January 05, 2006
|Climate Change May Take Tens Of Thousands Of Years To Dissipate||Environment|
Today's scariest news item has nothing to do with NSA wiretaps or the "war on terror". It's a study published today in Nature that has dire implications for global warming.
Scientists have found that a sudden warming period some 55 million years ago caused dramatic shifts in the world's ocean currents, causing climate shifts that stayed in place for tens of thousands of years. Such ocean current shifts have long been predicted by modern climate models and have begun to be observed. The Nature study shows that the effects may be very long-lasting indeed — for all practical purposes, permanent. AFP:
An extraordinary burst of global warming that occurred around 55 million years ago dramatically reversed Earth's pattern of ocean currents, a finding that strengthens modern-day concern about climate change, a study says.
The big event, the Palaeocene/Eocene Thermal Maximum (PETM), saw the planet's surface temperature rise by between five and eight degrees Celsius (nine and 16.2 Fahrenheit) in a very short time, unleashing climate shifts that endured tens of thousands of years. [...]
Before the PETM, deep water upwelled in the southern hemisphere; over about 40,000 years, the source of this upwelling shifted to the northern hemisphere and it took another 100,000 years before recovering completely.
What unleashed the PETM is unclear. Most fingers of blame point to volcanic eruptions that disgorged gigatonnes of carbon dioxide, or coastal reservoirs of methane gas, sealed by icy soil, that were breached by warmer temperatures or receding seas.
The huge temperature rise may have occurred within just a few thousand years, but as [study authors] Nunes and Norris point out, the effects were enduring and the lesson for humans today is clear.
"Modern CO2 input to the biosphere from fossil fuel sources is approaching that estimated for the PETM, raising concerns about future climate and circulation change," they warned.
"The PETM example shows that anthropogenic (man-made) forces may have lasting effects not only in global climate but in deep-ocean circulation as well." [...]
[The concentration of atmospheric CO2 is] 380ppm [parts per million] today, which is already the highest concentration of CO2 for 650,000 years.
The higher the level, the greater the risk that a vicious circle of global warming could be unleashed, inflicting potentially irreversible damage to Earth's climate system, scientists said. [Emphasis added]
People talk, rightly, about the need to consider the effects of our actions for seven generations to come. What this study shows is that our activities right now, today, may have effects that are felt for thousands of generations — for many, many times the length of recorded history to date.
Yet the Titanic steams blithely on. Where are the words to express the depths of our denial and irresponsibility?
Good thing I'll be dead by then.
Posted by: CATS at January 6, 2006 05:04 AM