JoNova

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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The Sahara may flip from desert to grass every 20,000 years. Blame The Sun.

MIT researchers think they have solved a bit of a mystery regarding Sahara dust, but if they’re right it means the Sahara Desert has already come and gone 3 – 5 times since humans walked the Earth. The Sahara is the largest desert on Earth, and this would be the largest and longest drought “ever” on the planet (as far as we know).

UPDATED: Commenter Javier points out these drying cycles were known years ago. (See below)

This would rather redefine the whole idea of “climate change” — 3.5 million square miles of Green Sahara turns into Dust-bowl Sahara — and it’s all thanks to sunlight. The drought doesn’t just last 7 years, but more like 7,000. And it’s happening over 9 million square kilometers, an area larger than Australia. The major climate models leaned towards the monsoonal cycle, rather than the longer ice age one. So this theory may have resolved one of the 495 contradictions in climate models. Or not. But the bigger message here is that the sun causes climate change and on a massive scale.

h/t to Roger Tallbloke.

The Sahara is the largest dust bowl in the world, dumping 10 million trucks of dust across [...]

Now that was “climate change” 8200 years ago — California lashed by 150 years of storms

Don’t tell me that cold is nice and the climate was ever ideal

A few scientists thought that the climate was stable and well behaved during the Holocene until we invented coal power and the Ford Model T and everything fell apart “unprecedentedly”.

But 8200 years ago things apparently got pretty wild. See the GISP graph below where there was a three degree fall in temperatures suddenly (circled in red below). A new study found that at the same time China and California also cooled. Strangely, this cooling effect probably did not produce calm, happy days for the Californians at the time. Instead it looks like they got 150 years of intense winter storms and a lot of wet weather.

UPDATE: This graph shows the ice-core data up until 1855. The last 150 years (1705 to 1855) are highlighted in red to show the warming as the Earth began coming out of the LIA. Obviously that red line would continue up further if it was drawn to the present.

Looks like real climate change….

The reason for the sudden snap is possibly that a couple of massive glacial lakes in North East America collapsed and suddenly drained out [...]

Will Steffen in denial of entire Holocene?

Either Will Steffen thinks humans didn’t exist five thousand years ago, or he hasn’t heard of the Holocene. The Herald Sun tells us the extraordinary news that:

“Humans are living in the hottest temperatures they have ever lived and I can guarantee this will only get worse.”

Will Steffen also says the climate is “complex”, and “impossible to entirely predict”. I guess that means his guarantee that it will get worse comes direct from God, since it’s not possible through science. I don’t know why Matthew Dunn, technology editor of the Herald Sun, didn’t ask more about that — obviously that would be big news.

Otherwise, nearly every proxy that’s ever been proxied suggests there were a lot of warmer times in the period 5,000 – 8,000 years ago. Ice cores say it was hotter in Greenland, barnacles, corals, sea worms, and “swash” tell us sea levels were something like 2 meters higher in stable West Australia* and nearly 1m higher in Hawaii and Polynesia, oceans were 2 degrees warmer around in Indonesia, and 6,000 boreholes sunk in the oceans all over the world show it was a global deal. Australian Aboriginals apparently struggled through a 1,500 year [...]

Greenland ice cores show natural swings are large and warming means less storms

A new high resolution ice core in Greenland surprises even me with the wild swings and detail. The authors are discussing wind direction and storms that occurred in specific years 12,000 years ago, which is extraordinary information if accurate. They use elements like sodium (from sea salt) to figure out how many storms have dumped salt on the ice and take bands so thin they identify each summer so long ago*. The slices are so thin, they claim to have hundreds of samples per year.

The message here is that the cold younger dryas period ended abruptly (within one year) and so did the storms. Naturally, they warn that the abrupt changes mean the climate is unstable, “be afraid” type stuff. My take on this is that if natural factors cause abrupt climate change, we need to know what those natural factors are. The obsession with CO2 is hindering that. Also if warming brings less storms, that’s probably not such a bad thing. The caveats being that this is only one site, and less storms over the GISP site doesn’t tell us if less storms occurred elsewhere. It could be that jet streams shifted and moved the storms to another [...]

Ocean heat content around Indonesia shows Medieval Warm Period and 2C warmth in holocene

Rosenthal et al have put out quite a humdinger of a paper. They’ve reconstructed the temperature of the water flowing out of the Pacific to the Indian Ocean over the last 10,000 years and as deep as 900m. The Indonesian Throughflow is pretty significant in global ocean currents. There’s narrow routes for Pacific upper waters to squeeze through to the Indian Ocean through the Makassar and Lombok Straits, and via the Lifamatola Passage through the Banda Sea, and water comes in from both the North and South Pacific.

An important point in global ocean currents where the Pacific flows through to the Indian Ocean.

Points to note (assuming the study is right):

Temperatures started rising around 1700AD – long before our carbon emissions. That temperatures were much warmer (0.65C) in 1100AD than they were in 1950. 8,000 years ago water was 1.5 to 2 degrees warmer — isn’t that meant to be a global catastrophe? Apparently coral reefs, fish, and turtles survived.

 

Figure 4. Holocene changes in Pacific Ocean heat content. (A) Reconstructed anomalies in Pacific OHC in the 0- to 700-m depth interval for the early Holocene, mid-Holocene, MWP, and LIA periods. Reconstructed anomalies are calculated [...]

The Marcott Hockey-stick: smoothing the past and getting a spike from almost no data?

The message to the world is unequivocal:

“We are heading for somewhere that is far off from anything we have seen in the past 10,000 years – it’s through the roof. In my mind, we are heading for a different planet to the one that we have been used to,” said Jeremy Shakun of Harvard University, a co-author of the study.

Source: The-world-is-hottest-it-has-been-since-the-end-of-the-ice-age–and-the-temperatures-still-rising.

There are two factors in the new Marcott paper that are major red flags. For one, there is hardly any data in the modern end of the graph. Ponder how researchers can find 5,000 year old Foraminifera deposits, but not ones from 1940? Two: they’ve smoothed the heck out of longer periods. Marcott et al clearly say there is “…essentially no variability preserved at periods shorter than 300 years…” So if there were, say, occurrences of a warming rise exactly like the last century, this graph won’t show them.

Some of the data has a resolution as poor as “500 years” and the median is 120 years. If current temperatures were averaged over 120 years (that would be 1890 to now), the last alarming spike would blend right in with the other data. Where would the average [...]