Key highlights of the study-
- Cultivation area under bioenergy crops occupies 3.8 percent ± 0.5 per cent of the global total land area, but they exert strong regional biophysical effects, leading to a global net change in air temperature of −0.08 ~ +0.05 degrees Celsius.
- Researchers found that global air temperature decreases by 0.03~0.08 °C, with strong regional contrasts and inter-annual variability, after 50 years of large-scale bioenergy crop cultivation.
- Compared to the herbaceous crops, changes in the energy fluxes induced by woody crops in the cultivation regions are larger, and the cooling effect is stronger and healthier across different cultivation maps.
- Eucalyptus, poplar, willow, miscanthus and switchgrass were the bioenergy crops used in the study.
- The study warned that temperature changes in the bioenergy crop scenarios may have very large spatial variations and important climate teleconnections to other areas of the globe.
- Warming effects in Alaska and northwestern Canada may cause greenhouse gas release from thawing permafrost, from the four idealised bioenergy crop scenarios based on the composited cultivation map.
- Strong cooling effects in Eurasia, between 60°N and 80°N, may protect permafrost from thawing or reduce methane emissions from wetlands.
- The study also demonstrated the importance of the crop type choice, the original land use type upon which bioenergy crops are expanded, the total cultivation area and its spatial distribution patterns.
- Cultivating eucalyptus generally shows cooling effects that are more robust than if switchgrass is used as the main bioenergy crop.
About Bioenergy crops-
- Bioenergy crops are defined as any plant material used to produce bioenergy.
- They are grown and maintained at lower costs for biofuel production.
- These crops have the capacity to produce a large volume of biomass, high energy potential, and can be grown in marginal soils.
- They can positively impact the environment to reduce the level of carbon dioxide, emission of greenhouse gases and soil erosion.
- The bioenergy crops are classified into five types namely, first-, second- and third-generation bioenergy crops, dedicated energy crops and halophytes.
- The first-generation bioenergy crops include corn, sorghum, rapeseed and sugarcane, whereas the second-generation bioenergy crops are switchgrass, miscanthus, alfalfa, reed canary grass, Napier grass and other plants.
- The third-generation bioenergy crops contain boreal plants, crassulacean acid metabolism (CAM) plants, eucalyptus and microalgae.