Last year, SciCheck hypothesized that they would have no dearth of false and misleading claims to cover in 2017. That proved true.

In our roundup of 2016 claims, we hypothesized that SciCheck would have no dearth of false and misleading claims to cover in 2017. That proved true.

From President Donald Trump’s decision to exit the Paris Agreement to Environmental Protection Agency head Scott Pruitt’s ruling against banning a commonly used insecticide, politicians kept us busy this year. As 2017 comes to a close, we present the most notable claims from this year.

Humans to Blame: EPA Administrator Pruitt and Department of Energy Secretary Rick Perry claimed CO2 emitted by humans isn’t the “primary” contributor to global warming. As we have written multiple times, the U.N. Intergovernmental Panel on Climate Change’s 2014 assessment report says it’s “extremely likely” (>95 percent probable) that more than half of the observed temperature increase since the mid-20th century is due to human activity. “Emissions of CO2 from fossil fuel combustion and industrial processes contributed about 78 percent of the total GHG emissions increase from 1970 to 2010,” the report adds. In 2017, the U.S. Global Change Research Program — a collection of 13 federal agencies — released a report that supported the IPCC’s findings.

Pruitt on Climate Change, Again, March 9

Trump Official Wrong About Warming, Again, June 21

Worst Polluters: Both Trump and Pruitt falsely said China and India are the worst polluters of CO2. Per kiloton, China and the U.S. emit the most. Per capita, the U.S. emits much more than both China and India. Trump made his claim in June, while announcing that the U.S. would withdraw from the Paris Agreement. By 2015, China had emitted 29.4 percent of the total kilotons of CO2 emitted by the world’s countries. It was followed by the U.S. at 14.3 percent, the European Union at 9.6 percent and India at 6.8 percent. Per capita, Americans emitted more than twice as much as the Chinese and over eight times as much as Indians in 2015.

Pruitt on the Paris Accord, March 28

FactChecking Trump’s Climate Speech, June 1

The Paris Effect: In June, Trump and Pruitt both misleadingly said the Paris Agreement would only reduce the world’s average temperature by 0.2 degrees Celsius. One Massachusetts Institute of Technology report did give that figure, but the report’s author said the Trump administration “cherry-picked” that number. The Paris Agreement builds on the United Nations Framework Convention on Climate Change. It’s the “cumulative effect” of all commitments made under this framework that’s the “relevant number, not 0.2 degrees,” the MIT report author said. For example, another analysis found that UNFCCC parties’ contributions, including Paris pledges, would reduce projected temperatures by 0.9 C. For comparison, roughly 1 degree C is the amount of warming the planet has seen in about 150 years, during which “we’ve observed retreating mountain glaciers, rising sea levels and other significant impacts,” the MIT report author said.

Will Paris Have a ‘Tiny’ Effect on Warming?, June 14

CO2’s Impact on Agriculture: In July, Rep. Lamar Smith, the chairman of the House science committee, said climate change “alarmists” ignore the “positive impacts” of more carbon dioxide in the atmosphere, including increasing food production and quality. But the net effect of higher CO2 levels on agriculture is likely negative, especially in the future. Other factors aside, an atmosphere with more CO2 does boost crop yield in the short term via increased rates of photosynthesis. Over the long haul, multiple experts told us that the positive effect of increased CO2 on crops will shrink, and the negative impacts of climate change, such as higher temperatures and unreliable rainfall, will grow. Research also suggests climate change will disproportionately benefit weeds and reduce the nutritional value of staple food crops, such as wheat, barley and rice.

CO2: Friend or Foe to Agriculture?, August 10

Better Air Quality: In September, Pruitt condemned former President Barack Obama for leaving 40 percent of Americans with air quality that doesn’t meet the agency’s standards. That’s misleading. A report his office cited as evidence said there had been a “major improvement” in air quality under Obama. The American Lung Association’s 2017 air quality report says that 38.9 percent of the population was breathing “unhealthy air” based on EPA data from 2013 to 2015 for two of the most common air pollutants — particle pollution and ozone. However, that figure is down from 58 percent of the population from before Obama took office in 2009.

Did Air Quality Improve Under Obama?, September 21

Toxic Cleanups: In September, Pruitt also misleadingly said Obama left “us with more Superfund sites than when he came in.” While Pruitt is correct, his agency doesn’t measure its progress in cleaning up the country’s most contaminated sites with this metric. By the EPA’s own standards, Obama did make progress. Besides, every president has left office with more sites on the Superfund National Priorities List than when he came in.

Obama’s Record on Toxic Cleanups, September 29

Autism: In February, Trump claimed there’s been a “tremendous” increase in autism in children in the United States. There has been a large increase in the reported cases of autism. But the Centers for Disease Control and Prevention say the increase is due to a broadening of autism’s definition and greater efforts in diagnosis, in addition to some actual increase in the number of individuals who have the disorder. Scientists also say that a large portion, if not the majority, of the reported increase may be due to what they call “diagnostic recategorization.” For example, one study found that, among children who received special educational services between 2000 and 2010, a decrease in children diagnosed with intellectual disability accounted for nearly two-thirds of the increase in children with autism spectrum disorder. The researchers also found links between increases in ASD prevalence and decreases in learning disorder prevalence.

