Human population growth over the next 40 or so years will cause the extinction of a great number of mammal and bird species, according to new research from Ohio State University.

Image Credit: Tarsier via Flickr CC

The new research states that a typical growing nation should expect at least 3.3% more threatened species in the next decade and an increase of 10.8% species threatened with extinction by 2050. (Author’s note: When taken together with the large body of previous research on this subject, these figures are very ‘optimistic’…)

As per the research — the US is currently ranked sixth in the world with regards to the number of new species expected to be listed as ‘threatened’ by 2050.

While there has been previous work done which has suggested “a strong relationship between human population density and the number of threatened mammal and bird species at a given point in time,” this is the first that definitively links expanding human populations to a decline for these other species, and to their possible extinction.

The lead researcher of this new work had previously created “a model based on 2000 data to forecast future threatened species connected to human population growth projections, and published the predictions in 2004. In this new study, that model’s predictions were confirmed by 2010 actual figures.” The researchers then utilized the same model — which contains data on 114 countries — to extend the predictions to the year 2050.

“The data speak loud and clear that not only human population density, but the growth of the human population, is still having an effect on extinction threats to other species,” said Jeffrey McKee, professor of anthropology at Ohio State and lead author of the study.

“The findings suggest that any truly meaningful biodiversity conservation efforts must take the expanding human population footprint into consideration — a subject that many consider taboo.”

“Our projection is based on human population density alone. It doesn’t take into account climate change, industrialization or wars. So the actual numbers that we predict for 2050 will be very different because everything we do will exacerbate the problem,” he said. “You can do all the conservation in the world that you want, but it’s going to be for naught if we don’t keep the human population in check.”

Ohio State University explains the specifics of the research:

McKee collected data on threatened species from the International Union for Conservation of Nature Red List, and obtained human census data for 2000 and 2010 from the world database of the U.S. Census Bureau. Overall species richness data came from the United Nations Environment Programme-World Conservation Monitoring Centre’s Animals of the World Database. He created a model using equations to analyze relationships among these variables.

After using 2010 data to confirm that the decade-old predictions came true, the researchers used the same equations to determine that between now and 2050, the nations that see the most population density growth will experience higher numbers of species facing new threats of extinction.

Only five nations rank higher than the United States in predicted new species threats by 2050. The Democratic Republic of the Congo tops the list, with a predicted new threat to more than 20 species in that time frame. The analysis suggests about 11 species will be newly threatened with extinction in the United States.

The model also suggests that the 21 countries with projected declining human populations by 2050 will see an average reduction in threatened species of 2.5%. The findings were bolstered by the fact that nine of the 12 nations with population declines between 2000 and 2010 showed a modest decrease in the number of threatened species of mammals and birds.

“There are an estimated 12 million species of plants and animals on earth, and the human population exceeds 7 billion — with a gain of an estimated 214,000 people each day.”

“When the population stood at 6 billion, McKee led a project with his students in which the group divided the planet’s land surface area among all the world’s people to determine how much space was available to each person. At that time, each of the world’s humans could claim space roughly equivalent to Ohio Stadium, which seats more than 102,000 football fans.”

“If we get to 11 billion people, which is where we’re supposed to peak, then the amount of space you have per person is a lot smaller than that stadium. When you’re left with less space, there’s virtually no space left for most other species,” he said.

The new research was published this week in the journal Human Ecology.

“Increased variability — this rather technical term translates into potentially severe impacts on people who cannot afford additional loss,” says Anders Levermann, one of the study’s authors and co-chair of PIK’s research domain Sustainable Solutions. “The fact that all these different models agree is a clear message that adaptation measures can be built on.” Even if seasonal mean precipitation would remain unchanged, impacts could be substantial, Levermann points out. “Focusing on the average is not always useful. If rainfall comes in a spell and is followed by a drought, this can be devastating even if the average is normal. This requires the right kind of adaptation measures that account for this variability — such as intelligent insurance schemes, for example.”

“Limiting global warming is key, adaptation cannot replace but rather complement it”

The strongest change of 13 to 50 percent is found in a scenario in which greenhouse gases continue to be emitted unabated. However, even if global warming would be limited to the internationally acknowledged threshold of 2 degrees Celsius of global warming, this would bear the risk of additional day-to-day variability between 8 and 24 percent above the pre-industrial level, according to the analysis. “So limiting global warming is key to reduce day-to-day monsoon variability, adaptation cannot replace but rather complement it,” says Levermann.

The researchers focused on the ten models with the most realistic monsoon pattern — a conservative approach, as these ten models yield generally lower rates of change. The other ten models showed higher rates of change. “This is not about exact percentages. It is the clear trend that conveys the message,” says Arathy Menon, lead-author of the study. The scientists used the latest ensemble of climate models, prepared for the 5th assessement report of the International Panel on Climate Change. All of them show increased variability.

“This is a robust indicator”

Taking into account all 20 models, the spread of results reduces when the scientists looked at the rainfall changes per degree of global warming independent of the exact time path of the warming. The consistent result is that 4 to 12 percent variability change of daily monsoon rainfall in India are to be expected per degree Celsius of warming. “This is a robust indicator,” says Menon.

About 80 percent of annual rainfall in India occur during the monsoon season from June through September. Factors that could perturb rainfall regularity include the higher holding capacity of moisture of the warmer air, but also more complex phenomena like cooling in the higher atmosphere which changes current pressure and thereby rainfall patterns.

