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| Feb 2 2010, 12:21 PM EST | paul.alexander | 826 words added |
| Feb 2 2010, 11:29 AM EST | paul.alexander |
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Paul Alexander
Climatologist
Univeristy College Dublin.
"Climate Change and Dublin" - Adapted from Talks at local Schools / Residency meetings, Dublin 15.
__________________________________________________________________________________________________________________________________
Global Climate Change is undoubtabily one of the most (if not the most) talked about, contested, and most challenging issue of our time.
It encroaches on every facet of live as we know
The term "Climate Change" almost instantly sparks questions, and similtaneously, debates on the answers when really there is nothing wrong with the term itself, nor is there anything wrong with the even less popular term "Global Warming".
The Climate does change: it changes all the time: every second, every minute, every hour, every day, every month, every year, century and millienum the climate is constantly in flux: it is ever changing, it is simply a matter of "what scale?" over (/) "what time?".
From microscale / short time (minor precipitation increases/decreases over a day) to macroscale / long time (Global changes in temperature, glacier formation).
Our planet is intimately linked with the Sun, life has thrived and diminshed based on the amount of solar radiation we recieve from it. This is the first thing to note in relation to this issue: that our planet goes through cycles of warm and cool periods controlled primarily by access to solar radiation, but has little to do with the amount of solar radiation emmitted by the sun - rather it has to do with the Earth's tilt and the Earth's orbit.
Everyone is aware of this: In Ireland we have distinct climatic seasons, four of them.
Summer, winter, spring and autumn represent orbitially related climatic changes induced by a change in our access to solar radiation -only marginal in scale and marginal in time. Seasons are far less distinct around the equalatorial zones.
Changes in our orbit were identifed by an Astronomer Milutin Milankovitch. He developed mathematical formulas upon which orbital variations are based, thus they became know as "Milankovitch-Cycles" or "M-Cycles" for short.
Picture a perfect circle, at the dead centre sits a large dot representing the sun, on the line of the circle itself, a smaller dot, representing earth - the line itself, represents our orbit around the sun. In this configuration, every side of earth gets some access to solar radiation depending on its location in orbit throughout our orbital cycle (one year).
Now we re-draw the configuration: All the intital elements are there, the sun, the earth and the orbit, but instead of placing the sun in the centre of the circle, we move it to the left-centre. So, for 1 season, one side of earth is going to get scorched, for 2 seasons, the status quo is maintained, and for the last season, things are going to get colder. A lot colder.
Now we re-draw the configuration again: Again all the intial elements are there, but this time we don't draw a perfect circle, we draw say, an elliptical shape (just imagine getting a squishy ball and pressing it flat down onto a table) - now everything is pretty messy, but for simplity lets say this orbital pattern means we get winter like conditions for 3/4 of the year, and about 1/4 of the year relief.
This underpins everything on earth as we know, Ice Age to Inter-Ice Age and back again, i.e. from cold spells, to warm spells, and back again.
The last cold spell began around 30,000 years ago and, in Ireland's neighbourhood, caused the Arctic ice to descend from the North Pole towards Europe. By 20,000 years ago Ireland was almost totally covered by a thick ice sheet stretching south-west from Scotland. Over the next 2000 years the expansion of the ice slowed, reached equilibrium and then began to retreat. By 15,000 years ago only Ulster was still buried under the dying ice sheet. Although the rising sea levels had begun to flood the lower lands, a land bridge still connected the south-eastern tip of Ireland to south-western England. Trapped between this land bridge, and the ice sheet in the north, the Irish Sea was filled forming a vast freshwater lake. It was at this time that the first plant life returned to reclaim the rocky wilderness that Britain and Ireland had been reduced to. First rugged grasses coated the land and, around 13,000 years ago, the first trees (hardy Junipers) began to grow.
Many animals, including the Giant Deer, crossed into Ireland across the land bridge and since then, homo-sapiens have flouristed and grown.
(Last edit 02/02/2010) - Next Update: 03/02/2010
Climatologist
Univeristy College Dublin.
