Roy Spencer is a satellite observation expert, who has reversed his opinion of satellite measurements, and now believes that warming is about as described by the traditional thermometer datasets.

Judith Curry doesn't disagree with AGW, she disagrees with the scale predicted. That would mean less immediate, strict action, but action nevertheless.

Freeman Dyson isn't a climatologist, he also says himself "[m]y objections to the global warming propaganda are not so much over the technical facts, about which I do not know much, but it’s rather against the way those people behave and the kind of intolerance to criticism that a lot of them have." He also believes in AGW.

It's good to have sceptics, and in particular being sceptical about the scale of AGW is very reasonable. The IPCC predictions actually have a wide variance for these reasons. These scientists don't really speak against the moderate action currently proposed, they aren't backing for Trump's position.

I don't mind AGW at all (it's obvious that human activity influences the climate, and probably the effects of deforestation are as severe as effects from CO2 emissions), but I find CO2-CAGW (i.e. anthropogenic warming caused by CO2 emissions and leading to catastrophic consequences) unconvincing, to a lesser degree due to personal knowledge (uncertainty in clouds feedback, under appreciation of positive effects of higher CO2 concentration etc), and to a higher degree, due to views of Lindzen, Curry, Spencer Dyson, and other scientists.

Yes, Dyson's rhetoric on climate moved a bit towards "alarmist" side, but he still doesn't believe in catastrophic consequences:

"The good news is that the main effect of carbon dioxide … is to make the planet greener, [by] feeding the growth of green plants of all kinds [and] increasing the fertility of farms and fields and forests."

Even by the late '90s there were renowned medical scientists who disagreed with the consensus around the "HIV causes AIDS" hypothesis, despite ample evidence.

https://en.m.wikipedia.org/wiki/HIV/AIDS_denialism

Climate change denialism is no different from AIDS denialism.

Ok, the minority view was wrong in this particular case. Minority views were also right in some other cases.

"Climate change denialism" - what's this? Is there any scientist out there who thinks that Earth's climate is stable in the long run?

You asked how there could be "consensus" on the existence of ACC when some scientists dispute its existence.

The parent post gave an example of a case where some credentialed scientists continued to dispute the HIV-AIDS link well after the balance of evidence was against them.

Many people would say there was a "consensus" on the HIV-AIDS link despite the continued skepticism of some scientists, and that this scenario has parallels with climate science.

Can you offer a counter example, where a holdout group of scientists who disagreed with consensus in their field were proved right?

Climate changes anyway, so why do anything about it? People die anyway, so who cares what causes AIDS?

Call it "climate science denialism" if you prefer. It's no different from AIDS denialism.

Thabo Mbeki, President of South Africa in 1999-2008, listened to the denialists' views about the AIDS outbreak. He had an AIDS advisory panel staffed with consensus critics -- just like Trump and Pruitt are doing. The estimated number of premature deaths due to Mbeki's counterproductive actions is around 300,000.

@swampangel: https://www.insidescience.org/news/scientific-consensus-almo...

here you go

The article is about paradigm shifts in science. Obviously those happen, but not every minority opinion is such a shift. They are notable because they are so very rare.

What do you see as the paradigm shift that turns climate science on its head and proves the consensus wrong?

Suppose that new discovery in natural climate variability provides IPCC with better models, and these models show that CO2 has only minor influence on global warming and climate overall. "Paradigm shift" would be a good description for this development.

Do, you don't accept the science because you think that perhaps in the furute it will be proven wrong.

Good thing, isn't?

This 'consensus' approach is biased from the start, because it automatically gives a benefit to the so-called "scientists" as if they are somehow more wise or knowledgable about anything any more than a soothsayer or even pulling a few stones out of the ground and interpreting the residual dirt in their cracks while intoxicated on some brewed concoction of plants.