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Important as these storage functions of wetlands are, however, another critical one is being overlooked, says Bill Mitsch, director of the Everglades Wetland Research Park at Florida Gulf Coast University and an emeritus professor at Ohio State University: Wetlands also excel at pulling carbon dioxide out of the air and holding it long-term in soil.

Writing in the July-August issue of the Journal of Environmental Quality, Mitsch and co-author Blanca Bernal report that two 15-year-old constructed marshes in Ohio accumulated soil carbon at an average annual rate of 2150 pounds per acre — or just over one ton of carbon per acre per year.

The rate was 70% faster than a natural, “control” wetland in the area and 26% faster than the two were adding soil carbon five years ago. And by year 15, each wetland had a soil carbon pool of more than 30,000 pounds per acre, an amount equaling or exceeding the carbon stored by forests and farmlands.

What this suggests, Mitsch says, is that researchers and land managers shouldn’t ignore restored and human-made wetlands as they look for places to store, or “sequester,” carbon long-term. For more than a decade, for example, scientists have been studying the potential of no-tillage, planting of pastures, and other farm practices to store carbon in agricultural lands, which cover roughly one-third of Earth’s land area.

Yet, when created wetlands are discussed in agricultural circles, it’s almost always in the context of water quality. “So, what I’m saying is: let’s add carbon to the list,” Mitsch says. “If you happen to build a wetland to remove nitrogen, for example, then once you have it, it’s probably accumulating carbon, too.”

In fact, wetlands in agricultural landscapes may sequester carbon very quickly, because high-nutrient conditions promote the growth of cattail, reeds, and other wetland “big boys” that produce a lot of plant biomass and carbon, Mitsch says. Once carbon ends up in wetland soil, it can also remain there for hundreds to thousands of years because of water-logged conditions that inhibit microbial decomposition.

“And carbon is a big deal — any carbon sinks that we find we should be protecting,” Mitsch says. “Then we’re going even further by saying: We’ve lost half of our wetlands in the United States, so let’s not only protect the wetlands we have remaining but also build some more.”

At the same time, he acknowledges that wetlands emit the powerful greenhouse gas (GHG), methane, leading some to argue that wetlands shouldn’t be created as a means to sequester carbon and mitigate climate change. But in a new analysis that modeled carbon fluxes over 100 years from the two constructed Ohio marshes and 19 other wetlands worldwide, Mitsch, Bernal, and others demonstrated that most wetlands are net carbon sinks, even when methane emissions are factored in. And among the best sinks were the wetlands in Ohio, possibly due to flow-through conditions that promoted rapid carbon storage while minimizing methane losses, the authors hypothesize.

The concerns about methane emissions and even his own promising findings point to something else, Mitsch cautions: It’s easy to undervalue wetlands if we become too focused on just one of their aspects — such as whether they’re net sinks or sources of GHGs. Instead, people should remember everything wetlands do.

“We know they’re great for critters and for habitat, that’s always been true. Then we found out they cleaned up water, and could protect against floods and storms,” he says. “And now we’re seeing that they’re very important for retaining carbon. So they’re multidimensional systems — even though we as people tend to look at things one at a time.”

Funding for the study came from the U.S. Environmental Protection Agency, the National Science Foundation, Ohio State University, and Florida Gulf Coast University.

Global food production isn’t increasing fast enough to support the world’s rapidly growing population, according to new research from the Institute on the Environment (IonE) at the University of Minnesota.

Image Credit: Deepak K Ray, Nathaniel D Mueller, Paul C West, Jonathan A Foley

Crop yields are actually falling rather notably in many of the warmer/poorer regions of the world as a result of rising temperatures and increasing natural disasters. Such agricultural declines are predicted to continue into the foreseeable future as a result of climate change. And something else to note — this new research (along with most) doesn’t take into account the rapidly approaching problem of running out of inorganic fertilizers… A very significant problem…

With regards to the new research — previous work has estimated that global agricultural production would need to increase by around 60-110% by 2050 in order to keep up with mid-range population growth estimates. But according to the new research, as of right now yields of the world’s four most important crops — maize, rice, wheat and soybean — are only increasing about 0.9-1.6% a year. “At these rates, production of these crops would likely increase 38-67% by 2050, rather than the estimated requirement of 60-110%. The top three countries that produce rice and wheat were found to have very low rates of increase in crop yields.”

“Particularly troubling are places where population and food production trajectories are at substantial odds,” Ray says, “for example, in Guatemala, where the corn-dependent population is growing at the same time corn productivity is declining.”

“The analysis maps global regions where yield improvements are on track to double production by 2050 and areas where investments must be targeted to increase yields. The authors explain that boosting crop yields is considered a preferred solution to meet demands, rather than clearing more land for agriculture. They note that additional strategies, such as reducing food waste and changing to plant-based diets, can also help reduce the large estimates for increased global demand for food.”

“Clearly, the world faces a looming agricultural crisis, with yield increases insufficient to keep up with projected demands,” says IonE director Jon Foley, a co-author on the study. “The good news is, opportunities exist to increase production through more efficient use of current arable lands and increased yield growth rates by spreading best management practices. If we are to boost production in these key crops to meet projected needs, we have no time to waste.”

The new research was just published in the open access journal PLOS ONE.