In 1989, a 185-page California climate report warned that a warming would slash the state's spring runoff by a full third. 30 years later, its warnings proved right, with mountain snow cover falling by half as droughts, floods and fires worsened

Thirty years ago, California was already being warned about what a warming climate could mean for the state. A 185-page report predicted shrinking mountain snow cover, declining spring runoff, worsening floods and greater pressure from drought and wildfire. Today, scientists say many of those changes are no longer projections. They are being observed.

In 1989, California received a warning that now reads with striking familiarity. A state report said rising heat-trapping gases could bring more droughts, floods, wildfires and heat waves. Three decades later, scientists looking back at the report say many of those projected changes have already begun showing up across California, as per Phys.Org.

"We've already observed some of the things we expected in 1989," said Susan Fischer Wilhelm, a research manager at the California Energy Commission.


The report was prepared after California lawmakers asked the California Energy Commission to examine "the effect of global warming trends on California's energy, economy, environment, agriculture, and water." Its findings helped lay the groundwork for later climate policies, although the response took years.

What did California’s 1989 report predict?

The 185-page assessment warned that doubling atmospheric carbon dioxide would raise California temperatures by about 3 degrees Celsius. The latest California Climate Change Assessment says that level of warming could occur by midcentury if emissions continue to rise.

The report did not predict a clear change in California's average annual precipitation. Instead, it focused on how warming could alter when and where water arrives.

Mountain snow cover, the report said, could fall by half with 3 degrees of warming. More winter precipitation would arrive as rain rather than snow, increasing the frequency and severity of winter floods.

Spring runoff was projected to decline by one-third.

Wilhelm said both changes have already started occurring.

The report also warned that reservoirs could face greater pressure as more water arrived during the rainy season, forcing them to release water to prevent overflowing. The 2017 Oroville Dam crisis later provided a striking example of the problem.

During summer, reduced water supplies could affect ecosystems, agriculture and hydropower. Forests, meanwhile, could face greater stress from heat and drought and become more vulnerable to fires, insects and disease.

How quickly did the warnings become reality?

Looking back, several of the report's predictions now appear remarkably close to what California is experiencing.

Forests are under greater pressure from heat and drought, while wildfire risk has become a major concern. The report also warned about rising sea levels, increased electricity demand, poorer air quality, more heat-related deaths and economic costs.

"It strikes me that we were right on," said Kari Smith, now a division manager at the San Jose Clean Energy department who helped oversee the report at the CEC.

Smith said the report may actually have underestimated how closely different climate impacts would become connected. In 1989, for example, few people anticipated that wildfire risks could lead utilities to consider shutting off electricity to thousands of residents.

"We now have observed data—not projections, nothing speculative—to show climate-related trends that are already affecting the state in ways that were anticipated 30 years ago," Wilhelm said.

The report's authors also believed they had more time.

"They thought that we had at least 100 years before it became existential," Smith said.

"Now, 30 years later, we're recognizing that it all happened a lot more quickly than we anticipated."

Why did California wait so long to act?

The report appeared at a time when climate change was still being debated politically and scientifically. Its authors included six pages on "Challenges to the Global Warming Concept."

Les Baxter, who worked on the report as a policy analyst at the California Energy Commission, said he believed the theory was sound but did not think there was yet enough evidence to show the changes were already happening.

"I remember thinking to myself, 'Well, we'll know enough in 20 or 25 years,'" he said.

That uncertainty made climate policy difficult, Smith said.

"It was difficult to lead with climate change for a long time because it was considered maybe a little radical."

Instead, policymakers often approached related issues through goals such as improving air quality and energy efficiency.

The legislation behind the report was Assembly Bill 4420, introduced by Byron Sher. The bill passed with a 58-13 vote in the Assembly and a 38-0 vote in the Senate.

"It's the first law enacted anywhere in the United States that used the term 'global warming,'" said Kip Lipper, who helped draft the bill.

The report itself did not create an immediate political transformation. But Lipper said it provided a foundation for policies that followed, including California's renewable energy portfolio standard and cap-and-trade program.

"It would be 12 years before the next piece of climate legislation passed," the account notes, while AB 32, which established the state's first emissions reduction target, did not become law until 2006.

For Baxter, the experience remains difficult to look back on.

"I felt a sense of pride of being able to participate in something like this, but also a sense of regret for us as a society," he said.

"We've known what we need to do and we just keep refusing to do it."

Today, the old report offers something more than a historical record. Its projections can be compared with what California is now observing, from changing snow cover and runoff to drought, wildfire and heat. What once appeared as a warning about a distant future has increasingly become part of California's present.

FAQs

What did California’s 1989 climate report warn about?
It warned of more droughts, floods, wildfires, heat and declining mountain snow cover.

Have those climate changes happened?
Scientists say many of the changes predicted in the report are now being observed.