johnsonma :
catswold :
They have not investigated natural causes. The vast bulk of all research, from the very beginning was directed solely at proving mankind was responsible. Very little research has ever been funded to search for natural mechanisms of warming…it has simply been assumed that global warming is manmade.
http://www.drroyspencer.com/global-warming-natural-or-manmade/
The fact is, there is very little evidence for human activity being the source of global warming. Nothing but an apparent correlation between the rise in CO2 levels and global temperatures and correlation is not the same as causation. The data they have only spans about 150 years everything else is through "proxies" which are inexact at best and sometimes contradictory, as in the case of the last 59 years of tree-ring data, which if included in the famous Michael Mann hockey-stick graph would have shown COOLING during a period that we know was warming.
Over the last 17 years, global temperatures have remained stable, but atmospheric CO2 levels have doubled--the proposed mechanism has failed.
A climatological database of 150 years is insufficient in a system that has been in constant flux over the past two-and-a-half billion years, with at least 5 major ice ages and long periods that were essentially ice-free--including at the higher latitudes. In fact, we are currently in the latest inter-glacial period, a time when temperatures naturally rise.
There is no evidence that man has any major effect on the planet's climate.
2010 had the hottest global temperature recorded
ever. Not only that but the sun has been in a cooling trend at yet we had the hottest year ever. What does that tell you? You say we do not account for natural causes but that is a complete fallacy. The only factor that has been observed that could possibly correlate with the rising temperatures is manmade CO2 output.
What about an internal cycle, perhaps from volcanoes or the ocean, that releases massive amounts of greenhouse gases? This wouldn't make sense either, not only because scientists keep track of volcanic and oceanic emissions of CO2 and know that they are small compared to anthropogenic emissions, but also because CO2 from fossil fuels has its own fingerprints. Its isotopic signature is depleted in the carbon-13 isotope, which explains why the atmospheric ratio of carbon-12 to carbon-13 has been going up as anthropogenic carbon dioxide goes up. Additionally, atmospheric oxygen (O2) is decreasing at the same rate that CO2 is increasing, because oxygen is consumed when fossil fuels combust.
Ice core samples give is a pretty good idea of what caused previous changes in the climate. None of those causation's are happening now. Instead the evidence all points to CO2. By all means, ignore the evidence if that is what you want to do.
In response to your link.
The Earth doesn't warm up because it feels like it. It warms up because something forces it to. Scientists keep track of natural forcings, but the observed warming of the planet over the second half of the 20th century can only be explained by adding in anthropogenic radiative forcings, namely increases in greenhouse gases such as carbon dioxide.
johnsonma :
I would be careful linking anything from Roy Spencer as well. It seems he has a nasty preposition to altering his data to fit his needs. The only way he can get published is by using journals that know nothing about the subject.
http://thinkprogress.org/climate/2011/07/29/282584/climate-scienists-debunk-latest-bunk-by-denier-roy-spencer/
Let me repeat,
There is very little evidence to indicate mankind is the primary source of climate change. Virtually all money invested in investigating climate change has been directed at proving man was the source. Natural causes have been almost completely ignored.
For any real scientist, the very first thought as to what is causing an apparent change in a natural system as hugely complex as climate would be to search for a natural cause, not an external cause.
Here are the hard facts. We have only about 135 years of actual global temperature data and some of that is pretty spotty in the beginning. AGW asserts an approximate 1°C increase between 1880 and 1997, when global warming ended. Proxies for temperature are only approximations and there is nowhere near the level of
precision one would need to proclaim that a rise of 1°C over a century is at all unusual.
Precision is one of the biggest stumbling blocks there is and it is simply ignored. You cannot attribute direct measurement precision to proxy data. Michael Mann's famous tree-ring divergence problem is illustrative. When Mann presented his famous hockey-stick to the world, he omitted telling anyone that his tree-ring proxy data cut off over the last several decades. The reason, the tree ring data showed global cooling during a time we know the earth was warming. Anyone wish to assert that these proxies are accurate to within 1°C? If they aren't, then everything that the AGW touts have asserted is wrong.
They have hence attempted to explain that away as being due to "global dimming." Wow, a brand new paradigm has suddenly been introduced from out of someone's posterior to explain away one of the most glaring flaws in the hypothesis of AGW/CC (there have been occasions of global dimming, most notably following volcanic eruptions like Pinatubo, but it is a temporary effect and global brightening has been occurring of late).
The main problem remains the fact that these so-called "scientists" are attempting to make epochal proclamations based on a century and a half of data and some "proxies," the accuracy of which is questionable and the precision of which is problematical.
As for your assertion that
"The only factor that has been observed that could possibly correlate with the rising temperatures is manmade CO2 output." Says who? If you don't look for it, how do you know it isn't there?
The climate is a hugely complex, chaotic system, far more complex than these scientists are willing to admit. They see surface phenomenon and then look for man-made causes virtually to the exclusion of nature. This just backfired on them over the Antarctic glacier melt, when it was discovered that the acceleration of melting was due, not to "global warming," but to magma migration beneath the ocean's surface heating the crust and melting the ice. http://www.utexas.edu/news/2014/06/10/antarctic-glacier-melting/
Finally, as for Dr. Roy Spencer . . . you're actually using ThinkProgress as an authoritative source? I mean, REALLY? Well, I'll just let Dr. Roy respond, if you dare to read it: http://www.drroyspencer.com/2011/07/fallout-from-our-paper-the-empire-strikes-back/
The data are "corrected," the models are "tweaked" with each new data set, the proxies are imprecise and merely approximations unsuitable for making projections or predictions, the "scientists" conspired to prevent skeptics from being allowed to publish, and every time a flaw is pointed out, the critic is attacked personally, lied about and another "explanation" (some would say crackpot hypothesis) pops up and the AGW Faithful just keep lapping up the Kool-Aid without taking the time to critically examine their explanations.
Whatever is happening out there, it has been observed on 6 or 7 other planetary bodies in the solar system, so it's doubtful that Uncle Chuck and his F-350 4X4 Dually with his camper bed cover and bass boat trailer attached, blasting hell-for-leather down the interstate had much to do with it.
The thing about chaotic systems, like the earth's climate is that they can go through long periods of apparent stability and then suddenly swing wildly along one axis for a while before returning to another period of apparent stability. That fact and the massive complexity of the entire "Gaia system"--the biosphere, climate, geology, etc--makes the unparalleled arrogance and certainty of the AGW advocates totally unwarranted and renders the entire question moot at this point until we can produce a better understanding of the entire system.
The law of unexpected consequences urges patience and better, more open research. Remember, science is never "settled" and anyone who makes that assertion has lost all credibility. If the debate is "over," then it's not science, it's politically motivated dogma.