Category Archives: Peer Reviewed Article Review

more on money, economic growth, and sustainability

Here’s a new study looking at economic growth, interest rates, the money supply, and ecological footprint.

Ecological monetary economics: A post-Keynesian critique

The monetary analysis of some ecological economists currently appears to be mostly articulated around the following core: a stationary economy (and a fortiori a degrowth economy) is incompatible with a system in which money is created as interest-bearing debt. To question the relevance of the debt-money/positive interest rate/output growth nexus, this paper adopts a critical stance towards the currently emerging ecological monetary economics from the standpoint of another strand of heterodox economics – the post-Keynesian approach. In its current state, ecological monetary economics is at odds with post-Keynesian economics in its analysis of the money–growth relationship. This will be shown using the theory of endogenous money and a simple Cambridgian–Kaleckian model where debt-money and a positive interest rate are compatible with a full stationary economy.

soil and carbon sequestration

This open-access article in Nature makes a surprising claim – that much better management of agricultural soil could offset a significant portion of annual carbon emissions from all sources (not just agriculture), while also being good for ecosystems and food security.

How important, in total, is this large, varied set of land-use and management practices as a GHG mitigation strategy? One of the challenges in answering this question is to distinguish between what is technically feasible and what might be achieved given economic, social and policy constraints. A comprehensive global analysis of agricultural practices combined climate-stratified modelling of emission reductions and soil C sequestration with economic and land-use change models to estimate mitigation potential as a function of varying ‘C prices’ (reflecting a social incentive to pay for mitigation). They estimated total soil GHG mitigation potential ranging from 5.3 Pg CO2(eq) yr−1 (without economic constraints) to 1.5 Pg CO2(eq) yr−1 at the lowest specified C price (US$20 per Mg of CO2(eq)). Average rates for the majority of management interventions are modest, <1 Mg CO2(eq) ha−1 yr−1. Thus, achieving large global GHG reductions requires a substantial proportion of the agricultural land base (Fig. 2). Although the economic and management constraints on biochar additions (not assessed by ref. 19) are less well known, ref. 67 estimated a global technical potential of 1–1.8 Pg CO2(eq) yr−1 (Fig. 2).

A more unconventional intervention that has been proposed is the development of crops with larger, deeper root systems, hence increasing plant C inputs and soil C sinks. Increasing root biomass and selecting for root architectures that store more C in soils has not previously been an objective for crop breeders, although most crops have sufficient genetic plasticity to alter root characteristics substantially and selection aimed at improved root adaptation to soil acidity, hypoxia and nutrient limitations could yield greater root C inputs as well as increased crop yields. Greater root C input is well recognized as a main reason for the higher soil C stocks maintained under perennial grasses compared to annual crops. Although there are no published estimates of the global C sink potential for ‘root enhancement’ of annual crop species, as a first-order estimate, a sustained increase in root C inputs might add ~1 Pg CO2(eq) yr−1 or more if applied over a large portion of global cropland area (Fig. 2).

Thus, the overall mitigation potential of existing (and potential future) soil management practices could be as high as ~8 Pg CO2(eq) yr−1. How much is achievable will depend heavily on the effectiveness of implementation strategies and socioeconomic and policy constraints.

I tried to get a quick answer on global annual emissions in Pg CO2(eq), and failed. Now I’m out of time. I’ll figure it out some other time.

launching the cosmic-ray neutron probe…


Okay this isn’t really about an evil plot to dominate the world. It’s about measuring soil moisture.

Estimating field-scale root zone soil moisture using the cosmic-ray neutron probe

Many practical hydrological, meteorological, and agricultural management problems require estimates of soil moisture with an areal footprint equivalent to field scale, integrated over the entire root zone. The cosmic-ray neutron probe is a promising instrument to provide field-scale areal coverage, but these observations are shallow and require depth-scaling in order to be considered representative of the entire root zone. A study to identify appropriate depth-scaling techniques was conducted at a grazing pasture site in central Saskatchewan, Canada over a 2-year period. Area-averaged soil moisture was assessed using a cosmic-ray neutron probe. Root zone soil moisture was measured at 21 locations within the 500 m  ×  500 m study area, using a down-hole neutron probe. The cosmic-ray neutron probe was found to provide accurate estimates of field-scale surface soil moisture, but measurements represented less than 40 % of the seasonal change in root zone storage due to its shallow measurement depth. The root zone estimation methods evaluated were: (a) the coupling of the cosmic-ray neutron probe with a time-stable neutron probe monitoring location, (b) coupling the cosmic-ray neutron probe with a representative landscape unit monitoring approach, and (c) convolution of the cosmic-ray neutron probe measurements with the exponential filter. The time stability method provided the best estimate of root zone soil moisture (RMSE  =  0.005 cm3 cm−3), followed by the exponential filter (RMSE  =  0.014 cm3 cm−3). The landscape unit approach, which required no calibration, had a negative bias but estimated the cumulative change in storage reasonably. The feasibility of applying these methods to field sites without existing instrumentation is discussed. Based upon its observed performance and its minimal data requirements, it is concluded that the exponential filter method has the most potential for estimating root zone soil moisture from cosmic-ray neutron probe data.