Nope. The IPCC consensus has been reached through a lot of hard, unpaid or very poorly paid, work by people passionate about helping others, that all the time know they could easily get bought to spread falsehoods and reap large rewards.

consensus as in general agreement, as in a majority. Pointing out that some minority group exists is hardly a refutation. Would you not say there is a consensus the Earth is round?

Why should one trust majority, and not minority, if "minority" people are also qualified and respected (Spencer, Curry)? There were episodes in the history of science, when the majority turned out to be wrong.

Here's one example:

https://www.insidescience.org/news/scientific-consensus-almo...

I won't object to the fact that majorities can be wrong. There are many examples, ancient and recent. But that is a different argument from your other comment.

I trust majority in science because it is rarely wrong. I'd need a bit more than "majorities have been wrong before!" to switch sides.

Well, I'd need a bit more than "minorities are rarely right" to switch sides.

Which part of the science do you find unconvincing? We have great ice core data going back 1000's of years, the greenhouse effect itself is universally agreed upon and understood, we have a measurable rise in global average temperature over the last 2 centuries, and we see that people are spewing greenhouse gases into the atmosphere. Solar cycles, volcanoes, and other non-human sources have been refuted and disproved time and time again. only scientists paid to lobby on behalf of the source of warming disagree with the cause. What's missing that could ever convince you?

Convincing part stops at cloud feedback for me.

The CAGW builds upon following argument: increased concentration of CO2 reduces the EM radiation's emission in frequencies that CO2 absorbs, ergo the surface temperature should rise in order to keep Earth's thermodynamic balance.

Increased temperature clearly affects the formation of clouds which have both positive and negative effects: they deflect incoming solar radiation, but also deflect surface radiation. The net effect is unclear, unfortunately.

I'm also quite puzzled by apparent lag between CO2 and temperatures in Vostok ice core data. Contrary to CAGW, temperature rises first, and CO2 follows.

My layman understanding is quite limited, of course, that's why eventually I go to the scientists for their expertise. I don't believe that all opponents of CAGW theory are shills; some of them are very respected people: Lindzen, Spencer, etc. My only conclusion is that science is not settled and CAGW is still an unconfirmed hypothesis.

ACC doesn't build upon the hypothesis that CO2 reduces the energy emission. The underpinning is the greenhouse effect whereby gasses, particularly CO2 prevent heat absorbed by the Earth's surface from radiating back out into space. Only about 26% of the Sun's energy is reflected by clouds or the atmosphere. CO2 concentration increases heat retention but not cloud albedo(reflectiveness) nor atmospheric reflectiveness.

Cloud formation is not related to CO2. CO2 is the primary factor driving the greenhouse effect. In fact research is beginning to show that a warmer planet may have lower cloud cover [1][2]. There is no cloud controversy, you are literally making that up.

[1] https://content.time.com/time/health/article/0,8599,1912448,... [2]https://www.nsf.gov/news/special_reports/clouds/question.jsp

It does build on the fact that increased concentration of CO2 reduces EM waves emission (in the parts of frequency spectrum that can be absorbed by CO2) from Earth to space. Earth is presumed to maintain thermodynamic balance (i.e. energy received should be equal to energy lost). To compensate for reduced emission caused by CO2, Earth's surface warms up and restores the balance. This is global warming 101, I believe.

Have you read your links?

"One of the biggest questions in climate sensitivity has been the role of low-level cloud cover. Low-altitude clouds reflect some of the sun's radiation back into the atmosphere, cooling the earth. It's not yet known whether global warming will dissipate clouds, which would effectively speed up the process of climate change, or increase cloud cover, which would slow it down.

But a new study published in the July 24 issue of Science is clearing the haze. A group of researchers from the University of Miami and the Scripps Institute of Oceanography studied cloud data of the northeast Pacific Ocean — both from satellites and from the human eye — over the past 50 years and combined that with climate models. They found that low-level clouds tend to dissipate as the ocean warms — which means a warmer world could well have less cloud cover. "That would create positive feedback, a reinforcing cycle that continues to warm the climate," says Amy Clement, a climate scientist at the University of Miami and the lead author of the Science study."

