Resilience in our models. (by Diego Fdez-Sevilla)
From a generalist approach to the subject of global environmental perturbations (human and non humanly driven) I understand that our environment has mechanisms of resilience that get activated at local and global scale. Are we aware of those mechanisms? Temperature in our atmosphere can increase due to a number of factors. Greenhouse gases and solar radiation among others. Just playing, the human body uses temperature to react against pathogens. It rises from its balance state giving fever symptoms and this increase triggers the release of water as sweat to absorb the heat through evaporation. Consequently the human body loses water that needs to be replaced. So, in our global ecosystem, there is a debate about if there has been an increase in heat or temperature. Which would be the mechanisms of resilience in our global environment working to absorb or release those increases in heat or temperature (I would go with water as the heat/energy carrier and the weather systems as the physical mechanics to redistribute and release heat/energy. Like stirring a spoon to cold down your soup. So I like to see the use of “storage of energy by the climate system” used to determine the range of climate perturbations in the 2013 IPCC Summary for Policymakers).
Now, I feel it is very important to understand the mechanisms of resilience at global scale. Which are they? Are they working properly? I don´t think the mechanisms of resilience against increases in temperature due to solar radiation are the same as increases in temperature due to greenhouse gases. Should not reflect such events the ionic charge of the atmosphere? And, would not they be more localised in time (start to finish) than constant heating from inside? (honestly curious) .
So, models can only work with non sporadic events opposite to solar radiation. So, from an anthropogenic point of view, “What about if the global ecosystem has mechanisms of resilience to absorb increases in temperature that makes our correlations weak in time?? Are these mechanisms of resilience being incorporated in our predictive models? The most provably repercussion from activating mechanisms of resilience would be to see cyclic patterns of change. Meaning, e.g. temperature raises, weather patterns would increase performance releasing energy until the atmosphere recovers to a point where to start again (warming “pause”?). However, the point of starting again might be each time different since the global ecosystem would adapt to the pressure of dominant increasing patterns of temperature. So each time the cycle would start at a higher temperature, inducing an adaptation to the biota to new conditions until the system would adapt to not feeling the perturbation or… the mechanism of resilience does not give a continuous predictable process. One mechanism activates another mechanism due to synergistic effects and so on. So, with each new mechanism activated a new model to be defined. I am not sure about if this is contemplated.
Which other parts of our ecosystem are getting affected by the mechanism of resilience working to absorb the increase in temperature? Would the human species interfere with the right functionality of the earth’s mechanisms of resilience?
Would we see an increase in global temperature just when the mechanism of resilience gets to the point of not being effective? Then, for how long has it been working already?
Comment on a linkedIn discussion by Tristam Sculthorpe, CEO at Enersphere Inc.: “The planet’s mechanism of resilience is glacial and sea ice.”
My comment: I believe that “Glacial and sea ice” is just one of the planet’s mechanism of resilience. And it can be made a model to predict the performance of this individual mechanism (though I pointed out before what I think about the limitations of modelling synergistic outcomes). My concerns stand still, Which other parts of our ecosystem are getting affected by the mechanism of resilience working to absorb the increase in temperature?. We might be able to record a change in an ecosystem just when the mechanisms of resilience get overloaded. So they have been working already for a while. And therefore, we might just see the last resource of resilience being activated missing to identify the relevance of the previous processes feeding the global resolution. Ice melting is a global response to the combine effects of local perturbations. And those perturbations come from more than one part of the ecosystem. Soil, water, biota and atmosphere.
I leave here an extract from an article that adds some information to my point. Also, you can look at my next post “Resilience in our environment” for a broader analysis.
Coupling between Biota and Earth Materials in the Critical Zone.
Ronald Amundson, Daniel D. Richter, Geoff S. Humphreys, Esteban G. Jobbágy, and Jérôme Gaillardet. 2007.
The surface of our planet is the result of billions of years of feedback between biota and Earth materials. The chemical weathering of soils and the resulting stream and ocean chemistry bear the signature of the biological world. Physical shaping of the Earth’s surface in many regions is a biologically mediated process. Given the pervasiveness of life, it is challenging to disentangle abiotic from biotic processes during field observations, yet it is of paramount importance to quantify these interactions and their feedbacks as the human impact on climate and ecosystems becomes more profound. Here we briefly review the fascinating connection between rocks and life and highlight its significance to science and society.
The Earth has an average surface temperature of about 15°C, which is, in terms of planetary conditions suitable for life, the equivalent of winning the cosmic lottery. Yet, without an atmosphere filled with biological waste gases capable of retaining heat (O2, N2O, CH4, CO2), the average temperature of the planet would be about −18°C (Smil 2002), making the present diversity and abundance of life virtually impossible. Thus, since the evolution of prokaryotic heterotrophic organisms early in the Archean some 4 billion years ago, the Earth’s Critical Zone has evolved as a dynamic and generally self-sustaining system. The interplay between biotic and abiotic components of the planet has directed the pace of evolution and shaped the climate of the Earth. This complex system containing life and Earth materials was first termed the biosphere in 1875 by the Austrian geologist Eduard Suess, but it remained for the Russian scientist Vladimir Vernadsky in 1926 to articulate the concept as a scientific paradigm. The processes that control the biosphere are now gaining attention, as one species, Homo sapiens, enters its third century of massive alteration of the planet.