"Climate Change and Dublin" - Adapted from Talks at local Schools / Residency meetings, Dublin 15.
__________________________________________________________________________________________________________________________________
Global Climate Change is undoubtabily one of the most (if not the most) talked about, contested, and most challenging issue of our time.
It encroaches on every facet of live as we know
- It is in our politics - Our most recent example being the COP-15 meetings
- It is in our media - Rarely a day goes by without news of a weather event deemed to be "out-of-the-ordinary" by news reports
- It is in our popular culture - I can wager that 1 in 2 of you reading this will have at some point seen the movie "The Day After Tomorrow" and/or "An inconvient Truth"
The term "Climate Change" almost instantly sparks questions, and similtaneously, debates on the answers when really there is nothing wrong with the term itself, nor is there anything wrong with the even less popular term "Global Warming".
The Climate does change: it changes all the time: every second, every minute, every hour, every day, every month, every year, century and millienum the climate is constantly in flux: it is ever changing, it is simply a matter of "what scale?" over (/) "what time?".
From microscale / short time (minor precipitation increases/decreases over a day) to macroscale / long time (Global changes in temperature, glacier formation).
Our planet is intimately linked with the Sun, life has thrived and diminshed based on the amount of solar radiation we recieve from it. This is the first thing to note in relation to this issue: that our planet goes through cycles of warm and cool periods controlled primarily by access to solar radiation, but has little to do with the amount of solar radiation emmitted by the sun - rather it has to do with the Earth's tilt and the Earth's orbit.
Everyone is aware of this: In Ireland we have distinct climatic seasons, four of them.
Summer, winter, spring and autumn represent orbitially related climatic changes induced by a change in our access to solar radiation -only marginal in scale and marginal in time. Seasons are far less distinct around the equalatorial zones.
Changes in our orbit were identifed by an Astronomer Milutin Milankovitch. He developed mathematical formulas upon which orbital variations are based, thus they became know as "Milankovitch-Cycles" or "M-Cycles" for short.
Picture a perfect circle, at the dead centre sits a large dot representing the sun, on the line of the circle itself, a smaller dot, representing earth - the line itself, represents our orbit around the sun. In this configuration, every side of earth gets some access to solar radiation depending on its location in orbit throughout our orbital cycle (one year).
Now we re-draw the configuration: All the intital elements are there, the sun, the earth and the orbit, but instead of placing the sun in the centre of the circle, we move it to the left-centre. So, for 1 season, one side of earth is going to get scorched, for 2 seasons, the status quo is maintained, and for the last season, things are going to get colder. A lot colder.
Now we re-draw the configuration again: Again all the intial elements are there, but this time we don't draw a perfect circle, we draw say, an elliptical shape (just imagine getting a squishy ball and pressing it flat down onto a table) - now everything is pretty messy, but for simplity lets say this orbital pattern means we get winter like conditions for 3/4 of the year, and about 1/4 of the year relief.
This underpins everything on earth as we know, Ice Age to Inter-Ice Age and back again, i.e. from cold spells, to warm spells, and back again.
The last cold spell began around 30,000 years ago and, in Ireland's neighbourhood, caused the Arctic ice to descend from the North Pole towards Europe. By 20,000 years ago Ireland was almost totally covered by a thick ice sheet stretching south-west from Scotland. Over the next 2000 years the expansion of the ice slowed, reached equilibrium and then began to retreat. By 15,000 years ago only Ulster was still buried under the dying ice sheet. Although the rising sea levels had begun to flood the lower lands, a land bridge still connected the south-eastern tip of Ireland to south-western England. Trapped between this land bridge, and the ice sheet in the north, the Irish Sea was filled forming a vast freshwater lake. It was at this time that the first plant life returned to reclaim the rocky wilderness that Britain and Ireland had been reduced to. First rugged grasses coated the land and, around 13,000 years ago, the first trees (hardy Junipers) began to grow.
Many animals, including the Giant Deer, crossed into Ireland across the land bridge and since then, homo-sapiens have flouristed and grown.
(Last edit 02/02/2010) - Next Update: 03/02/2010
