Dublin 8th February 2009 / 1st part
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It’s being snowing outside. It has been so over the last few days in what it is the worst snow fall snap in the last two decades. Despite of how bizarre may sound talking about global warming in a day like this to some of you the truth is that this cold snap that seems so strange to us it wouldn't to European people that lived before the industrial revolution. The reason is that back then this type of winter was as frequent as every 4 or 5 years. Not that far I still remenber my father winter histories of how snow falls of over two meters isolated for months his village, Salceda and all across Polaciones valley in the Picos de Europa (Cantabrian Cordillera, in Northern Spain). He used to tell my of how when he was a kid use to leave the house by the balcony as the front door wouldn’t open because of the previous night snow fall, that was around 75 years ago.
Whereas in many parts of Europe got blanketed by the largest snow fall in the last two decades and places like South Dakota in the US reached temperatures of -44°C in the other side of the world, China are experiencing crop failure intensified by this winter’s droughts and South East of Australia is going through its hottest heat wave in 100 years, recording temperatures of 48 °C in the shade in Kyancutta last Wednesday. Terrible fires spread like hell in such environments.
Let's make two things clear: First, global warming does not imp
ly that the temperature today is higher than yesterday (we would have melt already!). It is a global trend, in which the temperature rises and falls and this does not have to be consistently spread all over the world (different seasons In different hemispheres, these trends should be looked at during long periods of time.
Yes, despite the latest cold snap we are still warming. The global mean temperature meaning that in some areas could see increases of 0.1 degrees and others 15. The total mean global temperature has increased over the last 100 years by 0.7 °C most of it due to anthropogenic forcing (See figure 1).
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Secondly, weather is not the same as climate. Weather describes the short-term state of the atmosphere (basically you see when you look out the window!). Climate is defined as the “average” or “typical” weather over time in over one region. This is based on statistical analysis of trends over a minimum of 30 years not only locally but globally, it is not something that can be discerned but how the weather is like on your area, we must get the full picture to avoid to use misleading information and be able to detect real variability (See figure 2 and 3), trends anomalies and climate evolution patterns. This is what whoever studies the climate does, even if this research sometimes brings us millions of years back into the history of the Earth. The further we go back the better understanding we will get of how the climate system operates and could change in the future.
It’s being snowing outside. It has been so over the last few days in what it is the worst snow fall snap in the last two decades. Despite of how bizarre may sound talking about global warming in a day like this to some of you the truth is that this cold snap that seems so strange to us it wouldn't to European people that lived before the industrial revolution. The reason is that back then this type of winter was as frequent as every 4 or 5 years. Not that far I still remenber my father winter histories of how snow falls of over two meters isolated for months his village, Salceda and all across Polaciones valley in the Picos de Europa (Cantabrian Cordillera, in Northern Spain). He used to tell my of how when he was a kid use to leave the house by the balcony as the front door wouldn’t open because of the previous night snow fall, that was around 75 years ago.
Whereas in many parts of Europe got blanketed by the largest snow fall in the last two decades and places like South Dakota in the US reached temperatures of -44°C in the other side of the world, China are experiencing crop failure intensified by this winter’s droughts and South East of Australia is going through its hottest heat wave in 100 years, recording temperatures of 48 °C in the shade in Kyancutta last Wednesday. Terrible fires spread like hell in such environments.
Let's make two things clear: First, global warming does not imp
ly that the temperature today is higher than yesterday (we would have melt already!). It is a global trend, in which the temperature rises and falls and this does not have to be consistently spread all over the world (different seasons In different hemispheres, these trends should be looked at during long periods of time.Yes, despite the latest cold snap we are still warming. The global mean temperature meaning that in some areas could see increases of 0.1 degrees and others 15. The total mean global temperature has increased over the last 100 years by 0.7 °C most of it due to anthropogenic forcing (See figure 1).
.
