Volume 458 Issue 7242, 30 April 2009

The climate situation may be even worse than you think — this is the theme running through this week’s issue. Three News Features explore the difficulty of cutting back on carbon dioxide emissions and the potential to physically extract carbon dioxide from the atmosphere or cool the planet artificially. Two Letters address the big question of just how quickly greenhouse-gas emissions need to be reduced if we are to avoid dangerous climate change, and a variety of opinion pieces look at policies for managing the climate crisis and coping with climate deterioration. See the Editorial for a full ‘climate special’ contents list. Cover graphic: Jonathan Burton/ www.jonathanburton.net.

Authors

Editorials

  • Editorial |

    Without a solid commitment from the world's leaders, innovative ways to combat climate change are likely to come to nothing.

  • Editorial |

    We are clarifying the duties of lead authors and making author-contribution statements mandatory.

Research Highlights

Journal Club

News

News in Brief

Features

  • News Feature |

    The climate situation may be even worse than you think. In the first of three features, Richard Monastersky looks at evidence that keeping carbon dioxide beneath dangerous levels is tougher than previously thought.

    • Richard Monastersky
  • News Feature |

    It's simple to mop carbon dioxide out of the air, but it could cost a lot of money. In the second of three features on the carbon challenge, Nicola Jones talks with the scientists pursuing this strategy.

    • Nicola Jones
  • News Feature |

    Geoengineering schemes, such as brightening clouds, are being talked about ever more widely. In the third of three features, Oliver Morton looks at how likely they are to work.

    • Oliver Morton

Correspondence

Commentary

  • Commentary |

    We will probably overshoot our current climate targets, so policies of adaptation and recovery need much more attention, say Martin Parry, Jason Lowe and Clair Hanson.

    • Martin Parry
    • , Jason Lowe
    •  & Clair Hanson

Essay

  • Essay |

    Stephen Schneider explores what a world with 1,000 parts per million of CO2 in its atmosphere might look like.

    • Stephen Schneider

Spring Books

News & Views

  • News & Views |

    There are various — and confusing — targets to limit global warming due to emissions of greenhouse gases. Estimates based on the total slug of carbon emitted are possibly the most robust, and are worrisome.

    • Gavin Schmidt
    •  & David Archer
  • News & Views |

    When starved, cells resort to breaking down their assets — proteins, lipids and even whole organelles. An investigation of lipid metabolism indicates that one process — autophagy — targets all three cellular components.

    • Rudolf Zechner
    •  & Frank Madeo
  • News & Views |

    The sharpest X-ray image ever obtained of a portion of the Milky Way resolves a seemingly diffuse X-ray emission into discrete sources. These sources are likely to be stars of the 'garden variety' in the Sun's vicinity.

    • Michael Shull
  • News & Views |

    Nanobots — tiny robots that can be injected into the body to perform medical procedures — are the stuff of science fiction. Swimming microrobots propelled by artificial flagella bring that fantasy closer to reality.

    • Metin Sitti
  • News & Views |

    Evidence that speciation and adaptive radiation can change the properties of an ecosystem is a reminder of the pressing need to integrate ecosystems science and evolutionary biology.

    • Ole Seehausen
  • News & Views |

    A neat study gives clear-cut evidence that when a wire made of a magnetic material such as iron is squashed to the atomic scale, the material's magnetism disappears via an exotic physical process.

    • Richard Korytár
    •  & Nicolás Lorente
  • News & Views |

    There are more connections in the human brain than there are stars in the Milky Way, so scientists use simple organisms to search for universal neural-circuit motifs. Their latest find is a neuron for social behaviour.

    • Shawn R. Lockery

Progress

Articles

  • Article |

    Description of a novel function for autophagy in regulating lipid metabolism, called 'macrolipophagy', in which lipid droplets and autophagic components associate during starvation and inhibition of autophagy increases lipid storage in lipid droplets. A critical role of autophagy in regulating lipid metabolism is identified, and may provide a new approach to prevent lipid accumulation in disease.

    • Rajat Singh
    • , Susmita Kaushik
    • , Yongjun Wang
    • , Youqing Xiang
    • , Inna Novak
    • , Masaaki Komatsu
    • , Keiji Tanaka
    • , Ana Maria Cuervo
    •  & Mark J. Czaja
  • Article |

    The crystal structure of CRM1 in complex with a substrate called snurportin 1 is presented. Snurportin 1 binds CRM1 in a bipartite manner by means of an amino-terminal leucine-rich nuclear export signal (LR-NES) and its nucleotide-binding domain. Further analysis reveals a second NES epitope in the nucleotide-binding domain of snurportin 1, and multipartite recognition of individually weak NES epitopes may be a common feature of CRM1 binding.

