Hansen appears to be attempting to confuse the issues here, by ascribing wrong motives to skeptics and telling them what they already know.  Here are my major grumps about some of the salient points of his essay:

“Scientists reporting global warming are under attack for a supposed conspiracy”.  Maybe from the politically motivated, Jim, but not from skeptics.  No need for conspiracy theories when the science is compromised by the funding model.  If one pays a piper and wants to hear an Irish jig, will the piper play Mozart’s “Magic Flute”?  No, the piper will play a jig.  He has to eat.  So does everyone else, including scientists.  Including you, Jim Hansen.  Scientists depending on funding will tailor their research to support whatever the funder is paying for.  The moment they become advocates they compromise their objectivity.  Every piece of AGW-funded climate research I have seen quoted in climate blogs assesses impacts in the most extreme terms and couches the conclusions in terms of calls for urgent action to avoid disaster.  Funny that.

“Regional cold snaps are expected”. And your point, Jim Hansen, is what, exactly?  Skeptics already know that – we are not ignorant.  It’s not the cold winter that makes us skeptical of global warming.  It’s the fact that you claim that the rise in temperature since the 19th century is due to anthropogenic causes, but offer nothing but a model-based argument from ignorance as scientific proof.  It’s the exaggeration of the magnitude of that rise and the clumsy attempts to preserve the illusory hockey-stick.  It’s your insistence that the rise has continued unabated through the first decade of the 21st century (even Phil Jones has denied that)!  It’s the incessant cries of “wolf” that you issue in every “study” and every possible forum.  Cries which more and more are being shown to be bogus – especially those from the definitive IPCC 2007 report.

Skeptics display “honest, wishful thinking that climate change is not really happening.” Wrong again, Jim.  Skeptics know full well that climate change is happening, that the temperature of the earth has risen since the 19th century and may even rise further.  What they are skeptical about is your version of why this is so, and your insistence that the warming is disastrous.

“Our data show that 2009 was tied for the second warmest year in the 130 years of near‐global instrumental measurements”.  Your data as homogenised by whom, Jim?  UAH satellite data contradicts it.  Surprisingly, so does the revised GISS dataset, which now has 1934 as the warmest year!

“If we look back a century, we find cold anomalies that dwarf current ones.  Figure 1 shows photos of people walking on Niagara Falls in 1911.  Such an extreme cold snap is unimaginable today.” Thanks for the great photos,  Jim.   Now, we emerged from the Little Ice Age in the nineteenth century and the earth has unsurprisingly warmed up since then, so I suppose you are confident Niagara won’t freeze again any time soon.  But remember your supercilious “Regional cold snaps are expected”?  Careful – you may again be as embarrassed as you have obviously been by this winter.  A winter of a harshness which the meteorologists who oppose your agenda predicted last year.  And your people failed to predict – in fact, they predicted the opposite.

Still, I suppose if Niagara freezes over or the Mississippi freezes all the way to the Gulf, you will once again talk about the regional cold snaps we already know about.

Reference:

Hansen’s Essay (It has great pictures of Niagara Falls): http://www.columbia.edu/~jeh1/mailings/2010/20100127_TemperatureFinal.pdf

According to the Spacedaily website,”a new study led by Nadine Unger of NASA’s Goddard Institute for Space Studies (GISS) in New York City offers a more intuitive way to understand what’s changing the Earth’s climate. Rather than analyzing impacts by chemical species, scientists have analyzed the climate impacts by different economic sectors”.  In a paper published online by the Proceedings of the National Academy of Sciences, Unger and colleagues described how they used a climate model to estimate the impact of 13 sectors of the economy from 2000 to 2100. They based their calculations on real-world inventories of emissions collected by scientists around the world, and they assumed that those emissions would stay relatively constant in the future.

Inventories of emissions.   This study purports to be about “climate impacts by different economic sectors”.  It is nothing of the kind.  It studies only the proportions of man-made CO2, methane and aerosols introduced to the atmosphere by each sector.  Proportions, incidentally, that are only a fraction of what nature itself introduces.  But it sells itself as an analysis that “shows that emissions from the power, biomass burning, and industrial sectors of the economy promote aerosol-cloud interactions that exert a powerful cooling effect, while on-road transportation and household biofuels exacerbate cloud-related warming”.  How do they reach that conclusion?  By calculations based on the “climate impacts” of the emissions that they have studied.  It seems that they have assumed rather more than just the constancy of the emissions.

No impact has actually been measured.  The climate impacts are assumed from computer modelling that assigns climate impacts in the model parameters.  So if the present temperature variations of the earth are within a bull’s roar of the variations predicted by the models, it is assumed that the assigned impacts must be correct.   If the temperature variation cannot be explained without those assigned impacts, the impacts must be true.  That is argument from ignorance.  Nevertheless, “studies” like this one accept those impacts as the truth, and base their analysis on those assumptions.

There are many analyses that discredit those assumptions, but none from the AGW camp that actually test them.

Now, if the study had collected the data, verified it, classified it and produced an inventory of emissions by economic sector as its output, it would have been worth while.  It would have provided potentially valuable information about the emissions of the identified economic sectors.  We actually need the data.  Pollution was a problem long before the emergence of the AGW spectre, and will remain a concern long after AGW goes the way of Y2K and all the other false Armageddons.

But of course, it would not have obtained the necessary funding.  So instead, it calls itself a climate study and presents its results in the form of advocacy for the IPCC agenda.  And that makes this “study” nothing but propaganda using the language of scientific jargon.  We are seeing too much of this from GISS, the CRU, the IPCC et al.  Tragically, this study will swell the vast pool of so-called “overwhelming evidence” relied upon by evangelical AGW advocates, television pop-science presenters and tax-hungry politicians.  But then, that was why it was commissioned.

References:

http://www.spacedaily.com/reports/Road_Transport_Key_Driver_In_Global_Warming_999.html