From the CO2Science archive: These days the only rush affecting California is the exodus of people escaping the taxes and crime. But in days of yore (specifically the late 1840s; hence the San Francisco 49ers, for instance) the California gold rush brought some 300,000 people in search of quick riches. Of course if it sounds too good to be true it probably is, and the gold fields didn’t pan out for most of the settlers. But Lasthenia californica at least provided a different kind of gold, its pretty flowers that bloom across California and Oregon each Spring. In 1996 a pair of experiments showed that an extra 300 ppm of CO2 boosted “California goldfields” growth by an average of 27%. So all the extra CO2 in the air now compared to the 1840s has put a new kind of gold into the California countryside.