Former president George HW Bush, who died on 30 November at the age of 94, helped raise the profile of emissions trading in the US.
During his single term in office, from 1989-1993, Bush ushered through one of the most significant pieces of environmental legislation of recent decades, the 1990 amendments to the Clean Air Act. That legislation, among other things, created a cap-and-trade program to reduce SO2 emissions from power plants and curb acid rain in the northeast US.
"Thanks to president Bush, we do not hear much about acid rain these days," said Fred Krupp, president of the Environmental Defense Fund, one of the first environmental groups to support the use of emissions trading.
Krupp and other environmental groups say that the amendments will go down as one of Bush's most significant achievements.
"George HW Bush left a legacy all Americans share with every breath we take," Natural Resources Defense Council president Rhea Suh said.
Bush proposed the amendments in June 1989, specifically calling for the use of a credit trading program to reduce power plant emissions, mostly from the midwest, that caused acid rain, damaging forests and aquatic ecosystems in northeast states. Bush said an emissions market would be the best way to reduce emissions quickly and economically.
"We are allowing utilities to trade credits among themselves for reductions they make, to let them decide how to bring aggregate emissions down as cost-effectively as possible," he said, when he proposed the changes in June 1989.
Congress passed the amendments in late October 1990, and Bush signed them into law on 15 November 1990.
The Acid Rain Program launched in 1994 and required power plants across the country to cut SO2 emissions in half, to about 8.5mn short tons by 2010. Sources covered by the program emitted about 1.5mn st in 2016, according to the US Environmental Protection Agency (EPA).
Although still in place, the Acid Rain program has largely been supplanted by a series of other cap-and-trade programs, including the current Cross-State Air Pollution Rule, which targets SO2 and NOx emissions from power plants in the eastern half of the US to help with meeting federal air quality standards.
Despite the success of the programs, in recent years cap and trade has fallen out of favor among Republicans, particularly as part of their opposition to legislation to address climate change and reduce US greenhouse gas emissions.
Bush also helped elevate climate change as an environmental issue by securing US ratification of the UN Framework Convention on Climate Change, which set as a global goal stabilizing GHG emissions "at a level that would prevent dangerous anthropogenic interference" with the global climate.
"The US fully intends to be the world's preeminent leader in protecting the global environment. We have been that for many years. We will remain so," Bush said at the 1992 Rio Earth Summit, where he signed the UNFCCC treaty. "We believe that environment and development, the two subjects of this conference, can and should go hand in hand. A growing economy creates the resources necessary for environmental protection, and environmental protection makes growth sustainable over the long term."
The treaty, which the US ratified in October 1992, also serves as the main forum for global climate talks since, including those that produced the Paris agreement in 2015. The latest conference of the treaty's parties, COP 24, kicked off in Katowice, Poland, today.
Bush also established the US Global Change Research Program, which recently issued its fourth national climate assessment, warning that without more aggressive action to reduce global GHG emissions, climate change is likely to cause significant damage to the US economy.
