SKEPTICAL SCIENCE

Getting skeptical about global warming skepticism

Rebutting skeptic arguments in a single line

Posted on 20 July 2010 by John Cook

When I first started writing rebuttals to the various skeptic arguments, each rebuttal was a long, technical piece with graphs, detailed scientific discussion and links to peer-reviewed papers. At some point, someone suggested I write a short paragraph summary at the top of each page so people didn't have to read the whole page to get an answer to a skeptic argument. Initially, I frowned upon this idea. Firstly, it was a lot of work. More importantly, I figured if someone wanted to understand the science, they could jolly well take the time to read the full article. A proper understanding of climate requires the full picture which you can't get in a soundbyte! That's right, I'm quite the science curmudgeon.

Eventually, I began to see the need for a short summary. If Mohammad won't come to the mountain... So I began writing short paragraph summaries of each rebuttal. It wasn't easy - it's a tough ask boiling down complex concepts into a short paragraph, trying to cram as much science into as few words as possible. The result was all the skeptic arguments and a paragraph rebuttal on a single page which I thought was a fairly useful and concise summary.

In May this year, I received an email from Dr. Jan Dash, ex-theoretical physicist and Director of the Climate Initiative of the Unitarian Universalist United Nations Office. He had just co-led a series of "Counter the Contrarians" classes at the Unitarian Universalist Congregation of Monmouth County, NJ along with an expert in science communication who had dealt with evolution deniers while working at the Denver Zoo. Participants broke up into pairs with one playing the contrarian, given a skeptic argument, and the other rebutting the skeptic argument with the Skeptical Science paragraphs as source material (I have to confess it would've been fun getting to be the contrarian). The feedback from the participants was almost unanimous. My paragraph answers were too complicated to use.

Okay, that feedback was a bit of a kick in the guts but I guess I can see why. As I said earlier, I try to cram as much science as possible into a single paragraph. Jan suggested having a one-line, short sentence as a response to each skeptic argument. Something easy to remember and not too technical. The idea is the short one-liner would enable you to "bat the ball back over the net" and then more detail could be provided in subsequent discussion.

Now I must admit my initial reaction was skepticism, similar to my negative reaction to the initial paragraph idea. It was hard enough boiling the answers down to a paragraph, let alone a single line. So I emailed back, suggesting if Jan wanted to have a go at writing some one-liners, he was welcome to. After not getting a response, I assumed Jan found it as difficult as I did.
Then around a week later, I got a reply. Jan had gone through every skeptic argument and written a one-line answer! I started reading through them, thinking "okay, this'll be interesting". After the first page, it was obvious - by George, he'd done it! As I kept reading, I found myself thinking, "hmm, wish I'd said it like that!" He'd created a fantastic resource - short, non-technical, user-friendly answers to every skeptic argument.
I finally saw my problem was trying to cram every bit of science into my short answer as possible, in order to make the paragraph bullet proof to any objection. But Jan had the right approach - just "bat the ball back over the net" and get into the nitty gritty afterwards. So I'm immensely grateful for Jan for both providing some immensely useful content and also teaching me a lesson about science communication.
I've changed most of the rebuttals to skeptic arguments to Jan's one-liners. But if you're going to complain about any particular wording, I still take final responsibility for all the content - sometimes I changed his wording and often made the one-liners even shorter than Jan's version. You can also get the one-liners in printable format. This makes a handy resource to carry in your pocket in case a skeptic jumps out at you on the street. This also goes into the iPhone app and Android app so if you have either app on your phone, you probably already have the one-liners.

But being a hoarder who has trouble throwing anything out, I've kept all the old paragraphs and indulged in a comparison between the old paragraph answer and the new one-liners. I still keep the paragraph answer at the top of each skeptic argument page. So translators, no need to go back and change everything - hold off for a little while as I'm planning to restructure the whole database to use both the one-liner and paragraphs. More on this shortly...
By the way, a while back, Rob Honeycutt (author of Kung-fu Climate and Why does Anthony Watts drive an electric car?) suggested I should write 4 to 5 word answers to each skeptic argument. I'm going to go on record here and say that's impossible! Prove me wrong, Rob!

UPDATE: I forgot to mention, I welcome suggested improvements to any of the one line answers. So please post a comment suggesting how they can be better. But I do recommend rather than a "you should include something about..." in your comment, actually give specific wording, keeping it under 100 characters. If its better than the existing wording, I'll update the database. Thanks for your suggestions.

