Data, code, and workflows should be available and cited

Journals invite too few women to refereeJory Lerback and Brooks Hanson present an analysis that reveals evidence of gender bias in peer review for scholarly publications. US geoscientists on an expedition in

In keeping with the growing movement in scientific publishing toward transparency in data and methods, we propose changes to journal authorship policies and procedures to provide insight into which author is responsible for which contributions, better assurance that the list is complete, and clearly articulated standards to justify earning authorship credit. To accomplish these goals, we recommend that journals adopt common and transparent standards for authorship, outline responsibilities for corresponding authors, adopt the Contributor Roles Taxonomy (CRediT) (docs.casrai.org/CRediT) methodology for attributing contributions, include this information in article metadata, and require authors to use the ORCID persistent digital identifier (https://orcid.org). Additionally, we recommend that universities and research institutions articulate expectations about author roles and responsibilities to provide a point of common understanding for discussion of authorship across research teams. Furthermore, we propose that funding agencies adopt the ORCID identifier and accept the CRediT taxonomy. We encourage scientific societies to further authorship transparency by signing on to these recommendations and promoting them through their meetings and publications programs.

een up close, hydrogen looks like a recipe for success. Small and simple-one proton and one electron in its most common atomic form-hydrogen was the first element to assemble as the universe cooled off after the big bang, and it is still the most widespread. It accounts for 90% of the atoms in the universe, two-thirds of the atoms in water, and a fair proportion of the atoms in living organisms and their geologic legacy, fossil fuels. To scientists and engineers, those atoms offer both promise and frustration. Highly electronegative, they are eager to bond, and they release energy generously when they do. That makes them potentially useful, if you can find them. On Earth, however, unattached hydrogen is vanishingly rare. It must be liberated by breaking chemical bonds, which requires energy. Once released, the atoms pair up into two-atom molecules, whose dumbbell-shaped electron clouds are so well balanced that fleeting charge differences can pull them into a liquid only at a frigid-252.89°Celsius, 20 kelvin above absolute zero. The result, at normal human-scale temperatures, is an invisible gas: light, jittery, and slippery; hard to store, transport, liquefy, and handle safely; and capable of releasing only as much energy as human beings first pump into it. All of which indicates that using hydrogen as a common currency for an energy economy will be far from simple. The papers and News stories in this special section explore some of its many facets. Consider hydrogen's green image. As a manufactured product, hydrogen is only as clean or dirty as the processes that produce it in the first place. Turner (p. 972) describes various options for large-scale hydrogen production in his Viewpoint. Furthermore, as News writer Service points out (p. 958), production is just one of many technologies that must mature and mesh for hydrogen power to become a reality, a fact that leads many experts to urge policymakers to cast as wide a net as possible. In some places, the transition to hydrogen may be relatively straightforward. For her News story (p. 966), Vogel visited Iceland, whose abundant natural energy resources have given it a clear head start. Elsewhere, though, various technological detours and bridges may lie ahead. The Viewpoint by Demirdöven and Deutch (p. 974) and Cho's News story (p. 964) describe different intermediate technologies that may shape the next generation of automobiles. Meanwhile, the f ires of the fossil fuel-based "carbon economy" seem sure to burn intensely for at least another half-century or so [see the Editorial by Kennedy (p. 917)]. Service's News story on carbon sequestration (p. 962) and Pacala and Socolow's Review (p. 968) explore strategies-including using hydrogen-for mitigating their effects. Two generations down the line, the world may end up with a hydrogen economy completely different from the one it expected to develop. Perhaps the intermediate steps on the road to hydrogen will turn out to be the destination. The title we chose for this issue-Toward a Hydrogen Economyreflects that ...

repairs a broken navigation module in Greenland.© 2 0 1 9 S p r i n g e r N a t u r e L i m i t e d . A l l r i g h t s r e s e r v e d . A researcher accesses sediment cores collected during an ocean-drilling programme.MARC STEINME TZ/VISUM/EYEVINE 6 J U N E 2 0 1 9 | V O L 5 7 0 | N A T U R E | 2 9 COMMENT © 2 0 1 9 S p r i n g e r N a t u r e L i m i t e d . A l l r i g h t s r e s e r v e d .