A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).



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Denying 2000 years of the Medieval Warm Period, Little Ice Age on every continent

Here we go again. For five or so years believers didn’t really mention the Medieval Warm Period. Too bruised by the embarrassment of Hockey Stick Zombie failures. But it’s an inconvenient era they have to rub out because none of the expert models can explain what caused it, and it’s hard to panic about same temperatures that Edward the Confessor survived with oxen and carts.

And it’s hard to call the modern warmth “man-made” if nature created something just like it 1,000 years ago.

Climate change: We haven’t experienced anything like this in the past 2,000 years

By Michael Collett, ABC, Environmental Copy and Paste Promoter

Climate scientists writing in the journal Nature have found there is no evidence for “globally coherent warm and cold periods” over the past 2,000 years prior to industrialisation.

That’s significant, because climate change deniers have sometimes pointed to epochs like the so-called “Little Ice Age” or “Medieval Warm Period” to argue that the current global warming is one among multiple similar global climate events.

But what the research actually shows is that other “peak warming and cooling events” over the past two millennia appear to have […]

Award winning Peter Boyer attacks Myron Ebell — but who has an open mind, and who is in denial?

Peter Boyer seems to think Myron Ebell owes him an apology, but it’s the other way around. And Boyer ought say sorry to his readers.

“Science Communication” is a pretty dismal, immature profession. It’s so bad that an award-winning science communicator can talk about “blunt denial” even while denying basic tenets of logic and appearing to have done almost no research on the global warming debate. If he was ever taught the basics of reasoning, like “correlation is not causation” or “all models are wrong but some are useful,” he’s long forgotten them. What’s an Order of Australia worth these days? Apparently not much.

If he had the open mind he talks about, he might have bothered to read the skeptical sites before he wrote an article. We’d have provided all the evidence an open mind could need to know that Myron Ebell is right on the money. So here Peter, with all due respect, is the red pill — the stuff the UNSW profs of climate crisis won’t tell you even if you dared to ask them.

Talking Point: Keeping an open mind in climate of blunt denial

Peter Boyer

Asked in 2012 what he […]

Man Made Global Warming Disproved

Joanne Nova and Anthony Cox

The theory that failed

It takes only one experiment to disprove a theory. The climate models are predicting a global disaster, but the empirical evidence disagrees. The theory of catastrophic man-made global warming has been tested from many independent angles.

The heat is missing from oceans; it’s missing from the upper troposphere. The clouds are not behaving as predicted. The models can’t predict the short term, the regional, or the long term. They don’t predict the past. How could they predict the future?

The models didn’t correctly predict changes in outgoing radiation, or the humidity and temperature trends of the upper troposphere. The single most important fact, dominating everything else, is that the ocean heat content has barely increased since 2003 (and quite possibly decreased) counter to the simulations. In a best case scenario, any increase reported is not enough. Models can’t predict local and regional patterns or seasonal effects, yet modelers add up all the erroneous micro-estimates and claim to produce an accurate macro global forecast. Most of the warming happened in a step change in 1977, yet CO2 has been rising annually.

Observations from every angle point to a similar […]

Models get the core assumptions wrong– – the hot spot is missing

This is part of a series that Tony Cox and I are doing that references the most important points and papers, as a definitive resource about the evidence. The missing hotspot is not just another flaw in the theory, it proves the models are wrong: not just “unverified”, not just “uncertain”, but failed. Apologies to those who feel I harp on about this! This is a condensed review, squishing years of a scientific battleground down to it’s bare bones… — Jo

It is not well known that even the IPCC agrees that the direct effects of CO2 will only increase world temperatures by 1.2°C. All of the projections above that (3.3°C , 6°C etc) come from model projections based on assumptions of what water vapor and clouds will do (these are the feedback effects of the original 1.2°C).[i] Are the feedbacks correct?

If the IPCC models are right about the feedbacks, we would see a hot spot 10km above the tropics. The theory is that with more heat, more water will evaporate and rise, keeping relative humidity constant at all heights in the troposphere. The point has been conclusively tested with 28 million weather balloons since 1959.[ii]



We can’t predict the climate on a local, regional, or continental scale

This is part of a series that Tony Cox and I are doing that drills down to the most important points and papers, with proper references, as a definitive resource.The models are wrong: not just “unverified”, not just “uncertain”, but proven to have failed. — Jo

Joint Post: Tony Cox and Jo Nova

Across different regions, and different time-spans over the last century, the models fail.

Koutsoyiannis and Anagnostopolous et al show those models can’t model the recent century, and because the models fail to predict regional and smaller scale effects it’s impossible that they could predict longer and global values.[i]

On 30 year time frames, the original observations are nothing like the models projections on a local scale. (Click to enlarge).

The models should retrospectively match the actual temperature over the past 100 years. This test of retrospectivity is called hindcasting. If a model has valid assumptions about the climatic effect of variables such as greenhouse gases, particularly CO2, then the model should be able to match past known data.

“…all the models were “irrelevant with reality” at the 30 year climate scale…”

When tested, the global climate models failed to […]

Has CO2 warmed the planet at all in the last 50 years? It’s harder to tell than you think.

