June is the release time of Thomson Reuters's journal impact factors. The 2008 rankings have now been published, but Nature Geoscience has one more year to go before receiving its full journal impact factor. We have, however, received our 'immediacy index' — a number that ranks journals according to the number of citations their papers have received within the year of publication.

Of the 143 journals listed under the category of 'geosciences, multidisciplinary' Nature Geoscience comes third, after Gondwana Research and Petroleum Geoscience. Furthermore, for those interested in numbers, we would hold the third rank even after correcting for News & Views articles that cite a paper in the same issue.

In the notoriously slow publishing environment of the Earth sciences, the immediacy index is of limited use. Papers that appear in the second half of the year are unlikely to be cited before the end of the year, because even fast-turnover papers will probably still be working their way through the publishing pipeline.

The journal impact factor, by contrast, is based on the average citations to articles published in the preceding two years. For Nature Geoscience, having started in 2008, this number will first be available in June 2010, and will be based on the number of citations in 2009 to only one year of Nature Geoscience papers, those published in 2008. Only in 2011 will we receive a fully comparable impact factor based on two years of published papers.

For the reasons above, the immediacy index should be taken with a pinch of salt as a measure of geoscience journal ranking. Nevertheless, we take the encouraging outcome as a sign — from the viewpoint of Nature Geoscience's visibility in the field — that we are on the right track.