22/1/16

Abrupt Climate Change


UNION OF CONCERNED SCIENTIST
2 Brattle Square, Cambridge

Two high-profile events in 2004 put the issue of "abrupt climate change" squarely in the public eye. The first was a February 2004 Fortune Magazine article that broke the news of a report prepared for the Pentagon on abrupt climate change and its implications for U.S. national security. The Pentagon report describes a scenario in which human-caused global warming leads to a near-term collapse of the ocean's thermohaline circulation, which brings warm surface waters from the tropics to the North Atlantic, warming parts of Western Europe. The authors propose dramatic impacts, including rapid cooling in Europe, greatly diminished rainfall in many important agricultural and urban centers and consequent disruptions in food supply and water supply with enormous geopolitical and security implications.
The second was the May 2004 release of The Day After Tomorrow a 20th Century Fox blockbuster disaster movie with a similar premise. With a dashing paleoclimatologist as the action hero, The Day After Tomorrow depicts a world careening toward an ice age over a few weeks' time. Here too, the culprit is the warming-induced shutdown of the thermohaline circulation.
The authors of the Pentagon report and the producers of The Day After Tomorrowcaution readers and viewers against treating these extreme scenarios as serious possibilities. The Pentagon report intentionally considers the worst possible scenario, one that stretches the boundary of scientific plausibility. The Day After Tomorrow leaps beyond that boundary to unleash a collection of climate catastrophes intended to thrill audiences and showcase the latest special effects. Yet underlying even these extreme scenarios are the sober facts of human-caused global warming and the real opportunities to minimize climate change by reducing emissions of heat-trapping gases.
UCS views the publicity generated by these events as an opportunity to help the public and decision makers better understand what we know about the causes, consequences and solutions to climate change. Toward that end, we provide the following answers to some frequently asked questions.

Can what happens in The Day After Tomorrowhappen in real life?

No. The dramatic, virtually instantaneous and widespread cooling envisioned in the film is fiction. But like all good science fiction, the film is premised on several important scientific facts. We know with great certainty that Earth is already warming, largely because as we burn fossil fuels and clear forests we are releasing carbon dioxide and other heat-trapping gases in the atmosphere. This warming is expected to continue in the coming decades, accompanied by changes in rainfall patterns and rising sea levels. The possibility of an abrupt shift in the climate system is only one feature of a changing climate that is expected to become more erratic, with extreme weather events like droughts, torrential rainfall, and extreme heat becoming more common. We can slow down global warming and reduce the likelihood of future abrupt climate changes by reducing our emissions of heat-trapping gases.

What is "abrupt climate change?"

The term "abrupt climate change" describes changes in climate that occur over the span of years to decades, compared to the human-caused changes in climate that are occurring over the time span of decades to centuries. From ice cores, ocean sediments, tree rings, and other records of Earth's past climate, scientists have found that changes in climate have occurred quickly in the past—over the course of a decade. An example of an abrupt climate change event is the Younger Dryas (~12,000 years ago), a period of abrupt cooling that interrupted a general warming trend as Earth emerged from the last Ice Age. During the Younger Dryas period, average summertime temperatures in New England cooled by about 5-7°F (3-4°C). This and other abrupt events have been linked to changes in an ocean circulation pattern known as thermohaline circulation.

How might abrupt climate change affect people?

While the scenarios depicted in the Day After Tomorrow and the Pentagon report are extreme, changes in climate, including possible abrupt climate changes, will have serious consequences for people's lives and livelihoods. As Earth warms, higher temperatures and more common extreme heat conditions will affect human health, energy demand, water supply and demand, and agriculture. Rising sea levels will impact coastal communities as flooding happens more often and damage from coastal storms becomes more severe. Some regions will become much drier, while others will become much wetter, affecting agriculture, water supply, and the spread of diseases. Many of these impacts will be most severe in developing countries, where scarce resources and limited technological capacity will limit options for coping with the consequences of climate change.

Can we avoid abrupt climate change?

Yes. While abrupt climate change is not a certainty, human-caused climate change makes abrupt events more likely. What is certain is that human-caused climate change is already under way, and is expected to continue over the next century as a result of our emissions of carbon dioxide and other heat-trapping gases to the atmosphere. Levels of carbon dioxide in the atmosphere are higher today than they have been for more than 400,000 years. Earth's surface temperature has increased measurably over the past 100 years, and 10 of the warmest years on record have occurred since 1990. This warming has caused changes in rainfall—some regions have become wetter while others have become drier—and droughts and severe rainfall events have become more common. By making choices now to reduce our emissions of heat-trapping gases, we can slow the rate of global warming and reduce the likelihood of unexpected climate changes.

How can global warming make things cooler?

