https://www.jpl.nasa.gov/news/news.php?feature=6584Páginas

30/12/09

CIENTÍFICOS RUSOS SE APUNTAN A LA TEORÍA DE LA 'GLACIACIÓN GLOBAL'

EXPANSIÓN 

Publicado el 28-01-2008 , por M. Llamas / J. Ansorena 

Un descenso acusado de la actividad solar, previsto para mediados de siglo, podría suponer el enfriamiento global de la Tierra. Frente a las teorías del cambio climático, el principal observatorio astronómico ruso habla ya de una glaciación mundial.
El supuesto consenso científico sobre el temible calentamiento global que asolará la Tierra durante el presente siglo parece estar acusando un descenso gradual de temperaturas en el ámbito de su teoría climática. El Observatorio Astronómico Púlkovo, el más importante de Rusia, acaba de reiterar que la amenaza que se cierne sobre el planeta no proviene, precisamente, del ascenso de la temperatura global de entre 1,8 y 4 grados centígrados para finales de siglo, sino del inicio de una nueva glaciación mundial.

“A mediados del presente siglo XXI, en la Tierra comenzará un nuevo período glacial porque la energía proveniente del Sol, que comenzó a disminuir a partir de los años 90, alcanzará su punto de descenso máximo hacia el año 2041”, reveló recientemente Jabubiló Absusamátov, director del citado observatorio ruso. Durante cierto tiempo, la inercia térmica en los océanos atenuarán el enfriamiento del planeta, pero a partir de los años 2055-2060, el clima terrestre podría parecerse a una pequeña edad de hielo.

“Será el retorno a tiempos prehistóricos de los períodos glaciales, el último de ellos hace 80.000 años, en la era Cuaternaria o Pleistoceno”, según afirmó el científico a la agencia rusa de información RIA Novosti. Durante esa glaciación en Europa, el hielo cubrió la mayor parte de la isla de Gran Bretaña, el norte de Alemania y Polonia, y en Norteamérica, sepultó el territorio de Canadá y la zona de los grandes lagos estadounidenses. Pese a ello, la amenaza de un descenso drástico de temperaturas no tendrá las graves consecuencias de entonces.

A juicio de Abdusamátov, la próxima glaciación que ocurrirá en la Tierra se prolongará entre 45 y 65 años, frente a las anteriores, cuya duración se prolongó varios miles de años. Este científico viene denunciando desde hace algunos años el error de las previsiones climatólógicas avanzadas por los expertos del Panel Intergubernamental sobre Cambio Climático de la ONU (IPCC).
Esta misma teoría fue ratificada hace apenas un mes por otro centro de investigacíon espacial independiente norteamericano (ver EXPANSIÓN del pasado 10 de enero), en base al proceso de hibernación solar anunciado por la propia NASA en 2006: la actividad solar se está desacelerando, y ello provocará una bajada de la temperatura media a nivel planetario.

“Las observaciones de la actividad solar en los últimos años confirman la validez de la teoría de los ciclos de actividad solar como factor de influencia predominante en el clima global de la Tierra”, indicó Abdusamátov. De hecho, “en 2008 la temperatura global de la Tierra no solo dejará de aumentar sino que incluso puede comenzar a descender, debido a la baja intensidad de la iluminación del Sol, que será la más baja registrada en 30 años de mediciones hechas desde el cosmos”, advirtió.

Además, “a consecuencia del aumento de la concentración de gas carbónico en la atmósfera, muchos meteorólogos pronosticaron que en 2007 sería el año más caluroso en décadas, pero investigaciones más exactas demuestran que eso no ocurrió”. Tal y como avanzó este diario el pasado año fue el más frío de la última década pese a los pronósticos de los expertos defensores de la teoría del calentamiento (ver EXPANSIÓN del pasado 17 de enero). Según Abdusamátov, la temperatura en 2007 no fue superior a la de 2006, y en promedio, fue casi igual a la registrada durante el período comprendido entre 1998 y 2006. “Esto demuestra que entre 1998 y 2005 la Tierra superó el denominado valor máximo de calentamiento global”.

Durante ese mismo período, “la concentración de gas carbónico en la atmósfera aumentó más de un 4 %, y el calentamiento global prácticamente dejó de crecer”. Por ello, el planeta “se enfriará incluso si aumenta a niveles récord la concentración de gas carbónico”, concluyó.

GLOBAL WARMING AND THE NEXT ICE AGE




 

More than 120 scientists from 14 countries with expertise in the observation, theory, and modeling of climate change met to discuss how Earth’s climate responds to non–greenhouse gas forcings, and how to improve predictions of these responses.
17–21 July 2006
Santa Fe, New Mexico


by Manvendra K. Dubey, Charlie S. Zender, Chris K. Folland, and Petr Chylek
AMERICAN METEOROLOGICAL SOCIETY. December 2008 | 1905

