【Walker (2025)】

On Thursday,Walker (2025) in a packed federal courthouse in San Francisco, U.S. District Court Judge William Alsup donned a space-themed tie and listened as scientists and lawyers formally presented the fundamentals of climate science. The hearing, dubbed a "tutorial" by Judge Alsup, marked the first time a judge has ever asked for and heard a presentation of climate science for the purposes of deciding a court case.

The case Alsup is presiding over involves several fossil fuel companies and two major cities -- San Francisco and Oakland. The cities are suing the world's oil giants -- Chevron, BP, Shell, and others -- for extracting and selling fuels that the companies knew would stoke climate change and sea level rise.

Adapting to these changes requires massive infrastructure undertakings, such as building formidable concrete sea walls, and the coastal cities want Big Oil to pay.

Judge Alsup gave each side two hours to present charts, data, and research on both the history of climate science and "the best science now available on global warming, glacier melt, sea rise, and coastal flooding."

Although Alsup made clear from the outset that the event was not a trial of climate science -- but a climate lesson for himself -- the evidence provided likely foreshadows the arguments both sides will make during the actual trial. While admitting the reality of human-caused global warming, lawyers for Chevron (the other oil giants have two weeks to tell Alsup if they agree with Chevron's science presentation) presented outdated science and repeatedly emphasized uncertainties about how fossil fuel emissions will affect global warming.

They also presented climate change as a global problem requiring a global solution, foreshadowing a defense strategy of arguing that no single company should be held liable for climate change-related damages.

"Oil companies basically went from a climate deniers playbook," said Kassie Siegel, director of the Climate Law Institute, in an interview."They overemphasized and overstated really narrow issues of uncertainty about the effects of global warming."

Glad I got here early! Big crowd for climate science hearing in SF today #ClimateTrial pic.twitter.com/5YvwUI0D9J

— Amy Westervelt (@amywestervelt) March 21, 2018

For instance, the oil companies' lawyer, Ted Boutrous, cited a U.N. Intergovernmental Panel on Climate Change (IPCC) report from 1990, which stated that the observed increase in global temperature could just be due to natural shifts in the planet's climate.

Nearly three decades have since passed, however, and confidence has grown about tying increasing temperatures to fossil fuel burning. A federal climate report published in late 2017, for example, found that there is no natural explanation for recent global warming.

"This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century," the report said. "For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence."

As Don Wuebbles, a former White House climate science advisor and atmospheric scientist, said during the tutorial, 17 of the last 18 years have been the warmest years on record. The instrumental climate record began in the late 1800s, although researchers have far longer climate timelines gleaned from tree rings, ice cores, and other so-called "proxy" sources.

While three climate scientists presented climate science basics for the plaintiffs, the defendants relied exclusively upon Boutrous, who has previously defended both Walmart and the Standard Fire Insurance Company before the U.S. Supreme Court, to inform the judge about the nuances of climate science.

"I don’t know if Ted Boutrous has a background in climate science, but he has a background in spin," Siegel said.

Alsup grilling Chevron on rate of change of sea level rise. Chevron says sea level has been rising for centuries, nothing new. Plaintiffs’ experts presented evidence that it’s dramatically increased in recent years, fueled by climate change. #ClimateTutorial @ClimateLawNews

— Amy Westervelt (@amywestervelt) March 21, 2018

Chevron and the other oil companies may have a difficult time finding scientists who will, in a federal court, make scientific statements about climate change that oil companies find agreeable.

"The oil companies are now in a real pickle," said Siegel, noting that climate scientists have previously made false or misleading statements on behalf of oil companies. Publicly, most of these companies now admit that climate change is occurring, even if they continue to sell more oil and gas that contributes to the problem.

"It's a lot harder to lie to the court under penalty of perjury," said Siegel.

Richard Wiles, Executive Director of the Center for Climate Integrity, agrees.

"The fact that Chevron’s lawyer, rather than an actual climate scientist, provided the court with its version of climate history suggests that the industry could not find a scientist willing to carry its water," Wiles said in a statement.

Only scientists, however, presented evidence for the plaintiffs. Along with Wuebbles, geoscientist Myles Allen, who leads Oxford University's Climate Dynamics Group, and Gary Griggs, a professor of earth sciences at University of California at Santa Cruz, presented climate science information to Alsup.

Griggs noted that significant sea level rise has been measured just miles from the courthouse near the San Francisco shore, and Allen delivered quotes from Svante Arrhenius, a scientist who in 1895 noted that carbon dioxide emissions could have a warming effect on the Earth.

As for what comes next, the oil companies have filed a motion asking Alsup to dismiss the case. If this were to happen, there would be no trial, said Michael Burger, executive director of the Sabin Center for Climate Change Law at Columbia University, via email.

But if things proceed, the next step will likely be discovery, wherein plaintiffs and defendants exchange information that will be used as evidence in the trial. During the past few years, as climate change-related litigation has increased, oil companies have gone to great lengths to avoid the discovery process, since it could reveal what oil companies knew about climate change, when they knew it, and what they told the public and their shareholders about it.

The tutorial event may have been unprecedented, but the case is just one of many current lawsuits against oil companies. Across the country, New York City is also suing the same oil companies for damage caused by human-caused climate change.

“Taxpayers around the country should ask themselves whether they want to foot the bill for climate impacts that scientists now attribute directly to the oil and gas industry or demand that polluters pay for the damages they’ve caused," Wiles said.