The study looked at how wealthy countries in the EU impact the environment. Instead of just focusing on CO2 emissions like most research, they used a broader measure called the ecological footprint. They wanted to see if there's a pattern where environmental damage goes down as countries get richer (that's the environmental Kuznets curve idea). They looked at data from 1980 to 2013 for EU countries. The results showed that as real income increases, the impact on the environment improves but worsens with non-renewable energy use. On the bright side, using renewable energy and trading more globally help reduce environmental harm in the EU.