Earth’s climate is a complex dynamical system that is responding to an array of forcings, which include anthropogenic carbon dioxide and aerosols and solar variability. Aeorsol and solar forcings are imperfectly constrained and only monitored by observational systems with limited sensitivity and coverage. The Second International Conference on Global Warming and the Next Ice Age (GWNIA), like its predecessor in 2001 in Halifax, Nova Scotia, aimed to provide a venue for detailed discussions of how global climate responses to natural and anthropogenic forcings besides long-lived greenhouse gases (GHGs; Chylek et al. 2007a). Conference delegates discussed the shortcomings of current models, observations, and theory, and developed a path toward using observational data to refine these models. The second half of the conference focused on understanding and reducing climate prediction uncertainties caused by anthropogenic aerosol forcing.
U.S. House Representative Tom Udall of New Mexico met with participants informally, then welcomed conference attendees with a taped presentation and expressed appreciation for research contributing to understanding climate change. He also announced a congressional bill he introduced that would enable a cap and trade program for carbon dioxide to help mitigate the risks of potential climate change. Introductory remarks by senior Los Alamos National Laboratory (LANL) officials stressed the synergy among climate change research, energy security, and threat reduction programs to move toward a solution. These were the focus of a keynote session on progress toward clean and carbon neutral energy. Observations of worldwide decadal to interdecadal climate variability, with a focus on North America, show that spatial patterns of sea surface temperature (SST) and night mean air temperature (NMAT) warming are very similar. Meteorologists and researchers with the Hadley Centre and the Met Office attribute much of the winter European warming in the decades 1965–95 to the change from a generally negative to a generally strong positive phase of the North Atlantic Oscillation (NAO). However, this positive phase now seems to be ending. Hadley Centre scientists also believe that some of the current rapid warming of the North Atlantic is due to an accelerating thermohaline circulation related to the Atlantic multidecadal oscillation (AMO), although this is controversial. However, they predict a natural thermohaline circulation (THC) slowdown starting in about the next decade, which could be enhanced by increasing greenhouse gases (Parker et al. 2007).
Careful attribution of regional climate change between natural and anthropogenic causes was the subject of many lively discussions at the conference. Beginning with an overview of observed and modeled twentieth-century climate change, comparisons of the Geophysical Fluid Dynamics Laboratory (GFDL) model to satellite data show that relative humidity has remained nearly constant in the upper troposphere, which suggests that global warming triggers H2O feedbacks similar in strength to those used in general circulation models (GCMs). An applied mathematician’s view of the butterfly effect was used to carefully distinguish integration errors arising from initial conditions from those arising from the simplification of processes (Essex et al. 2007). Observations were used to derive an effective heat capacity and an adjustment time of the Earth’s climate system (about 5 yr, shorter than many other estimates), whose ratio is the climate sensitivity parameter (Schwartz 2007; Chylek et al. 2007b). Removing the direct GHG forcing from the sensitivity estimate yields an estimate of the total non-GHG direct and indirect forcing. Many subsequent presentations demonstrated that climate models continue to improve representations of processes that were previously oversimplified or were completely neglected as intractable.
Satellite measurements yield convincing data for the spatiotemporal distribution of indirect aerosol effects. For example, the Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol retrieval algorithms have helped to constrain aerosol direct radiative forcing. In addition, Multiangle Imaging Spectroradiometer (MISR) and MODISretrieved aerosol optical depths (AODs) are more accurate over land and ocean, respectively. MISR can also retrieve aerosol plume height using stereo observational methods. Optimal satellite viewing angles for retrieving AOD occur at medium-scattering angles where the phase function is less sensitive to assumed aerosol properties. An approach to inferring how aerosols increase cloud lifetime or cloud fraction over the Atlantic, developed by Yoram Kaufman1 [Goddard Space Flight Center (GSFC)], is being applied globally by other groups. Alternately, data gaps within the Aerosol Robotic Network (AERONET) implicitly contain information about cloud fraction that can be used to understand local aerosol cloud interactions (Popp et al. 2007). Polarimetric remote sensing platforms are increasing the spatial coverage and accuracy of measured aerosol size distributions and refractive indices. The spaceborne Polarization and Anisotropy of Reflectance for Atmospheric Sciences coupled with Observations from a Lidar (PARASOL) mission uses polarimetric principles to characterize aerosols. Likewise, the National Aeronautics and Space Administration (NASA) Glory mission uses similar principles to measure the freezing transition in clouds, and a future Glory-like mission that would retrieve very accurate liquid cloud droplet size distributions was recommended.
The “Next Ice Age” conference theme often manifested itself in animated discussions based on widely varying interpretations of observational data, its meaning, and future implications. One interpretation is that a natural pattern of low orbital obliquity exists where the dark tropical oceans warm at the expense of the polar regions, thereby increasing meridional vapor transport and glaciations. Based on an interglacial period ~400,000 yr ago, another interpretation estimated that the current interglacial period will persist for another 14,000 yr in the absence of anthropogenic forcing. Moreover, peat lands could modulate climate by storing carbon, while cosmic dust deposition alters climate through ocean fertilization and dimethyl sulfide emissions, and also explains some observed millennial-scale variability such as the Little Ice Age. Coccolithophores were used to infer significant North Atlantic slope water cooling during the Holocene, consistent with variations in Gulf Stream movements relative to the North American coast.
Progress in understanding the effects of solar variability on climate was also presented. In one recent study, results in[1]dicated less direct solar radiation variation on the century time scale than was previously thought. In another, the problems of homogenizing satellite solar radiance observations with different satellite offsets (a problem common to satellite data) raised concern about the continuity of future missions to monitor solar variability. Also, cosmic ray production was found to correlate with midplus high-level cloud amount over the International Satellite Cloud Climatology Project record, while radiocarbon (14C) records were used to infer total solar irradiance (TSI) forcing of recent and paleoclimate temperature changes. These data suggest that up to 50% of the twentieth-century global warming could be explained by solar radiation variability (Scafetta and West 2007). Evidence of solar output variation effects on the water cycle were also presented; however, the mechanisms are not well understood and sensitivity studies using climate models are needed to help examine this (Ferguson and Veizer 2007). It was also theorized that the effect of waves on sea surface emissivity can cause important climate feedbacks, which models currently neglect.
