Las primeras conclusiones del Año Polar Internacional confirman la magnitud global de la pérdida de las grandes masas heladas del planeta.
La fusión acelerada de los hielos árticos, del manto de Groenlandia y de las regiones más vulnerables de la Antártida ha alterado ya no sólo los hábitats propios sometidos al deshielo, sino también sistemas globales como la circulación atmosférica y las corrientes oceánicas. Todo esto se sospechaba y ahora, a punto de concluir en marzo el Año Polar (2007/09), se confirma con los datos aportados por más de 160 proyectos de investigación desarrollados por miles de científicos de 60 países.
La Organización Meteorológica Mundial (OMM) y el Consejo Internacional de la Ciencia, promotores del Año Polar, dieron a conocer este miércoles un primer avance de conclusiones que constata la magnitud global de los efectos del deshielo de las grandes masas heladas del planeta. Las últimas mediciones satelitales in situ demuestran que tanto Groenlandia, la segunda reserva de hielo, como la Antártida, la gran nevera de la Tierra, pierden hielo a un ritmo cada vez más rápido, con el consiguiente aumento del nivel del mar. Y nuevos registros certifican, además, que el calentamiento del continente blanco va mucho más allá de la Península Antártica y afecta ya a otras regiones que se creían relativamente a salvo.
El Ártico, por su parte, sufrió en el verano de 2007 la mayor pérdida de hielo marino perenne que se conoce desde los primeros registros por satélite, un millón de kilómetros cuadrados y, por primera vez, el manto de hielo anual en torno al Polo Norte era relativamente delgado en pleno invierno. Durante el Año Polar se observó que la deriva del hielo en la cuenca boreal seguía un ritmo sin precedentes. «Un prueba concluyente de que se están produciendo cambios en el sistema hielo-océano-atmósfera del Ártico», relata el informe de conclusiones.
Ecosistemas
Los investigadores del Año Polar han aportado nuevas pruebas sobre la fascinante riqueza y vulnerabilidad de los ecosistemas polares, la existencia de especies comunes en los océanos boreal y austral, de otras que han evolucionado de forma distinta a partir de ancestros comunes, y de la 'migración' de muchas hacia las aguas más próximas a los polos huyendo del calentamiento oceánico.
En la misma línea, se ha confirmado que el flanco sur de la corriente circumpolar antártica - un cinturón oceánico que rodea la Antártida en el sentido de las agujas del reloj- «se ha calentado más rápido que el resto de los océanos», y las densas aguas profundas circundantes han perdido salinidad en algunas zonas debido al deshielo continental. Se cree que este factor puede alterar los patrones circulatorios. «Estos cambios son indicio de que el calentamiento de la Tierra está afectando a la Antártida de maneras nunca antes imaginadas», subrayan los expertos.
Las investigaciones realizadas en estos dos años muestran en el Atlántico Norte ligeros cambios en las condiciones oceánicas, de los flujos térmicos y los movimientos entre la atmósfera y el océano condicionan en gran manera la fuerza y la trayectoria finales de las tormentas de gran intensidad, que son las principales fuentes de calor y humedad atmosféricos en el Ártico.
También se han identificado grandes reservas de metano almacenado en el 'permafrost' (suelos permanentemente congelados). Su fusión amenaza con liberar a la atmósfera grandes cantidades de este gas de efecto invernadero, más potente que el CO2 aunque de duración más efímera.
Para Michel Jarraud, secretario general de la OMM, las nuevas pruebas obtenidas en la investigación de ambos polos «consolidarán la base científica» para futuras investigaciones sobre el cambio climático.
Ben Webster, Environment Editor and Giles Whittell in Washington
President Obama must intervene personally to rescue a proposed global deal on climate change that is hanging in the balance, the British Energy and Climate Change Secretary has told The Times.
Ed Miliband said that there was a much greater chance of a successful deal being agreed in December if Mr Obama travelled to Copenhagen to lead the US delegation to the UN conference.
Gordon Brown has said that he will attend the conference but Mr Obama and most other world leaders have yet to commit themselves to going. White House officials offered no new assurances yesterday, saying only that the Administration would be represented at the “appropriate level”.
