In a world that is otherwise facing a plethora of severe environmental crises, there is a glimmer of optimism provided by a study published in the journal, Nature Sustainability, based on data from the NASA Earth Conservatory. In the last 20 years, the world has literally become a greener place to live in and the largest sources of this increase in foliage are India and China. This appears to be counterintuitive, given that both countries host the highest populations globally and are undergoing rapid urbanisation, industrialisation and development. These trends are typically associated with massive deforestation and land degradation.
The greening phenomenon was first detected in the mid-1990s, but at that time, it was unknown that human activity (land use management) was a key and direct contributor. This new insight emerged from a 20-year long record of data from a NASA instrument called the Moderate Resolution Imaging Spectrodiometer (MODIS) that orbits the Earth on two satellites with intensive coverage across space and time. MODIS has enabled researched to procure high-resolution shots, yielding accurate and detailed data and information about what is happening to vegetation on the planet, as close as 500 meters from the ground.
China’s ambitious tree planting programs for conserving and expanding forest cover to mitigate impacts of climate change, air pollution, soil erosion, land degradation as well as intensive agriculture in both, India and China are primary causes of this greening of the planet. This increase in the leaf area of trees and plants, of more than 2 million square miles per year, is equivalent to the coverage by Amazon rainforests. The lead author of the study has said that “China and India account for one-third of the greening, but contain only 9% of the planet’s land area covered in vegetation.”
According to Rama Nemani, research scientist at NASA and co-author of the study, “this long-term data lets us dig deeper. When the greening of the Earth was first observed, we thought it was due to a warmer, wetter climate and fertilization from the added carbon dioxide in the atmosphere, leading to more leaf growth in northern forests, for instance. Now, with the MODIS data that lets us understand the phenomenon at really small scales, we see that humans are also contributing.”
China accounts for 25% of the global net increase in leaf area with 6.6& of global vegetated area. Forests and intensive cultivation of croplands have contributed 42% and 32% respectively. In India, greening can be attributed mostly to croplands at 82% and forests contribute a minor 4.4%. Since 2000, food production in both countries has increased by more than 35% due to increase in harvested area and yield, based on multiple cropping patterns, fertilizer usage, multiple rounds of replantation annually and ground/surface water irrigation. The production of grains, vegetables, fruits have increased by about 35-40% since 2000 to feed the increasing populations.
The dominant indirect drivers include CO2 fertilization effects and climate change, amidst other factors like nitrogen deposition and recovery from natural disturbances. Along with the direct human influence, these can be factored into existing climate models to make improved predictions about the changing nature of different natural systems and take suitable actions. Their future is dependent on numerous global and local factors and changing environmental circumstances and losses.
Overall, 33% of the world’s vegetated lands are becoming greener while 5% of those are growing browner. Moreover, the increase in greenness in India and China has not offset the damage caused due to loss of natural vegetation across tropical regions in Indonesia and Brazil. Thus, concerns related to the consequences of loss in biodiversity and sustainability remain. Understanding of this striking greening trend can highlight the necessity of developing realistic representations of how human land-use practices impact Earth system models and can then be applied across countries for widespread environmental sustainability.
India Outbound
February 14, 2019
source https://indiaoutbound.org/greening-of-planet-earth-a-striking-phenomenon/
No comments:
Post a Comment