Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.


Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Bluesky Facebook LinkedIn Mastodon MeWe

Twitter YouTube RSS Posts RSS Comments Email Subscribe

Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...

New? Register here
Forgot your password?

Latest Posts


Mauna Loa and global network of CO2 measurements

What the science says...

Select a level... Basic Intermediate Advanced

The measurements of the amount of CO2 made at the Mauna Loa Observatory are accurate and uncontaminated by any emissions from the volcano. The measurements show a steadily increasing tend of CO2 concentrations in the air, a trend that is confirmed by many measurements made elsewhere.

Climate Myth...

Mauna Loa is a volcano

'Mauna Loa has been producing a readout which supports Manning's predetermined goal by showing steady growth in atmospheric CO2 concentrations since 1959. Just thirty miles from the observatory, Kilauea's Pu`u O`o vent sends 3.3 million metric tons of CO2 into the atmosphere every year. Pu`u O`o sends into "the undisturbed air" near "the remote location" the equivalent to yearly CO2 production from an average city of 660,000 people.' (Andrew Walden)

The observatory near the summit of the Mauna Loa volcano in Hawaii has been recording the amount of carbon dioxide in the air since 1958. This is the longest continuous record of direct measurements of CO2 and it shows a steadily increasing trend from year to year; combined with a saw-tooth effect that is caused by changes in the rate of plant growth through the seasons. This curve is commonly known as the Keeling Curve, named after Charles Keeling, the American scientist who started the project.

Why Mauna Loa? Early attempts to measure CO2 in the USA and Scandinavia found that the readings varied a lot due to the influence of growing plants and the exhaust from motors. Mauna Loa is ideal because it is so remote from big population centres. Also, on tropical islands at night, the prevailing winds blow from the land out to sea, which effect brings clean, well-mixed Central Pacific air from high in the atmosphere to the observatory. This removes any interference coming from the vegetation lower down on the island.

Conditions making Mauna Loa an ideal location for sampling atmospheric gases

But how about gas from the volcano? It is true that volcanoes blow out CO2 from time to time and that this can interfere with the readings. Most of the time, though, the prevailing winds blow the volcanic gasses away from the observatory. But when the winds do sometimes blow from active vents towards the observatory, the influence from the volcano is obvious on the normally consistent records and any dubious readings can be easily spotted and edited out (Ryan, 1995). 

Monthy CO2 measurements from four locations over the years 1970 to 2015

(Illustration updated on 9/5/2015)

Importantly, Mauna Loa is not the only atmospheric measuring station in the world. As the graph from NOAA shows, other stations show the same year-after-year increasing trend. The seasonal saw-tooth varies from place to place, of course, but the background trend remains steadily upwards. The Keeling Curve is one of the best-defined results in climatology and there really are no valid scientific reasons for doubting it.

Further reading: Spencer Weart's The Discovery of Global Warming describes Charles Keeling's research efforts in more detail. Weart also has a separate article on Keeling's struggle to fund his research. 

Last updated on 6 September 2015 by Andy Skuce. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.


Comments 1 to 3:

  1. I shared an office with Dave Keeling in Stockholm in the early 1960s and can report that Dave was aware that ML is a volcano. The trade wind blows 99.9% of the time with the CO2 station well upwind. When the wind changes the CO2 goes off the chart. The nearest upwind source is about 1500 miles away. The reading stays steady for weeks at a time.
  2. Great anecdote. Even Willis of WUWT concedes that Mauna Loa produces good data, the idea that somehow nobody noticed they were standing on the world's largest shield volcano is perfectly diagnostic of the state of awareness of somebody repeating the error. Sadly that won't stop this idea from continuing to rattle around like some kind of perfectly elastic pinball on friction-free table.
  3. Good stuff Dan, and good article Andy. The comments at American Thinker are just... argh! So boneheaded! Still, I wont judge all Americans by that - just the ones who let American Thinker do their thinking for them ;-)

Post a Comment

Political, off-topic or ad hominem comments will be deleted. Comments Policy...

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.

Link to this page

The Consensus Project Website


(free to republish)

© Copyright 2024 John Cook
Home | Translations | About Us | Privacy | Contact Us