The Modern Antiquarian. Ancient Sites, Stone Circles, Neolithic Monuments, Ancient Monuments, Prehistoric Sites, Megalithic Mysteries

Head To Head   The Modern Antiquarian   General Discussion Forum Start a topic | Search
The Modern Antiquarian
Re: OT: Government's attitude to green energy
80 messages
Select a forum:
First of all, my apologies to the forum if this is straying too far from its' remit. This argument has reared it's spiky head repeatedly on the U-know forum, clearly without moving anyone forwards, since the same protagonists are asserting the same assertions now, regardless of the strength and veracity of any rebuttals.

A sceptic should have an open mind, surely, yet many "sceptics" are as entrenched in their beliefs as any tree-hugging eco zealot.

My own, laymans' take on things is thus:

The Earth's climate changes naturally.

These changes can result in radical changes to the overall biosphere.

The amount of temperature change required to bring about radical change is generally only a few degrees in either direction.

For example, the average global temperature during the last ice age was between 3 and 6 degrees centrigrade less than today.

When these changes occur over thousands of years, flora and fauna have time to adapt and evolve.

The datasets appear to show that global average temperatures are changing by an equal magnitude, but over a period of just a couple of centuries.

Generally such rapid and profound changes are associated with major global events such as major vulcanism and extra-planetary impacts.

Such impacts tend to be one-offs, and negative feedback mechanisms tend to return things to an equilibrium.

A negative feedback mechanism acts to limit change.

An example of one is a thermostat.

As a room cools, the thermostat clicks, and heat is fed in. As the room warms, the thermostat turns the heat off.

In nature, a simple example of a negative feedback loop is this:

The Earth is largely covered by water. If it warms, the water will evaporate more quickly. This will lead to more clouds. More clouds increase the amount of sunlight being reflected back into space. The earth cools. Water evaporates more slowly. This leads to less clouds...

There is also positive feedback.

The classic example of this is when you put a microphone next to a loudspeaker.

The microphone picks up any air vibration and it is amplified by the loudspeaker, giving the microphone more vibration to send to the loudspeaker.

In nature too, positive feedback mechanisms occur.

A comparative example to the other feedback example above is as follows:

A warmer climate will cause the extent of sea ice to diminish. Ice is more reflective than water. More water and less ice will cause the earth to absorb more solar energy. This will cause an increase in temperature, which will lead to further ice loss.

I'm trying to generalise here obviously, but as far as I understand things, climatologists believe there is a tipping point, where positive feedback effects overwhelm the natural tendencies towards stability, and large changes occur until a new equilibrium is reached.

Whether there is scientific consensus on this issue? Well that's political that is. The British Antarctic Survey support the IPCC's position.

They say:

BAS wrote:
Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level.


BAS wrote:
Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in human-induced greenhouse gas concentrations.

And since the IPCC's reposrt in 2007, their position has become even more unequivocal.

BAS wrote:
Since this last Assessment Report the scientific evidence for dangerous, long-term and potentially irreversible climate change caused by human activity has strengthened significantly. Recent research, not available at the time AR4 was published, has shown that it is likely that human activity has contributed to climate change in Antarctica, as well as over the other continents.

I find it hard to believe they are making such statements because they want to flog some wind turbines.

Reply | with quote
Posted by PMM
24th November 2011ce

Messages in this topic: