Climate Myths

There is a lot of mythology generated in public discourse about climate change, and I find myself responding to these myths quite frequently. I thought it might be helpful to keep a running list of these myths with short rebuttals and links to a fuller treatments of each myth. Right now these myths are in random order. I plan to add to these as I write responses to more of these common myths. Eventually, I may reorganize these under subject headings.

To qualify as a "myth" that makes this list, I'm choosing false claims that are both demonstrably and incontrovertibly false. For most if not all of these, even many contrarian climate scientists would agree that these myths are false.

Myth 1. Only 3% of the increase in CO2 is due to human activity.
This myth probably comes from a misunderstanding of the fact that human emissions are a small percentage (~3-4%) of the total sources of CO2. However, nature removes slightly more CO2 from the atmosphere each year than it contributes. Human emissions flip the carbon cycle to a net source, and multiple lines of evidence demonstrate conclusively that virtually all the increase in CO2 above preindustrial levels is due to human activity. This post summarizes independent lines of evidence that human activity is responsible for virtually all the increase in CO2 above 280 ppm.

Myth 2. The atmosphere is saturated with CO2, so increasing CO2 can't warm the surface any more.
As CO2 concentrations increase, the range of wavelengths trapped by CO2 broadens and heat can't escape the atmosphere until it's at higher latitudes, where the air is thinner and cooler. The actual relationship between CO2 and temperature is logarithmic. Doubling CO2 causes a linear increase in temperature.

A. This post summarizes two reasons why the atmosphere is not saturated with CO2, and increasing CO2 will continue to increase global surface temperatures.

B. In this post, I updated the previous one with a little more detail.

Myth 3. Michael Mann committed fraud when he used a "nature trick" to "hide the decline" in global temperatures.
This myth is based on a misreading of one of the CRU emails. Mann's "Nature trick" was simply plotting both proxy and instrumental data on the same graph with a clear delineation of which parts of the graph were which data source. But in a WMO graph (that was inconsequential until after the CRU server hack) three time series were plotted without clearly identifying where the transition to the instrumental record took place. It's not evidence of any fraud. This post examines the email's text and associated studies, reports and graphs in sufficient detail to show that there was no fraud committed.

Myth 4. Old graphs show that NASA is faking global warming.
Tony Heller likes to dig up old newspaper clippings as if they prove the best available data we have now is fraudulent. Many times these old graphs in newspaper clippings are based on much less data (not all thermometers were included in the older versions of these datasets), and frequently the time series were either Northern Hemisphere, land only or both. There is no evidence that scientists are tampering with temperature data to fabricate warming.

A. This post shows Heller's confusion over what can be said from old temperature graphs.

B. This post shows Heller's confusion over what an be said from old Arctic sea ice graphs.

C. This post contains a summary of resources covering Heller's multifaceted deceptions and incompetence.

Myth 5. Global warming paused after 1998 or 2016.
Claims of recent "pauses" in global warming inevitably come from cherry picking a time frame beginning with a strong El Nino (like 1998 or 2016) and then calculating short-term trends that are not statistically significant. They do not by themselves show any actual pause in global warming, and the entire line of reasoning is misleading.

A. This post shows why short-term temperature trends are misleading when making claims about climate.

B. This post shows the kinds of Type II errors committed by those trying to declare that there has been a "pause" based on statistically insignificant short-term data.

Myth 6. There is no correlation between CO2 and GMST.
The actual correlation between CO2 and GMST, based on data following 1850, is r^2 = 0.87. Correlations can be seen on larger time scales with proxy evidence for CO2 and GMST as well, but it's very hard to calculate an actual r^2 value.

A. This post posts estimates ECS to be 3.2 C for doubling CO2, but it begins by establishing the correlation between CO2 and temperatures across the instrumental record.

B. This post shows broad correlation between CO2 and temperature across the Phanerozoic.

Myth 7. CO2 always lags behind global temperatures.
CO2 sometimes lags behind global temperatures but not always. During the glacial cycles of the Quaternary, warming is triggered by orbital cycles, and CO2 follows as the oceans degas CO2 and amplify warming. At other times, like the PETM, end-Permian extinction and today, CO2 comes first, and temperatures increase as a result. In either case, whether CO2 is a feedback amplifying warming or a driver of global warming, increasing CO2 pushes climate towards warming. 

1. This post shows that global temperatures actually rise after an increase of CO2, even though initial (local) warming was triggered by orbital cycles first, followed by an increase in CO2.
2. This post also shows that you can't blame the increase in CO2 since the industrial revolution on an increase in temperature.

