GOP presidential nominee Donald Trump appeared to do an about-face on the issue of climate change, urging Americans to move away from fossil fuels and signaling that there may be some truth to global warming theories.

The Washington Examiner reports that on Tuesday, Trump was asked about climate change on a questionnaire and said that "there is still much that needs to be investigated" about climate change, calling for Americans to transition from fossil fuels to alternative energy sources. Trump has called climate change a "hoax" in the past.

Here are seven things you need to know about global warming.

1. A few decades ago the media and many in the scientific community were in hysterics over global cooling. Newsbusters has a roundup of the various news outlets that promoted the global cooling hysterics from 1970:

"Scientists See Ice Age in the Future," Washington Post, January 11

"Is Mankind Manufacturing a New Ice Age for Itself?", Los Angeles Times, January 15

"Pollution Could Cause Ice Age, Agency Reports," St. Petersburg Times, March 4

"Scientist predicts a new ice age by 21st century," Boston Globe, April 16

"Pollution called Ice Age Threat," St. Petersburg Times, June 26

"U.S. and Soviet Press Studies of a Colder Arctic," New York Times, July 18

"Dirt Will Bring New Ice Age," Sydney Morning Herald, October 19

An article from Newsweek in 1975 cited the "almost unanimous" consensus among meteorologists that global cooling "will reduce agricultural productivity for the rest of the century." The article even cites a report from the National Academy of Sciences at the time warning: "A major climatic change would force economic and social adjustments on a worldwide scale."

Sounds familiar.

2. There is no consensus that global warming is a man-made phenomenon that requires "urgent" action. One of the most common talking points used by global warming alarmists is that 97 percent of scientists agree that it's man-made and unless action is taken, armageddon will ensue. This is patently false, as Joseph Bast and Dr. Roy Spencer explain in The Wall Street Journal, this number comes from three sources and they're all riddled with errors

  • In 2009, a University of Illinois student conducted a two-question survey for her master's thesis that asked respondents if "global temperatures have risen and that humans are a significant contributing factor." Skeptics and proponents typically answer yes to both questions, so unsurprisingly 97 percent said yes. Additionally, only 79 scientists responded to the survey.
  • A student at Stanford found in 2010 that 97 percent or 98 percent of "the most prolific climate change writers" believed that "anthropogenic greenhouse gases have been responsible for 'most' of the 'unequivocal' warming." No mention on how serious the problem was, and he only found the views of 200 researchers when the number of climate change researchers are in the "thousands."
  • Blogger John Cook determined in 2013 that 97 percent of "abstracts of peer-reviewed papers" believed that "human activity is responsible for some warming," but a more exhaustive study of Cook's work determined that only 0.3 percent of the 11,944 papers reviewed by Cook concluded that "human activity is causing most of the current warming."

There are also plenty of scientists, meteorologists and researchers who don't think human activity will result in overheating the planet:

Surveys of meteorologists repeatedly find a majority oppose the alleged consensus. Only 39.5% of 1,854 American Meteorological Society members who responded to a survey in 2012 said man-made global warming is dangerous.

Finally, the U.N.'s Intergovernmental Panel on Climate Change—which claims to speak for more than 2,500 scientists—is probably the most frequently cited source for the consensus. Its latest report claims that "human interference with the climate system is occurring, and climate change poses risks for human and natural systems." Yet relatively few have either written on or reviewed research having to do with the key question: How much of the temperature increase and other climate changes observed in the 20th century was caused by man-made greenhouse-gas emissions? The IPCC lists only 41 authors and editors of the relevant chapter of the Fifth Assessment Report addressing "anthropogenic and natural radiative forcing."

Of the various petitions on global warming circulated for signatures by scientists, the one by the Petition Project, a group of physicists and physical chemists based in La Jolla, Calif., has by far the most signatures—more than 31,000 (more than 9,000 with a Ph.D.). It was most recently published in 2009, and most signers were added or reaffirmed since 2007. The petition states that "there is no convincing scientific evidence that human release of . . . carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth's atmosphere and disruption of the Earth's climate."