Joint Post: Jo Nova and Tony Cox

Even most skeptics agree that the world has been warming during the last 50 years, but there is apparently no significant underlying warming trend in 46 out of 47 years of data. Something decidedly unusual happened to the world in 1977 and we don’t know for sure what it was. The world got warmer, and the change “stuck”. But there were no extra emissions of CO2 in that year, so there is no reason to pin this to CO2.

It’s difficult to believe we are not sure – but the last 50 years of warming trend depends on that single stepwise leap in 1977. Look at the graph below. Does it show one strong underlying warming trend, or is it really a trend so insignificant that it wouldn’t exist if there was not a step change that artificially bolstered it?

A series of two flat lines can appear to be a continuous warming trend if a linear trend line is fitted because it ignores the step change. McKitrick and Voselgang

This step effect was first noted by David Stockwell in 2009

The continuous warming appears to be obvious in the records of […]

The incredible power of clouds (and Roy Spencer’s work)

Joint Post by Tony Cox and Jo Nova Clouds cool the planet as it warms

Clouds cover an enormous 65% of the planet and are responsible for about half of the sunlight that is reflected back out to space.[i] The effects of clouds are so strong that most of the differences between IPCC-favoured-models comes from the assumptions the models make about clouds. Cloud feedbacks are the “largest source of uncertainty”.[ii] Numerous studies show models project wildly different results for clouds, and yet few could correctly simulate clouds as recorded by satellites.[iii] One researcher described our understanding of cloud parameters as being “still in a fairly primitive state.” [iv]

Sunlight that travels 150 million kilometers can be blocked a mere 1km away from the Earth’s surface and reflected back to space. The situation is complicated though, because clouds also slow the outgoing radiation — which has a warming effect. In general lower clouds are thicker and have a large cooling effect, while higher clouds are thinner and tend to trap more heat than they reflect (i.e. net warming). Observations show the cooling effect of clouds dominates the warming effect. (Allen 2011[v]) which means that, in general, more clouds means more cooling.


Last 30 years shows climate feedbacks are zero (at best)

Let’s be as generous as we can. The IPCC say feedbacks amplify CO2’s warming by a factor of about three.

Without the amplification from positive feedback there is no crisis

So being nice people, let’s assume it’s warmed since 1979 and assume that it was all due to carbon dioxide. If so, that means feedbacks are …. zero. There goes that prediction of 3.3ºC. Feedbacks are the name of the game. If carbon dioxide doesn’t trigger off powerful positive feedbacks, there was and is no crisis. Even James Hansen would agree — inasmuch as he himself said that CO2 would directly cause about 1.2ºC of warming if it doubled, without any feedbacks (Hansen 1984).

Consider the warming from1979 to 2007, when we measured temperatures using satellites and not corrupted and adjusted land thermometers. Douglass and Christy (2008) point out that, given how much CO2 levels increased in that time, the warming only amounts to what the IPCC scientists predict we should get from CO2 alone, from the direct effect of CO2, and not from the effect of CO2 plus positive feedbacks.

The warming trend expected from CO2 without any feedbacks at all is 0.07 ºC/decade. The trends […]

Satellites show a warmer Earth is releasing extra energy to space

(I’m revisiting older important papers and setting up resource pages, largely thanks to Tony Cox’s prodding. In this post I found it interesting that Lindzen’s work, which was so controversial because it proved the IPCC is wrong, was in many ways merely confirming earlier results. — Jo) Guest Post: Tony Cox and Jo Nova Satellite measurements agree with the ocean heat content measurements. As the Earth warms, more radiation escapes to space.

If feedbacks are positive (as the IPCC estimates), then as the Earth warms the amount of energy being radiated to space will shrink (thus warming the Earth even further). If feedbacks are negative, as the Earth warms more energy will radiate away.

Multiple studies show that feedbacks are negative.

Lindzen and Choi analyzed short periods of warming looking for changes in the outgoing long-wave radiation leaving from the top of the atmosphere. The satellite observations show, repeatedly, that as the Earth warms, the climate system shifts and lets more of the infra red or long-wave energy out to space.[1],[2] It’s like a safety release valve. This means that the system has negative feedbacks (like almost all known long-lived or stable natural systems). The changes dampen the effects of […]

Idso 1998 – eight different ways to show CO2 will have little effect

Here’s a forgotten paper that deserves more attention: Idso 1998.

Rather than using an enormously complex global circulation model (or 22) to come up with a figure for climate sensitivity, Sherwood Idso does calculations from eight completely different natural experiments which all arrive at similar figures. In short, he reviewed 20 years of work to arrive at a prediction that if CO2 is doubled we will get 0.4°C of warming at most, and even he admitted, it might be an overestimate. Basically by the time CO2 levels double, he says we ought expect 0 – 0.4°C of warming, after feedbacks are taken into account. Idso started off assuming that the feedbacks were largely positive, but repeatedly found that they were negative.

Idso’s approach was novel. Instead of climate sensitivity to CO2, he estimates the sensitivity of the Earth to any factor. He calls it the “surface air temperature sensitivity factor“. Once something known heats or cools the Earth, how much do the net feedbacks amplify or dampen that initial change? Rather than trying to measure and capture every single feedback and process, and then calculate the end results, Idso finds situations where he can isolate a factor and calculate […]