A top US Agriculture Department (USDA) scientist has quit because the Trump administration buried his research showing the climate change is reducing the nutritional properties of food grains such as rice.

Plant physiologist Lewis Ziska worked at the USDA under five presidents, both Republicans and Democrats.  The 62-year old told Politico that the USDA tried to block distribution of his study showing how human-caused global warming could threaten the nutrition of 600 million people.  This was despite the study being internally cleared at the department and peer reviewed prior to its publication in the journal Science Advances last year.

The Trump USDA claimed that there was disagreement among scientists about the validity of the study, and denies politics played a role.  Donald Trump and many members of his administration are on the record denying the scientific reality of climate change driven by human activity.

"There was a sense that if the science agreed with the politics, then the policymakers would consider it to be 'good science,'" said Ziska, "and if it didn't agree with the politics, then it was something that was flawed and needed to be done again."

The Trump USDA has refused to publicize dozens of government-funded studies that warn about the climate emergency's consequences, nor will it release a "multiyear plan that outlines how the department should help agriculture understand, adapt to, and minimize the effects" of the global warming crisis.

But it gets worse.

Jacob Carter of the Union of Concerned Scientists (UCS) wrote in a blog for Scientific American that "the Trump administration has suppressed, censored, and threatened to fire many of its experts for the work they do, or simply for discussing scientific information that is politically contentious.  In some cases, the Trump administration's actions are driving experts out." 

Ziska says his former coworkers fear that Trump would just like to take an axe to any scientific research that doesn't fit his far-right political agenda.

"You get the sense that things have changed, that this is not a place for you to be exploring things that don't agree with someone's political views," Ziska said.  "That's so sad.  I can't even begin to tell you how sad that is."