The British challenge will add to the pressure on Mr Obama to attend, but the case for staying in Washington to shepherd his healthcare reforms into law may prove irresistible.
The President would also risk a second embarrassment in the Danish capital, where his efforts to win the 2016 Olympics for Chicago faltered this month, if his likely failure to sign a domestic climate change Bill by December became the story of the summit.
Asked by The Times if Mr Obama’s presence in Copenhagen would increase the chances of a successful outcome, Mr Miliband said: “Yes. This only works if leaders engage. It’s a very interesting lesson that in July the leaders met in L’Aquila in Italy and agreed that they should commit to avoiding dangerous climate change above two degrees [centigrade]. If they had left it to negotiators it wouldn’t have happened. And Obama was there.”
He called on the US to make a binding and ambitious commitment to cutting its carbon dioxide emissions.
“We do need significant cuts in emissions from the US. We want as much action from America as we can get,” Mr Miliband said. “America and China are the two biggest emitters. They are very key to this. I think a deal without America would be a very bad deal.”
As a presidential candidate, Mr Obama promised to end US isolation on climate change. A cap-and-trade Bill that would allocate carbon emissions permits to major polluters was narrowly passed by the House of Representatives in June but has since been mired in Senate committees.
Senior advisers to the White House have said that alternative carboncutting strategies are being considered in case support for the cap-and-trade Bill, drafted by the Democratic congressmen Henry Waxman and Ed Markey, slips on its way to a final vote. They include limiting mandatory carbon cuts to power plants.
Another proposal involves handing responsibility for America’s carbon footprint to the US Environmental Protection Agency instead of Congress. Both scenarios would all but rule out full US participation in a successor to the Kyoto Protocol on cutting emissions, which is the goal of the Copenhagen summit.
The US never signed the protocol and its failure to do so continued to hamper negotiations, Mr Miliband said: “The biggest difficulty we face is that Kyoto was a partial deal because it didn’t have America in it.” Leaders of other countries are waiting to see what Mr Obama will do before making their own announcements.
Mr Miliband said the proposal in the Waxman Markey Bill to cut US emissions by 17 per cent between 2005 and 2020 “would be a very good start”. He said: “If you compare what America is planning to do from now until 2020 under Waxman Markey, it’s about the same as what we are doing, possibly more depending on how you calculate it. If you look back to 1990 it’s less but they are starting 20 years later.”
Britain has agreed to cut its emissions by 34 per cent on 1990 levels by 2020 and by 80 per cent by 2050.
Mr Miliband said that Mr Obama’s election was part of an “alignment of the stars” that made Copenhagen a unique opportunity to secure a deal.
Carbon target
— 190 nations will meet on December 7-18 to try to agree a global deal on cutting CO2 emissions to replace the Kyoto Protocol, which runs out in 2012
— The objective is to keep global warming within 2C (3.6F) of the pre-industrial average. The world currently emits 50 gigatonnes of CO2 equivalent a year
— Lord Stern of Brentford, former World Bank chief economist, says that emissions must fall to 44 gigatonnes by 2020 and 20 gigatonnes by 2050 to meet the 2C target
— Voluntary commitments by countries so far amount to a cut of two gigatonnes by 2020 — four gigatonnes short of the target
— Gordon Brown has proposed a global fund of $100 billion a year by 2020 to help developing countries to adapt to climate change and develop low-carbon economies
— The EU wants the Copenhagen deal to include a commitment to end the destruction of rainforests by 2030
Source: Timesdatabase
(Version en catellano)
Ed Miliband pide a Barack Obama para salvar el clima Cumbre de Copenhague
Ben Webster, Editor de Medio Ambiente y Giles Whittell en Washington,
El presidente Obama debe intervenir personalmente para rescatar a un acuerdo global propuesto sobre el cambio climático que está pendiente de un hilo, según Secretario de Energía Británico y del Cambio Climático, ha dicho The Times.
Ed Miliband, dijo que había muchas más posibilidades para el éxito de un posible acuerdo en diciembre, y si Obama viaja a Copenhague para dirigir la delegación de EE.UU. a la Conferencia de las Naciones Unidas.
