, * annual change (in %) is calculated relative to 1990,, Equivalent CO2 atmospheric amounts (in ppm) are derived with the relationship (Table 1) between CO2 concentrations and radiative forcing from all long-lived greenhouse gases. The decline in the CFCs has tempered the increase in net radiative forcing. Most of this increase is related to CO2. The increase in radiative forcing from CO2 alone since 1990 was 60.6% (see Fig. It would include all the important components but not all the components of climate forcing. Of the five long-lived greenhouse gases, CO2 and N2O are the only ones that continue to increase at regular rates over decades. Montzka, S. A., E. J. Dlugokencky, and J. H. Butler, (2011), Nisbet, E. G., Manning, M. R., Dlugokencky, E. J., Fisher, R. E., Lowry, D., Michel, S. E., et al. The perturbation to direct climate forcing (also termed “radiative forcing”) that has the largest magnitude and the least scientific uncertainty is the forcing related to changes in the atmospheric global abundance of long-lived, well mixed greenhouse gases, in particular carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and halogenated compounds (mainly CFCs). Nevertheless, the language of scientists often eludes policy makers, educators, and the general public. Elkins, (1999), Dlugokencky, E. J., K. A. Masarie, P. M. Lang, and P. P. Tans, (1998). The CO2 increase is accelerating — while it averaged about 1.6 ppm per year in the 1980s and 1.5 ppm per year in the 1990s, the growth rate increased to 2.4 ppm per year during the last decade (2009-2019). These results define atmospheric composition changes going back to 1750 and radiative forcing changes since preindustrial times (Figure 4). IPCC takes the pre-industrial era (chosen as the year 1750) as the baseline. Novelli, S.A. Montzka, K.A. AGGI is a measure of what human activity has already done to affect the climate system through greenhouse gas emissions. 1990 was chosen because it is the baseline year for the Kyoto Protocol (and the publication year of the first IPCC Scientific Assessment of Climate Change). It is based on the highest quality atmospheric observations from sites around the world. The NOAA monitoring program provides high-precision measurements of the global abundance and distribution of long-lived greenhouse gases that are used to calculate changes in radiative climate forcing. Click here to download this table as comma separated values (csv). The annual CO2 increase from 1 Jan 2019 to 1 Jan 2020 was 2.64 ± 0.08 ppm (see, which is slightly higher than the average of the previous decade, and much higher than the two decades before that. The AGGI is analogous to the dial on an electric blanket. These five gases account for about 96% of the direct radiative forcing by long-lived greenhouse gases since 1750. While the radiative forcing of the long-lived, well-mixed greenhouse gases increased 45% from 1990 to 2019 (by ~0.98 watts m-2), CO2 has accounted for about 80% of this increase (~0.78 watts m-2). The growth rate of methane declined from 1983 until 1999, consistent with its concentration approaching steady-state, assuming no trend in CH4 lifetime. Gatti, (2009). The change in energy flux (expressed in Watts/square meter) at the tropopause or top of the atmosphere due to a change in a climate driver (such as changes in atmospheric carbon dioxide concentrations). Conversion of NOAA atmospheric dry air CH4 mole fractions to a gravimetrically-prepared standard scale. Be… Changes in radiative forcing before 1978 are derived from atmospheric measurements of CO2, started by C.D. However, climate projections have model uncertainties that overwhelm the uncertainties in greenhouse gas measurements. Tel: +1 202 223 6262Fax: +1 202 223 3065Privacy Policy. Weekly data are used from a subset of these sites to create a smoothed north-south latitude profile from which a global average is calculated (Figure 2). Machida, T., T. Nakazawa, Y. Fujii, S. Aoki, and O. Watanabe, (1995). Increases in the abundance of atmospheric greenhouse gases since the industrial revolution are mainly the result of human activity and are largely responsible for the observed increases in global temperature [IPCC 2014]. Masarie, A.M. Crotwell, K.W. Figure 3. Keeling [Keeling et al., 1958], and from measurements of CO2 and other greenhouse gases in air trapped in snow and ice in Antarctica and Greenland [Etheridge et al., 1996; Butler et al,, 1999]. Elkins, J.T. White, L.K. The AGGI provides a way for this warming influence to be presented as a simple index. Except for the HFCs and SF6, which do not contain chlorine or bromine, these are also ozone-depleting gases and are regulated by the Montreal Protocol.