A few individuals and groups have queried Skeptical Science about a misleading and myth-filled climate page from PreventDisease.com. The page is actually a re-post of a document put together by amateur astronomer Gregg D. Thompson. We at Skeptical Science aim to please, so here we will examine the claims made in this document. Since it consists almost entirely of long-debunked myths, most of our response will consist of linking to existing rebuttals in the Skeptical Science database. Unfortunately, but unsurprisingly, the document contains no supporting evidence or references, so we will evaluate its arguments on their own merit (and lack thereof).
The document begins by making a number of irrelevant and misleading statements about human carbon dioxide (CO2) emissions. The three principle misleading statements and errors are:
"CO2 is less than a mere four 100ths of 1% [of the atmosphere]"
"Humans produce only 3% [of global CO2 emissions]"
"If the public were aware that man-made CO2 is so incredibly small there would be very little belief in a climate disaster"
These statements presume that anything that is present as a small proportion can have no effect, which is clearly nonsense. In reality, the percentages of CO2 in the atmosphere and of human CO2 emissions are irrelevant to the risk that those emissons pose. A very small proportion of arsenic in drinking water can be very dangerous, for example. 99% of the atmosphere is composed of non-greenhouse gases, so the entire greenhouse effect is caused by the remaining 1%
The second statement ignores the fact that although natural emissions are much larger than human emissions, the natural carbon cycle is in balance. Natural carbon sinks absorb more than natural carbon sources emit, and human emissions upset that balance. That's why humans are responsible for the 40% increase in atmospheric CO2 over the past 150 years.
"CO2 is a harmless, trace gas. It is as necessary for life - just as oxygen and nitrogen are. It is a natural gas that is clear, tasteless and odourless. It is in no way a pollutant."
They key to qualifying as a "pollutant" is whether it poses a threat to public health and welfare. CO2 clearly creates this threat through climate change, and thus qualifies as a pollutant. The fact that CO2 is colorless, tasteless, and odorless is completely irrelevant. The argument that CO2 is necessary for life, implying that it therefore can never cause harm, is nonsense. Water is equally necessary for life, but too much of it can be fatal.
"There is no proof at all [that CO2 causes a greenhouse effect]. The Intergovernmental Panel for Climate Change (the IPCC) has never produced any proof. There are, however the following proofs that it can’t cause a greenhouse effect."
The fact that CO2 is a greenhouse gas has been known for over a century. John Tyndall measured the CO2 greenhouse effect in laboratory experiments in 1859. To claim that there is no proof that CO2 causes a greenhouse effect is, to be blunt, a sign of extreme ignorance regarding basic climate science, and a red flag that Thompson and PreventDisease.com have not done their homework.
"It is true that CO2 can absorb heat a little faster than nitrogen and oxygen but it becomes no hotter because it cannot absorb anymore heat than there is available to the other gases. This is against the laws of thermodynamics."
If this argument were true, the greenhouse effect would not exist, which is obviously not the case. It has been debunked in The Greenhouse Effect and the 2nd Law of Thermodynamics.
"Even if CO2 levels were many times higher, radiative heating physics shows that it would make virtually no difference to temperature because it has a very limited heating ability. With CO2, the more there is, the less it heats because it quickly becomes saturated."
The document goes from arguing that CO2 is not a greenhouse gas, to arguing that the greenhouse effect does not exist, to arguing that the greenhouse effect exists, but atmospheric CO2 is saturated. The number of self-contradictions is rather appalling. Regardless, the atmospheric CO2 greenhouse effect is not saturated. Adding more CO2 to the atmosphere effectively adds more layers to absorb outgoing infrared radiation and re-emit some of it back towards the surface, increasing global warming.
"The planets Venus and Mars have atmospheres that are almost entirely CO2 (97%) yet they have no ‘runaway’ greenhouse heating effect. Their temperatures are stable."
The temperatures of Venus and Mars are stable because the amount of CO2 in their atmospheres is stable. A "runaway greenhouse effect" occurs when something warms the planet, triggering positive feedbacks which warm it further; however, even this does not mean the planet continues warming infinitely, forever. In fact, positive feedbacks do not necessarily lead to 'runaway warming'.