As we rapidly increase Earth's average temperature, some regions, such as high latitudes, will experience greater warming than others, such as the tropics. As warming alters ocean and atmosphere circulation patterns, some regions could even experience cooling. Much of Western Europe is now warmed by ocean circulation as well as the atmosphere. Heat is transported to the region by a global ocean circulation pattern variably known as thermohaline circulation, the North Atlantic heat pump, or the "Great Ocean Conveyor Belt." This "heat pump" pulls warm salty water northward from the tropics into the North Atlantic, where heat is released, warming air temperatures over Europe.
As Earth warms, melting of ice caps and glaciers, increased precipitation and other inflows of fresh water to the North Atlantic Ocean may weaken or shut down thermohaline circulation. This change in ocean circulation could disrupt the transfer of heat northward from the tropics, resulting in cooling in the North Atlantic region. Regional cooling of as much as 14-29°F (8-16°C) has been seen in the past climate record. However, any regional cooling would be superimposed on the global warming that is already underway. Contrary to the "Day After Tomorrow" dramatization, abrupt climate change will not result in an ice age, because the cooling effects are regional and Earth is currently in an interglacial, or warm, period.

What is thermohaline circulation?


Thermohaline circulation is a global ocean circulation pattern that distributes water and heat both vertically, through the water column, and horizontally across the globe. As cold, salty water sinks at high latitudes, it pulls warmer water from lower latitudes to replace it. Water that sinks in the North Atlantic flows down to the southern hemisphere, skirts the Antarctic continent, where it is joined by more sinking water, and then crosses south of the Indian Ocean to enter the Pacific Ocean basin. There, the cold deep water rises to the surface, where heat from the tropical sun warms the water at the ocean's surface and drives evaporation, leaving behind saltier water. This warm, salty water flows northward to join the Gulf Stream, traveling up the Eastern coast of the United States and across the Atlantic Ocean into the North Atlantic region. There, heat is released to the atmosphere, warming parts of Western Europe. Once this warm, salty water reaches the North Atlantic and releases its heat, it again becomes very cold and dense, and sinks to the deep ocean.

6/1/16

Predicen una nueva Edad de Hielo para el año 2030


ABC

josé manuel nieves - Madrid - 18/07/2015 a las 00:00:01h. - Act. a las 03:31:47h.Guardado en: Ciencia
La noticia ha causado impacto entre climatólogos de todo el mundo. Y no es para menos. Un grupo internacional de investigadores, liderado por V. Zharkova, de la Univesidad de Northumbria, acaba de revelar, durante elEncuentro Nacional de Astronomía en Llandudno, en Gales, que estamos a punto de experimentar una nueva «Pequeña Edad de Hielo» similar a la que congeló una buena parte del mundo durante el siglo XVII y principios del XVIII. Será entre 2030 y 2040.
Como es sabido, el campo magnético del Sol varía a lo largo del tiempo. Y estas variaciones magnéticas en la ardiente atmósfera solar tienen unainfluencia directa en la radiación electromagnética que emite el astro rey, así como en la intensidad de sus flujos de plasma y en el número de manchas en su superficie. La variación en la cantidad de manchas solares tiene una estructura cíclica, con máximos que se producen cada once años y que tienen efectos concretos sobre el medioambiente de la Tierra. Esos efectos pueden medirse observando la presencia de ciertos isótopos (como el carbono 14 o el berilio 10) en glaciares o en los árboles.
Pero existen numerosos ciclos diferentes que se repiten una y otra vez, condiferentes periodos y propiedades, aunque los mejor conocidos son los de once y noventa años. El primero se manifiesta con una reducción periódica de manchas sobre la superficie solar. Y su variante de 90 años se asocia con la reducción periódica en el número de manchas en determinados ciclos de once años.
En el siglo XVII se produjo un prolongado periodo de calma, llamado «elMínimo de Maunder», que se extendió desde 1645 a 1700 y durante el cual las manchas solares prácticamente desaparecieron por completo. Durante este periodo, en efecto, apenas se contabilizaron unas 50 manchas solares en lugar de las cerca de 50.000 habituales. El análisis de la radiación solar, además, ha demostrado que sus máximos y mínimos coinciden casi siempre con los máximos y mínimos en cuanto al número de manchas.
Ahora, en un amplio estudio publicado en tres artículos diferentes, los investigadores han analizado el campo magnético de fondo de todo el disco solar durante tres ciclos completos de actividad (del 21 al 23), aplicando el denominado «análisis de componentes principales», que permite reducir la dimensión de los datos y el ruido estadístico para identificar solo las ondas que contribuyen en mayor medida a los datos de observación. El método podría compararse a la descomposición de la luz blanca por medio de un prisma, para detectar por separado las frecuencias de los diversos colores del espectro luminoso.
Como resultado, los investigadores lograron desarrollar un nuevo método de análisis, que les ayudó a descubrir que las ondas magnéticas se generan en el Sol por pares, y que el par principal basta para dar cuenta del 40% de la variación de los datos. Por lo tanto, se puede considerar al par principal de ondas como responsable de las variaciones del campo dipolar del Sol, que cambia su polaridad de polo a polo en cada ciclo de actividad de once años.
Utilizando su nuevo método de análisis, los científicos describieron la evolución de estas dos ondas y calcularon la curva de variación de las manchas solares (principal indicador de la actividad solar). Lo primero que hicieron fue predecir la actividad magnética del sol en el ciclo 24 (en el que estamos actualmente, desde 2008), y sus datos coincidieron en un 97% con las observaciones directas.
Animados por este éxito, los autores de la investigación decidieron extender la predicción a los dos ciclos siguientes (el 25 y el 26) y descubrieron que el par principal de ondas provocará en ese periodo un número de manchas muy escaso. Lo que llevará a una fuerte disminución de la actividad solarhacia 2030 ó 2040, comparable a las condiciones que existieron durante el Mínimo de Maunder en el siglo XVII.
Esta reducción de la actividad implica una disminución de la radiación solar de 3W por metro cuadrado, más del doble de lo habitual, lo que llevará a unrecrudecimiento invernal extremoy a veranos muy fríos. «Muchos estudios han mostrado que el Mínimo de Maunder coincidió con la fase más fría del enfriamiento global (en el siglo XVII), hasta el punto de que se la conoce como 'Pequeña Edad de Hielo' –afirma Helen Popova, física de la Universidad Estatal Lomonosov de Moscú–. Durante ese periodo se sufrieron inviernos muy fríos en Europa y Norte América. Durante el Mínimo de Maunder el agua de ríos como el Támesis o el Danubio se congeló, el Moscova se cubría de hielo cada seis meses, la nieve cubría las llanuras todo el año y Groenlandiaestaba cubierta de glaciares». Helen Popova es la investigadora que desarrolló el modelo matemático que ha permitido predecir la evolución de la actividad magnética del Sol.