Myth 8. Global warming is due to urban heat islands.
Urbanization does introduce bias into the temperature record, but urban areas are a small portion of the globe. Cities are warming at the same rate as rural areas, and homogenization is effective in detecting and correcting an urbanization bias. The evidence we have shows that rural stations are warming at the same rate as all stations. This post examines the lines of evidence showing that urbanization is not affecting global temperature trends.

Myth 9. The "tropospheric hotspot" proves that climate models are wrong on global warming.
The failure to detect a "tropospheric hotspot" in satellite measurements is almost certainly due to uncertainties in satellite measurements. The hotspot is found in balloon datasets. This post shows that the lack of ability to detect the "hotspot" is likely due to contamination in satellite estimates but the hotspot is detected in balloon data. More importantly, the hotspot is expected from any warming event, not just from an increase in greenhouse gases.  

Myth 10. Sea level rise isn't occurring or SLR rates are not accelerating.
In tide gauges, SLR rates have increased following 1960 or so. Satellite datasets also show acceleration in sea level rise following 1991. Most current studies put SLR acceleration at just under 0.1 mm/yr^2.

A. This post summarizes the results of over a dozen studies demonstrating acceleration in SLR beginning around 1960 or so. 

B. This post shows the likely results for sea level rise on time scales of thousands of years based on current CO2 levels at ~420 ppm.

Myth 11. Greenland Ice Core shows that the globe has been much warmer in the past and that current modern warming is small in comparison.
The GISP2 ice core is a local proxy in Central Greenland. It's a a local temperature record. It does not account for elevation fluctuations, and does not show global temperatures. And the data ends in 1855, so the ice core shows no modern warming. Proxy reconstructions estimating global temperatures show that the globe is likely warmer than it has been at any point in the last 100,000 years. This post shows how contrarians completely misrepresent the GISP2 ice core data so badly that the author of the GISP2 study calls their use of it "stupid."

Myth 12. Photosynthesis stops at 150 ppm CO2, so fossil fuel emissions are saving the Earth from CO2 starvation.
Both laboratory and paleoclimate studies demonstrate plant life surviving at CO2 levels significantly below 150 ppm CO2. Low CO2 levels do heavily favor C4 plants over C3 plants. This post shows evidence of plant life growing below 150 ppm CO2, both in laboratory experiments and for about 1 million years during the Early Permian.

Myth 13. The Greenhouse Effect isn't real. Increasing CO2 does not cause warming.
Since the 1850s, scientists have understood that increasing greenhouse gas concentrations pushes climate towards warming. This was first discovered in laboratory estimates, but it has also been observed in numerous experiments in the atmosphere.

A. This post shows how scientists can get past correlation to causation with empirical data for CO2 and temperature.

B. This post contains observable evidence from in situ measurements at the surface and from satellites at the top of the atmosphere.

Myth 14. Global Mean Surface Temperature either doesn't exist or is a "dubious metric."
It's objectively true that the Earth's surface has mean temperature, and changes to that mean surface temperature can be estimated with thermometers and/or satellites.

A. This post covers one attempt to cast doubt on GMST as a dubious metric.

B. This post covers the bizarre claim that there is no global average temperature.

C. This post covers reasons why many datasets use anomalies instead of absolute temperatures.

Myth 15. The "Hockey Stick" has been disproven.
While it's true that additional evidence coming in since 1998 has altered the shape of the "hockey stick," it's absolutely false that it's been "disproven." In fact, many objections to MBH98 depend on some really terrible papers by McIntyre and McKitrick. But in reality the "hockey stick" has been replicated dozens of times.

A. This post is Part 1, responding to objections to MBH98 coming from their 2003 paper.

B.  This post is Part 2, responding to objections to MBH98 coming from their 2005 paper.

C. This post covers McIntyre's attempt to create an imaginary feud between Briffa and Mann regarding the hockey stick.

Myth 16. The Greenhouse Effect breaks the 2nd Law of Thermodynamics.
This is about as silly as it gets, but I hear it a fair amount, so I finally decided to write a response here. The net flow of heat from the Sun to Earth and from the Earth's surface to space is always from hot to cold.

Myth 17. The Greenhouse Effect is actually the result of surface pressure.
There are a couple papers describing a crackpot proposal that greenhouse gases are not responsible for surface temperature being 33 K warmer than the Earth's effective temperature, but instead are the result of atmospheric pressure and density. I decided to respond to both in one post.

Myth 18. Since cold kills more than heat, global warming will save lives.
This claim is based entirely on a misreading of a few studies and some very bad logic about how warming affects excess mortality. I respond to this terrible logic in this post.