Habitat niche modeling, predictions of extinction, and a dose of reality

We have all heard dire predictions that global warming will cause species extinction. Such predictions are based on ecological niche models (ENMs) that study where animals live now and assume that they must have the same habitat conditions to survive.

A new study from the University of Oregon, based on fossil evidence shows that these studies fail. The researchers studied the fossil records of five ancient mammalian species that survived North America’s last glacial period. All the models said they should have lived much farther south than the fossil evidence shows.

The paper abstract reads:

Ecological niche models (ENMs) are crucial tools for anticipating range shifts driven by climate change. As hypotheses of future biotic change, they can be difficult to test using independent data. The fossil record is the best way to assess the ability of ENMs to correctly predict range shifts because it provides empirical ranges under novel climate conditions. We tested the performance of ENMs using fossil distributions from the Last Glacial Maximum (LGM, ~21 000 yr ago). We compared hindcast ENM LGM distribution hypotheses for five species of small mammals, drawn from the published literature, to the known LGM fossil record for those species and found a consistent southern prediction bias in the ENMs. This bias urges caution in interpreting future range predictions, and we suggest that the Pleistocene and Holocene fossil record should be used as an additional resource for calibrating niche modeling for conservation planning.

One of the researchers commented in a press release about the short-tailed shrew, one of the species studied:

It’s almost as though it is living in all of the places that the model says it shouldn’t be living in and not in any of the places that the model says it should be living in,” said Davis, who also is manager of the paleontological collection at the UO Museum of Natural and Cultural History. “This suggests to me that whatever the model is keying on is not actually important to the shrew.”

Nor to the American marten, two species of flying squirrels and the Gapper’s red-backed vole, all of which lived mostly outside of predicted ranges, according to the fossil record. Northern and southern flying squirrels, the Davis study found, shared a compressed geographic region. It may be, Davis said, that some species tolerate competition under harsh conditions but separate when abundant resources are available.

See Press Release and Full Paper.

As with climate models, we see here, too, that modeling in other areas of science often diverges from actual observation. This occurs either because the modeled systems are too complex or the modelers work with erroneous assumptions. Remember that the next time you see headlines which proclaim extinction of species X due to global warming.

See also:

Ozone theory has holes

National Climate Assessment lacks facts, an analysis

Evidence that CO2 emissions do not intensify the greenhouse effect

How much global warming is dangerous?

The scale problem for solar and wind generation of electricity

The current eco-fad of trying to produce an ever greater percentage of our electricity from solar and wind has some consequences on land use that are poorly thought out.

Robert Bryce, writing in Energy Tribune, takes out his calculator to see how much land would be used to achieve the green utopia (see his full article here).

The International Energy Agency expects the increase in demand for new electrical generation to be 450 terawatt-hours per year, which was the average annual increase every year from 1985 to 2011 (1 terawatt = 1 million megawatts).

How much solar energy would be needed to meet that demand? Bryce notes, “Germany has more installed solar-energy capacity that any other country, with some 25,000 megawatts of installed photovoltaic panels. In 2011, those panels produced 18 terawatt-hours of electricity. Just to keep pace with the growth in global electricity demand, the world would have to install about 25 times as much photovoltaic capacity as Germany’s total installed base, and it would have to do so every year.” Where are we going to put all those panels? Apparently Germany has had enough with their solar experiment and are now building 23 new coal-fired plants.

For wind, the problem is even greater. For instance, Bryce notes that by the end of 2011, the U.S. had 47,000 megawatts of installed wind-energy capacity which produced about 120 terawatt-hours of electricity. “Thus, just to keep pace with the growth in global electricity demand by using wind energy, we would have to install about 3.75 times the current installed wind capacity in the U.S. every year.”

So how much land would be required for wind generation to meet the annual increase in demand? Bryce says that “The power density of wind energy is roughly two watts per square meter or about five megawatts per square mile. Therefore, just to keep up with the growth in global electricity demand by using wind energy alone, the global wind industry will need to cover a land area of some 35,000 square miles — about the size of Indiana — with wind turbines. And it will have to do so every year.”

Will those 35,000 square miles be carved out of natural habitat every year? Fossil fuel and nuclear plant generation have a much smaller footprint.

In the U.S., as the Department of the Interior designates more and more land suitable for solar, environmental groups have howled about the potential destruction of habitat for animals such as the desert tortoise.

As more and more wind farms are established, people are realizing the costs, not just for electricity, but for health and habitat as well as the scenery. Bryce reports that in Europe alone, there are now more than 500 anti-wind groups.


Health Hazards of Wind Turbines

Windsmills are killing our birds

Wind Turbines Spread While Bats Take Beating

Bats, Birds, and Blades

Wind farms raise local and regional temperatures