Gordon Brown ha dicho que asistirá a la conferencia, pero Obama y otros líderes del mundo, la mayoría, que todavía no se han comprometido, tienen que ir. Funcionarios de la Casa Blanca no ofrecían garantías de nuevo ayer, sólo dijeron que la Administración estaría representada en el "nivel apropiado".
El desafío británico aumentará la presión sobre Obama para que asista, pero en el caso de permanecer en Washington para preparar y apaciguar sus reformas de salud en la legislación, que puede resultar algo irresistible para él.
El Presidente también el puede temer el riesgo de un segundo tropiezo en la capital danesa, luego de sus esfuerzos para ganar los Juegos Olímpicos de 2016 para Chicago, que falló este mes, si su posible quiebra a firmar un proyecto de ley nacional del cambio climático en diciembre se convirtiera en la historia de la cumbre.
Preguntado por The Times si la presencia de Obama en Copenhague, aumentaría las posibilidades de un resultado exitoso, Miliband dijo: "Sí". Esto funciona sólo si los líderes se comprometen. Es una experiencia muy interesante luego que en julio los dirigentes se reunieron en L'Aquila en Italia, y de acuerdo en que deberían comprometerse a evitar un cambio climático peligroso por encima de dos grados [Celsius]. Si hubieran dejado a los negociadores que no habría ocurrido. Y Obama estaba allí”.
Pidió a los EE.UU. para hacer un compromiso vinculante y ambicioso, el reducir sus emisiones de dióxido de carbono.
"Necesitamos reducir significativamente las emisiones de los EE.U.U. Queremos de la acción de América tanto como podamos conseguir ", dijo Miliband. "Estados Unidos y China son los dos mayores emisores. Son muy clave para ello. Creo que un acuerdo sin que Estados Unidos sería un acuerdo muy malo”.
Como candidato presidencial, Obama prometió poner fin al aislamiento EE.UU. sobre el cambio climático. Un ante-proyecto de ley de comercio que para asignar los permisos de emisiones de carbono a los mayores contaminadores se aprobó por escasa mayoría en la Cámara de Representantes en junio, pero desde entonces ha estado inmerso en las comisiones del Senado.
Asesores de alto nivel a la Casa Blanca han dicho que las estrategias de carboncutting alternativas se están considerando en caso de apoyo para el ante-proyecto de ley, elaborado por los congresistas demócratas Henry Waxman y Ed Markey, el cual se desliza en su camino a una votación final. Se incluyen limitar las reducciones de carbono obligatorio para las plantas de energía.
Otra propuesta consiste en entregar la responsabilidad del seguimiento del carbono de Estados Unidos a los EE.UU. a la Agencia de Protección Ambiental en lugar del Congreso. Ambos escenarios, pero todos sin descartar la participación de EE.UU. completa en un sucesor del Protocolo de Kioto sobre la reducción de emisiones, que es el objetivo de la Cumbre de Copenhague.
Los EE.UU. nunca firmaron el protocolo y su incapacidad para hacerlo sigue obstaculizando las negociaciones, Miliband dijo: "La mayor dificultad que enfrentamos es que Kyoto es un acuerdo parcial, ya que no estaba América en ella." Los líderes de otros países estan esperando a ver lo que el Sr. Obama hará antes de hacer sus propios anuncios.
Miliband dijo que la propuesta en el proyecto de ley Markey Waxman a reducir las emisiones de EE.UU. en un 17 por ciento entre 2005 y 2020 "sería un muy buen comienzo". Dijo: "Si se compara lo que Estados Unidos tiene la intención de hacer de ahora hasta 2020 en virtud de Waxman Markey, que es casi lo mismo que lo que estamos haciendo, posiblemente más, dependiendo de cómo calcularlo. Si uno mira hacia atrás, 1990 es menor, pero el caso es que están comenzando 20 años después ".
El Reino Unido ha aceptado reducir sus emisiones en un 34 por ciento sobre los niveles de 1990 para el año 2020 y en un 80 por ciento en 2050.
Miliband dijo que la elección de Obama es parte de la alineación de una "de las estrellas" de Copenhague que hizo una oportunidad única para lograr un acuerdo.
