US President Joe Biden is pledging to slash greenhouse gas emissions in the world's largest economy. Speaking at a virtual summit on Earth Day, attended by about 40 heads of state, Biden reiterated US support for meeting globally agreed on climate goals. The Biden administration wants to replace subsidies for fossil fuels with clean energy incentives. The new policies are aimed at halving emissions by 2030, compared to 2005 levels. And help the world's second-worst polluter, become carbon neutral by 2050. TRT interviewed EfD's Thomas Sterner, professor of environmental economics at the University of Gothenberg.