Global temperature records were also critically examined (McKitrick and Michaels 2007; Pielke et al.2007; Reiter 2007). In particular, three regions where surface temperature measurements disagree with recent trends from specific GHG-driven models were identified. Data quality concerns about surface temperature records used by the Intergovernmental Panel on Climate Change (IPCC) were raised with clear evidence of some bad sites and thus the likelihood of bad local/regional trends. It was recommended that ocean heat content would be a more robust method to quantify energy storage, for example, from increasing GHGs. The effects of positive feedback processes in the stable nocturnal boundary layer, which amplify changes in the surface diurnal temperature range, such as the reduction induced by GHGs, were identified. It was argued that half of the tropospheric temperature trends over land in the twentieth century were attributable to sampling biases due to urban heat islands. It was also shown that Greenland had a previous warm period centered on 1930 and that the rate of warming was higher in 1920–30 than 1995–2005. These temperature variations correlated inversely with the NAO index at the time. A reconstruction of Greenland melting areas at high resolution (1 km2) was also presented and linked to warming (Chylek et al. 2007c). High-resolution data are needed to understand what is really happening to the Greenland ice sheet.
The second half of the conference focused on the complex climate forcing by anthropogenic aerosols and how they confound the task of quantifying climate sensitivity.
Global dimming, a large reduction in total hemispheric irradiance at many stations worldwide, was explained by the increase in anthropogenic aerosols emanating from cities exceeding about 20,000 inhabitants.
Dimming is not generally seen in truly rural areas. In a polar juxtaposition, evidence for natural (volcanic and biomass) and positive anthropogenic aerosol trends in the Arctic was discerned in data, but no anthropogenic trends were found in the Antarctic. Underscoring the importance of aerosol character, modelers emphasized the need to carefully represent aerosol shape and mixing state to calculate the direct forcing of climate and indirect effects on clouds: aerosols are regionally heterogeneous and can cool or warm the climate, depending on their optical properties, and aerosols also typically reduce surface
winds by stabilizing the boundary layer.
Satellite and in situ data were analyzed to show that estimates of shortwave (SW) clear-sky top-ofatmosphere (TOA) aerosol direct radiative forcing (ADRF) are very robust, whereas all-sky estimates are much less robust due to absorption uncertainties.
New evidence showed that absorbing aerosols amplify natural snowpack–albedo feedbacks and that soot and dust in the snowpack have caused significant past and present climates. In addition, modeled snow albedo feedback (SAF) was found to be an excellent predictor of a model’s sensitivity to
GHG forcing, although the range of model-predicted snow albedo was determined to be unrealistic, which currently explains much of the intermodel spread in SAF and climate response.
New experimental methods (Magi and Redemann 2007; Pan et al. 2007) and model techniques indicated progress is being made to improve our ability to quantify aerosol interaction with solar radiation and treatments of clouds. For example, new measurements of the 3D fractal geometry of complex soot particles can lead to significantly more efficient and accurate extinction estimates than properties based on 2D soot imagery (Adachi et al. 2007). Fortuitously, the widely used Optical Properties of Aerosols and Clouds (OPAC) soot properties, which are based on incorrect properties, yield approximately correct results. We now have more confidence in our ability to estimate atmospheric warming by soot. Ground-based aerosol optical depth and remote sensing measurements in polar regions were reviewed to decipher trends. This is important since Arctic ice is melting faster than models predict and pollution could be a potential culprit. The treatment of clouds and aerosol effects on them are highly idealized in climate models and a source of significant uncertainty. It was shown that clear-sky ice AMERICAN METEOROLOGICAL SOCIETY decEMber 2008 | 1907 super-saturated regions (ISSRs) occur more frequently
in nature than in models due to shortcomings in ice cloud and cirrus cloud parameterizations (Fusina et al. 2007). Detailed models of inorganic and organic aerosols and the effect of cirrus clouds on radiation were developed (Amundson et al. 2007). Novel process-level models to capture activation of black carbon (Henson 2007) and a probability distribution function method to improve the description of subgrid details and to improve cloud treatment in climate models and treat aerosol indirect effects were developed (Jeffery 2007).
Cloud-resolving models, which treat aerosol-cloud processes in detail, are used to incorporate laboratory and field observations to develop parameterizations for coarse global climate models (Tao et al. 2007). A new comprehensive cloud-resolving model that explicitly treats aerosol activation processes in detail was used to successfully reproduce field observations, which previous models had failed to do (Andrejczuk et al. 2008). These new methods will stimulate improvements in treatment of cloud processes in next-generation climate models.
A conference session highlighted the important connections between climate and energy to move forward toward solutions. For example, it was shown that widespread carbon dioxide sequestration is required to stabilize atmospheric levels below 1,000 ppmv. One method would be to pump carbon dioxide underground. In fact, Department of Energy (DOE) pilot programs have demonstrated the feasibility of geologic storage for GHGs, but scaling remains a challenge. Hydrogen-based fuels could facilitate carbon capture and storage and curtail the growth of GHGs while also improving air quality. Before the widespread adoption of hydrogen fuels, however, natural hydrogen variability should be characterized to provide an important baseline for the assessment
of future anthropogenic changes.
Plenary discussions highlighted a number of issues requiring attention before the third GWNIA conference planned for 2011. The following were identified as priorities of global climate research: 1) improve the global quality and coverage of in situ and satellite climate observations; 2) determine the sign and size of cloud feedbacks through a targeted observation of cloud properties and dynamics; 3) decrease the uncertainty in a number of forcing factors of climate
change, particularly the forcing due to anthropogenic and natural aerosols; 4) quantify the potential impact of solar cosmic ray and cloud nucleation-induced
forcings in GCMs with aerosol-cloud parameterizations; and 5) involve expert statisticians in key climate change studies.
It was determined during this conference that the optimal path to reduce uncertainties and increase precision of climate change forecasts is by bringing in observations to inform, test, and refine climate models. This is particularly important for aerosols and clouds, which are complex and influence the planetary albedo and radiation budget significantly. Progress is being made and the outlook it good since many aerosol-cloud perturbations and processes operate on shorter time scales rendering them measurable. However, this is a daunting task for other longer-term feedbacks such as ocean–ice–atmosphere changes where our community will have to use paleoclimate data or gather longer records to validate climate models, an interaction that our meeting alsocatalyzed. Observationalists and modelers (Xiao and Li 2007) must play a synergistic role in climate change research to increase the precision of climate forecasts for future energy options.