Acuerdo sobre el carbono
- 190 naciones se reunirán en diciembre de 7.18 para tratar de acordar un acuerdo global sobre la reducción de las emisiones de CO2 para reemplazar al Protocolo de Kioto, que vence en 2012
- El objetivo es mantener el calentamiento global dentro de 2C (3.6F) de la pre-media de la industria. El mundo que actualmente emite 50 gigatoneladas de equivalente de CO2 al año
- El señor Brentford Stern, ex economista jefe del Banco Mundial, dice que las emisiones deben caer a 44 gigatoneladas en 2020 y 20 gigatoneladas en 2050 para satisfacer la meta 2C
- Los compromisos voluntarios de los países hasta la fecha ascienden a un recorte de dos gigatoneladas en 2020 - cuatro gigatoneladas por debajo del objetivo
- Gordon Brown ha propuesto un fondo global de US $ 100 millones de dólares en 2020 para ayudar a los países en desarrollo a adaptarse al cambio climático y el desarrollo de las economías de bajo carbono
by Manvendra K. Dubey, Charlie S. Zender, Chris K. Folland, and Petr Chylek
THE SECOND INTERNATIONAL CONFERENCE ON GLOBAL WARMING AND THE NEX ICE AGE
What: 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. When: 17–21 July 2006 Where: Santa Fe, New Mexico
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 theAtlantic 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 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 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 indicated 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 hemisphericirradiance at many stations worldwide, was explained by the increase in anthropogenic aerosolsemanating 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 Antarcti c. Underscoring the importance of aerosol character, modelers emphasized the need to carefully represent aerosol shape and mixing state to calculatethe direct forcing of climate and indirect effects on clouds: aerosols are regionally heterogeneous and can cool or warm the climate, depending on their opticalproperties, 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 warming in 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 aerosolo ptical 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. Thetreatment 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 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 moveforward 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 also
catalyzed. 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.
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Sea level rise may be an additional 10 centimeters (4 inches) higher by populated areas in northeastern North America than previously thought. Extreme northeastern North America and Greenland may experience even higher sea level rise. (Graphic courtesy Geophysical Research Letters, modified by UCAR.) Click to enlarge.
As areas with permafrost thaw and more old carbon is released, the carbon balance changes. Credit: Zina Deretsky, National Science Foundation. Click to enlarge.
28 May 2009
Permafrost thaw will make potentially significant contributions to atmospheric concentrations of carbon more rapidly that previously thought, according to a new study published in the 28 May issue of the journal Nature.
A separate study led by the National Center for Atmospheric Research (NCAR), which is being published 29 May in Geophysical Research Letters, concluded that the melting of the Greenland ice sheet this century may drive more water than previously thought toward the already threatened coastlines of New York, Boston, Halifax, and other cities in the northeastern United States and Canada.
Permafrost
Permafrost soils in boreal and Arctic ecosystems store almost twice as much carbon as is currently present in the atmosphere. This pool of carbon, deposited over thousands of years, remains locked in the heretofore perennially frozen ground. In recent years this area began to thaw, providing increased access to plants and microbes that could shift the carbon from the land to the atmosphere.
In earlier work we estimated that widespread permafrost thaw could potentially release 0.8-1.1 gigatons of carbon per year. Before this study, we didn’t know how fast that carbon could potentially be released from permafrost, and how this feedback to climate would change over time.
—Ted Schuur, University of Florida and lead author of the study
An understanding of the rate of carbon release is necessary to estimate the strength of positive feedback to climate change, a likely consequence of permafrost thaw. From 2004 to 2006, Schuur and his team used radiocarbon dating, a technique typically used to determine the age of artifacts, to track the movement of old organic carbon accumulated within the soils and permafrost at an Alaskan site. The ability to distinguish old carbon from newer carbon allowed the researchers to track current metabolism of old carbon in an area where permafrost thaw is increasing.
This research revealed that during the initial stages of permafrost thaw, plant growth and photosynthesis, which remove carbon from the atmosphere, increase. This increase offsets the release of old carbon from thawing. However, sustained thaw eventually releases more carbon than plants can uptake, overwhelming their compensatory capacities.
