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| Jan 20, 2010 8:24 am |
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That Human Activity is a Significant Cause of Global Warming. |
John Stephen Veitch
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Thomas Holford claims that:
"The burden of proof is on the AFFIRMATIVE proposition, and the AFFIRMATIVE position has not provided compelling, unambiguous evidence based on the scientific method and sound epistemological principles that human activity is a significant cause of global warming."
OK, let me see what I can find.
From my own experience, I like Reg can cite lots of evidence from my own life where human activity has severely impacted negatively on the environment. Regarding climate change I've seen that we have fewer days of snow now than when I was a child. Often zero snow days now, when there used to be a week or more. (NZ has a mild climate.) There is no doubt that the NZ glaciers are retreating, and have been doing so for at least 30 years. There is also evidence of birds changing habitat as it gets warmer.
The standard science as I understand it, fits very well with what I've seen with my own eyes. Global warming is occurring, and give then changes I've seen in New Zealand in the last 60 years I've every confidence that human beings are directly causing most of it.
So, what do scientists say?
From Climate Progress we get.
How do we really know humans are causing global warming?*
http://climateprogress.org/2008/02/11/how-do-we-really-know-humans-are-causing-global-warming/
Wikipedia:
Arctic Climate Impact Assessment, 2004.
"Human activities, primarily the burning of fossil fuels (coal, oil, and natural gas), and secondarily the clearing of land, have increased the concentration of carbon dioxide, methane, and other heat-trapping ("greenhouse") gases in the atmosphere...There is international scientific consensus that most of the warming observed over the last 50 years is attributable to human activities."
There are hundreds of scientific and quasi-scientific organizations that support that view.
Wikipedia quotes only FIVE (in some detail) that are said to nave neutral views.
"Statements by dissenting organizations
With the release of the revised statement[77] by the American Association of Petroleum Geologists in 2007, no remaining scientific body of national or international standing is known to reject the basic findings of human influence on recent climate change."
So apparently there are ZERO scientific bodies of "national or international" which support Thomas Holford's stance.
From http://www.skepticalscience.com
Empirical evidence that humans are causing global warming.
"Direct observations find that CO2 is rising sharply due to human activity. Satellite and surface measurements find less energy is escaping to space at CO2 absorption wavelengths. Ocean and surface temperature measurements find the planet continues to accumulate heat. This gives a line of empirical evidence that human CO2 emissions are causing global warming."
Wikipedia Again:
"The majority of climate scientists agree that global warming is primarily caused by human activities such as fossil fuel burning and deforestation.[2][3][4][5] The conclusion that global warming is mainly caused by human activity and will continue if greenhouse gas emissions are not reduced has been endorsed by more than 75 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries."
http://www.skepticalscience.com/
Empirical evidence that humans are causing global warming
http://www.skepticalscience.com/empirical-evidence-for-global-warming.htm
From the BBC.
"Dr Geoff Jenkins, of the UK Met Office's Hadley Centre for Climate Prediction and Research, said recently: "Over the last few decades there's been much more evidence for the human influence on climate.
"We've reached the point where it's only by including human activity that we can explain what's happening." "
An Information Statement of the American Meteorological Society
(Adopted by AMS Council on 1 February 2007)
"Why is climate changing?"
"Climate has changed throughout geological history, for many natural reasons such as changes in the sun’s energy received by Earth arising from slow orbital changes, or changes in the sun’s energy reaching Earth’s surface due to volcanic eruptions. In recent decades, humans have increasingly affected local, regional, and global climate by altering the flows of radiative energy and water through the Earth system (resulting in changes in temperature, winds, rainfall, etc.), which comprises the atmosphere, land surface, vegetation, ocean, land ice, and sea ice. Indeed, strong observational evidence and results from modeling studies indicate that, at least over the last 50 years, human activities are a major contributor to climate change.