Una atmósfera terrestre más fría

Si se produce en la actividad solar una reducción similar a la registrada durante el Mínimo de Maunder, también la atmósfera terrestre se enfriará. Según Popova, si las actuales teorías sobre el impacto de la actividad solar en el clima terrestre son ciertas, entonces el próximo mínimo de 2030 traerá un enfriamiento significativo, muy similar al ocurrido durante el siglo XVII.
Sin embargo, solo durante los próximos entre 5 y 15 años será posible tener una certeza absoluta sobre lo acertado de estas predicciones.
«Dado que nuestro futuro mínimo tendrá una duración de al menos tres ciclos solares, que es de unos 30 años, es posible que la disminución de la temperatura no sea tan drástica como durante el Mínimo de Maunder –explica Helen Popova–. Pero debemos examinar los datos con detalle. Estamos en estrecho contacto con climatólogos de varios países y seguiremos trabajando en ello».
La idea de que la actividad solar afecta al clima en la Tierra apareció hace ya mucho tiempo. Se sabe, por ejemplo, que basta una ligera variación de un 1% en la actividad solar para causar cambios medibles en la distribución de temperaturas y del flujo de aire en todo el planeta. Los rayos ultravioletatienen efectos fotoquímicos, que llevan a la formación de ozono en la atmósfera, a una altura de 30 ó 40 km. Y el flujo de rayos ultravioleta aumenta considerablemente cuando se produce una llamarada solar. El ozono, que absorbe los rayos del sol lo suficientemente bien, se calienta como consecuencia de este aumento de radiación y afecta a las corrientes de aireen las capas bajas de la atmósfera y, en consecuencia, al clima.
También la emisión de partículas cargadas aumenta con la actividad solar. Y esas partículas alcanzan la Tierra y se mueven en complejas trayectorias, causando auroras, tormentas geomagnéticas y problemas en las comunicaciones por radio.

La "tormenta monstruosa" que tiene el Polo Norte con un nivel inédito de "calor"



Hasta un grado centígrado por encima del punto de congelación llegó la temperatura en el Polo Norte por la "tormenta monstruosa" que ingresó en la zona el martes.
El Programa Internacional de Boyas Árticas registró elevaciones de temperatura que son consideradas "extremadamente cálidas" para esa zona del planeta en esta época del año.
Los reportes de la Agencia Oceánica y Atmosférica de Estados Unidos (NOAA, por sus siglas en inglés) señalan que se trata de una de las tormentas más potentes jamás registradas en el Polo Norte.
"Incluso en el techo del mundo, en la época que debería ser la más fría del año en esa zona, el propio Polo Norte está inusualmente cálido", señaló el editor de ciencia de BBC David Shukman.
Para Shukman, se trata de uno de los efectos secundarios "más extraños de la turbulencia actual en el clima mundial".
En las últimas semanas se han registrado tornados mortales en Texas, inundaciones y desbordes de ríos en Reino Unido y Misuri, o calor extremo en Australia.
También le ha tocado su parte a México, donde se han vivido intensas nevadas en el norte del país.