ACKNOWLEDGMENTS. This conference was supported by Los Alamos National Laboratory’s Threat Reduction Directorate, Center of Space Science and Exploration, and the Institute of Geophysics and Planetary Physics. It was cosponsored by the American Meteorological Society and advertised by the American Geophysical Union. Los Alamos’s Laboratory Directed Research and Development Program supported the research in aerosol effects on clouds, climate, and the hydrological cycle. We thank all the participants for an active and diverse scientific dialogue, which will benefit climate change science.
We thank Congressman Tom Udall and LANL leaders for their plenary talks and championship.


REFERENCES
Adachi, K., S. H. Chung, H. Friedrich, and P. R. Buseck, 2007: Fractal parameters of individual soot particles determined using electron tomography: Implications for optical properties
Amundson,. J. Geophys. Res., 112, D14202, doi:10.1029/2006JD008296. N. R., A. Caboussat, J. W. He, A. V. Martynenko, and J. H. Seinfeld, 2007: A phase equilibrium model for atmospheric aerosols containing inorganic electrolytes and organic compounds (UHAERO), with application to dicarboxylic acids. J. Geophys. Res., 112, D24S13, doi:10.1029/2007JD008424.
Andrejczuk, M., J. Reisner, B. Henson, M. K. Dubey, and C. A. Jeffery, 2008: The potential impacts of pollution  on a non-drizzling stratus deck: Does aerosol number matter more than type? J. Geophys. Res., 113, D19204, doi:10.1029/2007JD009445. 1908 | decEMber 2008
Chylek, P., M. K. Dubey, and Q. Fu, 2007a: Introduction to special section on Global Warming and the Next Ice Age. J. Geophys. Res., 112, D24S01, doi:10.1029/2007JD009275.
—, U. Lohmann, M. Dubey, M. Mishchenko, R. Kahn, and A. Ohmura, 2007b: Limits on climate sensitivity derived from recent satellite and surface observations. J. Geophys. Res., 112, D24S04, doi:10.1029/2007JD008740.  —, M. McCabe, M. K. Dubey, and J. Dozier, 2007c: Remote sensing of Greenland ice sheet using multispectral near-infrared and visible radiances. J. Geophys.
Res., 112, D24S20, doi:10.1029/2007JD008742.
Essex, C., S. Ilie, and R. M. Corless, 2007: Broken symmetry and long-term forecasting. J. Geophys. Res.,
112, D24S17, doi:10.1029/2007JD008563.
Ferguson, P. R., and J. Veizer, 2007: Coupling of water and carbon fluxes via the terrestrial biosphere and its significance to the Earth’s climate system. J. Geophys. Res., 112, D24S06, doi:10.1029/2007JD008431.
Fusina, F., P. Spichtinger, and U. Lohmann, 2007: Impact of ice supersaturated regions and thin cirrus on radiation in the midlatitudes. J. Geophys. Res., 112, D24S14, doi:10.1029/2007JD008449.
Henson, B. F., 2007: An adsorption model of insoluble particle activation: Application to black carbon. J. Geophys. Res., 112, D24S16, doi:10.1029/2007JD008549.
Jeffery, C. A., 2007: Inhomogeneous cloud evaporation, invariance, and Damköhler number. J. Geophys. Res., 112, D24S21, doi:10.1029/2007JD008789.
Magi, B. I., Q. Fu, and J. Redemann, 2007: A methodology to retrieve self-consistent aerosol optical properties using common aircraft measurements. J. Geophys. Res., 112, D24S12, doi:10.1029/2006JD008312.
McKitrick, R. R., and P. J. Michaels, 2007: Quantifying the inf luence  of anthropogenic surface processes and inhomogeneities on gridded global climate data. J. Geophys. Res., 112, D24S09,
doi:10.1029/2007JD008465.
Pan, Y., R. G. Pinnick, S. C. Hill, J. M. Rosen, and R. K. Chang, 2007: Single-particle laser-induced-fluorescence spectra of biological and other organic-carbon aerosols in the atmosphere: Measurements at New Haven, Connecticut, and Las Cruces, New Mexico. J. Geophys. Res., 112, D24S19, doi:10.1029/2007JD008741.
Parker, D., C. Folland, A. Scaife, J. Knight, A. Colman, P. Baines, and B. Dong, 2007: Decadal to multidecadal variability and the climate change background. J. Geophys. Res., 112, D18115, doi:10.1029/2007JD008411.
Pielke, R. A., and Coauthors, 2007: Unresolved issues with the assessment of multidecadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229.
Popp, C., A. Hauser, N. Foppa, and S. Wunderle, 2007: Remote sensing of aerosol optical depth  over central Europe from MSG-SEVIRI data and accuracy assessment with ground-based AERONET measurements. J. Geophys. Res., 112, D24S11, doi:10.1029/2007JD008423.
Reiter, M., 2007: Variability of recent ground surface temperature changes in the Albuquerque basin, central New Mexico. J. Geophys. Res., 112, D24S07,
doi:10.1029/2006JD008215.
Scafetta, N., and B. J. West, 2007: Phenomenological reconstructions of the solar signature in the Northern Hemisphere surface temperature records since 1600. J. Geophys. Res., 112, D24S03, doi:10.1029/2007JD008437.
Schwartz, S. E., 2007: Heat capacity, time constant, and sensitivity of Earth’s climate system. J. Geophys. Res., 112, D24S05, doi:10.1029/2007JD008746.
Tao, W., X. Li, A. Khain, T. Matsui, S. Lang, and J.
Simpson, 2007: Role of atmospheric aerosol concentration on deep convective precipitation: Cloudresolving model simulations. J. Geophys. Res., 112, D24S18, doi:10.1029/2007JD008728.
Xiao, D., and J. Li, 2007: Spatial and temporal characteristics of the decadal abrupt changes of global atmosphere-ocean system in the 1970s. J. Geophys.
Res., 112, D24S22, doi:10.1029/2007JD008956.



E-mail: dubey@lanl.gov
©2008 American Meteorological Society


[1] Yoram Kaufman (GSFC), one of the conference organizers, died in an accident a few weeks before the conference. In two sessions dedicated to him, and in many other talks, speakers noted Kaufman’s many contributions to satellite remote sensing and climate studies. Kaufman’s family felt that research carried out with Kaufman’s positive attitude would help to keep his spirit alive.
1906 | decEMber 2008



21/12/09

LAS CORRIENTES DEL ATLÁNTICO MUESTRAN SIGNOS DE DEBILITAMIENTO



Las corrientes del Atlántico muestran signos de debilitamientoEl sistema de calefacción natural de Atlántico Norte, que trae el tiempo benigno a Europa occidental, está mostrando señales de declinación. Los científicos informan que las corrientes calidas del océano Atlántico, que llevan calor de las zonas tropicales a las altas latitudes, se han debilitado substancialmente en los últimos 50 años. Los oceanógrafos que examinan la ‘ circulación meridional atlántica de vuelta ‘, el sistema actual que incluye la corriente calida de la Corriente de Golfo, informan que parece ser un 30% más débil que hace medio siglo.


La falta de un sistema de circulación del océano Atlántico se piensa que ha sido el responsable de los cambios abruptos y extremos del clima durante la edad de hielo pasada. Más recientemente, una parada ficticia de la corriente de Golfo inspiró la película en 2004 de Hollywood: The Day after Tomorrow.

Las cambios del clima representadas en la película, en la cual Nueva York es engullida por una edad de hielo inmediata, son mera suposición. Pero los científicos están preocupados de los cambios verdaderos medidos en el Atlántico norte. La salinidad y la densidad del agua, que influyen con el transporte de las aguas calidas, está disminuyendo.

Pegado a un lazo





La causa probable es que más agua dulce fluye al océano desde los ríos, de la lluvia y del hielo que se derrite en el Ártico y esto se piensa estar ligado al calentamiento global. Pero los modeladores del clima están preocupados que el debilitamiento de las corrientes del océano podría conducir, en última instancia, a un refrescamiento substancial del Atlántico norte.