how aliens could be hiding in plain site

There’s always that puzzle – if conditions were such that life could arise on this planet, and the universe is so vast that there must be similar conditions out there, and given the unfathomable amounts of time for that to happen, is it really likely or even possible that this is the only place it ever happened? And if life is actually common, how could it be that we have never detected it? One answer to the puzzle would be if sophisticated life is out there, even relatively nearby, and doesn’t want to be detected by us for some reason.

Serious people at serious universities like Columbia study this, the technology side at least if not the existential questions. If aliens are hiding from us right now, here’s one way they might be doing it. Or if we thought there was somebody bad out there (one of those infinitesimal probability, infinite consequence risks that are hard to wrap your head around) and wanted to hide, here is how we could try to do it.

A Cloaking Device for Transiting Planets

The transit method is presently the most successful planet discovery and characterization tool at our disposal. Other advanced civilizations would surely be aware of this technique and appreciate that their home planet’s existence and habitability is essentially broadcast to all stars lying along their ecliptic plane. We suggest that advanced civilizations could cloak their presence, or deliberately broadcast it, through controlled laser emission. Such emission could distort the apparent shape of their transit light curves with relatively little energy, due to the collimated beam and relatively infrequent nature of transits. We estimate that humanity could cloak the Earth from Kepler-like broadband surveys using an optical monochromatic laser array emitting a peak power of ∼30 MW for ∼10 hours per year. A chromatic cloak, effective at all wavelengths, is more challenging requiring a large array of tunable lasers with a total power of ∼250 MW. Alternatively, a civilization could cloak only the atmospheric signatures associated with biological activity on their world, such as oxygen, which is achievable with a peak laser power of just ∼160 kW per transit. Finally, we suggest that the time of transit for optical SETI is analogous to the water-hole in radio SETI, providing a clear window in which observers may expect to communicate. Accordingly, we propose that a civilization may deliberately broadcast their technological capabilities by distorting their transit to an artificial shape, which serves as both a SETI beacon and a medium for data transmission. Such signatures could be readily searched in the archival data of transit surveys.

Antarctica, it was nice knowing you

Thank you, Eric Holthaus, for your entertaining, mildly sensational climate change coverage at Slate.

In a study released Wednesday, a new estimate of how much Antarctic ice would melt in a warmer world nearly doubles previous projections of sea level rise by the end of the century. And it might be even worse than that: The study did not explore the true worst-case scenario, and its lead author said the work is still incomplete. Taken together with recent results from other research teams—most notably James Hansen’s, just last week—it’s increasingly clear that consensus projections of near-term sea level rise, about three feet in the next 85 years, are likely an underestimate.

The latest information comes via a breakthrough in simulating the behavior of Antarctica’s vast and complex network of glaciers and ice shelves. That’s brought a more complete understanding of how warmer air temperatures—projected to surpass those regularly experienced on Earth at any point during at least the last few million years—are affecting the sea level. At the same time, the study provides new certainty that—should the world act immediately to curb carbon emissions at a scale far beyond current efforts—virtually all Antarctic ice melt could be avoided.

autonomous vehicles displacing traditional vehicles

If self-driving cars come into their own, will they reduce the total amount of vehicles on the road, or will everybody who owns a car now just buy a self-driving one? This study set in Austin says that each self-driving car will displace 9 normal cars. So even if the same or more cars are in motion at any given time, there will be a lot less land required for parking. That land can be used for something else – housing, commerce, habitat, recreation, gardening/farming, or some combination. Bring it on!

James Hansen: Ice Melt, Sea Level Rise, and Superstorms

James Hansen’s paper on “sea level rise of several meters this century” has now been peer reviewed and published in Atmospheric Chemistry and Physics.

Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous

We use numerical climate simulations, paleoclimate data, and modern observations to study the effect of growing ice melt from Antarctica and Greenland. Meltwater tends to stabilize the ocean column, inducing amplifying feedbacks that increase subsurface ocean warming and ice shelf melting. Cold meltwater and induced dynamical effects cause ocean surface cooling in the Southern Ocean and North Atlantic, thus increasing Earth’s energy imbalance and heat flux into most of the global ocean’s surface. Southern Ocean surface cooling, while lower latitudes are warming, increases precipitation on the Southern Ocean, increasing ocean stratification, slowing deepwater formation, and increasing ice sheet mass loss. These feedbacks make ice sheets in contact with the ocean vulnerable to accelerating disintegration. We hypothesize that ice mass loss from the most vulnerable ice, sufficient to raise sea level several meters, is better approximated as exponential than by a more linear response. Doubling times of 10, 20 or 40 years yield multi-meter sea level rise in about 50, 100 or 200 years. Recent ice melt doubling times are near the lower end of the 10–40-year range, but the record is too short to confirm the nature of the response. The feedbacks, including subsurface ocean warming, help explain paleoclimate data and point to a dominant Southern Ocean role in controlling atmospheric CO2, which in turn exercised tight control on global temperature and sea level. The millennial (500–2000-year) timescale of deep-ocean ventilation affects the timescale for natural CO2 change and thus the timescale for paleo-global climate, ice sheet, and sea level changes, but this paleo-millennial timescale should not be misinterpreted as the timescale for ice sheet response to a rapid, large, human-made climate forcing. These climate feedbacks aid interpretation of events late in the prior interglacial, when sea level rose to +6–9 m with evidence of extreme storms while Earth was less than 1 °C warmer than today. Ice melt cooling of the North Atlantic and Southern oceans increases atmospheric temperature gradients, eddy kinetic energy and baroclinicity, thus driving more powerful storms. The modeling, paleoclimate evidence, and ongoing observations together imply that 2 °C global warming above the preindustrial level could be dangerous. Continued high fossil fuel emissions this century are predicted to yield (1) cooling of the Southern Ocean, especially in the Western Hemisphere; (2) slowing of the Southern Ocean overturning circulation, warming of the ice shelves, and growing ice sheet mass loss; (3) slowdown and eventual shutdown of the Atlantic overturning circulation with cooling of the North Atlantic region; (4) increasingly powerful storms; and (5) nonlinearly growing sea level rise, reaching several meters over a timescale of 50–150 years. These predictions, especially the cooling in the Southern Ocean and North Atlantic with markedly reduced warming or even cooling in Europe, differ fundamentally from existing climate change assessments. We discuss observations and modeling studies needed to refute or clarify these assertions.

Citation: Hansen, J., Sato, M., Hearty, P., Ruedy, R., Kelley, M., Masson-Delmotte, V., Russell, G., Tselioudis, G., Cao, J., Rignot, E., Velicogna, I., Tormey, B., Donovan, B., Kandiano, E., von Schuckmann, K., Kharecha, P., Legrande, A. N., Bauer, M., and Lo, K.-W.: Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous, Atmos. Chem. Phys., 16, 3761-3812, doi:10.5194/acp-16-3761-2016, 2016.

Carbon Nanotubes Produced from Ambient Carbon Dioxide

Producing carbon nanofibers from ambient carbon dioxide seems like a potential breakthrough. You are removing the greenhouse gas from the air, and producing an incredibly useful product that can be used for everything from batteries to store renewable energy (discussed in this article) to (I am speculating) strong, light-weight carbon-negative materials that could replace a portion of the heavy-footprint steel and concrete we use today.

Carbon Nanotubes Produced from Ambient Carbon Dioxide for Environmentally Sustainable Lithium-Ion and Sodium-Ion Battery Anodes

The cost and practicality of greenhouse gas removal processes, which are critical for environmental sustainability, pivot on high-value secondary applications derived from carbon capture and conversion techniques. Using the solar thermal electrochemical process (STEP), ambient CO2 captured in molten lithiated carbonates leads to the production of carbon nanofibers (CNFs) and carbon nanotubes (CNTs) at high yield through electrolysis using inexpensive steel electrodes. These low-cost CO2-derived CNTs and CNFs are demonstrated as high performance energy storage materials in both lithium-ion and sodium-ion batteries. Owing to synthetic control of sp3 content in the synthesized nanostructures, optimized storage capacities are measured over 370 mAh g–1 (lithium) and 130 mAh g–1 (sodium) with no capacity fade under durability tests up to 200 and 600 cycles, respectively. This work demonstrates that ambient CO2, considered as an environmental pollutant, can be attributed economic value in grid-scale and portable energy storage systems with STEP scale-up practicality in the context of combined cycle natural gas electric power generation.

