Logging threatens at least 4,049 species worldwide, more than twice as many as climate change does. | Photo: Derek Severson, some rights reserved Climate change is dangerous, and it's happening now. It threatens wildlife and the ecosystems they live in. It will make life harder for billions of people, with the greatest harm hitting the world's poorest people. It may make some parts of the world uninhabitable for humans, and will almost certainly drive many species to extinction.
But there are a half-dozen other environmental threats that are even worse.
That's according to a study published this month in Nature, generally considered the world's most respected scientific journal. According to the study, which lists ten kinds of human-caused environmental damage and ranks them according to the number of wildlife species they now threaten, climate change comes in at just seventh place behind things like logging, farming, and urban development.
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In the study, headed up by University of Queensland graduate student Sean Maxwell, researchers studied the threats to 8,868 species around the world currently listed as either Threatened or Near Threatened in the Red List of Threatened Species maintained by the International Union for the Conservation of Nature. Species included in the study ranged from birds, mammals, reptiles, and amphibians to sea anemones, isopod crustaceans, conifers, flowering plants, clams, most types of fish, and jellyfish.
When a species is designated as Threatened or Near-Threatened on the Red List, the listing includes a citation of the types of threats facing causing that species problems. Maxwell and his colleagues tabulated those threats to each of the almost 9,000 species and ranked them in ten large categories, according to the number of species each threat affected.
Here are those big threats, in descending order of harm:
Overexploitation, including logging, fishing, hunting, and gathering of plants: 6,241 species, 71.8 percent of the total
Agriculture, including farming, livestock raising, and aquaculture: 5,407 species, 62.2 percent
Urban development, including residential, industrial-commercial, recreation, and tourism: 3,014 species, 34.7 percent
Invasion and disease, including invasive species, problematic native species, and introduced genetic material: 2,298 species, 26.5 percent
Pollution, including air pollution, municipal waste, industrial and agricultural effluent: 1,901 species, 21.9 percent
System modification of natural ecosystems, including both fires and fire suppression, dams, and a few other things: 1,865 species, 21.5 percent
Climate change, including drought, habitat change, storms and extreme temperatures: 1,688 species, 19.4 percent
Human disturbance, including disturbance of affected species when people recreate, work, and wage war: 1,223 species, 14.1 percent
Transportation, including land, air, and sea: 1,219 species, 14.0 percent
Energy production, including oil and gas development, coal and uranium mining, and renewable energy development: 913 species, 10.5 percent.
Those percentages don't total 100 because many of the species examined are endangered by more than one of the threats. (Its probably worth mentioning that by introduced genetic material, Maxwell et al and the IUCN arent referring to genetically modified organisms, but rather the threat of rare species hybridizing with more common relatives, as is happening with the endangered California tiger salamander and the invasive barred tiger salamander.)
I did a little digging in the IUCN database, and California's beleaguered species reflect a mostly similar pattern of threats and their severity, but with climate change coming in in ninth place instead of seventh. Of 877 California species mentioned in the Red List, overexploitation threatens 172, urban development 110, agriculture 105, transportation 40, invasion and disease 40, system modification 38, energy production 36, pollution 24, climate change 23, and human disturbance 16.
And as in the rest of the world, many California species in trouble are beset by more than one threat. The federally Threatened desert tortoise (whose Red List entry was last updated 20 years ago) is hard-hit by disease and the raven, a problematic native; habitat loss to urban development; renewable energy production; and historic losses to collection as pets, a form of overexploitation. The Delta smelt is in trouble due to system modification in the form of water diversions, invasive species, pollution, and climate change. Logging and fire suppression each contribute to declines in the California spotted owl's population. And so forth.
Commercial, recreational, and subsistence fishing threatens 1,118 species worldwide. | Photo: Rebeca Anchondo, some rights reserved
If you're accustomed to thinking of climate change as the main peril facing life on earth, the notion that there are several pervasive environmental problems worse than climate change may be surprising. Climate change does imperil a lot of species, but overexploitation imperils more than three times as many. Logging alone, which is responsible for declines in 4,049 species, accounts for more than twice as much harm to wildlife species as climate change in all its forms.
That's especially sobering given that logging for biomass energy production is often touted as a partial solution to addressing climate change.
Even if you're not sure you care about things like isopods and sea anemones, the more charismatic species on the list are especially hard-hit by the old-school environmental threats. Three quarters of the mammals, birds, amphibians, reptiles, and plants studied are threatened by overexploitation, agriculture, or both, with invasive species playing an important role in many of those declines.
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