2 ºC

La temperatura marcada por las boyas meteorológicas estadounidenses en el Polo Norte es considerada "sorprendentemente cálida", dado que el promedio para esta época del año fluctúa alrededor de -25 grados centígrados.
Por si fuera poco, las estimaciones servicio meteorológico noruego indican que las temperaturas llegan hasta los 2 grados.

La "tormenta monstruosa" en el

Polo Norte
  • - La caída de la presión atmosférica empujó consigo vientos cálidos de sur a norte que elevaron el clima.
  • - Boyas árticas reportan que la temperatura llegó a subir entre 1 y 2 grados centígrados por encima del punto de congelamiento.
  • - Según modelos meteorológicos, estatormenta está relacionada con los tornados que pasaron por Estados Unidos el fin de semana y las inundaciones en Reino Unido.
"Por ahora no existen instrumentos para proporcionar lecturas exactas, pero las boyas han grabado el extraordinario hecho de temperaturas por encima de cero", señala Shukman.
El hecho está relacionado con el fenómeno de El Niño, que, entre finales de 2015 y los primeros meses de 2016, afecta el clima de todo el planeta.

Estados Unidos y Reino Unido

Según las estimaciones de los modelos meteorológicos, esta tormenta antes de llegar a tan altas latitudes pasó por Estados Unidos causando grandes y mortales tornados.
Polo Norte
Image captionLas inusuales temperaturas están relacionadas al cambio climático y al fenómeno de El Niño.
Tormentas de nieve y granizo paralizaron el lunes el transporte en partes de aquel país.
Más de 40 personas murieron por tornados e inundaciones durante el fin de semana en Estados Unidos, donde se emitieron inusuales advertencias sobre tornados y fenómenos climáticos extremos.
La tormenta que eleva las temperaturas en el Polo Norte también coincide con las fuertes inundaciones de comienzos de semana en Reino Unido.
Allí se vivió el dicimebre más cálido y el segundo más lluvioso desde hace más de un siglo.
En el final de 2015, se registraron temperaturas medias de 8 grados centígrados, más típicas de la primavera y que están 4,1 grados por encima de la media habitual en esta época del año.
El récord anterior se registró en 1934, con una temperatura media de 6,9 grados centígrados en territorio británico.
Tres tormentas han azotado tierras británicas en diciembre causando graves inundaciones.
Ha sido también el segundo mes más lluvioso desde que en 1910 empezaron los registros estadísticos, con precipitaciones medias de 211 milímetros de altura.
Varios puntos del Reino Unido, principalmente en Escocia y el norte de Inglaterra, siguen hoy en alerta de inundaciones por las tormentas Desmond, Eva y Frank.
Sus potentes efectos, según los expertos, son atribuidos en buena medida al cambio climático.

27/4/15

Un planeta de extremos climáticos


Inundaciones en Hamburgo en 2007 y terreno desecado en Chile en 2015. AFP / REUTERS

