Mankind Is the Main Cause of Global Warming

I thank Sabutai for letting me part of this debate. I have only just seen the part of the Round 2 requirements which includes the terminology "no rebuttals by Pro", which I do consider somewhat odd being that Con has provided material which I believe probably does deserve an immediate response in order to give Con time to revise or clarify certain parts of his argument. Still, I do have enough in my arsenal for me to present a better case than what Con presents for my case that humans are indeed the main cause of global warming. Let us begin: Agriculture Something that people are not so aware of with regards to global warming is the contribution of agriculture - which is to say livestock and farming - which is third in the world for CO2 emissions. CO2 isn"t even the leading GHG emission from farming, as methane is the major contributing by-product. It is huge (1). To quote: "In 2010, global greenhouse gas emissions from the agricultural sector totaled 4.7 billion tons of carbon dioxide (COv(2)) equivalent, up 13 percent over 1990. Agriculture is the third largest contributor to global emissions by sector, following the burning of fossil fuels for power and heat, and transportation. In 2010, emissions from electricity and heat production reached 12.5 billion tons, and emissions from transport totaled 6.7 billion tons. Despite their continuing rise, emissions from agriculture are growing at a much slower rate than the sector as a whole, demonstrating the increasing carbon efficiency of agriculture. From 1990 to 2010, the volume of agricultural production overall increased nearly 23 percent, according to data compiled by the United Nations Food and Agriculture Organization (FAO) for its program, FAOSTAT. FAO released a new Greenhouse Gas Emissions database for agriculture, forestry and other land use changes in December 2012, which can be found here (http://www.fao.org...). According to FAO, methane accounts for just under half of total agricultural emissions, nitrous oxide for 36 percent, and carbon dioxide for some 14 percent. The largest source of methane emissions is enteric fermentation, or the digestion of organic materials by livestock, predominantly beef cattle. This is also the largest source of agricultural emissions overall, contributing 37 percent of the total." There is, quite simply, no way that this much methane and nitrous oxide are from natural causes, and the fact that 50%of the earth"s surface is given over to farm and grazing land means a huge loss of forest, which serves as a carbon sink(the main sink is the oceans, however), so combined deforestation plus emissions from agriculture are man made. The amount of Arctic Ice Loss This is now greater than it has been in 3 million years, and this absolutely cannot be said to be from natural causes. To quote (2): "The thaw and release of carbon currently frozen in permafrost will increase atmospheric CO2 concentrations and amplify surface warming to initiate a positive permafrost carbon feedback (PCF) on climate". [Our] estimate may be low because it does not account for amplified surface warming due to the PCF itself". We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42-88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO2 concentration. The permafrost permamelt contains a staggering "1.5 trillion tons of frozen carbon, about twice as much carbon as contained in the atmosphere, much of which would be released as methane. Methane is 25 times as potent a heat-trapping gas as CO2 over a 100 year time horizon, but 72 times as potent over 20 years! One of the most conservative assumptions the study made, the lead author Dr. Kevin Schaefer confirmed in an email, is that all of the carbon would be released as CO2 and none as methane." And to quote from another study about the Arctic (3): " "The bad news is that there is a clear connection between temperature and the amount of sea ice. And there is no doubt that continued global warming will lead to a reduction in the amount of summer sea ice in the Arctic Ocean. The good news is that even with a reduction to less than 50% of the current amount of sea ice the ice will not reach a point of no return: a level where the ice no longer can regenerate itself even if the climate was to return to cooler temperatures," [lead author Svend] Funder says. " So chalk up another point for how influential mankind is in contributing to global warming. Deforestation This one is plainly simple (4), because according to CO2 NOW, we find the situation where forest loss contributes 9% to CO2 build up, and forests account for 26% of CO2 absorption, so deforestation has been a huge man made contributor as well. The reliability and enduring nature of the hockey stick graph According to the New Scientist article covering the 2006 report of the US National Academy of Science (5): "The report states: "The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1000 years. This conclusion has subsequently been supported by an array of evidence that includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators, such as melting on ice caps and the retreat of glaciers around the world". Most researchers would agree that while the original hockey stick can - and has - been improved in a number of ways, it was not far off the mark. Most later temperature reconstructions fall within the error bars of the original hockey stick. Some show far more variability leading up to the 20th century than the hockey stick, but none suggest that it has been warmer at any time in the past 1000 years than in the last part of the 20th century. ... Climate scientists, however, are only too aware of the problems (see Climate myths: It was warmer during the Medieval period), and the uncertainties were both highlighted by Mann's original paper and by others at the time it was published. ... The new reconstruction has been generated using two statistical methods, both different to that used in the original study. Like other temperature reconstructions done since 2001 (see graph), it shows greater variability than the original hockey stick. Yet again, though, the key conclusion is the same: it's hotter now than it has been for at least 1000 years. In fact, independent evidence, from ice cores and sea sediments for instance, suggest the last time the planet approached this degree of warmth was during the interglacial period preceding the last ice age over 100,000 years ago. It might even be hotter now than it has been for at least a million years. Further back in the past, though, it certainly has been hotter - and the world has been a very different place. The crucial point is that our modern civilisation has been built on the basis of the prevailing climate and sea levels. As these change, it will cause major problems." It is quite clear that all this evidence is very strong for the weight of man's influence in helping global warming along. I now hand back to Con. Sources: (1) http://www.worldwatch.org... (2) http://thinkprogress.org... (3) http://thinkprogress.org... (4) http://co2now.org... (5) http://www.newscientist.com...