A looming issue at this critical juncture in geological and human time is to understand how resilient this system is to human activities. The Critical Zone is the portion of the biosphere that lies at the interface of the lithosphere, atmosphere, and hydrosphere, and it encompasses soils and terrestrial ecosystems. While many processes occur within this system, we focus here on how biota and Earth materials interact during chemical weathering and landscape evolution. Because of their impact on society, these processes are important areas of research in Earth sciences. The biotic–abiotic feedback system in the Critical Zone is poorly understood but is important for predicting the near-term habitability of our planet.
Chemical weathering is the aqueous alteration of minerals that is coupled to the release of soluble weathering products and the formation of new minerals. This process impacts global water composition (Gaillardet et al. 2004), soil formation, ecosystem nutrient availability, and atmospheric CO2 levels (Berner 2003), but until recently, it has been viewed primarily as a set of inorganic reactions (e.g. Berner et al. 2004). Over the past few decades, progress has been made in determining the rates of chemical weathering at the watershed and regional scales (e.g. Gaillardet et al. 1999; Dupré et al. 2003). However, the direct role of life is not easy to separate from the role of climate, because biota is so strongly affected by water and heat. Thus, the search for the specific role of plants and fungi on chemical weathering has intensified (Lucas 2001; Berner et al. 2004; Richter et al. 2007). The evolution of land plants and animals in the distant past had profound effects on the rate of mineral weathering and ultimately on the global climate and atmospheric chemistry—effects that continue today.
The biotic impact on soil weathering is translated to the composition and reactivity of streams and oceans. Rivers reflect the biogeochemical fractionation in the Critical Zone. Biota increases the dissolved chemical load in rivers through production of organic acids and ligands that complex dissolved species, greatly increasing their solubility relative to abiotic conditions (Gaillardet et al. 2004). Gaillardet et al. (2004) noted that the organic speciation of many metals in river waters has been poorly documented because these molecules are large and difficult to characterize. Nevertheless, correlations between major elements and dissolved organic carbon have been reported, suggesting that organic matter enhances chemical weathering (Viers et al. 1997).
Because of the rapid changes that have occurred on Earth since the beginning of the Industrial Revolution, Crutzen (2002) argued that humans have steered the Earth into a new geological epoch—the Anthropocene (~250 y BP to present). Large and sudden changes in the biological record form the basis of major divisions in the geological timescale, and based on these criteria the Anthropocene is encompassing one of the most pronounced changes in Earth history by any measurement scale one chooses: extinction rates, extent of climate change, etc. These changes affect other global processes in ways that are only beginning to be quantified. For example, human activity has increased the rate of sediment transport by rivers (2.3 × 109 Mg y-1) as a result of accelerated soil erosion, yet less sediment reaches flood plains and coastal margins (1.4 × 109 Mg y-1) because it accumulates in reservoirs created by dam construction (Syvitski et al. 2005). In turn, enhanced physical erosion is associated with a corresponding increase in the chemical weathering rate (Gaillardet et al. 1999). Another well-documented example is the increase in atmospheric CO2, which augments the efficiency with which plants use water; this has been cited as a mechanism behind the global increase in river runoff over the past 50 years (Gedney et al. 2006). The increase in runoff in the Mississippi River basin is, in turn, associated with increases in the rate of chemical weathering (Raymond and Cole 2003). Thus, the immense human impacts on one global cycle (erosion, for example) provoke pronounced changes in other cycles (such as chemical weathering). Understanding the human role in a given geochemical cycle, and the corresponding feedback into other systems, is a challenging task (see Brantley et al. 2007).
Given the severity of human impact on the Earth’s biosphere, is the Critical Zone capable of surviving and sustaining our species? In the ecological sciences, the term resilience refers to the ability of a system to maintain its function even under disturbance. How resilient are Critical Zone processes? How much disturbance can biotic and abiotic systems withstand before they cease to function in a manner conducive to human survival? To avoid a global, one-time, unrepeatable experiment with our biosphere, it is imperative that the Earth science community embark on an integrated effort to understand the interaction between humankind and life, rocks, air, and water. In that light, Critical Zone research must focus on the imprint of humans on the planet. The geographical extent of agriculture, for example, with its intensive physical mixing, addition of strong acids, and accelerated erosion, is as great as the landmass scoured by the last glacial advance. Agricultural practices add massive quantities of fertilizers (derived from rocks), such as P and K, and lime to highly weathered soils. Agriculture, forestry, and grazing, combined with extensive urbanization, make the “human biome” the largest land-based ecosystem on the planet. When agricultural and urban lands are overlaid on soil maps of the United States, for example, many areas show an abundance of soil types that are endangered, or even extinct, because these lands have been commandeered for various human uses (Amundson et al. 2003).