Year/Month CO_{2\}Concentration(ppm) 1987/1 353.2 1987/2 354.0 1987/3 354.8 1987/4 356.5 1987/5 354.7 1987/6 349.6 1987/7 346.0 1987/8 345.6 1987/9 344.8 1987/10 350.0 1987/11 352.8 1987/12 354.6 1988/1 356.0 1988/2 356.9 1988/3 357.6 1988/4 358.5 1988/5 358.0 1988/6 351.7 1988/7 347.2 1988/8 348.6 1988/9 348.4 1988/10 354.1 1988/11 356.5 1988/12 357.1 1989/1 358.3 1989/2 359.5 1989/3 359.5 1989/4 360.5 1989/5 360.2 1989/6 354.3 1989/7 350.4 1989/8 348.1 1989/9 351.3 1989/10 354.9 1989/11 357.7 1989/12 358.5 1990/1 360.0 1990/2 360.6 1990/3 361.9 1990/4 361.7 1990/5 360.0 1990/6 354.2 1990/7 350.6 1990/8 350.5 1990/9 351.8 1990/10 355.0 1990/11 358.1 1990/12 358.9 1991/1 361.0 1991/2 362.0 1991/3 363.4 1991/4 363.6 1991/5 362.3 1991/6 356.3 1991/7 352.3 1991/8 351.2 1991/9 351.4 1991/10 356.5 1991/11 359.0 1991/12 361.2 1992/1 361.9 1992/2 363.2 1992/3 363.3 1992/4 364.7 1992/5 364.2 1992/6 355.8 1992/7 348.7 1992/8 351.5 1992/9 351.8 1992/10 357.1 1992/11 359.6 1992/12 361.8 1993/1 361.8 1993/2 363.2 1993/3 364.0 1993/4 365.0 1993/5 364.0 1993/6 358.9 1993/7 352.5 1993/8 351.5 1993/9 352.3 1993/10 358.3 1993/11 360.0 1993/12 362.1 1994/1 364.1 1994/2 364.0 1994/3 365.4 1994/4 367.4 1994/5 365.8 1994/6 358.9 1994/7 356.5 1994/8 356.5 1994/9 355.8 1994/10 359.7 1994/11 363.8 1994/12 364.9 1995/1 366.1 1995/2 366.2 1995/3 366.7 1995/4 367.6 1995/5 366.6 1995/6 363.0 1995/7 361.6 1995/8 354.7 1995/9 357.5 1995/10 363.5 1995/11 365.5 1995/12 366.7 1996/1 367.6 1996/2 368.8 1996/3 369.5 1996/4 369.6 1996/5 369.5 1996/6 364.7 1996/7 361.2 1996/8 356.5 1996/9 357.7 1996/10 363.8 1996/11 366.4 1996/12 368.1 1997/1 368.3 1997/2 369.8 1997/3 370.8 1997/4 371.4 1997/5 369.7 1997/6 365.5 1997/7 363.4 1997/8 355.7 1997/9 359.9 1997/10 366.7 1997/11 367.9 1997/12 369.1 1998/1 370.4 1998/2 371.3 1998/3 372.4 1998/4 373.6 1998/5 371.7 1998/6 369.0 1998/7 364.8 1998/8 362.6 1998/9 363.9 1998/10 369.4 1998/11 372.3 1998/12 373.1 1999/1 374.2 1999/2 375.0 1999/3 375.3 1999/4 375.5 1999/5 375.5 1999/6 367.2 1999/7 368.3 1999/8 365.1 1999/9 363.9 1999/10 369.7 1999/11 372.9 1999/12 373.7 2000/1 373.9 2000/2 375.7 2000/3 376.8 2000/4 378.0 2000/5 375.4 2000/6 369.5 2000/7 369.8 2000/8 365.0 2000/9 367.3 2000/10 371.5 2000/11 374.4 2000/12 376.2 2001/1 376.4 2001/2 377.9 2001/3 379.0 2001/4 379.0 2001/5 377.1 2001/6 370.5 2001/7 366.6 2001/8 363.7 2001/9 367.7 2001/10 372.2 2001/11 375.7 2001/12 376.7 2002/1 378.3 2002/2 380.3 2002/3 380.5 2002/4 380.8 2002/5 378.2 2002/6 371.6 2002/7 371.8 2002/8 368.7 2002/9 369.3 2002/10 376.1 2002/11 377.8 2002/12 379.0 2003/1 380.4 2003/2 381.6 2003/3 382.5 2003/4 384.4 2003/5 383.0 2003/6 377.5 2003/7 372.1 2003/8 370.1 2003/9 372.8 2003/10 378.3 2003/11 380.4 2003/12 382.4 2004/1 382.9 2004/2 385.0 2004/3 385.3 2004/4 385.7 2004/5 385.4 2004/6 378.6 2004/7 374.6 2004/8 370.2 2004/9 373.9 2004/10 378.3 2004/11 382.2 2004/12 383.5 2005/1 384.9 2005/2 385.0 2005/3 387.0 2005/4 388.1 2005/5 386.5 2005/6 381.5 2005/7 374.7 2005/8 375.2 2005/9 377.0 2005/10 380.7 2005/11 384.6 2005/12 385.9 2006/1 387.4 2006/2 388.4 2006/3 389.3 2006/4 390.2 2006/5 390.2 2006/6 384.6 2006/7 377.6 2006/8 378.7 2006/9 378.9 2006/10 384.0 2006/11 387.1 2006/12 388.4 2007/1 388.9 2007/2 390.5 2007/3 391.4 2007/4 391.3 2007/5 390.2 2007/6 385.5 2007/7 378.0 2007/8 378.9 2007/9 381.7 2007/10 384.7 2007/11 388.8 2007/12 390.0 2008/1 390.9 2008/2 392.3 2008/3 394.0 2008/4 394.4 2008/5 391.9 2008/6 388.1 2008/7 381.0 2008/8 377.6 2008/9 382.3 2008/10 387.4 2008/11 390.1 2008/12 392.2 2009/1 392.5 2009/2 393.8 2009/3 394.2 2009/4 395.5 2009/5 393.2 2009/6 388.2 2009/7 384.9 2009/8 379.7 2009/9 382.2 2009/10 388.9 2009/11 391.4 2009/12 393.3 2010/1 394.2 2010/2 395.6 2010/3 396.7 2010/4 396.9 2010/5 397.7 2010/6 390.8 2010/7 392.0 2010/8 386.8 2010/9 387.6 2010/10 392.1 2010/11 395.1 2010/12 396.8 2011/1 397.1 2011/2 399.3 2011/3 399.3 2011/4 -- 2011/5 398.4 2011/6 393.8 2011/7 388.2 2011/8 385.5 2011/9 388.8 2011/10 393.1 2011/11 396.8 2011/12 398.0 2012/1 399.0 2012/2 400.0 2012/3 401.2 2012/4 402.2 2012/5 400.3 2012/6 394.2 2012/7 392.5 2012/8 389.7 2012/9 391.1 2012/10 396.3 2012/11 399.3 2012/12 400.8 2013/1 401.4 2013/2 403.6 2013/3 404.1 2013/4 404.8 2013/5 402.9 2013/6 397.6 2013/7 391.4 2013/8 392.8 2013/9 392.7 2013/10 398.1 2013/11 402.6 2013/12 402.9 2014/1 405.3 2014/2 405.6 2014/3 406.2 2014/4 407.0