U.S. Department of Commerce

1. National Oceanic & Atmospheric Administration 2. NOAA Research 3. Search ESRL: Calendar| People | Publications

Earth System Research Laboratory Global Monitoring Division

GMD Home About About GMD GMD Research Plan Organization Chart Staff Staff by Group Contacts Employment Research
Research Areas Overview GMD Research Plan Climate Forcing Ozone Depletion Baseline Air Quality Central Calibration Laboratory Research Groups Aerosols Greenhouse Gases Halocarbons and Trace Gases Ozone and Water Vapor Solar and Infrared Radiation Data and Products
Data Search for Data Data Archive Measurement Sites
Tools Interactive Data Viewer Solar Calculator
Products Greenhouse Gas Index ESRL Global Monitoring Division - Global Greenhouse Gas Reference ... http://www.esrl.noaa.gov/gmd/ccgg/trends/

1 of 7 6/17/2015 2:43 PMOzone Depletion Index Trends in CO 2 CarbonTracker ObsPack GLOBALVIEW Barrow Snow Melt Dates
Visualization Ozone and Water Vapor Radiation Trace Gases Aerosols South Pole Ozone Hole More Options... Observatories

Observatory Operations
Barrow, Alaska
Trinidad Head, California
Mauna Loa, Hawaii

American Samoa

South Pole
Summit, Greenland Information Education/Outreach News Publications FAQ's Seminars Safety Program Links Visitor Information Photo Gallery South Pole Webcam Mauna Loa Webcams Barrow Webcam Global Monitoring Division Review Global Monitoring Annual Conference

The Global Monitoring Conference will be held May 1 9-20, 2015 in Boulder. Site Map ESRL Global Monitoring Division - Global Greenhouse Gas Reference ... http://www.esrl.noaa.gov/gmd/ccgg/trends/

2 of 7 6/17/2015 2:43 PMIntranet



### Global Greenhouse Gas Reference Network Toggle navigation
Reference Network Home About the Reference Network Reference Network Sites Cooperative Sampling Network In-Situ Measurements Aircraft Measurements AirCore Sampling System Products and Data Products and Data Overview CarbonTracker CarbonTracker CH 4 Current Trends in CO 2 Obs ervation Pack age GLOBALVIEW Marine Boundary Layer Reference Annual Greenhouse Gas Index Data Visualization Search for Datasets Data Archive Figures Data Policy Reference Gas Calibrations WMO Standard Gas Comparisons Information Information News How CO 2 is Measured Computation of Global Means Curve Fitting Methods Basics of the Carbon Cycle Measuring Greenhouse Gases About Isotope Measurements Carbon Cycle FAQ Reference Network Brochure Isotope Measurements 

# Trends in Atmospheric Carbon Dioxide Mauna Loa, Hawaii Weekly Mauna Loa Global CO 2 Movie Interactive Plots CO 2 Emissions ESRL Global Monitoring Division - Global Greenhouse Gas Reference ... http://www.esrl.noaa.gov/gmd/ccgg/trends/

3 of 7 6/17/2015 2:43 PMContents

Recent Monthly CO 2 at Mauna Loa Full Mauna Loa CO 2 Record Annual Mean CO 2 Growth Rate at Mauna Loa Mauna Loa CO 2Data 

### Recent Monthly Average Mauna Loa CO 2 

# May 2015: 403.94 ppm May 2014: 401.78 ppm
Last updated: June 5, 2015

PNG Version PDF Version The graph shows recent monthly mean carbon dioxide measured at Mauna Loa Observatory, Hawaii. The last four complete years of the Mauna Loa CO 2 record plus the current year are shown. Data are r eported as a dry air mole fraction defined as the number of molecules of carb on dioxide divided by the number of all molecules in air, including CO 2 itself, after water vapor has been removed. The mole fracti on is expressed as parts per million (ppm). Example : 0.000400 is expressed as 400 ppm. In the above figure, the dashed red line with diamo nd symbols represents the monthly mean values, cent ered on the middle of each month. The black line with the square symbols represents the same, aftercorrection for the average seasonal cycle. The ESRL Global Monitoring Division - Global Greenhouse Gas Reference ... http://www.esrl.noaa.gov/gmd/ccgg/trends/

4 of 7 6/17/2015 2:43 PMlatter is determined as a moving average of SEVEN a djacent seasonal cycles centered on the month to be corrected, except for

the first and last THREE and one-half years of the record, where the seasonal cycle has been averaged over the first and last SEVEN years, respectively. The last year of data are still preliminary, pendin g recalibrations of reference gases and other quality control checks. The Mauna Loa data are being obtained at an altitude of 3400 m in the northern subtropics, and may not be the sa me as the globally averaged CO 2concentration at the surface

. 

