The Global Warming Myth

With reference to the ecological footprint (i.e., ecological impact) of humans, your friend is way off. Here's a simplified calculation I did awhile back. The ecological footprint of the average American - using us as the standard for “developed world” - as keresu noted is approx. 1.5 ha (3.5 acres) per person at a minimum. For this simplified calculation, ecological footprint only considers food and forest product consumption, and the inevitable degradation due to waste, living accommodations, etc. I’ve read estimates up to 10 ha (24.5 acres), but let’s go with the low number. If we were to raise the developing world to US consumption standards (assuming a current population of 6 billion, zero population growth, etc), that would mean we would require 9 billion ha (22.05 billion acres) of combined prime agricultural land, pasture, and forest. The Earth currently has approx. 8.9 billion ha (21.9 billion acres) of ecologically productive land - much of it marginal. IOW, even if we exploited every single available hectare of land, the Earth simply can’t support a planet-wide developed world with the ecological footprint of an average American (figures derived from Palmer AR 1999, Ecological Footprint and Carrying Capacity). Note that this calculation doesn’t even address the environmental costs except in the abstract. I don't know where he got the 1.4% figure, but that's way off. The US alone accounts for the gross output of almost 5% of the earth's primary productivity. Add in the industrialized nations of Western Europe, and we are looking at approximately 19% already - without factoring in the other 5 billion inhabitants.Translating that into CO₂ emission is problematic. Actually, CO₂ emission is only part of possible anthropogenic input into atmospheric change - we need to factor in the much more damaging methane emissions (from factories, coal burning, cow flatulence - not joking, all those hamburgers McDonalds sells have an ecological cost), as well as the net change in the Earth's albedo from deforestation (which would have the opposite effect of global warming).

Once again, kuresu is correct. One of the potential problems with global warming is the possibility that an influx of cold, fresh water from melting polar caps could disrupt the "Atlantic conveyor". In a nutshell, normally cold, dense water from the North Polar icecap flows southwest along the Atlantic coast of North America. It slowly warms as it approaches the tropics. There is an inversion that occurs near the equator as the now warmer water rises and due to the coriolis effect of the Earth's rotation, begins to flow eastward (here it is known as the Gulf Stream). This warm tropical water strikes the European landmass, and flows north along the surface. The current is one of the key climate modifiers for Western Europe, including the UK. Fresh water is less dense than salt, so the concern is that a massive influx of cold, fresh water may disrupt this current at its northern inversion zone, either pushing it southward or even disrupting it completely (something that has apparently happened in the past). If that happens, some extreme predictions indicate that the average temperature in northwestern Europe (including the UK, France, etc), may drop as much as 10C. These are approximately the same temperatures that were prevalent at the Last Glacial Maxima 18-20,000 years ago. North American temperatures will drop a bit less (they already get cold winters). In short, Scotland and Ireland may become uninhabitable, and the UK and northern France would have a climate similar to Labrador or even Greenland.Not a pretty thing to contemplate - especially since it could happen relatively rapidly (decades, not centuries). The concensus seems to be that there is a threshold beyond which things will snowball (sorry, couldn't resist). Some of the more alarmist modelers are saying that it may already be happening (a "slow down" in the conveyor by ~30% between 1957 and 2004 was recently reported in Nature - Bryden, H.L., et al., 2005, "Slowing of the Atlantic meridional overturning circulation at 25N", Nature, 438:655-657).

Well, the best evidence I've seen indicates that CH₄ constitutes almost 25% of the current greenhouse effects (about 70% of current methane emissions are anthropogenic). There are two pieces of good news on this front, however. 1) Methane emissions in the developed world (North America and Western Europe) have actually declined over the last 10-15 years. In addition, there was a whopping decrease in atmospheric methane emission following the collapse of the Soviet Union. 2) Methane is relatively volitile, and breaks down after about a decade. Now for the bad news: there is roughly 3000 times the current level of methane locked up in methane hydrates - part or all of which could be released if global warming causes a melting of permafrost and/or rises in sea levels. Talk about a runaway heat wave!In any case, I'm not overly surprised your farmers in NZ were upset about the idea of taxes. In their favor, sheep farts are not considered to be a significant contributor - cattle and rice farming are the greatest culprits, followed by non-anthropogenic emissions from wetlands, and then most of the other anthropogenic sources (mining, natural gas extraction, burning biomass, waste treatment, etc).

There are a number of technical studies available from Nature and Science, but those mostly require expensive subscriptions. Here's a pretty handy site from U. of Oregon that has some very nice graphics. National Academy Press has a couple of good "primers" on climate change: Surface Temperature Reconstruction for the last 2000 years, and Climate Change Science: An Analysis of Key Questions. Another book you might enjoy is Understanding and Responding to Multiple Environmental Stresses. Although not specifically about global warming, it does take into consideration climate change as a factor. Interesting read. I of course have an opnion . Unfortunately, I don't have much to back it up. I strongly favor reforestation - as long as it is done in the context of either rebuilding a natural ecosystem OR analog/silvopastoral agroforestry. Mature forest IMO is substantially more likely to perform the duties of carbon sink than either a forestry monoculture (as was done in Costa Rica) or pasturage.

I realize it wasn't really fair of me to dismiss your request for links by pawning them off (laziness) on Science, etc. So I dug around the Proceedings of the National Academy of Sciences (which is kind enough to publish their full text articles on-line for those of us too cheap to buy a subscription to Nature). So here are a few more general technical papers:Hansen J, et al, 2000, “Global warming in the twenty-first century: An alternative scenario”, PNAS 97: 9875-9880Friedlingstein P, et al, 2005, “Contributions of past and present human generations to committed warming caused by carbon dioxide”, PNAS 102: 10832-10836Hansen J, et al, 2006, “Global temperature change”, PNAS 103: 14288-14293And one that has a good discussion of CH₄, West JJ, et al, 2006, “Global health benefits of mitigating ozone pollution with methane emission controls”, PNAS 103: 3988-3993 Heh. Half of my job consists in convincing local farmers, etc, that they can increase yields by doing some basic agroforestry, silvopasture, or other reforestation processes using native species. I still haven't gotten anyone to bite on trying an analog forestry project yet - maybe someday.