Friday, October 31, 2014

New paper finds climate sensitivity to CO2 significantly less than claimed by IPCC; low-sensitivity paper #37

A new paper published in Earth System Dynamics finds equilibrium climate sensitivity [ECS] to doubled CO2 levels is 1.8C, about 44% less than claimed by the IPCC AR5 report. The paper adds to at least 36 other peer-reviewed papers finding climate sensitivity to be significantly less than the IPCC mean modelled estimate of 3.2C [range 1.5 - 4.5C].

Excerpt from The IPCC’s 2007 Fourth Assessment Report (AR4) estimated a “likely” ECS range of 2°C-4.5°C, with a “best estimate” of 3°C. Since 2011, however, the warming pause and the growing divergence of model predictions and observed global temperatures have been the impetus for several studies finding that IPCC sensitivity estimates are too hot.

Cato Institute scientists Patrick Michaels and Chip Knappenberger maintain a growing list of such studies, which totaled 18 as of February 2014:

The average sensitivity estimate of the 18 studies compiled by Michaels and Knappenberger is just under 2°C. In other words, the IPCC AR4 “best estimate” of 3°C is 50% higher than the mean estimate of the new studies. That may be why the IPCC’s 2013-2014 Fifth Assessment Report (AR5) declines to offer a “best estimate.”

A new “best estimate” of 2°C would deflate the scary climate change impacts featured elsewhere in AR5, but recycling the same old 3°C “best estimate” would deflate the IPCC’s claim to be an honest broker. So instead the IPCC chose to lower the low end of the “likely” sensitivity range. Whereas the “likely” range in AR4 was 2°C-4.5°C, in AR5 it is 1.5°C-4.5°C.

That small concession, however, does not dispel the growing challenge to consensus climatology. As indicated in the Michaels and Knappenberger chart above, the average sensitivity of the climate models used in AR5 is 3.2°C. That is 60% higher than the mean of recent estimates (<

An additional 21 peer-reviewed papers based upon observations and compiled by the Hockey Schtick find even lower ECS estimates of < 1C, about 7 times less than claimed by the IPCC. In total, there are now at least 37 published, peer-reviewed studies compiled by Michaels, Knappenberger, and the HS finding climate sensitivities significantly less than claimed by the IPCC. In contrast, there is a drought of studies finding climate sensitivities higher than claimed by the IPCC AR5 mean modelled estimate of 3.2C. 

The new paper below finds an ECS of 1.8C, but does not consider natural changes in ocean oscillations, cloud cover, global "brightening" & "dimming," which can alone explain all of the post-1950 warming. The paper also uses long-term ocean heat content [OHC] data as the basis of the ECS calculation, but the OHC trends have been determined to be exaggerated due to sampling biases in a paper published this week. The paper also does not consider the possibility of solar amplification mechanisms, which can explain 95% of climate change over the past 400 years. Consideration of these 4 factors would further lower the ECS estimates significantly. 

A description of the paper from the Swedish Stockholm Initiative site is below [Google translation], followed by the abstract and full paper in English. 

Norwegian research team got climate sensitivity (ECS) between 0.9 and 3.2 degrees C