Venus appears to have undergone a runaway greenhouse effect long ago in its history, but has now stabilised. Venus is twice as hot as Mercury, despite being twice as far from the Sun, in large part because of the greenhouse gases in its atmosphere. And Mars isn't particularly hot because its atmosphere is thin and has little water vapor - another greenhouse gas.
"The geological record over hundreds of millions of years has shown that CO2 has had no affect whatsoever on climate. At times, CO2 was hundreds of times higher, yet there were ice ages."
CO2 is not the only factor which impacts global temperatures, but to infer that it therefore cannot have any effect is nonsense, akin to saying that not all deaths are due to cancer, therefore no deaths are due to cancer.
Over billions of years, the Sun has become gradually brighter. Over millions of years, movements of continents and the rise and fall of mountain ranges has had great effects on our climate. Over tens of thousands of years, Milankovich cycles have increased and decreased seasonality, leading to periods of greater ice cover which in turn reflect away sunlight, cooling the planet. However, through it all the geologic record tells us that the climate is quite sensitive to CO2, and that CO2 is the principle control knob for the Earth's temperature.
"Earth was considerably warmer during the Roman Warming and the Medieval Warming"
This is simply false. Every peer-reviewed millenial temperature reconstruction shows current temperatures hotter than during the Roman and Medieval periods.
"Water vapour is 4% of the air and that‘s 100 times as much as CO2. Water vapour absorbs 33 times as much heat as CO2 making CO2’s contribution insignificant."
Water vapor is a feedback, not a forcing. Furthermore, as Lacis et al. (2010) found:
"Because carbon dioxide accounts for 80% of the non-condensing GHG forcing in the current climate atmosphere, atmospheric carbon dioxide therefore qualifies as the principal control knob that governs the temperature of Earth."
"Over the last few years Earth has had much colder winters"
This is another blatantly false statement. The average global surface temperature continues to rise during every season. In fact, winters are warming faster than summers!
"the Arctic has re-frozen and glaciers that were receding are now surging due to the heavy snow falls."
Once again, the document makes completely false assertions. Arctic sea ice continues to decline rapidly, as does global glacier mass.
"as the Sun is now entering probably 2-4 decades of low solar activity, this is expected to cause global cooling."
Solar activity has been flat over the past half century, during which time global surface temperatures increased over a half degreee Celsius. The Sun is not driving global temperatures.
"The hottest records in the USA and Greenland were in the 1930s due to a strong solar cycle."
First of all, the USA and Greenland are not the world. The global surface air temperature is currently approximatley 0.6°C hotter than it was during the 1930s. Secondly, today's temperatures are hotter than the 1930s even in the USA and Greenland.
"It became cooler from 1940 to 1970. This was due to a weak solar cycle."
The mid-century cooling was not caused by the Sun. In fact, solar activity increased slightly between 1940 and 1970.
"It has again become increasingly colder since 2006 due to another weak solar cycle."
Although five years is far too short of a timespan to determine a significant trend, the trend since 2006 is positive (warming). 2009 and 2010 were two of the hottest years on record, despite the weak solar cycle.
"We were told CFCs caused the Ozone ‘hole’ yet after billions of dollars were spent removing CFCs over 30 years, the slight depletion of Ozone at the South Pole has not changed. Scientists now think it is natural."
The ozone layer is recovering, and scientists still think its depletion was caused by human chlorofluorocarbon (CFC) emissions, because that's what the scientific evidence indicates. However, we only started seriously reducing CFC emissions 20 years ago (with the Montreal Protocol - the ozone version of the Kyoto Protocol), and CFCs have a long atmospheric lifetime, so the recovery will take time. There are of course ozone "skeptic" scientists just like there are global warming "skeptic" scientists, but the consensus and evidence are not in their favor.
"A carbon tax will have a disastrous impact on lower and middle income earners."
Fear of a carbon tax may be the underlying motivation behind this ill-conceived document. However, the benefits of carbon pricing outweigh its costs, and results in smaller economic impacts on lower and middle income households.
As you can see, this document is little more than a Gish Gallop of Moncktonian proportions. It's merely a result of Thompson not taking the time to learn some basic climate science, putting together a document full of misleading misunderstandings and misinformation, and PreventDisease.com propagating that misinformation.
Posted by dana1981 on Tuesday, 22 March, 2011
 |
The Skeptical Science website by Skeptical Science is licensed under a Creative Commons Attribution 3.0 Unported License. |