Tuesday, 31 October 2017

Land-System Change


Basic principles of good husbandry include: respecting land capacity; preserving genetic diversity, conserving soil (quality and quantity); managing rainwater; maintaining plant cover. Today, the aggregated impacts of agricultural transformations are replacing sustainable land use practices and contribute significantly to global environmental changes. Studying these changes requires questioning the sustainability of land-use dynamics, how they might affect changes in climate and global biogeochemistry and vice versa


The 9 Planetary Boundaries of Earth System Processes to guide the way humanity governs Earth. Check out all the Control variables for the 9 Earth System Processes
A planetary boundary is a concept created by Earth System scientists from the Stockholm Resilience Center to ''define a safe operating space for human societies to develop and thrive'' (Steffen et al., 2015). The control variables for land-system change include the irreversible and widespread conversion of native biomes, affecting carbon storage and resilience through losses in biodiversity and landscape heterogeneityThe short video below gives an idea of why it is important to identify 'limits' to human activities:



One of the main ways in which the agricultural sector contributes to climate change is deforestation. Methane and nitrous oxide have significantly higher warming potentials compared to carbon dioxide (in a 100-year time horizon) and are the main greenhouse gases from agricultural activities. However, carbon dioxide is the deforestation and forest degradation account for around 20% of global greenhouse gas emissions

Source
Forests are globally important in regulating climate and locally important in sustaining communities and supporting biodiversityhowever, industrial-scale human activities have altered the physical properties of land surfaces and its interactions with the biosphere and atmosphere. Biomass burning (for land clearing), fertilizers and pesticides, species transfer, plowing, irrigation, drainage, livestock pasturing, amongst others, have impacts that lead to secondary environmental impacts such as biodiversity loss, soil erosion, degradation, albedo alteration (Meyer and Turner, 1994)Environmental feedbacks to land-system change, in turn, require resilient human responses (B.L Turner, 1994).

 Land-cover change in temperate regions

The reflecting power of incoming solar radiation by surfaces (albedo) depends on land cover. Modelling studies estimated that increased surface albedo due to deforestation in temperate regions has most likely exerted a negative radiative forcing, in other words, produced a cooling effect. Bett's research (2000) shows that afforestation efforts to mitigate CO2 concentrations in temperate and boreal regions can actually ''offset the potential carbon sink'' by creating a low surface albedo that exerts a warming influence on climate. Thus it is important to consider the effects of land-cover change and land-use dynamics, ''both of which have strong human controls'' in mitigation targets.

Land-cover change in tropical regions


    If the deforestation of the temperate and boreal forests has now broadly stabilized, it is the tropical forests that are being rapidly destroyed. More than 50% of rainforests have been severely degraded or converted mainly for agricultural expansion, accounting for nearly 90% of the total forest lossThe conversion of forests for cattle pasture is the second major contributor to tropical deforestation and is almost entirely concentrated in Latin America (Lovell S. Jarvis, 1986). 

    Credit: Nicolle Rager Fuller, NSF

    Friday, 27 October 2017

    What the world eats


    Hey everyone! I came across an interesting series of photographs taken by photo-journalist Peter Menzel for his book called ''Hungry Planet: what the world eats''. Here are a few:

    The Melander family from Bargteheide, Germany, with a week's worth of food. Food expenditure for one week: $500.07 USD

    The Caven family. American Canyon, California, with a week's worth of food. Food expenditure for one week: $159.18 USD
    The Mendoza family in Todos Santos Cuchumatán, Guatemala, with a week's worth of food. Food expenditure for one week: $75.70 USD

    The Ayme family in their kitchen house in Tingo, Ecuador, a village in the central Andes, with one week's worth of food. Food expenditure for one week: $31.55 USD

    Powerful images, right? 

    Recent studies (Behrens et al., 2017) show that there is an increasing demand for foods with high environmental and health impacts. Meat consumption has grown unprecedently over the past decades, putting pressure on forests and resources. Animal products are considered a ''luxury'' food for rural populations, whereas they have become widely available and accessible in urban areas.

    The first family, from Germany, spends three times as much as the American family, including many beverages, and what appears to be higher quality meats. The American family seems to eat a lot of ''brands''. Compared to the rural, the urban families eat little "natural" foods and mostly processed foods. It is also interesting to notice the food expenditures. For urban families, the ability to spend more on food reflects socioeconomic status, whereas rural families reflect wealth from the amount of food available. How much would it cost for the German family to consume as much (organic) produce as the Guatemalan's?

    Equilibrium?

    The supply of animal products depends on reproductive capacity, and natural resources, in general, have an equilibrium harvest. Can we say our current agro-industrial practices are unsustainable? What are the interactions between the social and the biological system when we think of our food? 

    Should we think of our global food production systems as major drivers of change in terms of the linear consumption patterns of societies? 


    Many questions with perhaps a variety of complex answers...