The Norwegian research team consists of climate scientists and statistical mathematician. They have used every conceivable observations, together with a relatively simple climate model, a so-called energy balance model in which climate sensitivity is one of the input parameter values. They have adjusted the parameter values ​​of the climate model to observations using Bayesian statistics. They were then equilibrium climate sensitivity (ECS = Equilibrium Climate Sensitivity) to 1.8 degrees C (0.9 to 3.2 degrees C with 90% probability) for the doubling of carbon dioxide levels.
The article of Skeie et al. (2014) is published in the geosciences journal Earth System Dynamics.Three of the authors belong climate research center CICERO, University of Oslo, Terje Berntsen ,Gunnar Myhre and Ragnhild Bieltvedt Skeie . The other two authors are statistical mathematician belonging Norsk Regnesentral, Marit Holden and Magne Aldrin .
It inspires confidence that climate scientists here collaborates with statistical mathematician who is proficient in Bayesian statistics . The idea is to use a climate model that includes climate sensitivity as a parameter and to find out the value of climate sensitivity by adapting the model to the observed data. To do this properly with Bayesian statistics needed the expertise of statistical mathematics.
Magne Aldrin (2010) has given a presentation of the methods that they use at a workshop in Cambridge, UK in 2010. The simple climate model is not of the simplest kind, the atmosphere is divided into northern and southern hemispheres. The model ocean is still more complicated and divided into the southern polar ocean, the southern hemisphere's main body, the northern hemisphere's body and the northern polar ocean. The following figure gives an approximate schedule for this climate model (the dimensions listed are only possible examples).
Climate model
This simple climate model , according to previous studies cited in Skeie et al. (2014) have been able to reproduce the simulations with advanced climate models. The reason for for this kind of adaptation of the model parameters to the observed data are not using an advanced climate model directly, is that such models are very complex and require too much computing power. One way to solve this problem is to do what the writers have done, using a simple model that has been confirmed by simulation can reproduce sophisticated climate model results.
Climate model includes climate sensitivity at equilibrium (ECS = Equilibrium Climate Sensitivity) as an unknown parameter, and six additional parameters related to the heat flows into the ocean to do. You also need radiation exchange between the atmosphere and the upper and solar. This type of data is called "radiative forcing" and that climate science has devoted considerable effort to determine, but the uncertainties in the data are still large. As is known, the impact of increased levels of greenhouse gases in the atmosphere, which mainly affects the "radiative forcing" and that they have pretty good data as well as changed aerosol influence and where the uncertainty is much larger.
Has values ​​of these seven parameters and a graph of how the "radiative forcing" has varied with time since pre-industrial times so this simple climate model to figure out how the temperature has varied in both the northern and southern hemispheres, and how the heat content of the ocean has changed. You can then modify the parameter values, whereby man is above all interested in climate sensitivity, within the possible limits of error, and also vary the "radiative forcing" within their error limits. In this way, one can see for what combinations of parameter values ​​to obtain curves for the temperatures and ocean heat content, which agrees with observations. This is what is called the parameter adjustment .
It's such a parameter adjustment statistical mathematician can help with making in a professional manner and really exploit the knowledge of Bayesian methods to get the best possible results. In this way one can determine a probability interval for climate sensitivity, in this case one can say about the ECS that the most likely value is 1.8 degrees C for a doubling of carbon dioxide and that with 90% probability value lies between 0.9 and 3.2 degrees C (compared to the UN Climate Change (IPCC) range to the 66-100% probability value lies between 1.5 and 4.5 degrees C).
The observations that the authors have used for their study is part six temperature series: HadCRUT3, NCDC and GISS for the northern and southern hemisphere (there is a significant body of scientific work that has taken a long time to implement, why not HadCRUT4 been used throughout, but only for a supplemental analysis ), and data for ocean heat content from Levitus research team at NOAA and two other research groups. So it is incredibly much data as adapting the model parameters to. It has also, as is possible in a Bayesian analysis, taken with data for ocean parameters based on independent observations as input data (so-called "prior probability distribution").
The result for the equilibrium sensitivity ECS is low, 1.8 degrees C for a doubling of carbon dioxide levels, but especially noteworthy is that the uncertainty interval, 0.9 to 3.2 degrees C, is shorter than in other similar studies. Compare, for example, with the much talked about recently published study by Lewis and Curry who were 1-4 degrees C.
The authors therefore studied how the results varied with the data ended. If they used data only up to 2000, they received a slightly higher climate sensitivity, but above all was the uncertainty range for much longer.
They suggest thereof an explanation of why this is so. This is partly due to "radiative forcing" has risen significantly during the past decade, so that the relative error of this has diminished. The second contributing factor is the availability of data for the heat content of the ocean has increased by 20% (depending on the test series starting about 1950). They say not to the reduced length of the uncertainty interval would have to do with heating the break.
The transient climate sensitivity is also of interest because it is this which, in theory, primarily determines the temperature will increase with increased greenhouse gas concentrations within 50 to 100 years. It uses as a measure of the climate sensitivity of the temperature increase due to how the temperature is affected by a change in the carbon content of 1% per year (ie 400 ppm increase in one year to 404 ppm). Climate sensitivity measure is called TCR (Transient Climate Response) and indicates the temperature rise at the time when carbon dioxide levels doubled, with 1% annually takes about 70 years.
Skeie et al. got the TCR value 1.4 degrees C with 90% probability that the value is in the range 0.8-2.2 degrees C. Even in this case was the uncertainty interval longer, almost 70% increase, if only the data up to 2000 were used .
The most exciting aspect of this very reassuring study, I think, is the already mentioned comparison with the UN climate panel climate sensitivity range, ie that climate sensitivity is likely, with 66-100% probability, is between 1.5 and 4.5 degrees Celsius . The latest scientific summary for policy makers (Summary for Policymakers, SPM) writes more accurately:
Equilibrium climate sensitivity is likely in the range 1.5 ° C to 4.5 ° C (high confidence), Extremely Unlikely less than 1 ° C (high confidence), and very Unlikely Greater Than 6 ° C (medium confidence).
(Likely = 66-100% probability, Extremely Unlikely = 0-5%, Very Unlikely = 0-10%).
This present study has instead concluded that with 90% probability is climate sensitivity between 0.9 and 3.2 ° C . The difference from the UN Climate Panel range of 1.5-4.5 degrees C is remarkable.
Skeie RB, Berntsen T, Aldrin M, Holden M, Myhre G (2014) A lower and more constrained estimate of climate sensitivity using updated observations and detailed radiative forcing time series . Earth Syst Dyn 5: 139-175. doi: 10.5194 / esd-5-139-2014
Earth Syst. Dynam., 5, 139-175, 2014