Direct human impact is through changes in the concentration of certain trace gases such as carbon dioxide, chlorofluorocarbons, methane, nitrous oxide, ozone, and water vapor, known collectively as greenhouse gases. Enhanced greenhouse gases have little effect on the incoming energy of the sun, but they act as a blanket to reduce the outgoing infrared radiation emitted by Earth and its atmosphere; the surface and atmosphere therefore warm so as to increase the outgoing energy until the outgoing and incoming flows of energy are equal. Carbon dioxide accounts for about half of the human-induced greenhouse gas contribution to warming since the late 1800s, with increases in the other greenhouse gases accounting for the rest; changes in solar output may have provided an augmentation to warming in the first half of the 20th century.
Carbon dioxide concentration is rising mostly as a result of fossil-fuel burning and partly from clearing of vegetation; about 50% of the enhanced emissions remain in the atmosphere, while the rest of the Earth system continues to absorb the remaining 50%. In the last 50 years atmospheric CO2 concentration has been increasing at a rate much faster than any rates observed in the geological record of the past several thousand years. Global annual-mean surface temperatures are rising at a rapid rate to values higher than at any time in the last 400 (and probably in the last 1000) years. Once introduced in the atmosphere, carbon dioxide remains for at least a few hundred years and implies a lengthy guarantee of sustained future warming. Further, increases in greenhouse gases are nearly certain to produce continued increases in temperature. Such changes in temperature lead to changes in clouds, pressure, winds, and rainfall in a complex sequence of further effects.
Human activity also affects climate through changes in the number and physical properties of tiny particles (aerosols) suspended in the atmosphere, and through changes in the land surface. Aerosols arise from dust, sea salt, and air pollution. They absorb and redirect radiation emitted by the sun and Earth. They also modify the ability of clouds to reflect sunlight and to form precipitation. Most aerosols originating from human activity act to cool the planet and so partly counteract greenhouse gas effects; this effect will diminish as clean-air legislation leads to reduced emissions of fine aerosols. Stratospheric aerosols emitted by occasional large sulfur-rich volcanic eruptions can cause temporary (1–3 years) reductions in surface temperature. By contrast, carbon soot from wildfires and biomass burning warms the planet, so that decreases in soot would reduce warming. Aerosols have much shorter lifetimes in the atmosphere than most greenhouse gases and exhibit large regional variations in concentration and properties. A deeper understanding of their global and regional roles is a high priority for climate science.
Changes in the land surface also change the surface water and energy budgetsand act to redirect the incoming solar energy. Humans alter land surface characteristics through irrigation practices, removal and reintroduction of forests, agricultural changes to vegetative cover, reduction of soil water recharge by soil compaction, and modification of heat storage by cities and reservoirs. Many of these lead to changes in the reflectivity of the surface. Although net global effects are not expected to be large, such changes can have significant effects on regional and local climate patterns.
The interaction of all these effects on climate is complex. For example, decreases of stratospheric ozone have likely contributed to the recent contraction and intensification of the polar vortex around Antarctica, producing warming in the Antarctic Peninsula, the northern most peninsula that points toward South America, and cooling over Antarctica. As a further example, the east–west difference in U.S. temperature trends may be tied to the spatial patterns of global ocean warming, or to differences in aerosol distribution and effects, or to natural climate variations that affect atmospheric circulation, cloudiness, and precipitation within the nation. Accurate characterization of the influence of each of the greenhouse gases, of aerosols, of oceans and natural climate variability, and of land-surface influences, along with their combined effects, is a high priority for the climate science research community."
A links from Climate Progress.
http://climateprogress.org/2009/12/02/realclimate-gavin-schmidit-what-fraction-of-global-warming-is-due-to-human-causes-vs-natural-causes/
http://climateprogress.org/2009/08/17/positive-methane-feedbacks-permafrost-tundra-methane-hydrates/
I expect that none of this extensive evidence meets Thomas Holford's exacting standard of proof. Frankly that's not my problem. I'm more than satisfied that I stand on the scientifically valid side of the debate.
John Stephen Veitch; The Network Ambassador
Open Future Limited - http://www.openfuture.co.nz/
Innovation Network - http://veech-network.ryze.com/
Building an Open Future - http://openfuture-network.ryze.com/Private Reply to John Stephen Veitch (new win) |
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