El equipo que está detrás del nuevo estudio afirma que es la primera señal de la declinación de las corrientes atlánticas. Harry Bryden del Centro Nacional de Oceanografía en Southampton, Reino Unido, y su informe del equipo muestra sus resultados en la revista Nature de esta semana. Ver referencia.

Durante una travesía en la primavera de 2004 desde las Bahamas a las Canarias, a bordo del barco RRS Discovery, el equipo midió la temperatura del agua y la salinidad a lo largo de 25º del norte, tomando muestreas cada 50 kilómetros. Calcularon las diferencias de la densidad y de la presión entre cada muestra, el volumen y la velocidad de la circulación en varias profundidades, suponiendo que de costa a costa el balance de agua que fluye del norte y del sur debe ser cero. Medidas similares a lo largo de la misma latitud fueron hechas previamente en 1957, 1981, 1992 y 1998.

Pero hasta este momento, los datos nunca mostraron ningún debilitamiento significativo en la circulación." En 1998 vimos solamente cambios muy pequeños," dice Bryden. "Estábamos a punto de destapar el problema”.

Sin embargo, las cosas en esta vez fueron muy diferentes. La corriente del Golfo cercana a la superficie ha seguido siendo casi constante desde 1957. Pero el flujo de retorno del océano profundo de un agua más fresca ha disminuido dramáticamente. Este ciclo devuelve generalmente el agua a latitudes más al sur desde más lejos del norte como Groenlandia y Escandinavia.

Pero mucha de esta agua ahora parece estar atrapada en un lazo en el Atlántico subtropical, en vez de completar un ciclo completo en latitudes más al norte del océano. Bryden y sus colegas estiman que la circulación se ha ralentizado cerca de un 30% desde 1957.

"Esta es absolutamente información sensacional en sí misma," dice Detlef Quadfasel, oceanógrafo de la universidad de Hamburgo en Alemania. "Es también un mensaje importante a los políticos para que negocien el futuro de los acuerdos de Kyoto: cambiamos nuestro clima."

Un impacto directo de una circulación debilitada en la temperatura del aire en Europa occidental no se ha observado hasta ahora. Las temperaturas medias han aumentado cerca de alrededor 0.6 ºC desde 1900. Si o no el calentamiento verdadero es eclipsado en parte por una tendencia de refrescamiento oceánico opuesta no está claro, dice Quadfasel.

¿Una tendencia a largo plazo?

Otros oceanógrafos advierten que ésta no sea una prueba de una tendencia a largo plazo. Las posibles perturbaciones tales como los remolinos del océano y las fluctuaciones naturales en la fuerza del sistema de la circulación, deben ser consideradas, dicen. "Claramente algo está ocurriendo y en proceso," dice Jochem Marotzke, oceanógrafo en el instituto Max Planck para la meteorología en Hamburgo. "Solamente tenemos una serie de datos instantáneos. El quid es determinar cómo y cuan representativas realmente son estas medidas." Agrega que las posibilidades del derrumbamiento inminente del sistema de la circulación son pequeñas.

Los sensores instalados en 25 localizaciones a través del Atlántico subtropical ahora han comenzado a supervisar continuamente la circulación en todas las profundidades. Los cuatro años próximos, más o menos, deben decirnos si el sistema de calefacción atlántico todavía está funcionando bien, dice Marotzke.

Referencias

BrydenH., LongwortH. & CunninghamS. Nature, 438. 665 - 657 (2005

El texto fue tomado del portal de Nature:

http://www.nature.com/news/2005/051128/full/051128-9.html

Las corrientes del Atlántico muestran signos de debilitamientoEl sistema de calefacción natural de Atlántico Norte, que trae el tiempo benigno a Europa occidental, está mostrando señales de declinación. Los científicos informan que las corrientes calidas del océano Atlántico, que llevan calor de las zonas tropicales a las altas latitudes, se han debilitado substancialmente en los últimos 50 años. Los oceanógrafos que examinan la ‘ circulación meridional atlántica de vuelta ‘, el sistema actual que incluye la corriente calida de la Corriente de Golfo, informan que parece ser un 30% más débil que hace medio siglo.


La falta de un sistema de circulación del océano Atlántico se piensa que ha sido el responsable de los cambios abruptos y extremos del clima durante la edad de hielo pasada. Más recientemente, una parada ficticia de la corriente de Golfo inspiró la película en 2004 de Hollywood: The Day after Tomorrow.

Las cambios del clima representadas en la película, en la cual Nueva York es engullida por una edad de hielo inmediata, son mera suposición. Pero los científicos están preocupados de los cambios verdaderos medidos en el Atlántico norte. La salinidad y la densidad del agua, que influyen con el transporte de las aguas calidas, está disminuyendo.

Pegado a un lazo





La causa probable es que más agua dulce fluye al océano desde los ríos, de la lluvia y del hielo que se derrite en el Ártico y esto se piensa estar ligado al calentamiento global. Pero los modeladores del clima están preocupados que el debilitamiento de las corrientes del océano podría conducir, en última instancia, a un refrescamiento substancial del Atlántico norte.

El equipo que está detrás del nuevo estudio afirma que es la primera señal de la declinación de las corrientes atlánticas. Harry Bryden del Centro Nacional de Oceanografía en Southampton, Reino Unido, y su informe del equipo muestra sus resultados en la revista Nature de esta semana. Ver referencia.

Durante una travesía en la primavera de 2004 desde las Bahamas a las Canarias, a bordo del barco RRS Discovery, el equipo midió la temperatura del agua y la salinidad a lo largo de 25º del norte, tomando muestreas cada 50 kilómetros. Calcularon las diferencias de la densidad y de la presión entre cada muestra, el volumen y la velocidad de la circulación en varias profundidades, suponiendo que de costa a costa el balance de agua que fluye del norte y del sur debe ser cero. Medidas similares a lo largo de la misma latitud fueron hechas previamente en 1957, 1981, 1992 y 1998.

Pero hasta este momento, los datos nunca mostraron ningún debilitamiento significativo en la circulación." En 1998 vimos solamente cambios muy pequeños," dice Bryden. "Estábamos a punto de destapar el problema”.

Sin embargo, las cosas en esta vez fueron muy diferentes. La corriente del Golfo cercana a la superficie ha seguido siendo casi constante desde 1957. Pero el flujo de retorno del océano profundo de un agua más fresca ha disminuido dramáticamente. Este ciclo devuelve generalmente el agua a latitudes más al sur desde más lejos del norte como Groenlandia y Escandinavia.