El año 2014 fue el más cálido de la Historia. Y 14 de los 15 años más calurosos se han registrado en el siglo XIX. El aumento de temperaturas globales, la reducción de las masas de hielo y nieve y el aumento del nivel del mar han llevado a los científicos hacia el consenso inequívoco de que el mundo se está calentando a consecuencia de la actividad humana. Pero la pregunta del millón aún no ha podido ser contestada: ¿La ola de calor de 2003 en Europa, las inundaciones de Bangladesh el año pasado o la sequía que asola California desde hace meses son consecuencia directa del calentamiento causado por el ser humano?
La ciencia del clima sólo es capaz de hablar de tendencias de aumento de temperatura y de probabilidades de que ocurran más eventos extremos, pero hasta ahora no podía explicar el grado de responsabilidad del cambio climático en un acontecimiento concreto. Una nueva investigación dirigida por el prestigioso investigador de del Instituto de Ciencias del Clima y la Atmósfera de Suiza, Reto Knutti, ha roto con esos viejos miedos y ha desarrollado un modelo capaz de evaluar hasta qué punto está aumentando el cambio climático la ocurrencia de las olas de calor y de las lluvias torrenciales. Y los resultados son sorprendentes. El 75% de los eventos de temperaturas extremas y el 18% de los grandes aguaceros son atribuibles al cambio climático, según las conclusiones del trabajo, publicado hoy en la revista 'Nature Climate Change'.
Los expertos en ciencias del clima llevan años tratando de diseñar modelos que permitan averiguar el grado de implicación del calentamiento global en eventos meteorológicos extremos, como olas de calor, sequías o tormentas. Lo que han hecho los autores del estudio es aplicar a escala global los modelos diseñados para acontecimientos concretos, como la ola de calor europea de 2003, que mató a decenas de miles de personas en el continente.
Las conclusiones y la estadística del trabajo son robustas, según los expertos, pero se sigue sin poder decir 'esta inundación se debe al cambio climático'. A lo máximo que podrán llegar los investigadores es a asegurar que el 18% de esas lluvias son consecuencia directa del calentamiento.
España y el sur de Europa son puntos de riesgo que sufrirán en mayor medida las olas de calor extremo
«Lo que han estudiado los autores es lo que conocemos como atribución, es decir, asignar una relación de causa-efecto, y eso es algo muy difícil», explica José Manuel Moreno, catedrático de la Universidad de Castilla La Mancha y vicepresidente del Grupo II del Panel Intergubernamental para el Cambio Climático de Naciones Unidas (IPCC, por sus siglas en inglés). «El símil del fumador es perfecto. No podemos decirle a nadie que haya muerto por fumar, pero sí podemos explicarle cuánto ha crecido la probabilidad de morir anticipadamente debido al tabaco», explica Moreno.
Lo que sí han elaborado los autores es un mapa del mundo con las probabilidades de ocurrencia de temperaturas y lluvias extremas en distintos puntos del planeta. «El aumento de la probabilidad de que ocurran eventos extremos en España y en el resto del sur de Europa es sustancialmente mayor que en Europa central o del norte», explica Erich Fischer, investigador del Instituto de Ciencias del Clima y Atmosféricas de Suiza y autor principal del trabajo.
En este escenario de aumento global de extremos climáticos, España no está precisamente bien situada. «Aunque nuestros resultados no se fijan en las diferencias regionales, el cambio a largo plazo es consistente con las tesis aceptadas hasta ahora de que España y el sur de Europa son 'hotspots' (zona de riesgo) que sufrirán en mayor medida los eventos extremos de altas temperaturas», dice Fischer. «Con respecto a las lluvias extremas, los cambios en el sur de Europa no están claros», reconoce.
«En un mundo dos grados más cálido, cerca de la mitad de las lluvias torrenciales no hubieran ocurrido»
No obstante, a escala global sí se ha evaluado lo que ocurrirá en el futuro en diferentes escenarios de aumento de temperatura. Lo más llamativo quizá es el impacto que tendrá el cambio climático sobre las lluvias torrenciales si se cumplen los objetivos marcados por los científicos y que se prevé que sean reconocidos por la comunidad internacional en la Cumbre del Clima de París en diciembre de 2015. En un mundo 2ºC más cálido, el 40% de las grandes tormentas se deberán al cambio climático.

«La idea de que en un mundo dos grados más caliente cerca de la mitad de las lluvias extremas no hubieran ocurrido si no fuera por el cambio climático causado por el ser humano debería dar que pensar a los políticos que tratan de mitigar y de adaptarse al cambio climático», plantea en un artículo que acompaña a la investigación Peter Stott, investigador del Met Office, el servicio meteorológico británico.

24/3/15

Atlantic Ocean overturning found to slow down already today

POSTDAM INSTITUTE FOR CLIMATE IMPACT RESEARCH



03/24/2015 - The Atlantic overturning is one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards. Also known as the Gulf Stream system, it is responsible for the mild climate in northwestern Europe. Scientists now found evidence for a slowdown of the overturning – multiple lines of observation suggest that in recent decades, the current system has been weaker than ever before in the last century, or even in the last millennium. The gradual but accelerating melting of the Greenland ice-sheet, caused by man-made global warming, is a possible major contributor to the slowdown. Further weakening could impact marine ecosystems and sea level as well as weather systems in the US and Europe.

