The changes made in the (EPI), which has ranked India among the bottom five countries, have not been explained or backed by scientific arguments, and seem to be "arbitrary", the government has said.
According to it, India's ranking in Global Environment Performance Index (EPI) was 141 in 2016 and 177 in 2018.
Minister of State for Environment Mahesh Sharma said that the report relied on data gathered by NASA satellite in place of actual monitored data and has not been peer reviewed.
"An assessment indicates that the weightages given to the parameters at the three hierarchical levels (policy objectives, issue categories and indicators) are different in 2016 and 2018 iterations.
"The changes made have not been explained or backed by scientific arguments, and seem to be arbitrary," Sharma said in written reply to a question in Lok Sabha on August 3.
He said the World Economic Forum ranked 180 countries on their performance across 24 metrics aggregated into 10 issue categories including environmental health, air quality, water resource management, biodiversity and habitat, forestry, fisheries, agriculture, and climate change.
Sharma said in 2016, the two policy objectives environmental health and ecosystem vitality had a weightage of 0.5 (or 50 per cent) each, whereas in EPI 2018, it is 0.4 and 0.6 respectively.
Further, for the category air quality, the weightage given in EPI 2016 was 0.3, which has been increased by over 100 per cent to 0.65 in EPI 2018, he pointed out.
In EPI 2016, air quality figured as a category only under environmental health.
"However, in EPI 2018, air quality figures under environmental health, and there is a category air pollution under ecosystem vitality, which seems misplaced.
"Different weightages and difference in methodology used implies that rankings arrived at are not comparable and has its limitations," he said.
Under the category water resources, the only indicator shown is waste water treatment, which puts developed countries on the top since it is a measure of the capacity to address a problem, he said.
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