Pero mucha de esta agua ahora parece estar atrapada en un lazo en el Atlántico subtropical, en vez de completar un ciclo completo en latitudes más al norte del océano. Bryden y sus colegas estiman que la circulación se ha ralentizado cerca de un 30% desde 1957.

"Esta es absolutamente información sensacional en sí misma," dice Detlef Quadfasel, oceanógrafo de la universidad de Hamburgo en Alemania. "Es también un mensaje importante a los políticos para que negocien el futuro de los acuerdos de Kyoto: cambiamos nuestro clima."

Un impacto directo de una circulación debilitada en la temperatura del aire en Europa occidental no se ha observado hasta ahora. Las temperaturas medias han aumentado cerca de alrededor 0.6 ºC desde 1900. Si o no el calentamiento verdadero es eclipsado en parte por una tendencia de refrescamiento oceánico opuesta no está claro, dice Quadfasel.

¿Una tendencia a largo plazo?

Otros oceanógrafos advierten que ésta no sea una prueba de una tendencia a largo plazo. Las posibles perturbaciones tales como los remolinos del océano y las fluctuaciones naturales en la fuerza del sistema de la circulación, deben ser consideradas, dicen. "Claramente algo está ocurriendo y en proceso," dice Jochem Marotzke, oceanógrafo en el instituto Max Planck para la meteorología en Hamburgo. "Solamente tenemos una serie de datos instantáneos. El quid es determinar cómo y cuan representativas realmente son estas medidas." Agrega que las posibilidades del derrumbamiento inminente del sistema de la circulación son pequeñas.

Los sensores instalados en 25 localizaciones a través del Atlántico subtropical ahora han comenzado a supervisar continuamente la circulación en todas las profundidades. Los cuatro años próximos, más o menos, deben decirnos si el sistema de calefacción atlántico todavía está funcionando bien, dice Marotzke.

Referencias

BrydenH., LongwortH. & CunninghamS. Nature, 438. 665 - 657 (2005

El texto fue tomado del portal de Nature:

http://www.nature.com/news/2005/051128/full/051128-9.html


2/12/09

MAJOR CITIES AT RISK FROM RISING SEA LEVEL THREAT


(Mischa Keijser/Hollandse Hoogte/eyevine)

TIMES
December, 1, 2009

The predicted rise in sea levels would engulf island nations such as the Maldives in the Indian Ocean and Tuvalu in the Pacific, devastate coastal cities such as Calcutta and Dhaka and force London, New York and Shanghai to spend billions on flood defences


Sea levels will rise by twice as much as previously predicted as a result of global warming, an important international study has concluded.

The Scientific Committee on Antarctic Research (SCAR) calculated that if temperatures continued to increase at the present rate, by 2100 the sea level would rise by up to 1.4 metres — twice that predicted two years ago.

Such a rise in sea levels would engulf island nations such as the Maldives in the Indian Ocean and Tuvalu in the Pacific, devastate coastal cities such as Calcutta and Dhaka and force London, New York and Shanghai to spend billions on flood defences.

Even if the average global temperature increases by only 2C — the target set for next week’s Copenhagen summit — sea levels could still rise by 50cm, double previous forecasts, according to the report.

SCAR, a partnership of 35 of the world’s leading climate research institutions, made the prediction in the report Antarctic Climate Change and Climate. It far exceeds the 0.59 metre rise by the end of the century quoted by the Intergovernmental Panel on Climate Change (IPCC) in 2007. This was based on a “business as usual” approach by governments that allowed temperatures to rise by 4 degrees. It will underpin the negotiations in Copenhagen.

SCAR scientists said that the IPCC underestimated grossly how much the melting of the Antarctic and Greenland ice sheets would contribute to total sea-level rises.

One of the world’s leading experts on climate science has called for the world to intensify efforts to control global warming by actively removing carbon dioxide from the atmosphere.

In an interview with The Times, Dr Rajendra Pachauri, chairman of the IPCC, said that geo-engineering, where carbon is stripped from the atmosphere using specialist technologies, would be necessary to control runaway damage to the climate. “At some point we will have to cross over and start sucking some of those gases out of the atmosphere.”

He added that world leaders meeting in Copenhagen should aim for a tighter target of no more than a 1.5C rise in global temperatures.

The IPCC report predicted that the melting of ice sheets would contribute about 20 per cent of the total rise in sea levels, with the majority coming from the melting of glaciers and the expansion of the water as it warms. It said that it was not able to predict the impact of melting ice sheets, but suggested this could add 10-20cm.

The SCAR report uses detailed climate observations over the past century linking temperature to sea levels to produce a more sophisticated estimate. It puts the likely contribution from ice sheets at more than 50 per cent.

The calculations were carried out by Stefan Rahmstorf, Professor of Physics of the Oceans at the Potsdam Institute for Climate Impact Research in Germany. Sceptics seized upon his figures as further evidence of the unreliability of climate change predictions.

“It’s 50cm, 60cm, 100cm — 60m if you ask James Hansen from Nasa,” said Benny Peiser, director of the Global Warming Policy Foundation . “The predictions come in thick and fast, but we take them all with a pinch of salt. We look out of the window and it’s very cold, it doesn’t seem to be warming. We’re very concerned that 100-year policies are being made on the basis of these predictions”

25/11/09

La France propose son projet d'accord sur le climat

LE MONDE

19.11.09
10h33 • Mis à jour le 23.11.09
15h50



Jean-Louis Borloo, ministre français de l'écologie, a communiqué à ses collègues réunis à Copenhague, lundi 16 et mardi 17 novembre, une proposition d'accord de 16 pages pour la conférence de l'ONU sur le climat qui aura lieu dans la capitale danoise du 7 au 18 décembre.

Ce texte est l'aboutissement d'une démarche engagée depuis plusieurs mois par M. Borloo, convaincu que les négociations ne pourront aboutir sans un engagement politique au plus haut niveau. Il s'est donc rapproché, dès le printemps 2008, des pays africains afin de construire une alliance entre les "vertueux" Européens et les plus grandes "victimes" à venir du changement climatique.

Le plan d'équipement énergétique de l'Afrique qu'il a proposé promet de faire en vingt ans ce que l'aide au développement a échoué à apporter au cours des cinquante dernières années. Mais ce projet a reçu un accueil mitigé. A aucun moment, les partenaires européens n'ont clairement manifesté leur soutien.