Combined with renewable energy sources, maybe this is the breakthrough technology that gets us over the current hump where we are pushing against the ecological limits, and sets us on a path of continuing growth with a lower footprint until we eventually push against the limits again. Or, put the right incentives and policies in place to control the unsustainable portion of the growth, and with this technology in place maybe we can make it all the way until the asteroid hits. And by then, we can try to have people spread across a few planets. And then we are good until the sun burns out, or the aliens come for us, or the universe collapses. None of which will be my problem.

instrinsic vs. utilitarian value of nature

This thoughtful opinion piece in Trends in Ecology and Evolution talks about resolving conflicts between moral and economic arguments for conservation.

Biodiversity exists at multiple levels of organization, including at the levels of genes, populations, species, and ecosystems [11]. Although it might be argued that intrinsic value is associated with all levels of biological organization, this interpretation is of no practical use for planning and decision-making. If all levels of biological organization have equal intrinsic value, and if all species are regarded as having equal intrinsic value, then the implication is that no harm can be done in any way to any component of biodiversity [I don’t quite follow this last sentence…]. The concept of intrinsic value applied equally to all of nature therefore offers no way to prioritize and points only toward a halt to human progress because most human developments impact on nature to some degree. In practice, then, intrinsic value is commonly associated with certain species and ecosystems…

Species conservation and the beauty of nature are reasons for conservation commonly associated with intrinsic and non-use values. For instance, it can be regarded as morally right to maintain the existence of tigers in the wild, and to conserve the beauty of Yosemite Valley, regardless of human use. But accepting this should not preclude accepting arguments for conservation that are based on utilitarian value, particularly when we consider different levels of biological organization. For instance, populations of species provide vital ecosystem services such as pollination, such that loss of a population can cause loss of an ecosystem service that has utilitarian value. If the continued existence of populations of the species elsewhere means that the species itself is not threatened, or if the population lives in a human-dominated, non-wild landscape, then arguments for the intrinsic value of species and ecosystems are inadequate. Given that population declines are perhaps the most prevalent aspect of biodiversity loss [14], failure to recognize the utilitarian value of populations does a disservice to conservation.

Viewing reasons for conserving nature at different levels of biological organization thus clarifies when alternative arguments are most relevant, in particular that arguments based on intrinsic value are most commonly associated with species and ecosystem levels. This takes us some way toward melding utilitarian and intrinsic reasons for conservation, enabling both to be included within a multifaceted approach.

The article also wades into the debate on monetization.

I agree with using all the tools. We also have to recognize that even reasonable people have a range of values, and there are also unreasonable people out there, and we have to find arguments that appeal to a critical mass of people in order to make any progress.

green roofs

Here’s a green roof modeling study from Singapore. Green roofs reduce peak flows enough to help with flooding. They reduce the volume of runoff a little bit through increased evapotranspiration, which would have an effect on the water supply in Singapore where urban runoff is used as a water source.

Effect of Catchment-Scale Green Roof Deployment on Stormwater Generation and Reuse in a Tropical City

Low-impact development (LID) comprises a broad spectrum of stormwater management technologies for mitigating the impacts of urbanization on hydrological processes. Among these technologies, green roofs are one of the most adopted solutions, especially in densely populated metropolitan areas, where roofs take up a significant portion of the impervious surfaces and land areas are scarce. While the in situ hydrological performance of green roofs—i.e., reduction of runoff volume and peak discharge—is well addressed in literature, less is known about their impact on stormwater management and reuse activities at a catchment or city scale. This study developed an integrated urban water cycle model (IUWCM) to quantitatively assess the effect of uniform green roof deployment (i.e., 25, 50, and 100% conversion of traditional roofs) over the period 2009–2011 in the Marina Reservoir catchment, a 100-km2100-km2, highly urbanized area located in the heart of Singapore. The IUWCM consists of two components: (1) a physically based model for extensive green roofs integrated within a one-dimensional numerical hydrological-hydraulic catchment model linked with (2) an optimization-based model describing the operation of the downstream, stormwater-fed reservoir. The event-based hydrological performance of green roofs varied significantly throughout the simulation period with a median of about 5% and 12% for the catchment scale reduction of runoff volume and peak discharge (100% conversion of traditional roofs). The high variability and lower performance (with respect to temperate climates) are strongly related to the tropical weather and climatic conditions—e.g., antecedent dry weather period and maximum rainfall intensity. Average annual volume reductions were 0.6, 1.2, and 2.4% for the 25, 50, and 100% green roof scenarios, respectively. The reduction of the stormwater generated at the catchment level through green roof implementation had a positive impact on flood protection along Marina Reservoir shores and the energy costs encountered when operating the reservoir. Vice versa, the drinking water supply, which depends on the amount of available stormwater, decreased due to the evapotranspiration losses from green roofs. Better performance in terms of stormwater reuse could only be obtained by increasing the time of concentration of the catchment. This may be achieved through the combination of green roofs with other LID structures.