### Full Mauna Loa CO 2 

### record

PNG Version PDF Version Monthly mean atmospheric carbon dioxide at Mauna Lo a Observatory, Hawaii The carbon dioxide data (red curve), measured as th e mole fraction in dry air, on Mauna Loa constitute the longest record of direct measurements of CO 2in the atmosphere. They were started by C. David Keeling of the Scripps Institution of Oceanography in March of 1958 at a facility of the National Oceanic and Atmospheric Administration [Keeling, 1976] . NOAA started its own CO 2 measurements in May of 1974, and they have run in parallel with those made by Scripps since then [Thoning, 1989] . The black curve represents the seasonally corrected data. Data are reported as a dry mole fraction defined as the number of molecules of carbon dioxide divided by the number of molecules of dry air multiplied by one million (ppm). 

### Annual Mean Growth Rate for Mauna Loa, Hawaii ESRL Global Monitoring Division - Global Greenhouse Gas Reference ... http://www.esrl.noaa.gov/gmd/ccgg/trends/

5 of 7 6/17/2015 2:43 PMPNG Version

PDF Version The table and the graph show annual mean carbon dio xide growth rates for Mauna Loa. In the graph, also decadal averages of the growth rate are plotted, as horizon tal lines for 1960 through 1969, 1970 through 1979, and so on.

The annual mean rate of growth of CO 2 in a given year is the difference in concentrationbetween the end of December and the start of January of that year. If used as an average for the globe, it would repre sent the sum of all CO 2 added to, and removed from, the atmosphere during the year by human activities and by natural processes. There is a small amount of mo nth-to-month variability in the CO 2concentration that may be caused by anomalies of the winds or weather systems arriving at Mauna Loa. This variability would not be representative of the underlying trendfor the northern hemisphere which Mauna Loa is intended to represent. Therefore, we finalize our e stimate for the annual mean growth rate of the prev ious year in March, by using the average of the most rec ent November-February months, corrected for the average seasonal cycle, as the trend value for Janu ary 1. Our estimate for the annual mean growth rate (based on the Mauna Loa data) is obtained by subtra cting the same four-month average centered on the previous January 1. Preliminary values for the prev ious year are calculated in January and in February

. The estimated uncertainty in the Mauna Loa annual mean growth rate is 0.11 ppm/yr. This estimate is based on the standard deviation of the differences between monthly mean values measured independently by the Scripps Institution of Oceanography and by N OAA/ESRL. The annual growth rate measured at Mauna is not the same as the global growth rate, bu t it is quite similar. One standard deviation of th e annual differences MLO minus global is 0.26 ppm/yea r. ESRL Global Monitoring Division - Global Greenhouse Gas Reference ... http://www.esrl.noaa.gov/gmd/ccgg/trends/

6 of 7 6/17/2015 2:43 PM

### Data

The complete Mauna Loa CO 2 records described on this page are available. Mauna Loa CO 2 monthly mean data Mauna Loa CO 2 annual mean data Mauna Loa CO 2 annual mean growth rates Additional CO 2 data from Mauna Loa and other worldwide sampling s ites can be found using the ESRL/GMD Data Navigator of public data sets. These values are subject to change depending on qua lity control checks of the measured data, but any revisions are expected to be small. See change log and notes A description of how we make measurements at Mauna Loa. How to reference content from this page Dr. Pieter Tans, NOAA/ESRL (www.esrl.noaa.gov/gmd/c cgg/trends/) and Dr. Ralph Keeling, Scripps Institu tion of Oceanography (scrippsco2.ucsd.edu/). Contact Pieter Tans , NOAA/ESRL, ph. 303 497 6678, Pieter.Tans@noaa.gov Further Reading C.D. Keeling, R.B. Bacastow, A.E. Bainbridge, C.A. Ekdahl, P.R. Guenther, and L.S. Waterman, (1976), A tmospheric carbon dioxide variations at Mauna Loa Observatory, Hawaii, Tellus, vol. 28, 538-551 K.W. Thoning, P.P. Tans, and W.D. Komhyr, (1989), Atmospheric carbon dioxide at Mauna Loa Observatory 2. Analysis of the NOAA GMCC data, 1974-1985, J. Geophys. Research, vol. 94, 8549-8565 U.S. Department of Commerce | National Oceanic and Atmospheric Administration Earth System Research Laboratory| Global Monitoring Division http://www.esrl.noaa.gov/gmd/ccgg/trends/index.html Privacy Policy | Accessibility | Disclaimer | USA.gov Contact Us | Webmaster Site Map ESRL Global Monitoring Division - Global Greenhouse Gas Reference ... http://www.esrl.noaa.gov/gmd/ccgg/trends/

7 of 7 6/17/2015 2:43 PM