User:Greg Harris/Climate change
The account of this former contributor was not re-activated after the server upgrade of March 2022.
Climate change is best summed up with one word: inevitable.
As a boy, I remember seeing articles about the large global warming that had taken place between 1900 and 1945. No one understood or knew if this warming would continue. Then the warming abated and I heard little about such warming through the late 1940s and into the 1970s. In fact, surface measurements showed a small global cooling between the mid-1940s and the early 1970s. During the 1970s, there was speculation concerning an increase in this cooling. Some speculated that a new ice age may not be far off. Then in the 1980s, it all changed again. Nearly all of my colleagues who have been around 40 or 50 years are skeptical as hell about this whole global-warming thing. But no one asks us. If you don’t know anything about how the atmosphere functions, you will of course say, “Look, greenhouse gases are going up, the globe is warming, they must be related.” Well, just because there are two associations, changing with the same sign, doesn’t mean that one is causing the other. [0]
Professor William Gray, Colorado State University, Atmospheric Science and Tropical Meteorology Expert
The climate of the Earth is not static, nor has it ever been. It is a dynamic result of competing forces, some of which are somewhat regular and predictable. Other contributors are seemingly random, even chaotic. We cannot ignore clear geologic records of unique events such as catastrophic impacts and titanic eruptions which had signficant influence. Still, it is clear there are self-limiting factors at play, also known as negative feedback loops. Proof of this is found in the fact that we know the Earth has been both hotter and much colder than it is today. Without stabilizing feedback processes the climate, once it entered one of these proven past states of excess warmth or cold, could not have recovered and life as we know it certainly would not exist.
When it comes to climate, what is the norm? During the past 600 million years the Earth experienced climate changes that included conditions signficantly warmer and colder than what we now enjoy. NASA points out that the norm for most of this time was a warmer climate than we know today [1] even though, on a very much shorter timescale, we seem to be in a colder period that features long ice ages and short interglacial periods such as that we are experiencing now. In fact it is precisely because we are in an interglacial and recovering from the last unusual cooling event [2] that current global temperatures are clearly below any reasonable "normal" and rising steadily towards it, obviously for a good reason.
Part of what makes it so difficult to keep thigs in context comes from errors in presentation. As we know, media sources tend to sensationalize things, don't always tell the whole story and sometimes miss or mutilate key facts. One good example is the fact that the current polar icecaps are oddities based on an unusual arrangement of landforms. They would not exist but for these accidents in geography. [3] This doesn't stop the media from overreporting the fact that the northern hemisphere summer of 2007 featured allegedly extreme melting of northern polar ice coupled with dire predictions that the Northwest Passage would soon be open "for the first time" and reports that soon the polar bear could vanish entirely even though the species managed to survive past known periods of significantly greater warmth and less polar ice. What the media failed to report was that this allegedly unusual arctic melting was due to known unusual conditions of wind and ocean currents, that it is only unusual over the short time we've actually had any real idea of the actual extent of arctic ice since we've had modern satellite based observation and measurement systems and that even as the northern ice was melting to a new record the southern ice froze to a new record extent, suggesting that all we were seeing was a north-south climate oscillation. Any unusual warmth in the arctic was apparently balanced if not exceeded by cold down south in the antarctic. The media also failed to do adequate research for their reports as the Northwest Passage has been navigated in both directions within the last 110 years [4] and clearly must have been open prior to that or else why would rumors of it's existence have driven those who searched for it for hundreds of years?