Has Autism Prevalence Increased?, February 18

Pot vs. Heroin: Back in March, Attorney General Jeff Sessions claimed marijuana is “only slightly less awful” than heroin. But experts say heroin is three times more harmful than marijuana based on a rating scale that considers the harmful effects of drugs on users and society. For example, no one has ever died of a marijuana overdose, but nearly 13,000 people died of heroin overdose in the U.S. in 2015 alone. Heroin is also highly addictive, whereas only about 1 in 10 marijuana users become addicted, according to the CDC.

Sessions’ Dubious Drug Claims, March 31

Curbing Opioid Deaths: Sessions also said he was “astonished to hear people suggest that we can solve our heroin crisis by legalizing marijuana.” Medical marijuana may not “solve” the opioid epidemic, but research suggests legalization may help curb overdoses, which have skyrocketed in recent years. For example, studies have found that states that legalized medical marijuana saw reductions in opioid-related deaths and hospitalizations. There’s also research that suggests people are swapping prescription opioids for marijuana to treat chronic pain.

Sessions’ Dubious Drug Claims, March 31

To Ban or Not to Ban: When the EPA chose not to ban chlorpyrifos, an insecticide often used in agriculture, both the EPA and its critics said “sound” or “solid” science backed their claims. Some studies do suggest that chlorpyrifos exposure can lead to developmental issues in children. But they’re correlational studies, so they don’t provide causal links. However, research in rodents has found causal links between chlorpyrifos and developmental issues.

The Facts on Chlorpyrifos, April 27

Obesity Rates: In May, Obama falsely said that Let’s Move, a project of former First Lady Michelle Obama, “helped bring down America’s obesity rates for our youngest kids for the first time in 30 years.” Research shows the obesity rate for 2- to 5-year-olds has been decreasing since 2004 – way before the Let’s Move project began. It’s true that the obesity rate for young children continued to decrease after the first lady launched her project in February 2010, but there’s no evidence that it played a part in that decrease. Experts say this would be difficult to measure because childhood obesity is a problem caused by multiple factors.

Obama on Childhood Obesity Rates, May 12

No Cure for Addiction: In May, Tom Price, then the health and human services secretary, said, “Folks need to be cured” of opioid addiction. But there’s currently no cure for addiction to opioids, or any drug, says the National Institute on Drug Abuse, which is part of HHS. Addiction is a physiological as well as a psychological disorder. After a person develops a physiological dependence on a drug, tolerance and withdrawal make it difficult to quit. But people also have psychological triggers associated with the addiction, such as seeing people or places, that might cause an otherwise drug-free person to use again. In other words, there’s “no cure” for drug addiction, “because you can’t undo memories,” one expert told us.

Can Opioid Addiction Be Cured?, May 19

Not Opioid Swapping: In May, Price claimed, “If we’re just substituting one opioid for another, we’re not moving the dial much.” But using opioids, such as methadone and buprenorphine, to combat addiction to more dangerous opioids, including heroin, is effective, says the National Institute on Drug Abuse, which is part of HHS. Doctors give patients small amounts of methadone and buprenorphine to stave off withdrawal over time because they are long-acting opioids, unlike heroin. Doctors also use methadone and buprenorphine to prevent addicts from returning to illicit opioid use, which poses greater risks. Overall, studies show medication-assisted treatment decreases opioid-related overdose deaths, criminal activity and infectious disease transmission.

Can Opioid Addiction Be Cured?, May 19

Not Just a Sneeze Study: In October, while advocating for legislation he introduced to change the federal grant funding process, Sen. Rand Paul said it’s “absurd” that the NIH gave $2 million for a study on whether “kids don’t like food that has been sneezed on.” But that funding went to a six-year project, composed of multiple studies, on children’s reasoning about foods. The overall aim of the project is to help find ways to convince kids to make safer and healthier food choices by comprehending why they make specific choices in the first place.

Senator Misleads on ‘Absurd’ Science, November 2

Drugged Driving: In June, Attorney General Sessions claimed that more car accidents were “caused” by drugs than alcohol for the first time in 2016. But the report his office cited found that alcohol was present in the system of more drivers killed in car crashes than drugs in 2015. The report also didn’t state the fatal accidents were “caused” by drugs. It’s more difficult to definitively say a person is under the influence of drugs than alcohol while driving. Unlike alcohol, testing positive for a drug doesn’t necessarily mean a person is intoxicated. Marijuana can be detected days or even weeks after consumption.

Sessions Wrong About Drugged Driving, December 14

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This articleoriginaaly appeard in  FactCheck.org, which writes about false and misleading scientific claims in a feature it calls SciCheck.