Our data document significant losses of soil carbon with permafrost thaw that, over decadal timescales, overwhelms increased plant carbon uptake at rates that could make permafrost a large biospheric carbon source in a warmer world.
—Vogel et al. (2009)
To put this in a global context, if the average global temperature continues to rise, current calculations predict that positive feedback from permafrost thaw could annually add as much carbon to the atmosphere as another significant source, land use change.
The Alaskan site where Schuur and colleagues carried out their research was monitored over the past two decades, with permafrost temperature measurements beginning before the permafrost began to thaw. This detailed record coupled with Schuur’s study of ecosystem carbon exchange and old carbon release provide a comprehensive picture of the dynamics of carbon exchange in response to permafrost thaw.
Records from this site exist on a decadal time scale, meaning we are able to more accurately account for the slow pace of change within the system. Overall, this research documents the long-term plant and soil changes that occur as permafrost thaws, thus providing a basis for making long term predictions about ecosystem carbon balance with increased confidence.—Ted Schuur
Melting Greenland Ice Sheets May Threaten Northeast United States, Canada
The NCAR study finds that if Greenland’s ice melts at moderate to high rates, ocean circulation by 2100 may shift and cause sea levels off the northeast coast of North America to rise by about 12 to 20 inches (about 30 to 50 centimeters) more than in other coastal areas. The research builds on recent reports that have found that sea level rise associated with global warming could adversely affect North America, and its findings suggest that the situation is more threatening than previously believed.
If the Greenland melt continues to accelerate, we could see significant impacts this century on the northeast US coast from the resulting sea level rise. Major northeastern cities are directly in the path of the greatest rise.
—NCAR scientist Aixue Hu, the lead author
A study in Nature Geoscience in March warned that warmer water temperatures could shift ocean currents in a way that would raise sea levels off the Northeast by about 8 inches (20 cm) more than the average global sea level rise. But it did not include the additional impact of Greenland’s ice, which at moderate to high melt rates would further accelerate changes in ocean circulation and drive an additional 4 to 12 inches (about 10 to 30 cm) of water toward heavily populated areas of northeastern North America on top of average global sea level rise. More remote areas in extreme northeastern Canada and Greenland could see even higher sea level rise.
Scientists have been cautious about estimating average sea level rise this century in part because of complex processes within ice sheets. The 2007 assessment of the Intergovernmental Panel on Climate Change projected that sea levels worldwide could rise by an average of 7 to 23 inches (18 to 59 cm) this century, but many researchers believe the rise will be greater because of dynamic factors in ice sheets that appear to have accelerated the melting rate in recent years.
The new research was funded by the US Department of Energy and by NCAR’s sponsor, the National Science Foundation. It was conducted by scientists at NCAR, the University of Colorado at Boulder, and Florida State University.
To assess the impact of Greenland ice melt on ocean circulation, Hu and his coauthors used the Community Climate System Model, an NCAR-based computer model that simulates global climate. They considered three scenarios: the melt rate continuing to increase by 7% per year, as has been the case in recent years, or the melt rate slowing down to an increase of either 1% or 3% per year.
If Greenland’s melt rate slows down to a 3% annual increase, the study team’s computer simulations indicate that the runoff from its ice sheet could alter ocean circulation in a way that would direct about a foot of water toward the northeast coast of North America by 2100. This would be on top of the average global sea level rise expected as a result of global warming. Although the study team did not try to estimate that mean global sea level rise, their simulations indicated that melt from Greenland alone under the 3% scenario could raise worldwide sea levels by an average of 21 inches (54 cm).
If the annual increase in the melt rate dropped to 1%, the runoff would not raise northeastern sea levels by more than the 8 inches (20 cm) found in the earlier study in Nature Geoscience. But if the melt rate continued at its present 7% increase per year through 2050 and then leveled off, the study suggests that the northeast coast could see as much as 20 inches (50 cm) of sea level rise above a global average that could be several feet. However, Hu cautioned that other modeling studies have indicated that the 7% scenario is unlikely.
