US President Donald Trump has reversed a key Obama-era scientific ruling that underpins all federal actions on curbing planet-warming gases. The so-called 2009 'endangerment finding' concluded that a range of greenhouse gases were a threat to public health. It has become the legal bedrock of federal efforts to rein in emissions, especially in vehicles. The White House called the reversal the 'largest deregulation in American history', saying it would make cars cheaper, bringing down costs for automakers by $2,400 per vehicle. Environmental groups argue this is the most significant rollback on climate change yet attempted and are set to challenge it in the courts.

Speaking from the Oval Office, Trump condemned the ruling by saying it was 'a disastrous Obama era policy' that hurt the auto industry and drove up consumer prices. Former President Barack Obama countered that eliminating the finding would jeopardize American safety and health while benefitting the fossil fuel industry. Trump’s administration claims the rollback could save over $1 trillion, but skeptics worry it will actually force Americans to endure higher fuel costs and lead to an increase in health risks, including thousands of premature deaths and asthma attacks.

This regulation has also served as the foundation for numerous other environmental laws, affecting sectors from motor vehicles to power plants. Critics are concerned about the long-term implications of these actions and are preparing to launch legal challenges against the decision.