Science teachers and legislators are fighting back after a conservative advocacy organization mailed false information on climate science to thousands of school science teachers nationwide.

After the Heartland Institute began a mass mailing of teaching materials denying the scientific consensus on climate change, lawmakers and teachers' organizations have raised the alarm over what they characterize as propaganda disguised as information.

"I am writing to ask you to consider the possibility that the science in fact is not 'settled,'" Heartland Institute's Lennie Jarratt, manager for the institute's Center for Transforming Education, wrote in a cover letter sent to the teachers accompanying the book, Why Scientists Disagree About Global Warming. "If that's the case, then students would be better served by letting them know a vibrant debate is taking place among scientists on how big the human impact on climate is, and whether or not we should be worried about it."

These statements are false, as is the book's contention that the overwhelming majority of scientists do not agree on the manmade cause of global warming.

The National Science Teachers Association (NSTA), a professional organization representing 55,000 teachers nationwide, sent a letter to its members calling on them to resist what they characterized as an "unprecedented attack."

"First, scientists don't disagree about climate change or its causes," David Evans, the executive director of NSTA, wrote in a letter to members earlier this week. "Second, labeling propaganda as science does not make it so. Third, science teachers are the critical bastion in the war against reason. And the special interests know it."

Some leading Democrats in Congress denounced the distribution of materials they described as politically motivated.

"Public school classrooms are no place for anti-science propaganda, and I encourage every teacher to toss these materials in the recycling bin," Rep. Bobby Scott (D-Va.), ranking member of the House Committee on Education and the Workforce, said in a statement.

"If climate deniers think our public schools are the right place for their propaganda, they need to be exposed in no uncertain terms," said Rep. Raúl Grijalva (D-Ariz.), ranking member of the Committee on Natural Resources.

The National Center for Science Education, a nonprofit that defends the integrity of science education against ideological interference, launched a fundraiser to counter the misinformation and "help teachers present climate change accurately, honestly and completely."

The organization, which fought successfully for accurate teaching of evolution, helped to develop the national science standards released in 2013 that made the teaching of global warming part of the public school curriculum. The non-mandatory standards are now used by approximately 20 states, NCSE spokesperson Robert Luhn said.

"We've heard from dozens of teachers already, expressing heartfelt concern, genuine anger, and hilarious sarcasm over the mailing," NCSE deputy director Glenn Branch wrote in a blog post. "A few enterprising teachers have taken the opportunity for a teachable moment with their classes on the nature of propaganda."

Brandie Freeman, courtesy of The Sustainable Teacher

Brandie Freeman, an environmental science and chemistry teacher at Woodland High School in Cartersville., Ga., is one such teacher. Freeman has taught science for more than a decade and was named 2015 Georgia Science Teacher of the Year by the Georgia Science Teachers Association. Last year she won a National Science Teachers Association STEM award. She received the Heartland Institute's packet on March 29 and found it insulting.

"We're not novices," Freeman said. "We're science teachers, this is what we do for a living."

When she got the mailer Freeman had just finished showing her class Before the Flood, Leonardo DiCaprio's 2016 documentary about climate change that calls out organizations including the Heartland Institute for spreading climate science misinformation. She wrote a post on her blog, The Sustainable Schoolteacher, where she called out the book's errors. Afterwards, she discussed it with her students.

"I very easily started refuting every point they made like 'climate change is not caused by humans' and 'it's not getting any warmer,'" she said. "I laid out in detail with peer-reviewed sources the errors in their statements."

The first mailings targeted 25,000 teachers and the Heartland Institute said it plans to send the information to 200,000 teachers nationwide, according to a report by Frontline and the Groundtruth Project.

The book produced by Heartland states, "Probably the most widely repeated claim in the debate over global warming is that '97% of scientists agree' that climate change is man-made and dangerous. This claim is not only false, but its presence in the debate is an insult to science."

According to NASA, "Multiple studies published in peer-reviewed scientific journals show that 97 percent or more of actively publishing climate scientists agree: Climate-warming trends over the past century are extremely likely due to human activities."

A recent study involving a first-ever national survey of public school science teachers found that about 75 percent of instructors surveyed were teaching the issue, but only half were correctly explaining that humans are driving climate change. An even smaller number of teachers were aware of how overwhelming the scientific consensus is on climate change.