Secondly, weather is not the same as climate. Weather describes the short-term state of the atmosphere (basically you see when you look out the window!). Climate is defined as the “average” or “typical” weather over time in over one region. This is based on statistical analysis of trends over a minimum of 30 years not only locally but globally, it is not something that can be discerned but how the weather is like on your area, we must get the full picture to avoid to use misleading information and be able to detect real variability (See figure 2 and 3), trends anomalies and climate evolution patterns. This is what whoever studies the climate does, even if this research sometimes brings us millions of years back into the history of the Earth. The further we go back the better understanding we will get of how the climate system operates and could change in the future.
Figure 2 and 3
Now that we are back on the right track again let’s leave the atmosphere for a while and enter the wonderful world the cryosphere.
What is the cryosphere? It is the portion of the Earth covered in ice and snow. It greatly affects temperature. When sea ice forms, it increases the planetary reflective capacity, thereby enhancing cooling. Sea ice also insulates the atmosphere from the relatively warm ocean, allowing winter air temperatures to steeply decline and reduce the supply of moisture to the atmosphere. Glaciers and snow-covered lands of all types maintain Earth cold conditions because of their high reflectivity and because surface temperatures cannot rise above freezing until the snow melts. Cryosphere plays an important role in regional and global climate.
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Considerable fluxes of meltwaters acted as trigger mechanisms, the past tells us, causing abrupt climate changes like those that occurred during the shutdown of the North Atlantic thermohaline circulation that started one of the most recent cold periods (Younger Dryas, 12,900–11,500 years ago). Back then Greenland was 15 °C colder than now and about half of this increased occurred in abrupt step of 5-10 °C degrees doubling the snow accumulation in central Greenland in probably few years (some think in less than a decade) and half during a the following millennia. Land ice it is an important source of fresh water. Cryosphere in other words is a friendly component of the Earth. If we are to reduce it as we are by increasing the greenhouse emissions that accentuate the global warming, we must be aware of the consequences.
Considerable fluxes of meltwaters acted as trigger mechanisms, the past tells us, causing abrupt climate changes like those that occurred during the shutdown of the North Atlantic thermohaline circulation that started one of the most recent cold periods (Younger Dryas, 12,900–11,500 years ago). Back then Greenland was 15 °C colder than now and about half of this increased occurred in abrupt step of 5-10 °C degrees doubling the snow accumulation in central Greenland in probably few years (some think in less than a decade) and half during a the following millennia. Land ice it is an important source of fresh water. Cryosphere in other words is a friendly component of the Earth. If we are to reduce it as we are by increasing the greenhouse emissions that accentuate the global warming, we must be aware of the consequences.
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One of the questions that immediately rise when we consider global warming is: How much ice is the global warming going to melt?. How fast is this going to happen?. How fast could the sea level rise? As Kunzig and Broecker put it on his last book “Fixing Climate”: “If one of the large ice sheets becomes unstable, the rise would come uncomfortably fast!”...
One of the questions that immediately rise when we consider global warming is: How much ice is the global warming going to melt?. How fast is this going to happen?. How fast could the sea level rise? As Kunzig and Broecker put it on his last book “Fixing Climate”: “If one of the large ice sheets becomes unstable, the rise would come uncomfortably fast!”...
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What do I mean? That the big melting has already begun? What is really happening? Let’s put ourselves into context and review what the evidences are telling us before answering those questions….
What do I mean? That the big melting has already begun? What is really happening? Let’s put ourselves into context and review what the evidences are telling us before answering those questions….
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To be continued……
To be continued……
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Bibliografía:
Alley R. B, The Younger Dryas cold interval as viewed from central Greenland. Quaternary Science Reviews 19 (2000) 213} 226.
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Kunzig. R & Broecker. W.,2008. “Fixing Climate”. Publisher: Farrar, Straus and Giroux. Pub. Date: April 2008.
Kunzig. R & Broecker. W.,2008. “Fixing Climate”. Publisher: Farrar, Straus and Giroux. Pub. Date: April 2008.
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Weather forecast section, Sunday times, N9, 622, Februabry 1, 2009.
Weather forecast section, Sunday times, N9, 622, Februabry 1, 2009.
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