If you believe all the present day media hype then you are certainly convinced that our current climate is unusually warm and our current weather is unusually bad. Fortunately that is not the case. In fact neither assertion is correct according to hudreds of peer reviewed studies. [5]
The one thing that emerges from all attempts to reconstruct and study past climate is that climate chage is indeed inevitable. A recent study confirmed that the Little Ice Age and the Medieval Warm Period were clearly global events despite attempts by some to suggest otherwise. This study showed that all sampled sites registered temperatures warmer than those we see today during the Medieval Warm Period. [6]
Is there an "optimum" climate and if so how does our current climate rate? One thing that seems relatively certain, based on historic accounts as well as geologic studies, is that cooler tends to be worse and warmer tends to be better overall, although each condition has it's advantages and drawbacks. Compare and contrast what we know about the Little Ice Age [7], when life was hard and humans struggled to survive, with the Medieval Warm Period, when climate improved to allow thriving settlements in Greenland and Iceland as western civiilization thrived throughout Europe. [8]
This leads one to question the current popular trend towards catastrophic anthropogenic climate change alarmism. If one starts from the contention that warmer is generally better, as suggested by historical, geological and paleological evidence, rather than the automatic belief that change is bad, suddenly a little global warming doesn't seem like such a terrifying thing. This line of thinking is supported by peer reviewed research that shows a warming Earth is a greening Earth. [9]
Causes of Climate Change
We know that there are significant natural causes of climate change. These include, but are not necessarily limited to:
Changes in the luminous output of the sun which directly control how much solar radiation reaches the Earth [10] Changes in the magnetic field of the sun which affect cloud formation and directly affect both reflection and retention of potentially warming solar radiation and reflected long wave heat radiation. [11] Milankovitch cycles - changes in the orbital eccentricity, obliquity and precession - all of which influence the amount and effect of solar radiation that hits the Earth. [12] Continental drift that changes the patterns of atmospheric and oceanic circulation. [13] The "greenhouse effect" of water vapor in the atmosphere. [14] Major volcanic eruptions, which curiously release large quantities of allegedly potent greenhouse gasses over a short time yet have a net cooling effect due to other factors [15], [16] Changes in the albedo of the Earth, both in the atmosphere [17] and on the surface. [18]
Effects of Climate Change
One clear result of climate change is a noted greening of the Earth. [9] Another obvious effect of climate change involves sea level changes for multiple reasons. As recently as 18,000 years ago global sea levels were approximately 410 feet (125 meters) lower. [19] Despite alarmist warnings of dire increases in sea levels with catastrophic results, research suggests the Earth has ways of coping with sea level changes. [20] Some suggest that storms, in particular tropical storms, will get worse yet observational evidence and peer reviewed literature suggests otherwise. [21], [22], [23], [24]
References
0. http://news.bbc.co.uk/2/hi/in_depth/sci_tech/2000/climate_change/1023334.stm and http://discovermagazine.com/2005/sep/discover-dialogue/
1. http://www.giss.nasa.gov/research/paleo/
2. http://www.bbc.co.uk/weather/features/understanding/iceage_01.shtml
3. ibid
4. http://www.athropolis.com/map9.htm
5.
6. http://www.ingentaconnect.com/content/mscp/ene/2007/00000018/F0020007/art00011;jsessionid=1t2nxpeb06668.alexandra?format=print&token=004b17b0ba545ac3f6a4b4b6e6e42576b642738687b76504c48766a70453a44467b6c386f2c
7. http://www2.sunysuffolk.edu/mandias/lia/little_ice_age.html
8. http://www2.sunysuffolk.edu/mandias/lia/vikings_during_mwp.html
9. http://www.unc.edu/~aaronm/MS/Global.pdf
10. http://www.agu.org/revgeophys/reid00/node2.html
11. http://public.web.cern.ch/PUBLIC/en/Spotlight/SpotlightCloud-en.html
12. http://earthobservatory.nasa.gov/Library/Giants/Milankovitch/
13. http://www.geosc.psu.edu/Courses/Geosc320/Campbell_Cont_Drift_Climate.pdf
14. http://physicsworld.com/cws/article/print/17402
15. http://www.atmos.umd.edu/~owen/CHPI/IMAGES/volceff.html
16. http://pubs.usgs.gov/of/1997/of97-262/of97-262.html
17. http://www.physicalgeography.net/fundamentals/7f.html
18. http://visibleearth.nasa.gov/view_rec.php?id=3411
19. http://www.discoverourearth.org/student/sea_level/index.html
20. Snowfall-Driven Growth in East Antarctic Ice Sheet Mitigates Recent Sea-Level Rise; Curt H. Davis, Yonghong Li, Joseph R. McConnell, Markus M. Frey, Edward Hanna; http://www.nasa.gov/pdf/121648main_ais2.pdf
21. http://www.aoml.noaa.gov/hrd/Landsea/reply_globwarm.pdf
22. http://www.weatherstreet.com/hurricane/2006/hurricane-atlantic-2006-below-normal-season.htm
23. http://www.coaps.fsu.edu/~maue/tropical/
24. http://www.marshall.org/pdf/materials/465.pdf
--Greg Harris 02:47, 31 January 2008 (CST)