There is no "consensus" that there's man-made global warming that will cause an ensuing catastrophe.

3. Some global warming alarmist scientists weren't able to get the results they wanted, so they tampered with the data. For instance, there was the infamous scandal known as "Climate-Gate" where leaked emails showed that a cabal of world-renowned scientists discussed hiding the lack of warming because it wasn't the outcome they wanted, as documented here and here. Additionally, NASA appeared to have cooked the books as well; in 2007 they found that 1934 was the hottest year in its record instead of 1998, so they recalculated the data to make it seem like 1998 was actually the hottest year on record.

4. There has simply not been a lot of global warming in recent years. As The Daily Wire editor-in-chief Ben Shapiro has written:

For example, The Economist reported in 2014, “Between 1998 and 2013, the Earth’s surface temperature rose at a rate of 0.04°C a decade, far slower than the 0.18°C increase in the 1990s.” That forced the National Oceanic and Atmospheric Administration to come up with a whole new way of evaluating its data to fight those results. It also forced global warming advocates to claim that the oceans somehow ate up all of the excess heat in the air. All of that led President Obama to claim to the world in Paris that 14 of the past 15 years have been the hottest on record. But when scientists said that 2014 was the hottest year on record, they admitted they were only 38% sure that was the case.

This trend continued in 2015, which was nowhere near the hottest year recorded by satellite, meaning that there has been an 18-year pause in global warming. Additionally, there has been a "trend since 1900 [that] is equivalent to 0.75 Cº per century," which is statistically insignificant, according to Christopher Monckton.

5. The sea levels are not rising by record levels, and there has not been an increase in extreme weather events. Here are the relevant facts for each, as previously reported by The Daily Wire:

  • For the past 50 years, the sea levels have gone up by a little more than one millimeter a year, which is normal. There is no evidence that they're going to rise by faster levels in the future.
  • There has been a net increase in ice growth in Antarctica.
  • Data from NOAA shows that there has been a decrease of tornadoes, falling hurricanes, droughts, heat waves and bitter winters. There is also evidence that is no link between global warming and wildfires and extreme rainfall.

6. There is evidence to suggest that it is actually higher temperatures that result in higher levels of CO2. The videos below provide the evidence and explain why this occurs:

In fact, there is a graph in Al Gore's An Inconvenient Truth that shows exactly this, but it's only shown for a short amount of time in the movie so the viewer doesn't see the correlation.

7. Not only will the left's "solutions" to global warming do little to actually stop warming, they would cause massive harm to the economy. As radio host and constitutional scholar Mark Levin has written in his book Liberty and Tyranny: A Conservative Manifesto, Dr. Niv Shariv at Hebrew University concluded: "Even if we halved the CO2 output, and the CO2 increase by 2100 would be, say, a 50 percent increase relative to today instead of a doubled amount, the expected reduction in the rise of global temperature would be less than 0.5C. This is not significant."

California Gov. Jerry Brown (D), President Barack Obama and Democratic presidential nominee Hillary Clinton have all called for an 80 percent reduction in carbon emissions by 2050. Shapiro explains just how devastating this would be:

In California, the average resident is responsible for 9.42 tons of carbon emissions each year. By 2050, that would have to drop to 1.88 tons. That’s about what the current residents of North Korea emit, according to Robert Bryce of the Manhattan Institute. Per capita GDP in that country is currently $1,800 per year. If we extend that model out to the entire United States, every resident would have to drop to below-Mexican standards of carbon usage, and likely to Mexico-standards of GDP (try $10,400 per year). It would apparently cost us $5 trillion by 2050 just to subsidize businesses to create more energy efficient solutions. And that doesn’t mean that the solutions are better than what we currently have.

This suggests that the left is using the idea of global warming as a cause to promote their de-growth agenda.