Lastly, Jan asked me to mention he prefers the "contrarians" nomenclature for people who reject mainstream climate science, following the professional climate website RealClimate.org. This is because mainstream climate scientists are the true skeptics. In general, it takes a lot of good evidence to convince a scientist. I personally agree with this assessment of true skepticism but use the term 'skeptic' so we don't get distracted into arguments about labels and instead stick to discussing and understanding science.

Global Warming & Climate Change Myths

Here is a summary of global warming and climate change myths, sorted by recent popularity vs what science says. Click the response for a more detailed response. You can also view them sorted by taxonomy, by popularity, in a print-friendly version, with short URLs or with fixed numbers you can use for permanent references.

	Climate Myth	vs	What the Science Says
1	"Climate's changed before"		Climate reacts to whatever forces it to change at the time; humans are now the dominant forcing.
2	"It's the sun"		In the last 35 years of global warming, sun and climate have been going in opposite directions
3	"It's not bad"		Negative impacts of global warming on agriculture, health & environment far outweigh any positives.
4	"There is no consensus"		97% of climate experts agree humans are causing global warming.
5	"It's cooling"		The last decade 2000-2009 was the hottest on record.
6	"Models are unreliable"		Models successfully reproduce temperatures since 1900 globally, by land, in the air and the ocean.
7	"Temp record is unreliable"		The warming trend is the same in rural and urban areas, measured by thermometers and satellites.
8	"Animals and plants can adapt"		Global warming will cause mass extinctions of species that cannot adapt on short time scales.
9	"It hasn't warmed since 1998"		For global records, 2010 is the hottest year on record, tied with 2005.
10	"Antarctica is gaining ice"		Satellites measure Antarctica losing land ice at an accelerating rate.
11	"Ice age predicted in the 70s"		The vast majority of climate papers in the 1970s predicted warming.
12	"CO2 lags temperature"		CO2 didn't initiate warming from past ice ages but it did amplify the warming.
13	"Climate sensitivity is low"		Net positive feedback is confirmed by many different lines of evidence.
14	"We're heading into an ice age"		Worry about global warming impacts in the next 100 years, not an ice age in over 10,000 years.
15	"Ocean acidification isn't serious"		Ocean acidification threatens entire marine food chains.
16	"Hockey stick is broken"		Recent studies agree that recent global temperatures are unprecedented in the last 1000 years.
17	"Climategate CRU emails suggest conspiracy"		A number of investigations have cleared scientists of any wrongdoing in the media-hyped email incident.
18	"Hurricanes aren't linked to global warming"		There is increasing evidence that hurricanes are getting stronger due to global warming.
19	"Al Gore got it wrong"		Al Gore book is quite accurate, and far more accurate than contrarian books.
20	"Glaciers are growing"		Most glaciers are retreating, posing a serious problem for millions who rely on glaciers for water.
21	"It's cosmic rays"		Cosmic rays show no trend over the last 30 years & have had little impact on recent global warming.
22	"1934 - hottest year on record"		1934 was one of the hottest years in the US, not globally.
23	"It's freaking cold!"		A local cold day has nothing to do with the long-term trend of increasing global temperatures.
24	"Extreme weather isn't caused by global warming"		Extreme weather events are being made more frequent and worse by global warming.
25	"Sea level rise is exaggerated"		A variety of different measurements find steadily rising sea levels over the past century.
26	"It's Urban Heat Island effect"		Urban and rural regions show the same warming trend.
27	"Medieval Warm Period was warmer"		Globally averaged temperature now is higher than global temperature in medieval times.
28	"Mars is warming"		Mars is not warming globally.
29	"Arctic icemelt is a natural cycle"		Thick arctic sea ice is undergoing a rapid retreat.
30	"Increasing CO2 has little to no effect"		The strong CO2 effect has been observed by many different measurements.
31	"Oceans are cooling"		The most recent ocean measurements show consistent warming.
32	"It's a 1500 year cycle"		Ancient natural cycles are irrelevant for attributing recent global warming to humans.
33	"Human CO2 is a tiny % of CO2 emissions"		The natural cycle adds and removes CO2 to keep a balance; humans add extra CO2 without removing any.