    • Xiuhua Dong
    • , Anindita Biswas
    • , Katherine E. Süel
    • , Laurie K. Jackson
    • , Rita Martinez
    • , Hongmei Gu
    •  & Yuh Min Chook

Letters

  • Letter |

    Its source has been a mystery since the discovery 25 years ago of the Galactic ridge X-ray emission. The gravitational well of the Galactic disk cannot hold the hot gas generating the X-ray glow and no other single source of energy that is large enough exists, but perhaps the hot plasma is bound to a multitude of faint sources. Here most of the diffuse-seeming X-ray emission is resolved into discrete sources, probably accreting white dwarfs and coronally active stars.

    • M. Revnivtsev
    • , S. Sazonov
    • , E. Churazov
    • , W. Forman
    • , A. Vikhlinin
    •  & R. Sunyaev
  • Letter |

    Ultrafast real-time optical imaging is used in diverse areas of science, but conventional imaging devices such as CCDs are incapable of capturing fast dynamical processes with high sensitivity and resolution. This imaging method overcomes these limitations and offers frame rates that are at least 1,000 times faster than those of conventional CCDs. The approach is applied to continuous real-time imaging of microfluidic flow and phase-explosion effects that occur during laser ablation.

    • K. Goda
    • , K. K. Tsia
    •  & B. Jalali
  • Letter |

    Magnetism in metals is typically considered an intrinsic property of the material. But when the diameter of a magnetic wire is reduced to atomic dimensions, the material's magnetic properties are strongly altered, to the point where magnetism can even be eliminated. This is an unexpected realization of the so-called Kondo effect, and highlights the need to take into account atomic-scale geometry when investigating the properties of magnetic nanostructures.

    • M. Reyes Calvo
    • , Joaquín Fernández-Rossier
    • , Juan José Palacios
    • , David Jacob
    • , Douglas Natelson
    •  & Carlos Untiedt
  • Letter |

    With extralarge pores, zeolites could catalyse reactions between larger molecules. Here a zeolite with the largest pores to date is synthesized, about 25 ångstroms across; the structure is also chiral, which is useful in the separation of enantiomorphic molecules. The synthesis is done by crystallization of a gel of germanate and silicate dissolved in a bulky organic molecular template, using high-throughput techniques.

    • Junliang Sun
    • , Charlotte Bonneau
    • , Ángel Cantín
    • , Avelino Corma
    • , María J. Díaz-Cabañas
    • , Manuel Moliner
    • , Daliang Zhang
    • , Mingrun Li
    •  & Xiaodong Zou
  • Letter |

    The politically defined threshold of dangerous climate change is an increase of 2 degrees Celsius in the mean global temperature. Simulations here show that when carbon dioxide and a full suite of positive and negative radiative forcings are considered, total emissions from 2000 to 2050 of about 1,400 gigatonnes of carbon dioxide yield a 50% probability of exceeding this threshold by the end of the twenty-first century. 'Business as usual' emissions will probably meet or exceed this 50% probability.

    • Malte Meinshausen
    • , Nicolai Meinshausen
    • , William Hare
    • , Sarah C. B. Raper
    • , Katja Frieler
    • , Reto Knutti
    • , David J. Frame
    •  & Myles R. Allen
  • Letter |

    The effect of a cumulative emission of carbon on peak global mean surface temperature is better constrained than the effect of stabilizing the atmospheric composition. The approach is also insensitive to the timing or peak rate of emissions. Using carbon cycle models, it is shown that a trillion tonnes of carbon emissions (about half of which has already been emitted since industrialization began) will produce a most likely peak warming of 2 degrees Celsius.

    • Myles R. Allen
    • , David J. Frame
    • , Chris Huntingford
    • , Chris D. Jones
    • , Jason A. Lowe
    • , Malte Meinshausen
    •  & Nicolai Meinshausen
  • Letter |

    A test of the ecosystem effects of a pair of stickleback species that have undergone a recent adaptive radiation and now colonize different niches, and also a related generalist that resembles their common ancestor. Adaptive radiation causes changes in lower trophic levels and in ecosystem productivity, and the sticklebacks act as ecosystem engineers by influencing the light transmissibility of the water.