In addition to sea level rise, Hu and his co-authors found that if the Greenland melt rate were to defy expectations and continue its 7% increase, this would drain enough fresh water into the North Atlantic to weaken the oceanic circulation that pumps warm water to the Arctic. Ironically, this weakening of the meridional overturning circulation would help the Arctic avoid some of the impacts of global warming and lead to at least the temporary recovery of Arctic sea ice by the end of the century.
The northeast coast of North America is especially vulnerable to the effects of Greenland ice melt because of the way the meridional overturning circulation acts like a conveyer belt transporting water through the Atlantic Ocean. The circulation carries warm Atlantic water from the tropics to the north, where it cools and descends to create a dense layer of cold water. As a result, sea level is currently about 28 inches (71 cm) lower in the North Atlantic than the North Pacific, which lacks such a dense layer.
If the melting of the Greenland Ice Sheet were to increase by 3% or 7% yearly, the additional fresh water could partially disrupt the northward conveyor belt. This would reduce the accumulation of deep, dense water. Instead, the deep water would be slightly warmer, expanding and elevating the surface across portions of the North Atlantic.
Unlike water in a bathtub, water in the oceans does not spread out evenly. Sea level can vary by several feet from one region to another, depending on such factors as ocean circulation and the extent to which water at lower depths is compressed.
The oceans will not rise uniformly as the world warms. Ocean dynamics will push water in certain directions, so some locations will experience sea level rise that is larger than the global average.
—NCAR scientist Gerald Meehl, a co-author of the paper
Resources
·Jason G. Vogel, Kathryn G. Crummer, Hanna Lee, James O. Sickman, T. E. Osterkamp, Edward A. G. Schuur (2009) The effect of permafrost thaw on old carbon release and net carbon exchange from tundra. Nature 459, 556-559 doi: 10.1038/nature08031
·Aixue Hu, Gerald Meehl, Weiqing Han, and Jianjun Yin (2009) Transient Response of the MOC and Climate to Potential Melting of the Greenland Ice Sheet in the 21st Century. Geophysical Research Letters
New York, le promesse di Cina e Stati Uniti: ridurre le emissioni di gas nocivi da subito, con possibili trasferimenti di nuove tecnologie ai Paesi emergenti dal nostro corrispondente
FEDERICO RAMPINI
NEW YORK - Obama e Hu Jintao hanno usato per la prima volta toni identici, nel denunciare i pericoli del cambiamento climatico alla conferenza Onu sull'ambiente.
"La minaccia è urgente - ha detto il presidente americano - , il tempo stringe se non vogliamo lasciare alla generazioni future una catastrofe irreversible". Gli ha fatto eco il leader cinese: "in gioco la sopravvivenza dell'umanità, abbiamo una responsabilità comune". Il tono è cambiato, dai tempi in cui l'Amministrazione Bush negava perfino la realtà del surriscaldamento da CO2, e la Cina scaricava ogni colpa sui paesi più ricchi.
Il summit di New York ha dato la misura di un atteggiamento nuovo. Parlano un linguaggio più simile i due giganti che insieme generano il 40% di tutte le emissioni carboniche della terra.
La convergenza tra Obama e Hu sui grandi principi è un progresso importante ma non sufficiente.
Paradossalmente, malgrado la grande distanza tra i due sistemi politici americano e cinese, in questo campo ambedue i presidenti sono più avanti dei rispettivi paesi. Non fu così in passato. Ma oggi nella democrazia Usa come nel regime autoritario di Pechino, è ai vertici di governo che spesso si trovano le posizioni più avanzate. Devono affrontare resistenze tenaci nella società, in particolare nel mondo delle imprese.
A Washington la Camera ha approvato una legge importante sul risparmio energetico che al Senato si è arenata; la lobby del petrolio e del carbone organizzano un ostruzionismo efficace, usano il ricatto della crisi economica per respingere vincoli e nuove regole. Hu Jintao ha promesso di ridurre "l'intensità energetica" del modello di sviluppo cinese, cioè di spezzare l'automatismo perverso tra crescita economica e distruzione di risorse naturali. E' vero che la Cina avanza rapidamente verso il 15% di fonti alternative, ha in campo investimenti colossali nel solare, eolico, nucleare. E ha rincarato la benzina per incentivare gli automobilisti al risparmio. Resta però potente la lobby dell'industria pesante, e il boom di investimenti in infrastrutture deciso da Pechino in funzione anti-recessione segue una vecchia logica di sviluppo non sostenibile.