“It is conspicuous that one specific area in the North Atlantic has been cooling in the past hundred years while the rest of the world heats up,” says Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research, lead author of the study to be published inNature Climate Change. Previous research had already indicated that a slowdown of the so-called Atlantic meridional overturning circulation might be to blame for this. “Now we have detected strong evidence that the global conveyor has indeed been weakening in the past hundred years, particularly since 1970,” says Rahmstorf.
Because long-term direct ocean current measurements are lacking, the scientists mainly used sea-surface and atmospheric temperature data to derive information about the ocean currents, exploiting the fact that ocean currents are the leading cause of temperature variations in the subpolar north Atlantic. From so-called proxy data – gathered from ice-cores, tree-rings, coral, and ocean and lake sediments – temperatures can be reconstructed for more than a millennium back in time. The recent changes found by the team are unprecedented since the year 900 AD, strongly suggesting they are caused by man-made global warming.
“The melting Greenland ice sheet is likely disturbing the circulation”
The Atlantic overturning is driven by differences in the density of the ocean water. From the south, the warm and hence lighter water flows northwards, where the cold and thus heavier water sinks to deeper ocean layers and flows southwards. “Now freshwater coming off the melting Greenland ice sheet is likely disturbing the circulation,” says Jason Box of the Geological Survey of Denmark and Greenland. The freshwater is diluting the ocean water. Less saline water is less dense and has therefore less tendency to sink into the deep. “So the human-caused mass loss of the Greenland ice sheet appears to be slowing down the Atlantic overturning – and this effect might increase if temperatures are allowed to rise further,” explains Box.
The observed cooling in the North Atlantic, just south of Greenland, is stronger than what most computer simulations of the climate have predicted so far. “Common climate models are underestimating the change we’re facing, either because the Atlantic overturning is too stable in the models or because they don’t properly account for Greenland ice sheet melt, or both,” says Michael Mann of Pennsylvania State University in the US. “That is another example where observations suggest that climate model predictions are in some respects still overly conservative when it comes to the pace at which certain aspects of climate change are proceeding.”
No new ice-age – but major negative effects are possible
The cooling above the Northern Atlantic would only slightly reduce the continued warming of the continents. The scientists certainly do not expect a new ice age, thus the imagery of the ten-year-old Hollywood blockbuster ‘The Day After Tomorrow’ is far from reality. However, it is well established that a large, even gradual change in Atlantic ocean circulation could have major negative effects.
“If the slowdown of the Atlantic overturning continues, the impacts might be substantial,” says Rahmstorf. “Disturbing the circulation will likely have a negative effect on the ocean ecosystem, and thereby fisheries and the associated livelihoods of many people in coastal areas. A slowdown also adds to the regional sea-level rise affecting cities like New York and Boston. Finally, temperature changes in that region can also influence weather systems on both sides of the Atlantic, in North America as well as Europe.”
If the circulation weakens too much it can even break down completely – the Atlantic overturning has for long been considered a possible tipping element in the Earth System. This would mean a relatively rapid and hard-to-reverse change. The latest report by the Intergovernmental Panel on Climate Change (IPCC) estimates there to be an up to one-in-ten chance that this could happen as early as within this century. However, expert surveys indicate that many researchers assess the risk to be higher. The study now published by the international team of researchers around Rahmstorf provides information on which to base a new and better risk assessment.

Article:Rahmstorf, S., Box, J., Feulner, G., Mann, M., Robinson, A., Rutherford, S., Schaffernicht, E. (2015): Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulationNature Climate Change (online) [DOI:10.1038/nclimate2554]

Further information:
- Weblink to NASA animation “The Great Ocean Conveyor Belt” (downloadable video that shows the current system that now is found to slow down in the North tlantic):http://pmm.nasa.gov/education/videos/thermohaline-circulation-great-ocean-conveyor-belt
- Weblink to a study on possible impacts of a shutdown of the thermohaline circulation:http://link.springer.com/article/10.1007%2Fs10584-009-9561-y
- Weblink to the expert assessment of an AMOC tipping:http://www.pnas.org/content/early/2009/03/13/0809117106.abstract


