Working Group I: The Scientific Basis


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II.2.2: CH4 abundances (ppb)
Year A1B A1T A1FI A2 B1 B2 A1p A2p B1p B2p IS92a IS92a/SAR
1970 1420 1420 1420 1420 1420 1420 1420 1420 1420 1420 1420 1420
1980 1570 1570 1570 1570 1570 1570 1570 1570 1570 1570 1570 1570
1990 1700 1700 1700 1700 1700 1700 1700 1700 1700 1700 1700 1700
2000 1760 1760 1760 1760 1760 1760 1760 1760 1760 1760 1760 1810
2010 1871 1856 1851 1861 1827 1839 1899 1861 1816 1862 1855 1964
2020 2026 1998 1986 1997 1891 1936 2126 1997 1878 2020 1979 2145
2030 2202 2194 2175 2163 1927 2058 2392 2159 1931 2201 2129 2343
2040 2337 2377 2413 2357 1919 2201 2598 2344 1963 2358 2306 2561
2050 2400 2503 2668 2562 1881 2363 2709 2549 2009 2473 2497 2793
2060 2386 2552 2875 2779 1836 2510 2736 2768 2049 2552 2663 3003
2070 2301 2507 3030 3011 1797 2639 2669 2998 2077 2606 2791 3175
2080 2191 2420 3175 3252 1741 2765 2533 3238 2100 2625 2905 3328
2090 2078 2310 3307 3493 1663 2872 2367 3475 2091 2597 3019 3474
2100 1974 2169 3413 3731 1574 2973 2187 3717 2039 2569 3136 3616

Note: The IS92a/SAR column refers to values as reported in the SAR using IS92a emissions; whereas the IS92a column is calculated using IS92a emissions but with year 2000 starting values and the new feedbacks on the lifetime. See Chapter 4 for details.

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