Le difficoltà di Obama e Hu sono comuni ad altri attori mondiali. L'Europa "virtuosa" si nasconde dietro i ritardi americani, ma il suo esperimento sul "cap-and-trade" (la monetizzazione dei permessi sulle emissioni) ha dato luogo ad abusi, e i risultati sono meno positivi del previsto. Complice la recessione, anche i paesi europei sono riluttanti ad assumere impegni precisi sul calo dell'anidride carbonica entro il 2020. India, Russia, Brasile, da parte loro si fanno scudo della posizione cinese: tocca ai paesi di vecchia industrializzazione muoversi per primi e sopportare l'onere prevalente. Tutti sembrano più disponibili a ragionare sul 2050 che sul medio termine. "E' disonesto - denuncia il ministro dell'Ambiente indiano Jairam Ramesh - perché significa spostare gli obiettivi a una data in cui nessuno di noi sarà qui a rendere conto di quel che ha fatto".
Sarkozy ha raccolto queste preoccupazioni, proponendo un altro summit prima della fine dell'anno, per riunire tutti i "grandi inquinatori", quei paesi che insieme generano l'80% delle emissioni carboniche. Anche sull'ambiente gli europei cominciano a dare segni di insofferenza verso Obama. La tendenza a "demonizzare" la Cina lascia il campo a un revival di accuse verso Washington. Sarà colpa del complicato processo legislativo, ma la svolta verde di Obama non è così sostanziale come si aspettavano le opinioni pubbliche europee.
Tuttavia nel duetto Obama-Hu ieri a New York è emerso un vero margine di manovra negoziale. La Cina, l'India e altri paesi emergenti chiedono impegni precisi da parte dell'Occidente sul trasferimento di tecnologie verdi e di capitali, per aiutare i paesi emergenti ad affrontare l'adattamento necessario. Hu Jintao non ha messo il suo paese fra quelli bisognosi di aiuti, che invece vuole vedere indirizzati soprattutto verso i più poveri del pianeta. E' una posizione politicamente abile, rafforza il credito di Pechino nei confronti dei suoi alleati del Terzo mondo. La richiesta cinese e indiana non è esorbitante: l'1% del Pil dei paesi più ricchi è quanto chiedono di destinare agli "aiuti verdi" verso il Sud del Pianeta. Si tratta di 300 miliardi di dollari, un decimo di quanto è stato usato per i salvataggi delle banche americane. Hu Jintao non si è sbilanciato su quanto la Cina potrebbe tagliare le sue emissioni di CO2 ma ha parlato di una "riduzione notevole" entro il 2020. Questo linguaggio può essere colto come la disponibilità preliminare ad aprire un negoziato. In cui tutti devono arrivare disposti a mettere qualcosa sul tavolo.
NEW DELHI — When the United Nations convened its summit meeting on climate change last month, China and the United States, the two most important countries at the negotiating table, hewed to mostly familiar scripts, making promises without making too many specific commitments. Less familiar was the script followed by the third most important country at the table, India.
India’s public stance on climate change is usually predictable — predictably obstinate and unwilling to compromise, at least according to many industrialized nations. But at the United Nations, India’s delegation toned down its usual criticisms of the industrialized world, presented new plans to reduce India’s emissions and sought to reposition the country, in the words of the environment minister, as a “deal maker,” not a “deal breaker.”
The shift comes as Prime Minister Manmohan Singh is pushing India to adopt a more internationalist posture on issues like climate change and trade as he seeks to expand India’s global stature at a time when declining American influence is altering the geopolitical balance of power.
Mr. Singh’s government has concluded that addressing climate change is intertwined with addressing domestic priorities like pollution, energy security and even national security.
Moreover, analysts say, India’s rigid, hard-line posture has backfired; the country has been typecast as intransigent, even as its putative ally on the issue, China, a far bigger source of emissions, has succeeded in creating the impression that the Chinese are more active and engaged.