R. B. Skeie1, T. Berntsen1,2, M. Aldrin3,4, M. Holden3, and G. Myhre1
1Center for International Climate and Environmental Research – Oslo (CICERO), Oslo, Norway
2Department of Geosciences, University of Oslo, Oslo, Norway
3Norwegian Computing Center, Oslo, Norway
4Department of Mathematics, University of Oslo, Oslo, Norway

Abstract. Equilibrium climate sensitivity (ECS) is constrained based on observed near-surface temperature change, changes in ocean heat content (OHC) and detailed radiative forcing (RF) time series from pre-industrial times to 2010 for all main anthropogenic and natural forcing mechanism. The RF time series are linked to the observations of OHC and temperature change through an energy balance model (EBM) and a stochastic model, using a Bayesian approach to estimate the ECS and other unknown parameters from the data. For the net anthropogenic RF the posterior mean in 2010 is 2.0 Wm−2, with a 90% credible interval (C.I.) of 1.3 to 2.8 Wm−2, excluding present-day total aerosol effects (direct + indirect) stronger than −1.7 Wm−2. The posterior mean of the ECS is 1.8 °C, with 90% C.I. [confidence interval] ranging from 0.9 to 3.2 °C, which is tighter than most previously published estimates. We find that using three OHC data sets simultaneously and data for global mean temperature and OHC up to 2010 substantially narrows the range in ECS compared to using less updated data and only one OHC data set. Using only one OHC set and data up to 2000 can produce comparable results as previously published estimates using observations in the 20th century, including the heavy tail in the probability function. The analyses show a significant contribution of internal variability on a multi-decadal scale to the global mean temperature change. If we do not explicitly account for long-term internal variability, the 90% C.I. is 40% narrower than in the main analysis and the mean ECS becomes slightly lower, which demonstrates that the uncertainty in ECS may be severely underestimated if the method is too simple. In addition to the uncertainties represented through the estimated probability density functions, there may be uncertainties due to limitations in the treatment of the temporal development in RF and structural uncertainties in the EBM.

Citation: Skeie, R. B., Berntsen, T., Aldrin, M., Holden, M., and Myhre, G.: A lower and more constrained estimate of climate sensitivity using updated observations and detailed radiative forcing time series, Earth Syst. Dynam., 5, 139-175, doi:10.5194/esd-5-139-2014, 2014.

Three new studies demonstrate climate sensitivity to CO2 is very low

New excuse #57 for the "pause" of global warming: Increase in mid- and upper level clouds

Via email from climate data analyst John McLean of the Dept. of Physics, James Cook University, Australia, comes explanation #57 for the global warming "pause," related to an "increase in mid- and upper level clouds" after 1997, which increased albedo/reflection of sunlight.

McLean also finds that "CO2 played little if any part" in the post-1950 global warming, which the IPCC attributes with alleged "95% confidence" entirely to man-made greenhouse gases. He instead finds post-1950 warming explained by natural shifts in ENSO and cloud cover. As he notes, "This means that there is little if any "missing heat" that (supposedly but improbably) 16 years ago decided to start hiding itself away where no-one could find it."

