A strongly worded government report issued last week said that long-standing warnings about the dangers of climate change are now coming true, with more powerful storms, floods and fires already costing lives, as well as damaging regional and national infrastructure and the economy.

Worse lies ahead unless we take steps aggressively now to cut the human activities that are warming the atmosphere, especially our production of huge amounts of carbon dioxide through the burning of fossil fuels, the report warned.

By the end of the century, damage from the effects of a changing climate could reduce our gross domestic product by one-tenth or more, it claimed.

The report is the Fourth National Climate Assessment, or NCA4. Running more than 1,600 pages, it was prepared by 13 federal agencies, including the U.S. Department of Energy, for which the two national laboratories in Livermore are operated: Lawrence Livermore and Sandia.

Locally, LLNL in particular has an active climate research program. Despite this connection to the science that underlies the report, however, the two laboratories declined to comment on the findings.

Observers speculated that their silence was in deference to President Trump, who has often spoken dismissively of climate change in general and objected to the economic forecasts of NCA4 in particular.

The Trump Administration has been aggressive in rolling back governmental policies and regulations aimed at reducing the addition of greenhouse gases into the atmosphere.

The President is thus in the extraordinary position of denying the validity of a comprehensive scientific report from his own government without himself having scientific credentials or a science advisor to help guide him.

Phil Duffy, president of the Woods Hole Research Center and a former research scientist at LLNL, called the contrast between the administration’s policies and the report’s findings “bizarre.”

Unprecedented Detail

The report just published is actually the second volume of an assessment mandated by Congress. The first volume was published last year and dealt particularly with climate science.

The new volume evaluates in detail the damage that is occurring now and is predicted to increase as time passes if no interventions occur.

Separate chapters discuss present and expected conditions in 16 different impact areas ranging from agriculture to urban systems, from the economy to coastal regions, to tribes and indigenous peoples.

Ten other chapters discuss the climate’s effect on geographic regions, such as the Northeast, the Northern Great Plains and the Southwest, which includes California.

One chapter discusses potential steps that individuals, institutions and communities can take to adapt to present or future climate change. Another discusses mitigation -- steps aimed at reducing the amount of heat-trapping gases reaching the atmosphere or removing them once they are present.

According to Lawrence Berkeley National Laboratory’s Michael Wehner, who contributed to the assessment, the report is “so comprehensive that there should be something for everyone.”

He advised people to “find out for yourself. Read the parts you care about – if it’s the economy, read that section. If it’s fires in the forest, read that. If basic science, read that.”

Wehner started his career in 1985 in LLNL weapons design before shifting focus to atmospheric science. He moved to BerkeleyLab in 2002 and is now a major contributor to the science of extreme event attribution.

Extreme event attribution is the effort to determine how large a contribution climate change makes to extreme weather – phenomena like hurricanes, major droughts and storm surges.

It is a young, fast developing field. As recently as a decade ago, attributions were likely to be couched in vague terms suggesting general association between climate and extreme events, Wehner said.

Today, the field has advanced with more powerful statistical methods. As a result, Wehner was part of a recent study that was able to demonstrate a likely 38 percent increase in Hurricane Harvey precipitation due to climate change.

This in turn can be related to the costs of Harvey’s extreme flooding both in human lives and economic loss. The science is still developing, but on a warming planet, its advances are part of the growing confidence in predictions of specific future costs.

Human influence can now be identified in virtually all major heat waves, Wehner said. Drought conditions and hurricane wind speeds are more difficult to attribute today, but he believes that is likely to change in the near future as the field advances and the world warms.

To Robert Schock, a geologist and retired LLNL associate director who was not involved in preparing the NCA4, the new report brings a welcome expansion of detail over previous reports.

After leaving LLNL, Schock became head of research for the World Energy Council. He was lead author for a chapter of a report from the International Panel on Climate Change that he helped prepare 11 years ago.

The NCA4 report “does a very good job of talking about adaptation and mitigation together,” he said. “People in the past have tended to look upon them as two separate things, but they can work together. If you do more mitigation, you need less adaptation and so on.”

Schock believes the NCA4 report can be a model for other countries to draw on in dealing with their own climate issues.

He regrets that the U.S. plans to pull out of the international Paris climate agreements of 2015 and continues to believe that cooperation among countries – especially those with large economies -- will be necessary to deal with severe future climate disruptions.

Like Fire Insurance

Schock sees the risk as analogous to home fire insurance. Homeowners don’t expect a disaster, but they also don’t expend much passion quibbling about it. Instead, they take reasonable steps to fire-proof their homes and then pay premiums against the possibility that fire will occur anyway.

By the same token, he said, we should recognize the truth that the climate is changing in profound ways, with unprecedented speed, and the costs will be massive if we do nothing.

We should be taking steps to reduce the chance and magnitude of disaster by organizing efforts to adapt to the change and mitigate its consequences.

BerkeleyLab’s Wehner makes a comparable argument. We need to get past the “disinformation from vested interests” calling into question basic climate science that has been understood for a century and a half, he said.

We need to acknowledge the problem and then discuss “how much do you want to spend to avoid very large costs in the future.”

He called it a “multigenerational problem” in that we can spend more now, “but we don’t see the benefits (in reduced climate effects) for 30 years.” Alternatively, if we refuse to exert the effort now, we postpone the cost for the future, when costs look extreme.

To Ben Santer, senior climate researcher at LLNL, the new assessment report “diminishes the wiggle room” for those who want to deny that the climate is warming or that humans are playing a major role in climate change.

The common if unconvincing excuse that some warning comes from an international group and therefore can’t be expected to apply to America are obviously not valid in this case, he said.

“We own this report. It was mandated by Congress. Here it is and it has been signed off not by the Obama administration, but by the Trump administration. So how do you deny it?”

Santer was not involved in the preparation of NCA4, but his work has helped inform some parts of it.

For example, in a paper published earlier this year, he and a number of colleagues found disproportionately increased summer temperatures in middle latitudes, suggesting a likely connection with California megafires of recent years.

Santer considers NCA4 more comprehensive than previous climate assessments. “It breaks impacts down regionally, by sector, surveying all the information that we have about the likely impacts of human caused climate change on health, energy resources, agriculture, food security, vector-borne diseases – you name it.

“That is a big landscape to survey, but this report probably does, at least for the United States, a better job than any other…pointing out the very, very serious consequences for all aspects of our society.”

He noted also the report’s conclusion that climate impacts are already here: “Think Katrina, think Florence and Michael, think California wildfires, think rising sea levels, think Maria in Puerto Rico.”

What is next now that the report has been released?

“In an ideal world,” he said, “the consequence of this report would be a respectful political discourse on what to do about the problem of human caused climate change.

“That would be wonderful.”

The report is available online at https://nca2018.globalchange.gov/