19/3/15

ABRUPT CLIMATE CHANGE IS HERE

COUNTER PUNCH

FEBRUARY 02, 2015

by ROBERT HUNZIKER
Is abrupt climate change already here?
There are some serious scientists who believe it is already here. If their analysis is correct, the world could turn nearly uninhabitable within current lifetimes.
In that regard, the American public is overly, dangerously casual about the prospects/risks of abrupt climate change. This is found in numerous studies and polls, e.g. according to a Pew Research Global Attitudes Project, in an international survey of 39 countries, Americans were among the least concerned about climate change threatening the country. Global warming also ranked near the bottom of Americans’ priorities.
As it goes, the American public may be caught off guard, unprepared, and ill equipped to press its political establishment for appropriate action because abrupt climate change has a history of happening very, very quickly, within decades, not over hundreds of years.
Assuming these scientists are correct, by the time the U.S. Congress gets serious about climate change, they’ll be wearing waders.
As for the risks associated with abrupt climate change, according to Paul Beckwith, Laboratory for Paleoclimatology and Climatology, University of Ottawa, in the past: “The temperature of the planet has increased by 5C or 6C within one decade or two decades… not within a hundred years but within one or two decades… during the ice age period between 70,000 and 40,000 years ago, the temperature rose over Greenland 5-6C in a decade or two… and 55 million years ago… the temperature rose globally by 5C in 13 years, as shown in sediment samples.” (Source:COP20: Global Arctic Methane Emergency)
Based upon historic records, once abrupt climate change commences, and when viewed on a geological-time basis, it has the potential to take off like a house on fire. According to Paul Beckwith, unfortunately: “We’re undergoing the early stages of abrupt climate change,” already, right now! As such, a rapid self-fulfilling temperature rise of 5C or 6C would be devastating for life, as we know it.
This risk of further rapid abrupt climate change, as for example, temperatures zooming upwards, depends upon the integrity of the ice of the Arctic, among other considerations. As emphasized by Beckwith, when analyzing the climate system, it is important to understand that metrics can be misleading. For example, the consensus opinion talks about 2C as a cap for rising temperatures; however, in point of fact, “What is important is the temperature distribution on the planet on a latitudinal basis.”
Beckwith: “The Arctic is absorbing a lot more solar energy, and by itself at a much greater rate, than anywhere else on the planet. In fact, on average, in the last number of decades, the Arctic temperature has risen 1.0C per decade whereas the global average temperature rise has been about 0.15C per decade. So that ratio is 6 or 7 times more.”
Therefore, the most immediate risk of further abrupt climate change hinges on how well the Arctic withstands global warming. As the Arctic loses ice mass, it releases more, and more, methane (CH4), which is much more powerful at entrapping heat than is carbon dioxide (CO2), and because massive quantities of CH4 are embedded within the ice, only a small fraction may cause the planet to heat up rapidly, going into deadly overdrive, resulting in numerous outgrowths negatively impacting life. As for example, rapid increase in sea levels, flooding coastal cities, embedded droughts, diminishing agricultural production, severe storm activity, and horrific heat throughout the mid latitudes, resulting in panic, illness, and sudden death. It is likely the world turns chaotic.
Scientists are radically divided on the issue of abrupt climate change and few predict an upsurge any time soon. Nevertheless, it’s the scientists who base their opinion on first hand knowledge, “boots on the ground,” who are screaming the loudest. They do not let the “ computer models” override what they personally experience. In contrast, they see and feel the reality “in the field.” They are like scientific pioneers in the field, in the marsh, below and above the ice, on expeditions into the wilderness where nobody cares to tread. It’s hard work.
Those scientific pioneers, like John Nissen, Chairman of the Arctic Methane Emergency Group (“AMEG”), are deeply concerned about the rate of melt of the Arctic, and the attendant enormous plumes of methane, already observed in the Arctic seas, especially in the East Siberian Ice Shelf where waters are shallow and easily warmed, threatening to release gigatons of methane. Expeditions above, below, and on the surface have convinced these scientists that we’ve got a huge problem coming up, maybe soon, maybe too soon.
According to John Nissen: “Sea ice could disappear at the end of summer as soon as next September. At that point, further warming of the Arctic, sea level rise, methane release, in that time bomb, and abrupt climate change, could become unstoppable. The fuse will have been lit and will be going off very quickly. We consider it an absolute scandal that IPCC [Intergovernmental Panel on Climate Change] says nothing about the greatest threat to humanity since civilization began.”
In turn, these pioneering scientists listen to other scientists who also favor “boots on the ground” analysis over scientific modeling, people like Dr. Natalia Shakhova, who leads the Russia-U.S. Methane Study at the International Arctic Research Center, at the University Alaska Fairbanks and the Pacific Oceanological Institute, Far Eastern Branch of Russian Academy of Sciences. Dr. Shakhova’s expeditions to the Arctic convince her that only a tiny percentage of the vast amounts of methane buried in Arctic ice is necessary to double current atmospheric CH4. Worse yet, she suspects an outburst of 50 gigatons could happen at any time. In many respects, this would be a disaster beyond repair.
In an interview, Shakhova says, “We do not like what we see… absolutely do not like it.”
In the end, too much carbon dioxide emitted by burning too much gas, oil & coal, blankets the atmosphere enough to heat up the Arctic far above and way beyond past centuries, causing torrential weather patterns throughout the Northern Hemisphere, and shaking lose too much methane for human comfort.
Could civilization withstand a 50-gigaton release? Professor Wadhams’ response is: “No, I don’t think it can.”
Is there a solution?
Yes, there may be solutions but according to these scientists, a sense of urgency matters more than anything at this late hour.
Paul Beckwith is one of the scientific pioneers, an advocate, a researcher, and member of AMEG, co-founded by Peter Wadhams, professor of Ocean Physics, University of Cambridge.
Beckwith: “We have to slash emissions there’s no question, slash the CO2 emissions and quickly, but that’s not sufficient. We also have to cool the Arctic, and we also have to try to remove CO2 from the atmosphere.”
The technology is there, solar radiation management, reflecting incoming solar, and sea salt spraying, as well as employing concerted efforts to increase vegetation to absorb CO2, and carbon capture, and biochar.
However, there’s risk because nobody has proven these geoengineering techniques effective on a planetary scale. On that basis, they are experimental. There is no consensus in the world community to test geoengineering, which is very provocative subject matter amongst scientists, some favor, some oppose. And, those opposed adamantly oppose because of potential harmful feedback loops. It may be a risky venture.
But, what if these early-warning scientists are wrong? What if they are absolutely correct about the outcome of global warming/climate change but too optimistic about the timing? This, therefore, is all the more reason for governments to initiate conversions now from fossil fuels to renewables, hopefully rescuing future generations from the potential of a global warming nightmare.
If we lose the ice caps, civilization starves and the world’s coastal cities drown. It’s really as simple, and complex, as that. Already, CO2 levels are at an historic high.
Throughout geological history, “Every time we have hit high CO2, we’ve lost the ice caps,” Peter Ward, professor, Dept. of Earth & Space Sciences, University of Washington, Our Future in a World without Ice Caps, 2013 lecture series.