“We cannot compromise our basic national position on protecting our prospects for growth, but we can see things that can be done,” said Nitin Desai, a member of the prime minister’s special advisory council on climate change. “The signal that I get is that India is not going to be a spoiler at Copenhagen. If a reasonable deal can be worked out, they will be there.”
With less than three months before final talks commence in Copenhagen, many analysts are deeply pessimistic that a comprehensive deal can be reached. But others are already discussing Plan B’s that might give credit for domestic programs, like one proposed by India, instead of creating a global set of binding limits like those in the existing, but faltering, Kyoto Protocol.
India’s close alliance with China — they are co-leaders of the bloc of developing nations — has been rooted in their shared interest in protecting economic growth and has created the impression that the two countries share a similar emissions profile, but, in fact, they do not. China is a far bigger polluter. India’s environment minister, Jairam Ramesh, said India had one-fifth of China’s emissions, measured either in total or per capita amounts. Over all, China accounts for roughly 23 percent of all global emissions, while India accounts for less than 5 percent.
Those disparities are why some analysts say the relationship is subtly shifting. China has now overtaken the United States as the biggest emitter in the world and is under pressure to assume responsibilities more in line with industrialized countries.
India is worried that it could face similar expectations, based on its population size and potential for future growth, even though its levels of economic development and emissions lag far behind those of China.
David G. Victor, an energy analyst who has studied India’s situation, predicted that the Indian and Chinese positions could gradually separate.
As demands on developing countries increase, Mr. Victor predicted, their bloc will fragment. Low-per-capita emission countries, possibly led by India, may try to differentiate themselves from countries like Mexico, Brazil and China, which have more advanced economies and higher emissions.
“The Indians need to be very careful that they are seen as a different kind of country,” said Mr. Victor, who also teaches at the University of California, San Diego.
Mr. Ramesh, India’s environment minister, said China and India were closely coordinating their positions on the negotiations, but he also conceded that China was winning the public relations battle.
“China has raced way ahead of us, both in terms of emissions and in conveying the impression they are doing a lot on climate change,” he said in an interview in New Delhi before he left for the United Nations summit meeting.
Mr. Ramesh said India’s basic demands for signing an international accord were unchanged: that industrialized nations agree to significant emissions reductions by 2020 and also provide financial and technical assistance to the developing world. India also remains opposed to accepting any mandatory caps on emissions.
But regardless of the fate of the agreement, he said, India was moving forward anyway. His ministry would soon submit legislation to the Indian Parliament that would tighten fuel efficiency standards, set voluntary targets to improve energy efficiency, push ahead with solar power and expand the use of clean-coal technology in power plants.
“I want to be aggressive, because, frankly, we are a country that is climate dependent,” he said, alluding to the vulnerability of India to rising sea waters and potentially disruptive annual monsoons. “We don’t like to think about it, but we are vulnerable.”
He added: “Our prime minister’s clear message to me was, ‘India has to be part of the solution. We may not have caused the problem, but we have to be part of the solution.’ ”
At the United Nations, Mr. Ramesh focused on practical issues like expanding forest cover, extending a treaty program encouraging investment in clean technologies and expanding technological cooperation.
“I think a lot of people welcomed that as a positive contribution,” said Michael A. Levi of the Council on Foreign Relations. “It showed engagement on substance rather than rhetoric.”
For years, Indian negotiators defined climate change through the geopolitics of economic justice and national sovereignty, arguing that the industrialized world had a historical responsibility to bear the brunt of any global response while equating mandatory caps on emissions as being tantamount to capping India’s economic growth.
These arguments are still deeply felt in India and continue to shape the domestic political debate; Mr. Singh was sharply criticized by some members of Parliament after he agreed with other leaders last summer in Italy that nations should prevent the average global temperature from rising more than 2 degrees Fahrenheit from its current level.
His critics called the deal a trap to limit India’s development.
Mr. Ramesh said part of his job was to build a new domestic political consensus about how India could constructively address climate change without damaging its national interests because “without a solid domestic consensus, or even a domestic constituency, we cannot even think about engaging internationally.”
“And this is also true of the United States,” he added. “It’s true of all democracies.”
