Global warming: causes and impacts on agroecosystems productivity and food security with emphasis on cassava comparative advantage in the tropics/subtropics

Abstract

Earth's climate has experienced notable changes during the past 50-70 years when global surface temperature has risen by 0.8ºC during the 20th century. This was a consequence of the rise in the concentration of biogenic gases (carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, and ozone) in the atmosphere that contribute, along with water vapor, to the so-called 'greenhouse effect'. Most of the emissions of greenhouse gases have been, and still are, the product of human activities, namely, the excessive use of fossil energy, deforestations in the humid tropics with associated poor land usemanagement, and wide-scale degradation of soils under crop cultivation and animal/pasture ecosystems. General Circulation Models predict that atmospheric CO 2 concentration will probably reach 700 µmol(CO 2 ) mol -1 . This can result in rise of Earth's temperature from 1.5 to over 5ºC by the end of this century. This may instigate 0.60-1.0 m rise in sea level, with impacts on coastal lowlands across continents. Crop modeling predicts significant changes in agricultural ecosystems. The mid-and high-latitude regions might reap the benefits of warming and CO 2 fertilization effects via increasing total production and yield of C 3 plants coupled with greater water-use efficiencies. The tropical/subtropical regions will probably suffer the worst impacts of global climate changes. These impacts include wide-scale socioeconomic changes, such as degradation and losses of natural resources, low agricultural production, and lower crop yields, increased risks of hunger, and above all waves of human migration and dislocation. Due to inherent cassava tolerance to heat, water stress, and poor soils, this crop is highly adaptable to warming climate. Such a trait should enhance its role in food security in the tropics and subtropics.

Ecophysiology and Production Principles of Cassava (Manihot species) in Southeastern Nigeria

“…At the early growth stage, the adventitious roots are formed first from the nodes at the base of more than one axillary bud (nodal roots) 5-7 days after planting, which is then followed by the formation of rootlets from a recently formed callus at the base of the cutting (basal roots) [13]. The buds also begin to sprout and enlarge 5-8 days after planting, with the first leaves appearing by 10-13 days.…”

“…This may be because the plants mobilize photosynthates to the shoots early in the growing cycle and supply the roots more photosynthates during the later part of the growing cycle. This may, however, depend on critical eco-physiological conditions such as soil and water conditions, temperature regimes and photoperiodism [13,[17][18][19]. In general, cassava does not have specific water stress sensitive growth stage beyond crop establishment, and the crop tolerates prolonged drought and erratic precipitation [13].…”

“…This may, however, depend on critical eco-physiological conditions such as soil and water conditions, temperature regimes and photoperiodism [13,[17][18][19]. In general, cassava does not have specific water stress sensitive growth stage beyond crop establishment, and the crop tolerates prolonged drought and erratic precipitation [13]. The ability of cassava to tolerate elevated temperature, drought and increased concentration of atmospheric carbon dioxide, places it as a crop that can adapt to climate change impacts.…”

Meeting Global Food Needs: Realizing the Potential via Genetics × Environment × Management Interactions

“…The value of closing the yield gap for increased food production is evident. The challenge remains on how to close the yield gap because of interacting complex factors due to water availability, nutrient supply, and the genetic diversity (Högy et al, 2013; El‐Sharkawy, 2014). A synthesis document on the effects of climate change on agriculture recommends a balance of research on genetics and management practices to enable adaptation to the effects of climate change (Walthall et al, 2012).…”

The soil–peace nexus: our common future

“…While effects of global warming may even be positive for C3 plants (e.g., wheat (Triticum aestivum), barley (Hordeum vulgare), oats (Avena sativa), cotton (Gossipium hirsutum), sunflower (Hellianthus annuus), potato (Solanum tuberosum), tomato (Solanum lycopersicum), peanut (Arachis hypogea)) grown in northern latitudes, adverse impacts may likely prevail in C4 crops (e.g., maize (Zea mays), sugarcane (Saccharum officinarum), sorghum (Sorghum bicolor), millet (Pennisetum glaucum), amaranth (Amaranth spp.)). C4 crops are primarily grown in the tropics and sub-tropics where risks are high for the degradation of natural resources, food shortages, and population migration and dislocation (El-Sharkawy 2014). In addition to climate-induced food deficit, global warming may also lead to disruptive activities such as demonstrations, riots, strikes, communal conflict, and anti-government and organized rebellion violence (Hendrix and Salehyan 2012).…”