M. Borloo a élargi ce plan en un projet "justice climat" qu'il a présenté en octobre en Asie (Inde, Cambodge, Laos et Bangladesh) et aux petits Etats insulaires. Par ailleurs, une position commune franco-brésilienne a pu être annoncée samedi 14 novembre par les présidents Sarkozy et Lula.

Mais l'initiative française est encore loin d'être prise en compte dans les discussions. S'il peut se targuer du soutien de l'Allemagne et de nombreux pays pauvres, le ministre français ne semble pas s'être suffisamment concerté avec la Suède, à la tête de l'Union européenne, et le Danemark, qui présidera la conférence de décembre, et à qui revient la responsabilité de présenter un texte de compromis.

La voie privilégiée par les deux pays reste le processus traditionnel de discussion au sein de l'ONU. "Le texte français est irréaliste", note une source scandinave, "mais il comporte des éléments intéressants". Certains négociateurs – y compris parmi les Français – se disent décontenancés par cette stratégie poursuivie en marge de la discussion officielle, et qui ne s'est pas rapprochée des Etats-Unis et de la Chine.

Quoi qu'il en soit, l'activité diplomatique sur le changement climatique s'accélère. La réunion de 46 ministres de l'environnement à Copenhague s'est déroulée dans une atmosphère positive. "Je suis les négociations depuis plusieurs années, dit un diplomate international, je n'ai jamais vu une discussion aussi ouverte et franche." S'il est clair qu'un traité en bonne et due forme n'est plus à l'ordre du jour, les efforts se focalisent sur un "accord politique contraignant" dont les points majeurs émergent, même si aucun texte n'est pour l'instant sur la table.

Un accord éventuel se fonderait sur quatre points-clés : un engagement par les pays du Nord de réduire leurs émissions ; un engagement des pays en développement de mener des actions afin de limiter les leurs ; un accord sur le financement à court et à long termes ; et enfin un consensus sur la gouvernance de ce financement – afin que les décisions soient partagées entre pays du Nord et pays du Sud.

De surcroît, les Etats s'engageraient à une mise en œuvre immédiate des actions de soutien aux pays les plus pauvres et à formaliser, en 2010, dans un traité, l'ensemble des points retenus à Copenhague.

Reste que la position des Etats-Unis est jugée insuffisante. Connie Hedegaard, la ministre danoise de l'environnement, a déclaré qu'il "serait très utile que les Etats-Unis mettent sur la table des chiffres spécifiques sur les réductions des émissions et sur le financement".

Un point qui correspond, entre autres, à l'attente des pays africains, sans l'assentiment desquels un accord paraît impossible. Réuni mardi 17 novembre à Addis-Abeba, le groupe des dix Etats qui représenteront l'Afrique au Danemark a indiqué avoir fixé le montant des financements demandés aux pays riches pour compenser les effets du changement climatique. "Nous avons posé un minimum en dessous duquel nous ne descendrons pas", a dit le premier ministre éthiopien, Meles Zenawi, sans en révéler le montant.

Un autre signal positif est venu du sommet entre l'Union européenne et la Russie, à Moscou, le 16 novembre. Selon José Manuel Barroso, le président de la Commission européenne, Dimitri Medvedev, le président russe, a annoncé que son pays visait une réduction de ses émissions de 20 à 25 % en 2020 par rapport à 1990. M. Medvedev a déclaré que "nous avons un objectif qui est de convaincre nos collègues d'être plus sérieux sur cette question", précisant que le changement climatique représentait une "menace catastrophique".

Laurence Caramel et Hervé Kempf

Le réchauffement climatique pourrait atteindre 7 degrés en 2100

LEMONDE.FR

24.11.09
16h45 • Mis à jour le 24.11.09
17h39


C'est le pire scénario jamais imaginé. Le réchauffement climatique pourrait atteindre sept degrés en 2100 selon vingt-quatre climatologues de renom. L'Institut de recherche sur les impacts du climat de Potsdam, en Allemagne, publie en effet mardi 24 novembre un document de 64 pages représentant une synthèse des travaux scientifiques sur le changement climatique parus depuis le 4e rapport du Groupe intergouvernemental d'experts sur le climat (GIEC, 2007), assorti d'un

"La température moyenne de l'air devrait se réchauffer entre 2 et 7 degrés en 2100 par rapport à la période préindustrielle", affirment les auteurs. L'augmentation de 40 % des émissions de CO2 entre 1990 et 2008 rend plus difficile à atteindre l'objectif fixé en juillet de limiter à 2 degrés le réchauffement global. "Chaque année de retard dans l'action augmente les chances que le réchauffement dépasse 2 °C", avertissent-ils.

A l'attention de ceux qui douteraient encore de l'origine humaine du réchauffement, le document de Potsdam rappelle que durant le dernier quart de siècle, les températures moyennes ont augmenté de 0,19 degré par décennie, ce qui correspond parfaitement aux prévisions calculées sur la base des émissions de gaz à effet de serre.

PHÉNOMÈNES MÉTÉOROLOGIQUES EXTRÊMES

L'un des effets les plus alarmants du changement à venir concerne la multiplication des phénomènes météorologiques extrêmes, que ce soit au niveau des températures (canicules) ou des précipitations (sécheresses, inondations). Un autre concerne l'élévation du niveau des mers. "La montée actuelle du niveau des mers", de 3,4 mm par an durant les quinze dernières années, "est supérieure de 80 % aux prévisions passées du GIEC", selon les climatologues. Au lieu d'une fourchette comprise entre 18 et 59 cm d'augmentation, les experts estiment désormais que si les émissions de gaz à effet de serre ne sont pas réduites, la fonte des calottes glaciaires provoquera une montée des eaux comprise entre un et deux mètres d'ici à la fin du siècle.

Selon Hans Joachim Schellnhuber, directeur de l'Institut de Potsdam et membre du GIEC, le rapport est un "dernier appel des scientifiques à l'intention des négociateurs sur le climat de 192 pays qui doivent prendre le train de la protection climatique à Copenhague", du 7 au 18 décembre. "Ils doivent connaître la vérité sans détours sur le réchauffement global et les risques sans précédent qu'il implique", souligne-t-il.

Pour limiter le réchauffement à 2 degrés, il faut que les émissions cessent d'augmenter entre 2015 et 2020 et diminuent ensuite rapidement. "Une société mondiale "décarbonée" – avec zéro émission de CO2 et d'autres gaz à effet de serre durables – doit être atteinte bien avant la fin du siècle", espèrent les climatologues.

