Lee R. Raymond, the former chief executive officer of Exxon Mobil who led the company through its historic merger and staunchly questioned the scientific consensus on climate change, died on June 6 in Dallas. He was 87. His son, Colin Raymond, confirmed that his death followed complications from pneumonia.

Raymond’s tenure as CEO, from 1993 to 2005, was marked by significant cost-cutting measures and a focus on maximizing profitability. In 1998, he orchestrated Exxon’s $81 billion acquisition of Mobil, creating the world’s largest private-sector oil company by annual sales, with operations spanning about 200 countries. This deal reunited the two largest parts of John D. Rockefeller’s Standard Oil Trust, which had been broken up in 1911.

Under Raymond’s leadership, Exxon Mobil’s net income increased substantially, rising from $4.8 billion to $36.13 billion, while the company’s market value quadrupled to $375 billion. He implemented deep executive cuts following the merger, removing roughly one-third of executive positions. Known for a terse and unsparing management style, Raymond avoided public visibility and was famously dismissive in interactions with employees and financial analysts.

Prior to becoming CEO, Raymond played a prominent role in Exxon’s response to the 1989 Exxon Valdez oil spill in Alaska’s Prince William Sound, which released 11 million gallons of crude oil and severely damaged the local ecosystem. As Exxon’s president at the time, he oversaw the cleanup efforts and helped negotiate a $1 billion settlement of legal claims in 1991. However, he clashed with environmentalists and government officials over the use of chemical dispersants, which Exxon wanted to employ to contain the spill.

Legal battles stemming from the Valdez spill extended for years, culminating in a 2008 Supreme Court decision that reduced Exxon’s punitive damages from $5 billion to $500 million. During his career, Raymond was often criticized by environmental advocates for Exxon’s resistance to climate change regulation. In the early 2000s, while competitors like BP and Chevron highlighted investments in alternative energy, Exxon under Raymond opposed restrictions on fossil fuels and funded research that challenged the link between fossil fuel emissions and global warming.

Raymond, holding a Ph.D. in chemical engineering, attributed climate change to natural variability linked to phenomena such as solar activity and Earth’s geological shifts. He argued that alternative energy sources were too costly to replace oil and gas in the near term, advocating for expanded oil exploration, including in sensitive regions like the Arctic National Wildlife Refuge.

His stance on social issues also drew criticism. After Exxon merged with Mobil, the company rolled back policies preventing discrimination based on sexual orientation and discontinued benefits for same-sex partners, prompting calls for boycotts from LGBTQ advocacy groups. These policies were later reversed under Raymond’s successor, Rex Tillerson, who also acknowledged human contributions to climate change.

Born in Watertown, South Dakota, in 1938, Raymond earned degrees in chemical engineering from the University of Wisconsin and the University of Minnesota. He joined Exxon in 1963 and rose through its ranks, managing operations in Venezuela and turning around a struggling refinery in Aruba before assuming top leadership roles. Over his 12-year CEO tenure, his compensation exceeded $686 million.

Outside Exxon, Raymond served as a director of JPMorgan Chase for more than three decades and was affiliated with the American Enterprise Institute. A private individual, he rarely discussed his personal life publicly, though those close to him noted his loyalty to colleagues and moments of emotional openness during difficult times.

He is survived by his wife, Charlene Hocevar, three sons—Colin, John, and Rob—and seven grandchildren.