The Eiffel tower was illuminated in green with the words "Paris Agreement is Done" to celebrate the Paris U.N. COP21 Climate Change agreement in Paris, Nov. 4, 2016. Reuters

UPDATE: 6/1 at 3:55 PM - President Donald Trump announced at a press conference Thursday afternoon that his administration would officially pull out of the Paris Climate Agreement.

Original story: Democrats and Republicans in the Senate wrote letters urging President Donald Trump to remain a part of (Dems) or abandon (GOP) the Paris Climate Agreement. Days later, he announced via Twitter his intentions to side with his own party. But rather than provide regulatory relief for the private sector, pulling out of the climate accord might frustrate many businesses that have said they support the deal — and have already been making preparations to comply with new strictures.

In the months before Trump's decision, companies which have expressed support for the Paris Accord collectively spent millions on lobbying efforts related in part to the landmark agreement to avoid a 2-degree Celcius rise in global temperatures.

Since the U.S. formally entered into the accord in September, the right and left have argued over whether or not former President Barack Obama’s signing of the agreement, which had 175 signatories as of April, constituted the signing of a treaty, which would require a two-thirds vote of approval by the Senate.

Although questions of Senate approval may ultimately prove irrelevant, climate activist organizations, energy companies, major conglomerates and other groups have lobbied the upper house and other arms of the federal government extensively — and expensively — on the issue since Trump took office.

Through its lobbying firm Carbonleaf LLC, for example, the trade group Industrial Energy Consumers of America, which wrote Trump a letter in late April saying that it “fails to see the benefit of the Paris Climate Accord,” spent $130,000 on lobbying efforts that included the agreement in the first three months of this year. The organization's federal disclosures show that it lobbied the White House.

The vast majority of firms lobbying on the Paris accord, however, were at least ostensibly in favor of the U.S. remaining a signatory.

The chief executive of energy giant ExxonMobil Corp. — which spent $3.44 million on lobbying efforts involving climate and environmental issues, including “discussions related to the Paris Agreement” in the first quarter of 2017 — wrote an open letter to Trump last week pushing the president to stick to the accord, based on his assertion that the U.S. is “well positioned to compete” in the energy market.

Likewise, Shell Oil Co. spent $2.34 million on lobbying efforts including “U.S. participation in the Paris agreement.” (Lobbying records show only the issue, not the position being advanced.) The company was also one of 16 firms that signed an April letter to Trump stating, “We urge that the United States remain a party to the Paris Agreement” and “work constructively with other nations to implement the agreement.”

Statoil, another oil company that has expressed support for the accord, spent $100,000 lobbying the National Security Council on offshore oil and gas development initiatives and “issues related to the U.S. role in [the] Paris agreement” in the first quarter of this year.

Arch Coal Inc., which spent $90,000 in lobbying involving the Paris accord in the first three months of 2017, told White House officials privately that it would publicly support remaining in the agreement on the condition that the administration would financially support the coal industry, Politico reported at the end of March. Peabody Investments Corp. — a subsidiary of Peabody Energy Corp., another firm named in the Politico report siding with Arch Coal — spent $450,000 on lobbying related in part to the issue over the same period.

Nike Inc., which spent $126,000 in the first quarter on lobbying related to the Paris Agreement, was one of several hundred corporate signatories of an open letter urging the administration, members of Congress and leaders around the world to stay committed. Other large firms that have vocally supported the agreement and pledged tens of thousands lobbying dollars each related to the issue included Johnson & Johnson, which signed the same letter as Nike and whose subsidiary Johnson & Johnson Services Inc. spent $1.06 million on lobbying issues related in part to the agreement; the industrial giant Ingersoll Rand plc, which spent $251,000; Rio Tinto Group, whose subsidiary Rio Tinto Services Inc. spent $210,000; and French chemical company Arkema Group, which spent a total of $220,000, both through a lobbying firm and directly, in the first quarter of 2017.

Anant Sundaram, a professor at Dartmouth University's Tuck School of Business, said he's “more than positive” that the companies' public embraces of the Paris Climate Agreement are “genuine.”

“The bottom line is that most of these companies have moved on,” he said, adding that many firms had invested large sums of money in research and technology to reduce their carbon footprints. “At this point, the opposition to [the Paris Climate Agreement] is totally political.”

A full 70 percent of companies in the Standard & Poor's 500 index had signed some sort of energy-efficiency strategy, and some oil firms have even included “shadow prices” based on the expected costs of compliance in their future budgets, Sundaram said. And if American corporations lag behind those of the rest of the world when it comes to minimizing their environmental impact, he added, the effect on U.S. exports could be detrimental: Paris Accord signatories could impose a tax on American products with significant carbon footprints. Such a consequence, he said, “would be shameful.”

“They've been doing this for four or five years, many of them,” he said of the adaptive measures undertaken by the companies channeling lobbying dollars toward the agreement. “Despite all of the controversy, if you believe in the scientific method, you just move on.”