34	"IPCC is alarmist"		Numerous papers have documented how IPCC predictions are more likely to underestimate the climate response.
35	"Water vapor is the most powerful greenhouse gas"		Rising CO2 increases atmospheric water vapor, which makes global warming much worse.
36	"Polar bear numbers are increasing"		Polar bears are in danger of extinction as well as many other species.
37	"CO2 limits will harm the economy"		The benefits of a price on carbon outweigh the costs several times over.
38	"It's not happening"		There are many lines of evidence indicating global warming is unequivocal.
39	"Greenland was green"		Other parts of the earth got colder when Greenland got warmer.
40	"Greenland is gaining ice"		Greenland on the whole is losing ice, as confirmed by satellite measurement.
41	"CO2 is not a pollutant"		Through its impacts on the climate, CO2 presents a danger to public health and welfare, and thus qualifies as an air pollutant
42	"CO2 is plant food"		The effects of enhanced CO2 on terrestrial plants are variable and complex and dependent on numerous factors
43	"Other planets are warming"		Mars and Jupiter are not warming, and anyway the sun has recently been cooling slightly.
44	"Arctic sea ice has recovered"		Thick arctic sea ice is in rapid retreat.
45	"There's no empirical evidence"		There are multiple lines of direct observations that humans are causing global warming.
46	"We're coming out of the Little Ice Age"		Scientists have determined that the factors which caused the Little Ice Age cooling are not currently causing global warming
47	"There's no correlation between CO2 and temperature"		There is long-term correlation between CO2 and global temperature; other effects are short-term.
48	"It cooled mid-century"		Mid-century cooling involved aerosols and is irrelevant for recent global warming.
49	"CO2 was higher in the past"		When CO2 was higher in the past, the sun was cooler.
50	"It warmed before 1940 when CO2 was low"		Early 20th century warming is due to several causes, including rising CO2.
51	"Global warming stopped in ~~1998~~, ~~1995~~, ~~2002~~, ~~2007~~, ~~2010~~, ????"		Global temperature is still rising and 2010 was the hottest recorded.
52	"Satellites show no warming in the troposphere"		The most recent satellite data show that the earth as a whole is warming.
53	"It's aerosols"		Aerosols have been masking global warming, which would be worse otherwise.
54	"It's El Niño"		El Nino has no trend and so is not responsible for the trend of global warming.
55	"2009-2010 winter saw record cold spells"		A cold day in Chicago in winter has nothing to do with the trend of global warming.
56	"It's a natural cycle"		No known natural forcing fits the fingerprints of observed warming except anthropogenic greenhouse gases.
57	"Mt. Kilimanjaro's ice loss is due to land use"		Most glaciers are in rapid retreat worldwide, notwithstanding a few complicated cases.
58	"There's no tropospheric hot spot"		We see a clear "short-term hot spot" - there's various evidence for a "long-term hot spot".
59	"It's not us"		Multiple sets of independent observations find a human fingerprint on climate change.
60	"It's Pacific Decadal Oscillation"		The PDO shows no trend, and therefore the PDO is not responsible for the trend of global warming.
61	"IPCC were wrong about Himalayan glaciers"		Glaciers are in rapid retreat worldwide, despite 1 error in 1 paragraph in a 1000 page IPCC report.
62	"Scientists can't even predict weather"		Weather and climate are different; climate predictions do not need weather detail.
63	"Greenhouse effect has been falsified"		The greenhouse effect is standard physics and confirmed by observations.
64	"2nd law of thermodynamics contradicts greenhouse theory"		The 2nd law of thermodynamics is consistent with the greenhouse effect which is directly observed.
65	"CO2 limits will hurt the poor"		Those who contribute the least greenhouse gases will be most impacted by climate change.
66	"The science isn't settled"		That human CO2 is causing global warming is known with high certainty & confirmed by observations.
67	"Clouds provide negative feedback"		Evidence is building that net cloud feedback is likely positive and unlikely to be strongly negative.
68	"Sea level rise predictions are exaggerated"		Sea level rise is now increasing faster than predicted due to unexpectedly rapid ice melting.
69	"It's the ocean"		The oceans are warming and moreover are becoming more acidic, threatening the food chain.
70	"IPCC were wrong about Amazon rainforests"		The IPCC statement on Amazon rainforests was correct, and was incorrectly reported in some media.
71	"Corals are resilient to bleaching"		Globally about 1% of coral is dying out each year.
