Scientists don't debate policy for fear of losing their credibility. They worry that if they take part in a debate they will be seen as biased and partisan. The perception will lead to science being branded as partisan.

Recently some commentators and scientific leaders have argued that scientists should overcome this unease and contribute to urgent debates from climate change to gun control, alerting people to relevant scientific evidence and endorsing certain policies where their data provide support. Scientists spoke up in support of banning the chemicals that were damaging the ozone layer. The Montreal Protocol on Substances That Deplete the Ozone Layer has been an enormous success thanks to expert intervention.

The public may be interested in hearing from scientists who advocate policies that are within their realm of expertise. We conducted a survey of about 900 people in the US and Germany. Most people in both countries felt that climate scientists should be politically engaged and that they should increase their engagement. 70 percent of Germans and 74 percent of Americans felt that climate scientists should advocate for specific climate policies. The scientists were more reticent. In the US, only 59 percent of researchers said they should advocate for specific courses of action. It was higher in Germany.

Climate scientists were not endorsed by members of the public. It's possible that people distinguish between scientists with a capacity to make well-informed recommendations and scientists who take specific political stands.

Things get more complicated when specific policies are involved. When people considered an actual plan, their support for endorsements weakened. Germans and Americans supported scientists who advocated for carbon taxes. When it comes to abstract principles and how they are used, what people say is not the same as what they do.

What does this mean for scientists? Their generic fear of interacting with the public is not true. Scientists want to hear from people. Concerns that endorsing specific policies can weaken trust are not entirely wrong because they are less keen about advocacy for particular plans.

We only looked at the role of individual researchers in ours. Public health agencies seem to generate different responses. There is broad support for public health agencies and their activities in the U.S., according to a survey by researchers at the Harvard T.H. Chan School of Public Health. Many people don't know how serious climate change is.

It's not an either or proposition to trust in science. It is dependent on a lot of variables. Climate scientists shouldn't be giving stock tips or medical advice. Our research shows that they can offer policy advice in fields where they are experts. No one knew better about the cause of the hole in the ozone than the scientists who worked on it.

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