More slurs from continues with its same line of attack. writers try again and again to concoct what appears to be deep critiques against skeptic arguments, but end up doing a very shallow job. All in the name of saving the world. How gallant of them. This time it is an ill-founded attack by Jahnke and Benestad.

Open convection cells over the Negev?

OpenCellRadar Jerusalem was under siege, again. Last time it was Bush. This time, it was snow because of which we had two snow days. So, I didn't have to teach and instead could build a snowman with my kids. I could also look at the rain radar, which appeared to exhibit a few interesting phenomena.

One of the phenomena appears to be that of open-cell convection, i.e., air rising (and precipitating) on the cell boundaries.

The Hebrew University debate on Global Warming

The panel. From left to right: Prof. Colin Price, Prof. Nathan Paldor, Prof. Dan Yakir, and myself.

On Sunday last week, a global warming debate was held at the Hebrew University, in front of a large public audience. The speakers included myself, and Prof. Nathan Paldor from the HU, on the so called sceptic side, and Prof. Dan Yakir (Weizmann) and Prof. Colin Price (Tel-Aviv Univ.) on the anthropogenic greenhouse gas (AGHG) side.

You can watch the debate, in Hebrew at the Authority for Community and Youth of the Hebrew University. Since most of the readers are not from Israel (98% of the visitors to, here is a short synopsis. It is followed by a detailed response to the claims raised against the cosmic ray climate link.

The inconvenient truth about the Ice core Carbon Dioxide Temperature Correlations

One of the "scientific" highlights in Al Gore's movie is the discussion about the clear correlation between CO2 and temperature, as is obtained in ice cores. He leads his audience to beleive that this correlation implies a clear CO2→ΔT link, but does it really?

Parhelic Circles, Ice Haloes and Sun dogs over Jerusalem

A few weeks ago, a few students saw a nice phenomenon in the sky. Knowing I liked this kind of stuff (and that I may be able to explain it), they called me out of the office to look at the sky. Above us was a nice and almost complete parhelic circle. Unlike the usual 22° halo, often seen around the moon and occasionally around the sun, the parhelic circle keeps a fixed angle from the horizon, not from the bright object.

On the IPCC's summary for policy makers, and on getting interviewed without noticing

Yesterday I was surprised to find out that the IPCC didn't really come out with the Fourth Assessment Report (4AR). I was also surprised to find an article with something which appeared to look like an interview of me. Since I am not senile (getting there, but not just yet) I found it strange that I didn't remember actually being interviewed!

Climate Sensitivity - an interesting IPCC bias

Some time ago, I noticed an interesting bias in the TAR scientific report (the third assessment report of the IPCC - the intergovernmental panel for climate change) regarding the climate sensitivity, that is by how much the average global temperature will increase if we double the amount of CO2. The report mentions quite a few times that climate sensitivity "is likely to be in the range of 1.5 to 4.5°C". Why is this interesting? Because ...

On Climate Sensitivity and why it is probably small

What is climate sensitivity?

The equilibrium climate sensitivity refers to the equilibrium change in average global surface air temperature following a unit change in the radiative forcing. This sensitivity (often denoted as λ) therefore has units of °C/(W/m2).

Often, instead &\lambda;, the sensitivity is expressed through the temperature change &Delta Tx2, in response to a doubled atmospheric CO2 content, which is equivalent to a radiative forcing of 3.8 W/m2. Thus, &Delta Tx2 = 3.8 W/m2 λ

"SKY" experiment demonstrates link between cosmic rays and condensation nuclei!

After a long embargo, results from the Danish National Space Center (DNSC) Sky experiment were finally published in the Proceedings of the Royal Society. The results demonstrate a clear link between cosmic ray induced atmospheric ionization and the formation of condensation nuclei, thus strengthening the claims that cosmic rays affect cloud cover and climate (and consequently implying that a large fraction of 20th century global warming should be attributed to the increased solar activity).

Comments on nature's "A cosmic connection"

Last week, a report by Jeff Kanipe appeared in nature. In it, Kanipe explains the solar → cosmic-ray → climate connection, and the planned CLOUD experiment in CERN, expected to finally resolve the issue. Given that my work is mentioned in the review, I through I should mention a few relevant points.

The coming of another ice-age?

Blog topic: 
A few days ago I stumbled upon an interesting article from Time magazine, entitled: "Another Ice Age?". No it is not a recent article. It is politically incorrect to talk about global cooling these days. The article appeared in 1974, after "three decades of cooling" prompted some to believe that an imminent ice-age may be coming. It is interesting to read it in perspective, and perhaps there is a lesson we could learn from it. Here are a few excerpts from it. Read and enjoy.