What are some of the factors that affect
climate change:
Issues to consider: A) how fast do these factor change climate (rapid vs.
slow), and B) how do anthropogenic activities affect climate change.
- Atmospheric:
+ Carbon / Greenhouse effect
+ Sulfur dioxide
+ Methane
+ Particulate
+ Other
- Astronomic:
+
Milankovitch (d. 1958) cycles:
orbit shape, axis tilt (41,000 yr cycle), wobble of the axis (26,000 yr
cycle), orbit tilt (70,000 yr cycle)
The Wikapedia article about this ok. This accounts for the
˜40,000 - 100,000 yr cycle
of glacial periods.
+
sunspot activity (11 yr cycle):
more sunspots = warmer slightly sun (0.1% change)//solar maximum. Currently, we
are in a phase of greater solar flare activity. 2008 was a "low" year
within the cycle.
This sunspot variation (along with other factors) accounts for the Little Ice Age -- 1600 CE
The Wikapedia article about this ok. (Sunspots also cause the aurora
borealis and australis.)
+ where our solar system is in the
galaxy ( see http://news.bbc.co.uk/1/hi/sci/tech/2163646.stm)
- Geophysical:
+ plate tectonics
+ volcanic activity
+ ocean currents
| "This map shows the pattern of
thermohaline circulation.... This collection of
currents is responsible for the large-scale exchange
of water masses in the ocean, including providing
oxygen to the deep ocean. The entire circulation
pattern takes ~2000 years" but this is disputed and
may be as short as 30 years. |
Sources: Robert Simmon, Thermohaline
Circulation. Wikapedia. retrieved October 24, 2008
from
http://commons.wikimedia.org/wiki/Image:Thermohaline_Circulation_2.png
and from Explaining Rapid Climate Change: Tales from the
Ice, Earth Observatory. Retrieved October 24, 2008
from http://earthobservatory.nasa.gov/Study/Paleoclimatology_Evidence/paleoclimatology_evidence_2.html
This theory explaining this circulation was first proposed in an article by E. Boyle and A. Weaver,
1994. Conveying Past Climates. Nature. V 372, n.6501, p. 41
11/3/94).
Note: this circulation is not the same as
ocean currents, which
generally are cause by the wind and the Earth's rotation.
Perhaps, the best evidence for this changing climate occurred at the end of
the last glaciation.
A good
article about rapid climate change from NASA.
Ice Ages: Most articles list 4 major ice ages. Since the last
major ice age, glaciers have advanced (glacials) and retreated (interglacials)
on 40,000- and 100,000-year time scales. We are in an interglacial with
the last glacial period ending about 10,000 years ago. The Greenland and
the Antarctic icesheets are remnants of that glacial period. Apparently, during
the warm period around 2000 years ago (a thermal maximum), most glaciers melted dramatically.
See the glacial ages of the
Pleistocene.
