Science Literature

With millions of eyes on Copenhagen, this seems an appropriate time to ask whether ID thinking has any relevance to understanding the Earth's environment. Can design concepts help us weigh the diverse and often conflicting messages? I think ID is helpful, because features of the Earth's environments and ecologies start to take on new meaning. In this blog, I am thinking particularly of negative feedback mechanisms. Human design engineers will use negative feedback to promote stability and positive feedback to amplify an input signal. They select the mechanisms they need to achieve the desired effect. By analogy, if the Earth is designed for life, we would expect to see negative feedback mechanisms predominating to achieve stable environments. What do we find?

Higher levels of carbon dioxide have accelerated the growth rates of quaking aspen, one of North America's most important and widespread deciduous trees (Source here)

In the scientific news recently are two research papers relevant to biological feedback mechanisms. The first concerns the quaking aspen (Populus tremuloides), a dominant species in many northern forest ecosystems. "Aspen growth has increased an average of 53% over the past five decades, primarily in response to the 19.2% rise in ambient CO2 levels."

"Trees are already responding to a relatively nominal increase in atmospheric carbon dioxide over the past 50 years," says Rick Lindroth, a UW-Madison professor of ecology and an expert on plant responses to climate change. [. . .] The study's findings are important as the world's forests, which cover about 30 percent of the Earth's land surface, play an important role in regulating climate and sequestering greenhouses gases. The forests of the Northern Hemisphere, in particular, act as sinks for carbon dioxide, helping to offset the increase in levels of the greenhouse gas, widely viewed as a threat to global climate stability.

A second study is concerned with the impact of fertilisers on the species diversity of grasslands. These chemicals more than double the availability of nitrogen and whilst this stimulates some plants to thrive, others are quickly out-competed and they die off.

"In a long-term open-air experiment, grassland assemblages planted with 16 species were grown under all combinations of ambient and elevated CO2 and ambient and elevated N. Over 10 years, elevated N reduced species richness by 16% at ambient CO2 but by just 8% at elevated CO2. This resulted from multiple effects of CO2 and N on plant traits and soil resources that altered competitive interactions among species. Elevated CO2 thus ameliorated the negative effects of N enrichment on species richness."

These are but two examples of negative feedback to promote stability. There have been many examples like this in the past, and there will be many more to come. Examples of positive feedback are rare. The effect this has in my mind is to reinforce the thought that the Earth's environments and ecosystems have a robustness about them. This means that when a catastrophe comes, like the eruption of Mt St Helens volcano, recolonisation rarely takes as long as was first anticipated. Whilst this does not prove the Earth is designed, the marks of design are easy to find and the evidence is fully consistent with design.

How does this relate to Copenhagen? A frequently heard message is that the Earth is heading for a doomsday crisis: rapid melting of ice caps, rapid sea-level rise, ocean currents that flip and runaway climate change, etc. These scenarios all invoke positive feedback mechanisms and avalanche processes. What seems to be overlooked is the dominance of negative feedback processes, many of which we are not yet aware of, that counter such dramatic changes. One way to handle such thinking is to analyse feedback mechanisms that we know are operating and check whether they are positive or negative. If mainly positive, the case for sustainable green energy is strong. However, if the findings show mainly negative feedback, it is fair to conclude that the predictors of doomsday are alarmists. We still need to work towards a sustainable future, but intelligent evolution (rather than revolution) will be the agenda.

Rising concentrations of atmospheric CO2 have increased growth in natural stands of quaking aspen (Populus tremuloides)
Christopher T. Cole, Jon E. Anderson, Richard L. Lindroth, Donald M. Waller
Global Change Biology, Published Online: Oct 22 2009 | DOI: 10.1111/j.1365-2486.2009.02103.x

Abstract: As atmospheric CO2 levels rise, temperate and boreal forests in the Northern Hemisphere are gaining importance as carbon sinks. Quantification of that role, however, has been difficult due to the confounding effects of climate change. Recent large-scale experiments with quaking aspen (Populus tremuloides), a dominant species in many northern forest ecosystems, indicate that elevated CO2 levels can enhance net primary production. Field studies also reveal that droughts contribute to extensive aspen mortality. To complement this work, we analyzed how the growth of wild aspen clones in Wisconsin has responded to historical shifts in CO2 and climate, accounting for age, genotype (microsatellite heterozygosity), and other factors. Aspen growth has increased an average of 53% over the past five decades, primarily in response to the 19.2% rise in ambient CO2 levels. CO2-induced growth is particularly enhanced during periods of high moisture availability. [. . .] Owing to aspen's role as a foundation species in many North American forest ecosystems, CO2-stimulated growth is likely to have repercussions for numerous associated species and ecosystem processes.

Elevated CO2 Reduces Losses of Plant Diversity Caused by Nitrogen Deposition
Peter B. Reich
Science, 326, (4 December 2009), 1399-1402 | DOI: 10.1126/science.1178820

Abstract: The interactive effects of rising atmospheric carbon dioxide (CO2) concentrations and elevated nitrogen (N) deposition on plant diversity are not well understood. This is of concern because both factors are important components of global environmental change and because each might suppress diversity, with their combined effects possibly additive or synergistic. In a long-term open-air experiment, grassland assemblages planted with 16 species were grown under all combinations of ambient and elevated CO2 and ambient and elevated N. Over 10 years, elevated N reduced species richness by 16% at ambient CO2 but by just 8% at elevated CO2. This resulted from multiple effects of CO2 and N on plant traits and soil resources that altered competitive interactions among species. Elevated CO2 thus ameliorated the negative effects of N enrichment on species richness.

See also:

Collins, S.L. Biodiversity Under Global Change, Science, 326 (4 December 2009), 1353-1354 | DOI: 10.1126/science.1183271

Devitt, T. Greenhouse gas carbon dioxide ramps up aspen growth. University of Wisconsin-Madison News (4 December, 2009)