19/11/09

A CLIMATE-CHANGE AMPLIFYING MECHANISM



Average rainfall variations, simulated by models, after a collapse of deep ocean circulation (increases in blue, decreases in red; from Stouffer et al. 2006). The dotted arrow shows the actual flow of water vapour. The solid arrows indicate the multiple flows (trade winds -> rivers -> marine currents) during a climatic anomaly. Crosses show the paleoclimatic study sites. (Credit: Copyright CNRS 2006)

Science News

ScienceDaily (Mar. 8, 2007) — During the past ninety thousand years there were alternating hot and cold periods lasting several thousand years each which resulted in a modification of global oceanic circulation. With the help of paleoclimatic and paleooceanographic indicators, scientists at CEREGE1 have highlighted a feedback mechanism of ocean circulation on the climate which reinforces this heating or cooling. This mechanism relies on a close link between the circulation of the North Atlantic and the tropical hydrology of Central America. This study, published in the February 22, 2007 edition of the review Nature, should allow us to better understand and therefore better predict the effects of climate change on oceanic circulation.



________________________________________


In the past, major and rapid climatic variations which took place notably during the last glacial period (Heinrich period) disturbed ocean circulation. Climatic archives (marine and lake sediment, polar ice, stalagmites) show the close relationship existing between climatic variations and oceanic circulation. Changes in oceanic circulation in the North Atlantic have influence on a planetary level by affecting, in particular, the water cycle. These changes are accompanied by a shift in the climatic equator which separates the trade wind systems of the two hemispheres: southwards during cold events and northwards during hot ones.


Central America, a narrow continental strip which separates the Atlantic and Pacific oceans, plays a key role in this system. On the Atlantic side surface waters evaporate, which increases salinity. The water vapour is transferred by the trade winds to the Pacific where it is deposited as rain, thus lowering salinity there. This enormous transfer of water (several hundred thousand cubic meters per second) maintains a contrast in salinity between the two oceans. The surface waters of the tropical Atlantic are then transported, via the Gulf Stream, towards the high latitudes where they warm the atmosphere before plunging into the abysses in the convection zones situated in the seas of Norway, Greenland and Labrador. The deep waters formed by this process then flow into the world ocean, purging the North Atlantic of part of its excess salt.


The scientists at CEREGE1 reconstituted the variations in surface water salinity in the area where the water vapour coming from the Atlantic is deposited. To do this they worked on the measurements taken in marine sediments collected in 2002 west of the Isthmus of Panama by the French oceanographic ship the Marion Dufresne. This study shows that the cold Heinrich periods correspond to increases in salinity in the east Pacific. This is synonymous to a decrease in the transfer of water vapour. By comparing their results to other studies done in the Atlantic sector and in South America, the scientists were able to describe a feedback mechanism which amplified the climatic disturbance. During cold periods the trade winds, loaded with humidity, migrated southwards. Unable to cross the Andes part of the rain, which would normally have lowered the salinity of the East Pacific, fell in the Amazon basin. This feedback had the effect of re-injecting rainwater into the Atlantic, thereby decreasing the ocean's salinity. This water was then transported to the higher latitudes, contributing to the weakening of deep oceanic circulation, thereby reinforcing the cooling above and around the North Atlantic.


Today, the fact that global warming could disturb the water cycle and lead to a slowing down of the North Atlantic circulation is a real subject of concern. Oceanographic data from the last 50 years suggest that hydrographic changes (temperature and salinity) as well as a lessening of the flow of water transported by certain surface and deep-sea marine currents have already occurred in the North Atlantic. The risk of an even greater variation of oceanic circulation by the end of this century or the beginning of the next needs to be taken seriously and actively studied.










Average rainfall variations, simulated by models, after a collapse of deep ocean circulation (increases in blue, decreases in red; from Stouffer et al. 2006). The dotted arrow shows the actual flow of water vapour. The solid arrows indicate the multiple flows (trade winds -> rivers -> marine currents) during a climatic anomaly. Crosses show the paleoclimatic study sites. (Credit: Copyright CNRS 2006)

15/11/09

SHOULD CLIMATE DENIERS BE ALLOWED TO SPEAK ON THE TODAY PROGRAMME?



Bone of contention ... The climate change denier Ian Plimer. Photograph: Megan Lewis/Reuters





Had the BBC done its research, Ian Plimer's falsehoods would not been allowed to pass unchallenged



THE GUARDIAN

15 November 2009


Should the Today programme have interviewed Ian Plimer yesterday? According to many environmentalists, it shouldn't. Here, for example, is the Green party councillor Rupert Read:
"I literally could not believe my ears when I heard you giving an entire interview this morning (at 8.53) to the fringe Australian geologist still questioning man-made global over-heating, at this crucial time, when 1) it is now utterly obvious and everywhere accepted by atmospheric scientists that humans are responsible for the dire and continual upward trend in CO2 emissions, and 2) the Copenhagen summit is almost upon us … By doing interviews like that, that you chose to air this morning, you are materially damaging the chances of an agreement at Copenhagen, an agreement that might just save our civilisation and species from self-destruction."


I don't agree. I don't think any voice should be suppressed, unless it is directly inciting people to rise up and kill or hurt others. You could argue, rightly, that death and devastation is the likely result of a widespread failure to take climate change seriously. But on the same grounds you would have to stifle the voices of people who demand a reduction in taxes (that might have funded the NHS or overseas aid) or people who came out in favour of the Iraq war. It's not clear-cut of course: the laws that prevent people from inciting violence against British people of Iraqi origin don't prevent commentators from inciting state violence against Iraqis overseas. There is clearly a pay-off between free speech and the defence of vulnerable people. But would any of you seriously argue that such commentators should not be allowed to state their case, however repulsive we might find it?



Let Plimer speak, but let his interviewers do some sodding research first.
On the Today programme Justin Webb allowed him get away with some extraordinary claims. Plimer maintained, for example, that "we cannot stop carbon emissions because most of them come from volcanoes". How many times does this has to be debunked? Among many others, I have pointed out to Plimer that this is plain wrong: humans currently produce 130 times as much CO2 as volcanoes.


He has never tried to refute this. Instead he just keeps repeating his claim. Water off a duck's back doesn't begin to describe it. But Webb allowed this howling falsehood to pass unchallenged.