight against deforestation?