Nearly 700 scientists from the prestigious National Academy of Sciences have signed an open letter criticizing the Trump Administration for ignoring scientific evidence in public policy development.

The letter, released last week, was developed by three prominent National Academy scientists, each representing a different field of research.

One of these was Benjamin Santer, the Lawrence Livermore National Laboratory climate scientist, who emphasized that the letter expressed his personal view, not that of any institution.

The letter bemoans the “Administration’s denigration of scientific expertise and harassment of scientists…(affecting) wide areas of the social, biological, environmental and physical sciences.”

The problem “has been particularly egregious in climate science,” the letter says. “Scientific evidence and research should be an important component of policymaking.”

It calls on the federal government to “maintain scientific content on publicly accessible websites, to appoint qualified personnel to positions requiring scientific expertise, to cease censorship and intimidation of government scientists and to reverse the decision to withdraw the U.S. from the Paris agreement.”

The letter is a follow-on to an earlier open letter in September 2016, when the U.S. Presidential campaign was underway; the Trump campaign was calling climate change a hoax perpetrated by the Chinese.

The 2016 letter was signed by 375 prominent scientists warning that human-induced climate change is reality and that withdrawal from the Paris climate agreement would negatively affect the world’s climate system and also U.S. credibility and leadership.

That two-year-old warning is clearly becoming true, last week’s letter said. “In the intervening months, these negative consequences have become more obvious. Human-caused climate disruption is leading to suffering and economic loss. (These) are not future hypotheticals. They are happening now.”

The other drafters of last week’s letter were Charles Manski of Northwestern University, an economist, and Ray Weymann of the Carnegie Observatories, a retired astrophysicist.

Both are highly respected in their fields, as members of the National Academy of Sciences must be.

In a commentary published last week in Scientific American, Santer, Manski and Weymann reemphasized their views that the predicted problems have already emerged.

“Many of the negative consequences mentioned in (the 2016) letter are now unfolding,” they wrote.

“The Trump administration has initiated the process of U.S. withdrawal from the Paris agreement, and continues to cast doubt on the reality and seriousness of human-caused climate change.”

In contrast to the 2016 letter, which was signed mainly by climate experts, last week’s letter was signed by “a cross-section of National Academy members,” Santer noted in an interview. He considers this a reflection of the wide agreement among scientists that science is an essential component of public policy development.

In separate interviews, both Manski and Weymann acknowledged that the Trump Administration is unlikely to be swayed by release of last week's letter.

They did, however, hope that there would be value for other audiences, from the general public to legislators, in a clear and strongly worded communication from so many diverse members of a highly respected institution.

To Manski, the economist, math and science are essential to analyzing and modeling the economy at all levels -- from the “macro” scale of money supply and foreign trade to the “micro” scale of consumer behavior and individual business performance.

He finds it nearly unbelievable that a government would ignore and even disdain accepted scientific knowledge while formulating public policy. “How could it not be the case that science would be relevant?” he asked rhetorically. “That would seem mind-boggling to me.”

To astrophysicist Weymann, the tools of the sciences are as important in many fields of public policy – he mentioned health, air quality and climatology -- as in his own discipline.

He believes government would benefit from a better understanding of science and has been working with an organization called “314 Action,” which promotes evidence based public policy while encouraging scientists to run for public office.

Neither Manski nor Weymann had any hesitation in getting involved with the drafting and circulation of the letter, they said. As Manski pointed out, the National Academies were created by President Abraham Lincoln in 1863, in the midst of the Civil War, in order to advise the U.S. Government on scientific matters.

Although the letter itself is a personal project of individual National Academy members, its general goal aligns with the organization’s mission over the decades.

The National Academies “had a public policy purpose from the outset to bring scientific advice to bear on issues of government policy,” Manski said. “It has done that for 150 years.”

In an interview, Santer repeated a brief story that he told last month when speaking at Livermore’s Bankhead Theater. He had recently returned from the Canary Islands, where he visited a monitoring station that recorded concentrations of the primary greenhouse gas, carbon dioxide, in the atmosphere.

While he was there – “out in the Atlantic Ocean, far from sources of pollution” – the station measured CO2 concentrations well above 400 parts per million. This is in contrast to much lower worldwide levels inferred from ice cores and other measurements at 180 to 280 parts per million over the past million years.

As ice sheets melt and ocean levels rise, Santer’s own research has been a significant part of the scientific effort that has linked human activities, like burning fossil fuels, to the high rate of greenhouse gas production that alters climate in complex ways that are dangerous and possibly accelerating.

The kind of science that Santer carries out – peer reviewed, published and openly debated -- needs to be encouraged and factored in as public policy is being formulated, according to the hundreds of National Academy members who signed last week's letter.

The letter can be read online at Commentary by Santer, Manski and Weymann is at https://blogs.scientificamerican.