1250 - New group calls for action on methane
>
http://arctic-news.blogspot.com/2013/05/1250-new-group-calls-for-action-on-methane.html
> A new group, named 1250, calls for governments around the world to
> take action on methane.
>
> Just like 350 parts per million has become a popular target for
> carbon dioxide, the group similarly advocates a target for methane,
> aiming for a reduction of methane to 1250 parts per billion (ppb).
>
> On several occasions in April, 2013, the hourly average carbon
> dioxide concentration in the atmosphere of Mouna Loa, Hawaii,
> surpassed 400 parts per million (ppm). On May 9, 2013, the daily mean
> concentration of carbon dioxide in the atmosphere of Mauna Loa also
> surpassed 400 ppm. The National Oceanic and Atmospheric
> Administration (NOAA) comments that before the Industrial Revolution
> in the 19th century, global average carbon dioxide was about 280 ppm.
> During the last 800,000 years, carbon dioxide fluctuated between
> about 180 ppm during ice ages and 280 ppm during interglacial warm
> periods. Today’s rate of increase is more than 100 times faster than
> the increase that occurred when the last ice age ended.