    • Luke J. Harmon
    • , Blake Matthews
    • , Simone Des Roches
    • , Jonathan M. Chase
    • , Jonathan B. Shurin
    •  & Dolph Schluter
  • Letter |

    Nematodes socialize during feeding on bacteria; this behaviour depends on sophisticated integration of multiple sensory cues by a subset of the animal's 302 neurons. The RMG neurons are identified as the hub for such computations. Non-synaptic communication through 'gap junctions' is the key to RMG's regulation of neighbouring sensory neurons such as ASK (which responds to pheromones, a functional architecture that could be generalized to several other neuronal circuits).

    • Evan Z. Macosko
    • , Navin Pokala
    • , Evan H. Feinberg
    • , Sreekanth H. Chalasani
    • , Rebecca A. Butcher
    • , Jon Clardy
    •  & Cornelia I. Bargmann
  • Letter |

    Clostridium difficile, the cause of antibiotic-induced infection in hospitals, possesses two toxins, A and B, the former of which was believed to be the major C. difficile virulence factor. Using an animal model and C. difficile mutants, evidence is now presented that toxin B, and not toxin A, is essential for infection.

    • Dena Lyras
    • , Jennifer R. O’Connor
    • , Pauline M. Howarth
    • , Susan P. Sambol
    • , Glen P. Carter
    • , Tongted Phumoonna
    • , Rachael Poon
    • , Vicki Adams
    • , Gayatri Vedantam
    • , Stuart Johnson
    • , Dale N. Gerding
    •  & Julian I. Rood
  • Letter |

    The zinc finger protein Zc3h12a is identified as a ribonuclease that inhibits autoimmune disorders by controlling the degradation of messenger RNAs encoding proinflammatory cytokines.

    • Kazufumi Matsushita
    • , Osamu Takeuchi
    • , Daron M. Standley
    • , Yutaro Kumagai
    • , Tatsukata Kawagoe
    • , Tohru Miyake
    • , Takashi Satoh
    • , Hiroki Kato
    • , Tohru Tsujimura
    • , Haruki Nakamura
    •  & Shizuo Akira
  • Letter |

    The human immune system uses the TLR4-MD-2 complex to recognize the lipopolysaccharide (LPS) of Gram-negative bacteria, which cause diverse infections. The crystal structure of TLR4 in complex with MD-2 and the agonist LPS is described, showing how the TLR family can bind to the many different kinds of LPS.

    • Beom Seok Park
    • , Dong Hyun Song
    • , Ho Min Kim
    • , Byong-Seok Choi
    • , Hayyoung Lee
    •  & Jie-Oh Lee
  • Letter |

    A brachydactyly type A1 (BDA1) mutation in indian hedgehog (IHH) impairs the interaction between IHH and its receptor. In a mouse model that recapitulates this particular E95K mutation there is a change in the potency and range of IHH signalling, and the mice show digit abnormalities consistent with the human disorder.

    • Bo Gao
    • , Jianxin Hu
    • , Sigmar Stricker
    • , Martin Cheung
    • , Gang Ma
    • , Kit Fong Law
    • , Florian Witte
    • , James Briscoe
    • , Stefan Mundlos
    • , Lin He
    • , Kathryn S. E. Cheah
    •  & Danny Chan
  • Letter |

    The zinc finger binding protein ZFP809 is shown to work together with the TRIM28 protein to mediate transcriptional silencing of integrated retroviruses in infected embryonic stem cells.

    • Daniel Wolf
    •  & Stephen P. Goff

Futures

  • Futures |

    Family ties.

    • Michalis Barkoulas
    •  & Gemma Bilsborough

Naturejobs

  • Postdoc Journal |

    As we move halfway across the globe, I miss my friends. My son misses his toys.

    • Joanne Isaac
  • Career Brief |

    Many grantmakers expect to reduce the size or amount of their grants.

  • Career Brief |

    Investment at the Arizona's Solar Technology Institute.

  • Career Brief |

    The factors that determine the quality of universities' research and how prolific they are.

  • Regions |

    New Mexico, with its national labs and natural resources, is poised to become a central player in the US race for energy independence. Paul Smaglik reports.

    • Paul Smaglik

Corrections

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