Mauna Loa CO₂ measurements are the longest continuous record in the world

Mauna Loa volcano from outer space. Imaging radar maps the lava flows and other volcanic structures. The large summit crater, called Mokuaweoweo Caldera, is clearly visible near the center of the image. (Courtesy of the U.S. Geological Survey)

September 17—The Mauna Loa atmospheric CO₂ measurements, which began in 1958, constitute the longest continuous record of atmospheric CO₂ concentrations available in the world. The Mauna Loa site is considered one of the most favorable locations for measuring undisturbed air because possible local influences of vegetation or human activities on atmospheric CO₂ concentrations are minimal and any influences from volcanic vents may be excluded from the records. The methods and equipment used to obtain these measurements have remained essentially unchanged during the four-decade-long monitoring program.

The Mauna Loa record shows a 17% increase in the mean annual concentration, from 315.98 parts per million by volume (ppmv) of dry air in 1959 to 369.40 ppmv in 2000. The increase in mean annual concentration from 1999 to 2000 was 1.1 ppmv (the largest single yearly jump in the Mauna Loa record was the 2.9 ppmv increase from 1997 to 1998).

"Ambient atmospheric CO₂ data through 2000 from Mauna Loa, Hawaii," contributed by Charles David Keeling and Timothy Whorf (Scripps Institution of Oceanography), have been put online as updated numeric data package NDP-001 and as an updated entry in "Trends Online" by CDIAC's Tom Boden.

CDIAC has added to its Temperature chapter of "Trends Online" a database titled "Monthly surface air temperature time series area-averaged over the 30-degree latitudinal belts of the globe," contributed by K.M. Lugina (St. Petersburg State University, St. Petersburg, Russia), P.Ya. Groisman (National Climatic Data Center, Asheville, North Carolina), K.Ya. Vinnikov (University of Maryland, College Park), and V.V. Koknaeva and N.A. Speranskaya (State Hydrological Institute, St. Petersburg, Russia). The data, graphs, and associated documentation were prepared for online publication by Daria Beth Scott, a summer intern at CDIAC from St. Cloud State University in St. Cloud, Minnesota, and CDIAC's Dale Kaiser.

This database is actually an update of a well-known similar global temperature time series first produced by K.Ya. Vinnikov, P.Ya. Groisman, and Dr. Lugina in 1990 and presented previously in hardcopy editions of CDIAC's "Trends" in the early 1990s. Years later, Dr. Lugina became the principal investigator on this project. Since the untimely death of Dr. Lugina in 2000, several colleagues completed assembly and analysis of the data presented in "Trends Online" for the period 1881-1999.

Temperature anomaly time series are included for the "globe" (actually 90N to 60S), the Northern Hemisphere, the "Southern Hemisphere" (0-60S), the latitude band 60S-90S (beginning in 1957), and five other 30-degree latitude bands. These include annual and seasonal series for all regions.

The present update of the series through 1999 shows that the Northern Hemisphere has warmed at a rate of 0.6C/100 years, and the Southern Hemisphere (0S-60S) at a rate slightly greater than 0.5C/100 years. The warming rate for the globe (in this case, 90N-60S) is slightly less than 0.6C/100 years (0.58C/100 years). This trend is very close to that calculated in other recent studies, for example, "Global and hemispheric temperature anomalies—land and marine instrumental records," by P.D. Jones et al. (2000).

In the global record, the ten warmest years have occurred since 1981. In descending order they are 1998, 1995, 1990, 1997, 1991, 1988, 1987, 1981, 1994, and 1989.