72	"Volcanoes emit more CO2 than humans"		Humans emit 100 times more CO2 than volcanoes.
73	"CO2 effect is saturated"		Direct measurements find that rising CO2 is trapping more heat.
74	"Greenland ice sheet won't collapse"		When Greenland was 3 to 5 degrees C warmer than today, a large portion of the Ice Sheet melted.
75	"CO2 is just a trace gas"		Many substances are dangerous even in trace amounts; what really matters is the total amount of CO2 in the atmosphere.
76	"It's methane"		Methane plays a minor role in global warming but could get much worse if permafrost starts to melt.
77	"CO2 has a short residence time"		Excess CO2 from human emissions has a long residence time of over 100 years
78	"CO2 measurements are suspect"		CO2 levels are measured by hundreds of stations across the globe, all reporting the same trend.
79	"Humidity is falling"		Multiple lines of independent evidence indicate humidity is rising and provides positive feedback.
80	"500 scientists refute the consensus"		Around 97% of climate experts agree that humans are causing global warming.
81	"Neptune is warming"		And the sun is cooling.
82	"Springs aren't advancing"		Hundreds of flowers across the UK are flowering earlier now than any time in 250 years.
83	"Jupiter is warming"		Jupiter is not warming, and anyway the sun is cooling.
84	"It's land use"		Land use plays a minor role in climate change, although carbon sequestration may help to mitigate.
85	"Scientists tried to 'hide the decline' in global temperature"		The 'decline' refers to a decline in northern tree-rings, not global temperature, and is openly discussed in papers and the IPCC reports.
86	"CO2 is not increasing"		CO2 is increasing rapidly, and is reaching levels not seen on the earth for millions of years.
87	"Record snowfall disproves global warming"		Warming leads to increased evaporation and precipitation, which falls as increased snow in winter.
88	"They changed the name from global warming to climate change"		'Global warming' and 'climate change' mean different things and have both been used for decades.
89	"Solar Cycle Length proves its the sun"		The sun has not warmed since 1970 and so cannot be driving global warming.
90	"CO2 is coming from the ocean"		The ocean is absorbing massive amounts of CO2, and is becoming more acidic as a result.
91	"IPCC overestimate temperature rise"		Monckton used the IPCC equation in an inappropriate manner.
92	"Pluto is warming"		And the sun has been recently cooling.
93	"CO2 is not the only driver of climate"		Theory, models and direct measurement confirm CO2 is currently the main driver of climate change.
94	"Peer review process was corrupted"		An Independent Review concluded that CRU's actions were normal and didn't threaten the integrity of peer review.
95	"Arctic was warmer in 1940"		The actual data show high northern latitudes are warmer today than in 1940.
96	"Renewable energy is too expensive"		When you account for all of the costs associated with burning coal and other fossil fuels, like air pollution and health effects, in reality they are significantly more expensive than most renewable energy sources.
97	"Southern sea ice is increasing"		Antarctic sea ice has grown in recent decades despite the Southern Ocean warming at the same time.
98	"CO2 limits will make little difference"		If every nation agrees to limit CO2 emissions, we can achieve significant cuts on a global scale.
99	"Sea level rise is decelerating"		Global sea level data shows that sea level rise has been increasing since 1880 while future sea level rise predictions are based on physics, not statistics.
100	"It's microsite influences"		Microsite influences on temperature changes are minimal; good and bad sites show the same trend.
101	"Phil Jones says no global warming since 1995"		Phil Jones was misquoted.
102	"Humans are too insignificant to affect global climate"		Humans are small but powerful, and human CO2 emissions are causing global warming.
103	"Lindzen and Choi find low climate sensitivity"		Lindzen and Choi’s paper is viewed as unacceptably flawed by other climate scientists.
104	"Dropped stations introduce warming bias"		If the dropped stations had been kept, the temperature would actually be slightly higher.
105	"It's too hard"		Scientific studies have determined that current technology is sufficient to reduce greenhouse gas emissions enough to avoid dangerous climate change.
106	"It's not urgent"		A large amount of warming is delayed, and if we don’t act now we could pass tipping points.
107	"It's albedo"		Albedo change in the Arctic, due to receding ice, is increasing global warming.
108	"Tree-rings diverge from temperature after 1960"		This is a detail that is complex, local, and irrelevant to the observed global warming trend.
