What are the primary forcings of the Earth system? - NASA Science
According to scientists' models of Earth's orbit and orientation toward the Sun indicate that our world should be just beginning to enter a new period of cooling -- perhaps the next ice age.[Via Tucson Citizen]
However, a new force for change has arisen: humans...
Other important forcings of Earth's climate system include such "variables" as clouds, airborne particulate matter, and surface brightness. Each of these varying features of Earth's environment has the capacity to exceed the warming influence of greenhouse gases and cause our world to cool.
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2 comments:
"According to scientists' models of Earth's orbit and orientation toward the Sun indicate that our world should be just beginning to enter a new period of cooling -- perhaps the next ice age."
Looks like NASA stepped in it again.
Published science begs to differ. According to this paper:
"with or without human perturbations, the current warm climate may last another 50,000 years. The reason is a minimum in the eccentricity of Earth's orbit around the Sun."
SBVOR, you are referring to Loutre and Berger's 2002 or 2003 papers which were soundly trounced by Lisieki and Raymo's 2004 paper in Oceanography. Since the beginning of the Northern Hemisphere Glaciation (NHG), there hasn't been an interglacial which lasted more than 20-32k years (quoting here the range for MIS-11 from many papers on that interglacial).
Here's the seminal quote from Lisieki and Raymo (2004):
"Recent research has focused on MIS 11 as a possible analog for the present interglacial [e.g., Loutre and Berger, 2003; EPICA community members, 2004] because both occur during times of low eccentricity. The LR04 age model establishes that MIS 11 spans two precession cycles, with 18O values below 3.6h for 20 kyr, from 398-418 ka. In comparison, stages 9 and 5 remained below 3.6h for 13 and 12 kyr, respectively, and the Holocene interglacial has lasted 11 kyr so far. In the LR04 age model, the average LSR of 29 sites is the same from 398-418 ka as from 250-650 ka; consequently, stage 11 is unlikely to be artifcially stretched. However, the June 21 insolation minimum at 65 N during MIS 11 is only 489 W/m2, much less pronounced than the present minimum of 474 W/m2. In addition, current insolation values are not predicted to return to the high values of late MIS 11 for another 65 kyr. We propose that this effectively precludes a "double precession-cycle" interglacial [e.g., Raymo, 1997] in the Holocene without human in influence."
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