Saturday, June 17, 2006

Finally it was time to bring a new article!
To view a good map to better visualise the topic discussed, go to:

Steaming hot or Cold Trouble ?
By Désirée Lucchese

‘Uncertainty about climate change is no longer to be an issue’.
This more or less paraphrases what several scientific bodies and institutions have recently come to agree, in other words:
Climate Change is happening and there is enough proof to back it up.
Now, it is time to tackle it!
Complexity aside, will the global climate be getting warmer or will we plunge into ice-cold times instead?

Last year, exceptional dry conditions (in Africa, Australia, UK), wet weather leading to floods (in Brazil, China), or simply freak temperature fluctuations (in USA, India, Japan, Poland, Romania, Russia) and snowstorms (in France, Switzerland and Italy) have been common headlines on international newspapers. And we do not even seem to be surprised anymore. Hurricane Katrina in particular, which devastated New Orleans in September last year, is probably one of the grimmest examples of the scale of vulnerability of urban areas, in light of little foresight.

But how to forecast the unpredictable?
If there is one highly uncertain science, it is climatology.
Geological patterns, Atmospheric Science and Ocean Science all come together in one of the biggest riddles of the XXI century:
where is the climate of our ‘spaceship earth’ heading to?

(Once more), I would like to stress how complex ecological systems, and their interactions, are in the environment. There is no algebraic sum as such as two processes combining together might cause an effect bigger than the expected (this is a synergy) and some processes might increment their very source (what is referred to as a positive feedback loop). In the latter case, this is what they mean when they say that CO2 rise is going to accelerate in a warmer climate: as the way CO2 is up-taken by plants and dissolved into the oceans is temperature-sensitive, then a warmer global climate would inevitably affect both CO2 concentrations being absorbed - by plants and oceanic sediments - and released into the atmosphere. In this last scenario, the IPPC (the intergovernmental panel on climate change) has estimated a temperature increase of 3 degree Celcius for the next 50 years, when earlier estimates were of 100 years.
This falls within out own generation!

three degrees temperature rise might not seem a lot to us, and we might as well welcome it if that will mean milder weather in the northern hemisphere, but what is 1 degree at the equator, researchers warn, might mean up to 6 degrees at higher latitudes, therefore affecting higher melting rates of Glaciers.

The Glaciers are already melting, we all know it as we also hear about conservationists’ fears about the present stress and speeding extinction of polar bear populations and alike.
but what about our coastal cities with the prospected rise of sea levels?
About 65% of the world’s population live on the coast.
Is now Katrina ringing a bell within us?

Should we not leave our cars in the garage, lobby for good (and proper) public transport & more cycling routes for healthy biking ?
We might as well want to turn lights off and consume less, thus slowing down that whole huge oil-machine that makes up our economies.
We seem to have heard all this before but are we really doing something about it or do we tend to put good deeds aside from our life priorities?

The point is ripe for me to throw another little pebble at you.
Now, what would you think if instead of getting warmer, our climate would become very cold? What if global warming would actually cause us to step into an early mini-ice age?

For many years in academia there has been an indication of some oceanic patterns that might trigger a mini ice-age as it did happen about 12,000 years ago when the Scandinavian forest turned into a Tundra.
more recently, this astonishing piece of news has also seeped into the public domain, but what does it really mean?
It refers to the deep ocean currents, a complex as well as obscure network of deep currents like the known ‘Ocean Conveyor Belt Circulation’, one of the most studied oceanic systems.
These deep oceanic currents store and transport vast amounts of heat, moisture and carbon around the globe thus influencing temperatures and weather around the world.

Heat absorbed in one location, say in the south Indian ocean, may be released to the atmosphere after thousands of kilometres, as far as the North Atlantic Ocean (see map). Such currents are driven by winds and by heat & salt concentrations that lead them to either remain shallow or sink when denser (warm water is lighter than salty water).

In the example of the North Atlantic Circulation, when the conveyor reaches the north Atlantic, laden with warm water rich in nutrients, the so called Gulf Stream becomes the very current that keeps Europe warm as it drifts on to reach Greenland and Norway while part of the conveyor sinks as it cools with northern temperatures.

However, there are some great changes, though still obscure, happening among deep currents. A team of researchers from the University of Southampton (UK), have reported a slowing down of the Atlantic Circulation by a astonishing 30% in the last decade only.

This can be explained by melting ice in the Artic that happen to dilute the salty water of the North Atlantic Current. In fact, when the Conveyor reaches the Northern hemisphere, laden with warm salty waters, it starts to cool down and therefore the heavier salty water sinks under lighter one to then drift partly in the Gulf Stream and partly back southward. The rising discharge of fresh water by artic river flows (due to ice melting) therefore dilutes the heavier salty water of the Conveyor and ultimately interferes with its sinking.

If the Conveyor stops then Europe, being deprived of its natural heating system, will plunge into a mini-ice age but , strikingly, in its wake the whole weather system and rainfall patterns would change globally.
In this case, a drop in temperature of 5 degrees Celsius would hit farming hard while rainfall patterns might exacerbate elsewhere, probably where already critical. Complexity is such that we can only make assumptions and no forecasts. Some researchers even maintain that cooler climate conditions might mitigate global warming.

However, if oceanic currents are to drastically change this would bear more far reaching implications.
Oceanic waters, by mixing through up-welling and sinking, happen to supply vital nutrients to the phytoplankton (the basis of ocean food chains); further, water not mixing would speed the saturation of upper waters with Carbon and this, in a positive feedback loop, would exacerbate global warming as the Oceans are already soaking up carbon - by forming calcareous sediments.

Caution is necessary particularly as, scientifically, there is still conflicting evidence, not all observations fit conclusions and we might as well consider unanticipated changes of currents.
After all, despite its paramount importance for global weather patterns, the North Atlantic Conveyor accounts for only 10% of the Ocean (New Scientist, april ’06).

No need to panic yet as Armageddon is not to be expected soon!
but once uncertainty over climate change has finally been lifted from disputes, shall we not give some earnest thought to what might be happening?

In Australia, the Southern Ocean deep currents, accounting for about 20% of the Ocean (CSIRO Marine Research), are also continuously monitored and seem to be warming and becoming less salty.
The Southern Ocean processes directly affect the Australian climate while, at the same time, feed into the upper & lower branches of the global Ocean Conveyor.

What is really happening deep down in our Oceans?
As the greek philosopher Eraclitus wrote, ‘Pantha Rei’ (everything flows): change is a natural part of our lives and, indeed, of our life-supporting system. The point is: are we heading towards a warmer, flooded and drier future or towards deep & cold trouble? END