109	"It's soot"		Soot stays in the atmosphere for days to weeks; carbon dioxide causes warming for centuries.
110	"Hansen's 1988 prediction was wrong"		Jim Hansen had several possible scenarios; his mid-level scenario B was right.
111	"Roy Spencer finds negative feedback"		Spencer's model is too simple, excluding important factors like ocean dynamics and treats cloud feedbacks as forcings.
112	"It's global brightening"		This is a complex aerosol effect with unclear temperature significance.
113	"Arctic sea ice loss is matched by Antarctic sea ice gain"		Arctic sea ice loss is three times greater than Antarctic sea ice gain.
114	"It's a climate regime shift"		There is no evidence that climate has chaotic “regimes” on a long-term basis.
115	"Earth hasn't warmed as much as expected"		This argument ignores the cooling effect of aerosols and the planet's thermal inertia.
116	"Solar cycles cause global warming"		Over recent decades, the sun has been slightly cooling & is irrelevant to recent global warming.
117	"Less than half of published scientists endorse global warming"		Around 97% of climate experts agree that humans are causing global warming.
118	"Ice isn't melting"		Arctic sea ice has shrunk by an area equal to Western Australia, and summer or multi-year sea ice might be all gone within a decade.
119	"Over 31,000 scientists signed the OISM Petition Project"		The 'OISM petition' was signed by only a few climatologists.
120	"IPCC ‘disappeared’ the Medieval Warm Period"		The IPCC simply updated their temperature history graphs to show the best data available at the time.
121	"Climate is chaotic and cannot be predicted"		Weather is chaotic but climate is driven by Earth's energy imbalance, which is more predictable.
122	"It's ozone"		Ozone has only a small effect.
123	"Freedom of Information (FOI) requests were ignored"		An independent inquiry found CRU is a small research unit with limited resources and their rigour and honesty are not in doubt.
124	"The IPCC consensus is phoney"		113 nations signed onto the 2007 IPCC report, which is simply a summary of the current body of climate science evidence
125	"Sea level is not rising"		The claim sea level isn’t rising is based on blatantly doctored graphs contradicted by observations.
126	"Climate 'Skeptics' are like Galileo"		Modern scientists, not anti-science skeptics, follow in Galileo’s footsteps.
127	"Tuvalu sea level isn't rising"		Tuvalu sea level is rising 3 times larger than the global average.
128	"A drop in volcanic activity caused warming"		Volcanoes have had no warming effect in recent global warming - if anything, a cooling effect.
129	"Trenberth can't account for the lack of warming"		Trenberth is talking about the details of energy flow, not whether global warming is happening.
130	"Renewables can't provide baseload power"		A number of renewable sources already do provide baseload power, and we don't need renewables to provide a large percentage of baseload power immediately.
131	"Ice Sheet losses are overestimated"		A number of independent measurements find extensive ice loss from Antarctica and Greenland.
132	"CRU tampered with temperature data"		An independent inquiry went back to primary data sources and were able to replicate CRU's results.
133	"Naomi Oreskes' study on consensus was flawed"		Benny Peiser, the Oreskes critic, retracted his criticism.
134	"Melting ice isn't warming the Arctic"		Melting ice leads to more sunlight being absorbed by water, thus heating the Arctic.
135	"Breathing contributes to CO2 buildup"		By breathing out, we are simply returning to the air the same CO2 that was there to begin with.
136	"Satellite error inflated Great Lakes temperatures"		Temperature errors in the Great Lakes region are not used in any global temperature records.
137	"Soares finds lack of correlation between CO2 and temperature"		Soares looks at short-term trends which are swamped by natural variations while ignoring the long-term correlation.
138	"We're heading into cooling"		There is no scientific basis for claims that the planet will begin to cool in the near future.
139	"Murry Salby finds CO2 rise is natural"		Multiple lines of evidence make it very clear that the rise in atmospheric CO2 is due to human emissions.
140	"CO2 emissions do not correlate with CO2 concentration"		That humans are causing the rise in atmospheric CO2 is confirmed by multiple isotopic analyses.
141	"The sun is getting hotter"		The sun has just had the deepest solar minimum in 100 years.
142	"It's waste heat"		Greenhouse warming is adding 100 times more heat to the climate than waste heat.
143	"Water vapor in the stratosphere stopped global warming"		This possibility just means that future global warming could be even worse.
144	"It warmed just as fast in 1860-1880 and 1910-1940"		The warming trend over 1970 to 2001 is greater than warming from both 1860 to 1880 and 1910 to 1940.
145	"An exponential increase in CO2 will result in a linear increase in temperature"		CO2 levels are rising so fast that unless we decrease emissions, global warming will accelerate this century.
146	"Record high snow cover was set in winter 2008/2009"		Winter snow cover in 2008/2009 was average while the long-term trend in spring, summer, and annual snow cover is rapid decline.
147	"Mauna Loa is a volcano"		The global trend is calculated from hundreds of CO2 measuring stations and confirmed by satellites.
148	"Venus doesn't have a runaway greenhouse effect"		Venus very likely underwent a runaway or ‘moist’ greenhouse phase earlier in its history, and today is kept hot by a dense CO₂ atmosphere.
149	"Antarctica is too cold to lose ice"		Glaciers are sliding faster into the ocean because ice shelves are thinning due to warming oceans.
150	"Positive feedback means runaway warming"		Positive feedback won't lead to runaway warming; diminishing returns on feedback cycles limit the amplification.
151	"Skeptics were kept out of the IPCC?"		Official records, Editors and emails suggest CRU scientists acted in the spirit if not the letter of IPCC rules.
152	"Water levels correlate with sunspots"		This detail is irrelevant to the observation of global warming caused by humans.
153	"CO2 was higher in the late Ordovician"		The sun was much cooler during the Ordovician.
154	"It's internal variability"		Internal variability can only account for small amounts of warming and cooling over periods of decades, and scientific studies have consistently shown that it cannot account for the global warming over the past century.
155	"CO2 increase is natural, not human-caused"		Many lines of evidence, including simple accounting, demonstrate beyond a shadow of a doubt that the increase in atmospheric CO2 is due to human fossil fuel burning.
156	"It's CFCs"		CFCs contribute at a small level.
157	"Scientists retracted claim that sea levels are rising"		The Siddall 2009 paper was retracted because its predicted sea level rise was too low.
158	"Warming causes CO2 rise"		Recent warming is due to rising CO2.
159	"Coral atolls grow as sea levels rise"		Thousands of coral atolls have "drowned" when unable to grow fast enough to survive at sea level.
160	"Renewable energy investment kills jobs"		Investment in renewable energy creates more jobs than investment in fossil fuel energy.
161	"Greenland has only lost a tiny fraction of its ice mass"		Greenland's ice loss is accelerating & will add metres of sea level rise in upcoming centuries.
162	"DMI show cooling Arctic"		While summer maximums have showed little trend, the annual average Arctic temperature has risen sharply in recent decades.
163	"CO2 limits won't cool the planet"		CO2 limits won't cool the planet, but they can make the difference between continued accelerating global warming to catastrophic levels vs. slowing and eventually stopping the warming at hopefully safe levels
164	"Royal Society embraces skepticism"		The Royal Society still strongly state that human activity is the dominant cause of global warming.
165	"It's only a few degrees"		A few degrees of global warming has a huge impact on ice sheets, sea levels and other aspects of climate.
166	"It's satellite microwave transmissions"		Satellite transmissions are extremely small and irrelevant.
167	"CO2 only causes 35% of global warming"		CO2 and corresponding water vapor feedback are the biggest cause of global warming.
168	"Sea level fell in 2010"		The temporary drop in sea level in 2010 was due to intense land flooding caused by a strong La Nina.
169	"Arctic sea ice extent was lower in the past"		Current Arctic sea ice extent is the lowest in the past several thousand years.
170	"We didn't have global warming during the Industrial Revolution"		CO2 emissions were much smaller 100 years ago.
171	"Ljungqvist broke the hockey stick"		Ljungqvist's temperature reconstruction is very similar to other reconstructions by Moberg and Mann.
172	"Hansen predicted the West Side Highway would be underwater"		Hansen was speculating on changes that might happen if CO2 doubled.
173	"Removing all CO2 would make little difference"		Removing CO2 would cause most water in the air to rain out and cancel most of the greenhouse effect.
174	"Postma disproved the greenhouse effect"		Postma's model contains many simple errors; in no way does Postma undermine the existence or necessity of the greenhouse effect.