Publications Published in Nature

1. Abrupt reversal in ocean overturning during the Palaeocene/Eocene warm period. Nunes, Flavia; Norris, Richard D..
   Nature: 2006
   Notes
   An exceptional analogue for the study of the causes and consequences of global warming occurs at the Palaeocene/Eocene Thermal Maximum, 55 million years ago. A rapid rise of global temperatures during this event accompanied turnovers in both marine and terrestrial biota, as well as significant changes in ocean chemistry and circulation. Here we present evidence for an abrupt shift in deep-ocean circulation using carbon isotope records from fourteen sites. These records indicate that deep-ocean circulation patterns changed from Southern Hemisphere overturning to Northern Hemisphere overturning at the start of the Palaeocene/Eocene Thermal Maximum. This shift in the location of deep-water formation persisted for at least 40,000 years, but eventually recovered to original circulation patterns. These results corroborate climate model inferences that a shift in deep-ocean circulation would deliver relatively warmer waters to the deep sea, thus producing further warming. Greenhouse conditions can thus initiate abrupt deep-ocean circulation changes in less than a few thousand years, but may have lasting effects; in this case taking 100,000 years to revert to background conditions.
   
   
   
2. Acceleration of Greenland ice mass loss in spring 2004. Velicogna, Isabella; Wahr, John.
   Nature: 2006
   
   
3. A climatologically significant aerosol longwave indirect effect in the Arctic. Lubin, Dan; Vogelmann, Andrew M..
   Nature: 2006
   Notes
   The warming of Arctic climate and decreases in sea ice thickness and extent observed over recent decades are believed to result from increased direct greenhouse gas forcing, changes in atmospheric dynamics having anthropogenic origin and important positive reinforcements including ice–albedo and cloud–radiation feedbacks. The importance of cloud–radiation interactions is being investigated through advanced instrumentation deployed in the high Arctic since 1997 (refs 7, 8). These studies have established that clouds, via the dominance of longwave radiation, exert a net warming on the Arctic climate system throughout most of the year, except briefly during the summer. The Arctic region also experiences significant periodic influxes of anthropogenic aerosols, which originate from the industrial regions in lower latitudes. Here we use multisensor radiometric data to show that enhanced aerosol concentrations alter the microphysical properties of Arctic clouds, in a process known as the 'first indirect' effect. Under frequently occurring cloud types we find that this leads to an increase of an average 3.4 watts per square metre in the surface longwave fluxes. This is comparable to a warming effect from established greenhouse gases and implies that the observed longwave enhancement is climatologically significant.
   
   
   
4. A globally coherent fingerprint of climate change impacts across natural systems. Parmesan, Camille; Yohe, Gary.
   Nature: 2003
   Notes
   Causal attribution of recent biological trends to climate change is complicated because non-climatic influences dominate local, short-term biological changes. Any underlying signal from climate change is likely to be revealed by analyses that seek systematic trends across diverse species and geographic regions; however, debates within the Intergovernmental Panel on Climate Change (IPCC) reveal several definitions of a 'systematic trend'. Here, we explore these differences, apply diverse analyses to more than 1,700 species, and show that recent biological trends match climate change predictions. Global meta-analyses documented significant range shifts averaging 6.1 km per decade towards the poles (or metres per decade upward), and significant mean advancement of spring events by 2.3 days per decade. We define a diagnostic fingerprint of temporal and spatial 'sign-switching' responses uniquely predicted by twentieth century climate trends. Among appropriate long-term/large-scale/multi-species data sets, this diagnostic fingerprint was found for 279 species. This suite of analyses generates 'very high confidence' (as laid down by the IPCC) that climate change is already affecting living systems.
   
   
   
5. An alternative approach to establishing trade-offs among greenhouse gases. Manne, A. S.; Richels, R. G..
   Nature: 2001
   Notes
   The Kyoto Protocol permits countries to meet part of their emission reduction obligations by cutting back on gases other than CO2 (ref. 1). This approach requires a definition of trade-offs among the radiatively active gases. The Intergovernmental Panel on Climate Change has suggested global warming potentials for this purpose 2), which use the accumulated radiative forcing of each gas by a set time horizon to establish emission equivalence. But it has been suggested that this approach has serious shortcomings: damages or abatement costs are not considered(3-10) and the choice of time horizon for calculating cumulative radiative force is critical, but arbitrary(5). Here we describe an alternative framework for determining emission equivalence between radiatively active gases that addresses these weaknesses. We focus on limiting temperature change and rate of temperature change, but our framework is also applicable to other objectives. For a proposed ceiling, we calculate how much one should be willing to pay for emitting an additional unit of each gas. The relative prices then determine the trade-off between gases at each point in time, taking into account economical as well as physical considerations. Our analysis shows that the relative prices are sensitive to the lifetime of the gases, the choice of target and the proximity of the target, making short-lived gases more expensive to emit as we approach the prescribed ceiling.
   
   
   
6. A satellite view of aerosols in the climate system. Kaufman, Y. J.; Tanre, D.; Boucher, O..
   Nature: 2002
   Notes
   Anthropogenic aerosols are intricately linked to the climate system and to the hydrologic cycle. The net effect of aerosols is to cool the climate system by reflecting sunlight. Depending on their composition, aerosols can also absorb sunlight in the atmosphere, further cooling the surface but warming the atmosphere in the process. These effects of aerosols on the temperature profile, along with the role of aerosols as cloud condensation nuclei, impact the hydrologic cycle, through changes in cloud cover, cloud properties and precipitation. Unravelling these feedbacks is particularly difficult because aerosols take a multitude of shapes and forms, ranging from desert dust to urban pollution, and because aerosol concentrations vary strongly over time and space. To accurately study aerosol distribution and composition therefore requires continuous observations from satellites, networks of ground-based instruments and dedicated field experiments. Increases in aerosol concentration and changes in their composition, driven by industrialization and an expanding population, may adversely affect the Earth’s climate and water supply.
   
   
   
7. A sea change. Schiermeier, Quirin.
   Nature: 2006
   Notes
   A collapse in ocean currents triggered by global warming could be catastrophic, but only now is the Atlantic circulation being properly monitored. Quirin Schiermeier investigates.
   
   
   
8. Atmospheric science - African dust in Florida clouds. Toon, O. B..
   Nature: 2003
   Notes
   It is reported in 'Geophysical Research Letters,' by Sassen et al. and DeMott et al. that dust from the Sahara Desert in Africa can have an impact on clouds over Florida. Sassen previously found that dust from Asia was affecting clouds over the western United States. Intercontinental transport of dust has several implications. Dust scatters absorbs sunlight, as well as infrared light radiated by the Earth, which alters the radiation budget and is a major factor in studies of climate and climate change. It is difficult to regulate air-pollution standards when they are violated by dust storms occurring halfway around the world. By acting as nuclei for triggering ice formation, dust particles can also affect clouds by causing the water droplets to freeze at higher temperatures than expected. Pure water can become supercooled to temperatures near -40 degree Celsius.
   
   
   
9. Atmospheric science Tropospheric temperature series from satellites. Tett, Simon; Thorne, Peter.
   Nature: 2004
   
   
10. Biodiversity hotspots for conservation priorities. (Cover story). Myers, Norman; Mittermeier, Russell A..
    Nature: 2000
    Notes
    Cites the importance of identifying 'biodiversity hotspots' in the prevention of species extinction. Contribution of habitat destruction to extinction; Types and locations of `hotspots'; Assessment of endemism among higher taxa; Original implementation of the `hotspots' strategy in 1989.