Global warming myths can never be permanently killed. Once debunked, a climate myth will go into a state of hibernation, waiting for enough time to pass that people forget the last time a scientific stake was thrust through its heart. The myth will eventually rise from the grave once again, seeking out victims with tasty, underutilized brains to devour – every zombie’s favorite meal.

And so we have the long-debunked conspiracy theorist myth that scientists are falsifying temperature data to conjure global warming and frighten the masses. The story goes that in the raw temperature data from the continental USA, the second-hottest year on record was 1934, behind 2012. In the data adjusted by scientists, 1998 was the hottest year on record in the USA, until that record was broken in 2006 and then shattered in 2012 (1934 comes in 4th). The raw data are the gold standard, so this proves that climate scientists are falsifying data, right?

Wrong. Really, about as wrong as humanly possible. Scientists make adjustments to the raw data to remove factors that we know introduce biases and false trends. For example, temperature stations were once observed and data recorded in the afternoon, but later the observations switched to the mornings. Since mornings are colder than afternoons, that change introduced a cool bias into the raw data. Other factors that require adjustments include changes in the temperature monitoring system instrument setups, and the movement of temperature stations from one location to another.

Scientists have put substantial effort into accounting for all these changes that introduce known biases in the raw data across thousands of temperature monitoring stations. It’s not a vast conspiracy to trick us into buying solar panels; it’s just good science, which even contrarian climate scientists don’t dispute. In fact, when we compare raw and adjusted temperature data across the surface of the whole planet, the difference between the two is barely noticeable.

Comparison of global temperatures from raw and adjusted Global Historical Climatology Network (GHCN) v3 data, created by Zeke Hausfather. Photograph: Zeke Hausfather

Yet we suddenly have Christopher Booker at The Telegraph and Fox News' Sean Hannity claiming that climate scientists are ‘fabricating’ and ‘manipulating’ the raw temperature data, despite the fact that even most contrarian bloggers see right through this myth.



So what happened? Shauna Theel at Media Matters documented the path that this zombie myth took, starting from a fringe denialist blog, making its way up the conservative media echo chamber ladder until it reached media outlets like The Telegraph and Fox News that purportedly care about factually accurate reporting.

Tony Heller, a birther who criticizes climate science under the pseudonym "Steven Goddard," wrote a blog post that claimed "NASA cooled 1934 and warmed 1998, to make 1998 the hottest year in US history instead of 1934." After the Drudge Report promoted a report of this allegation by the conservative British newspaper The Telegraph, conservative media from Breitbart to The Washington Times claimed the data was "fabricated" or "faked." On June 24, Fox & Friends picked it up, claiming that "the U.S. has actually been cooling since the 1930s" but scientists had "faked the numbers".

Let’s take a few more shots at this zombie myth to see if we can send it back to its grave, temporarily.

Scientists make adjustments to remove known biases in the raw data. Average surface temperatures over the continental USA have indeed warmed by more than 1°F since the 1930s.

Even if you don’t trust those adjustments, raw and adjusted global temperature data are nearly identical. The USA represents less than 2% of the Earth’s surface.

On top of that, the warming of the atmosphere only accounts for about 2% of the warming of the planet as a whole. The oceans account for more than 90% of global warming, and have been heating up at a rate equivalent to 2 Hiroshima atomic bomb detonations per second since the 1950s, and 4 per second over the past decade.

Hence this particular myth is based on 2% of 2% of global warming, but it’s not even accurate for that 0.04%. The zombies are suggesting that we should rely on raw data that are known to be riddled with biases, and are claiming that scientific efforts to correct for those biases are part of some vast conspiracy.

Some advice for journalists – the next time you hear a global warming myth that sounds too good to be true, before letting the zombie snack on your brains, check SkepticalScience.com first to see if it’s riddled with scientific debunking bullet wounds.