That's one study that recorded the cloud data for subset of Earth.

Read about clouds feedback issue here, it's very pro-CO2-CAGW site: https://www.skepticalscience.com/clouds-negative-feedback.ht...

"Point to" is not confident enough. Even skepticalscience, the "alarmist"-side site, admits that "While clouds remain an uncertainty, the evidence is building that clouds will probably cause the planet to warm even further".

"A group of researchers from the University of Miami and the Scripps Institute of Oceanography studied cloud data of the northeast Pacific Ocean"

Study from your first link recorded cloud cover data over subset of Earth's atmosphere. It doesn't say anything about whether clouds feedback is positive, or negative. Local data is not very useful evidence, global data would be preferable.

Here is an explanation of what is cloud feedback: increase of temperature has effects on cloud formation. If feedback from changes in cloud formation is positive, it will lead to even more warming. Negative feedback would mean that changed cloud formation actually reduces warming.

I did read the links, they both point to positive feedback cycles, and you cherry picked that quote to obfuscate that point.

Your first statement is proving my point, CO2 contributes to the greenhouse effect, causing warming on average. Human activity is the cause of historically high CO2 levels.

  cloud data of the northeast Pacific Ocean — both from satellites and from the human eye

What methodology did they use to turn eyeballed guesstimates into data?

Freeman Dyson is not a climate scientist at all and never has been. Roy Spencer isn't a "renowned scientist"; he's a paid oil-industry shill. Lindzen used to be a scientist; now he's retired and gets paid to be a Cato Institute shill. Judith Curry also used to be a scientist and quit her academic job; presumably being a shill pays WAY better.

So, basically, yes, they are all bought and paid for, or, they simply have no credentials or knowledge of the field in question.

Dyson is a renowned physicist interested in climate science. I believe that his physics/math skills and general intelligence allow him to be quite competent in climate issues.

Lindzen retired only in 2013. I don't see how this makes his opinion about CAGW less valuable, especially given the fact that he was skeptical about CAGW hypothesis for a long time.

"Judith Curry also used to be a scientist and quit her academic job; presumably being a shill pays WAY better." - where's the proof that she is a "shill"?

Roy Spencer is a renowned scientist in my book: "Roy Warren Spencer is a meteorologist, a principal research scientist at the University of Alabama in Huntsville, and the U.S. Science Team leader for the Advanced Microwave Scanning Radiometer (AMSR-E) on NASA's Aqua satellite. He has served as senior scientist for climate studies at NASA's Marshall Space Flight Center."

Again, where is the proof that he is oil industry's shill?

To my knowledge, Freeman Dyson has no peer reviewed research contributions in the climate literature. That should be the price of entry, otherwise there is nothing of substance to critique.

Please don't do this here.

There are climate scientists who are proponents of CAGW and who believe in creationism: http://www.christianpost.com/news/climate-change-evangelical...

Does it automatically make CAGW hypothesis wrong? Does it make their skills and knowledge in climate science less valuable?

"Does it make their skills and knowledge in climate science less valuable?"

I was speaking specifically of Spencer, and, yes, it calls into question everything he professes.

This is exactly what I meant by fallacies. Either their research is legitimate or it is not. And that legitimacy is not a factor of the employer - if their science sucks, it'll manifest in the data, analysis, or conclusions, regardless of who's paying for it.

"Shills" is an insult, not an argument.

Are you qualified to decipher the data? Honest question.

They aren't doing any "research".

So basically, anyone who is a respectable scientist who disagrees with this is a shill?

This breaks the HN guidelines. Please remain civil, regardless of how wrong someone else is.

I know what the word shill means, and your inverse variant of red-baiting isn't very effective. Simply taking money from some group does not mean you are a shill for that group.