Robert Hunziker lives in Los Angeles and can be reached at roberthunziker@icloud.com

16/2/15

Spy agencies fund climate research in hunt for weather weapon, scientist fears

Scientist believes intelligence services are considering using climate-altering systems as weapons. Photograph: Mike Hollingshead/Barcroft Media


THE GUARDIAN
, science editor, in San Jose
Sunday 15 February 2015 

US expert Alan Robock raises concern over who would control climate-altering technologies if research is paid for by intelligence agencies

A senior US scientist has expressed concern that the intelligence services are funding climate change research to learn if new technologies could be used as potential weapons.
Alan Robock, a climate scientist at Rutgers University in New Jersey, has called on secretive government agencies to be open about their interest in radical work that explores how to alter the world’s climate.
Robock, who has contributed to reports for the intergovernmental panel on climate change (IPCC), uses computer models to study how stratospheric aerosols could cool the planet in the way massive volcanic eruptions do.
But he was worried about who would control such climate-altering technologies should they prove effective, he told the American Association for the Advancement of Science in San Jose.
Last week, the National Academy of Sciences published a two-volume report on different approaches to tackling climate change. One focused on means to remove carbon dioxide from the atmosphere, the other on ways to change clouds or the Earth’s surface to make them reflect more sunlight out to space.
The report concluded that while small-scale research projects were needed, the technologies were so far from being ready that reducing carbon emissions remained the most viable approach to curbing the worst extremes of climate change. Areport by the Royal Society in 2009 made similar recommendations.
The $600,000 report was part-funded by the US intelligence services, but Robock said the CIA and other agencies had not fully explained their interest in the work.
“The CIA was a major funder of the National Academies report so that makes me really worried who is going to be in control,” he said. Other funders included Nasa, the US Department of Energy, and the National Oceanic and Atmospheric Administration.
The CIA established the Center on Climate Change and National Security in 2009, a decision that drew fierce criticism from some Republicans who viewed it as a distraction from more pressing terrorist concerns. The centre was closed down in 2012, but the agency said it would continue to monitor the humanitarian consequences of climate change and the impact on US economic security, albeit not from a dedicated office.
Robock said he became suspicious about the intelligence agencies’ involvement in climate change science after receiving a call from two men who claimed to be CIA consultants three years ago. “They said: ‘We are working for the CIA and we’d like to know if some other country was controlling our climate, would we be able to detect it?’ I think they were also thinking in the back of their minds: ‘If we wanted to control somebody else’s climate could they detect it?’”
He replied that if a country wanted to create a stratospheric cloud large enough to change the climate, it would be visible with satellites and ground-based instruments. The use of the weather as a weapon was banned in 1978 under theEnvironmental Modification Convention (Enmod).
Asked how he felt about the call, Robock said he was scared. “I’d learned of lots of other things the CIA had done that didn’t follow the rules. I thought that wasn’t how my tax money was spent,” he said. The CIA did not respond to requests for comment over the weekend.
The US dabbled in weather modification before Enmod was introduced. In the early 1960s, researchers on Project Storm Fury seeded thunderstorms with various particles in the hope of diminishing their destructive power. A similar process was adopted during the Vietnam war, with clouds seeded over the Ho Chi Minh trail in a bid to make the major supply route for North Vietnamese foot soldiers too muddy to pass.
“I think this research should be out in the open and it has to be international so there won’t be any question that this technology will used for hostile purposes,” Robock said.