The declining significance of the agrarian economy, characterized by a decreasing share of agriculture in the national GDP and a shift of the workforce away from farming, has profound and multifaceted impacts on a society, particularly in a country like India where agriculture has historically been the backbone.

Economic Impacts:

1. Structural Transformation: A declining agrarian economy is often a sign of economic development, as resources and labor shift towards more productive sectors like manufacturing and services. This leads to a higher overall GDP per capita and a more diversified economy.
2. Rural-Urban Migration: As agricultural incomes stagnate or decline, and opportunities in urban areas grow, there's a significant exodus of people from rural areas to cities in search of better livelihoods. This fuels urbanization but also puts immense pressure on urban infrastructure and services.
3. Farmer Distress and Inequality: For those who remain in agriculture, especially small and marginal farmers, the declining significance can mean lower incomes, increased indebtedness, and a lack of market access. This often leads to farmer suicides, increased rural poverty, and widening income disparities between agricultural and non-agricultural sectors.
4. Food Security Concerns: While a smaller share of agriculture in GDP doesn't necessarily mean less food production, it can raise concerns about food security if agricultural productivity doesn't keep pace with population growth. Over-reliance on imports can make a nation vulnerable to global price fluctuations.
5. Land Use Change: Agricultural land may be converted for industrial, commercial, or residential purposes, leading to a reduction in cultivable land and potential environmental consequences.

Social Impacts:

1. Changes in Rural Society: The out-migration of youth, particularly men, can lead to the 'feminization of agriculture,' where women take on more farming responsibilities. It can also lead to the breakdown of traditional joint family structures and community support systems.
2. Poverty and Malnutrition: While overall poverty might decrease, pockets of severe poverty and malnutrition can persist in agrarian regions, especially among landless laborers and small farmers who are left behind.
3. Loss of Traditional Knowledge and Skills: As agriculture becomes less central, traditional farming practices, indigenous knowledge, and rural crafts may decline, leading to a loss of cultural heritage.
4. Increased Pressure on Urban Areas: The influx of rural migrants into cities can lead to the growth of slums, increased competition for jobs, and social tensions if urban infrastructure and social services cannot cope with the rapid population growth.

Environmental Impacts:

1. Intensification of Agriculture: To compensate for a smaller workforce or land area, agriculture might become more intensive, relying heavily on chemical fertilizers, pesticides, and irrigation, leading to soil degradation, water pollution, and depletion of groundwater resources.
2. Ecological Imbalance: Changes in land use patterns, such as conversion of forests or wetlands for agriculture or urban expansion, can lead to loss of biodiversity and ecological imbalances.

In summary, while a declining agrarian economy is often a marker of modernization, it necessitates careful policy interventions to manage the transition, support vulnerable farming communities, ensure food security, and address the social and environmental consequences of this fundamental economic shift.