Email from John McLean [emphasis added, h/t Marc Morano/Climate Depot]:

My new paper about late 20th century warming is now available via

I show that the pattern of global average temperature anomalies since 1950 can be described as a sequence of:

(a)  ENSO shifting from lots of La Nina events and very few El Ninos to the opposite situation
(b) from 1988 to 1997 a reduction in the total cloud cover anomaly
(c) after 1997 a decrease in low level cloud but an increase in mid and upper level cloud

The temperature data is HadCRUT4, the ENSO data the Troup data from Australia's Bureau of Meteorology and the cloud cover data the D2 dataset from ISCCP.

Of the above it was (b) that caused warming of about 0.45C degrees.  When I adjusted the data in the often-quoted energy balance diagram by Trenberth et al, I found that the increase in heat absorbed at the Earth's surface was about 5 watts per square metre, a figure greater than that given by the IPCC 5AR for the extra heat caused by greenhouse gas emissions.

If my hypothesis is correct then CO2 played little if any part.  This means that there is little if any "missing heat" that (supposedly but improbably) 16 years ago decided to start hiding itself  away where no-one could find it.

The paper is being discussed on WUWT:

and on Bishop Hill:

New excuse #56 for the "pause" in global warming: Satellites underestimate cooling from volcanic aerosols

A paper published today in Geophysical Research Letters states, 
"Understanding the cooling effect of recent volcanoes is of particular interest in the context of the post-2000 slowing of the rate of global warming"
and finds
"recent volcanic events are responsible for more post-2000 cooling than is implied by satellite databases" which "translates into an estimated global cooling of 0.05 to 0.12 °C."
By way of comparison, the IPCC formula claims post-2000 warming from CO2 was 5.35*ln(400/369) = 0.43W/m2 *(3C/3.7Wm-2) = 0.35C warming, which is at least three times larger than the estimated volcanic cooling found from this paper. Therefore, volcanic cooling would not be sufficient to account for the zero degrees global warming post-2000 (actually post-1996). This implies that either this new paper is incorrect regarding volcanic cooling account for the "pause," or that the IPCC exaggerates climate sensitivity to CO2.

Further, even James Hansen admits there have been no large volcanic eruptions post-2000:

"Remarkably, and we will argue importantly, the airborne fraction [of man-made CO2] has declined since 2000 (figure 3) during a period without any large volcanic eruptions."
and as demonstrated by the stratospheric aerosol index of volcanic eruptions:

How can volcanic aerosols explain the post-2000 "pause" without an increase of volcanic activity?

Total volcanic stratospheric aerosol optical depths and implications for global climate change

D. A Ridley et al

Understanding the cooling effect of recent volcanoes is of particular interest in the context of the post-2000 slowing of the rate of global warming. Satellite observations of aerosol optical depth (AOD) above 15 km have demonstrated that small-magnitude volcanic eruptions substantially perturb incoming solar radiation. Here we use lidar, AERONET and balloon-borne observations to provide evidence that currently available satellite databases neglect substantial amounts of volcanic aerosol between the tropopause and 15 km at mid to high latitudes, and therefore underestimate total radiative forcing resulting from the recent eruptions. Incorporating these estimates into a simple climate model, we determine the global volcanic aerosol forcing since 2000 to be −0.19 ± 0.09 Wm−2. This translates into an estimated global cooling of 0.05 to 0.12 °C. We conclude that recent volcanic events are responsible for more post-2000 cooling than is implied by satellite databases that neglect volcanic aerosol effects below 15 km.


New paper rules out volcanoes as the cause of the 'pause'

New paper finds temperature reconstructions from tree-rings overestimate volcanic cooling

Thursday, October 30, 2014

WSJ: "The gloves are off." Pathetic Steyer ad tries to sell climate scam with fake condom ban

Desperate, dirty-tricks climate-scam promoter & fossil-fuel-billionaire-hypocrite Tom Steyer buys ads falsely claiming a Republican will ban condoms, and tries to tie that absurd claim to climate change:

"That climate change enthusiasm deficit is not for [Steyer's] NextGen’s lack of trying. 
The committee has run slews of television ads blasting Republicans for “denying the science of climate change,” but it still hasn’t cracked the polls as a hotbed issue. Climate change doesn’t appear on Gallup’s monthly list of “most important problem” list, and even the more general “environment/pollution” category gets only 2 percent of the total. 
Perhaps as a result, even NextGen Climate isn’t focused solely on the climate. The committee also has sponsored commercials weighing in on standard Democratic Party talking points such as the Koch brothers and birth control aimed more at boosting Democrats than spreading the word on climate. 
For example, NextGen’s fingerprints are on a radio ad airing in the Senate race in Colorado that accuses Republican Rep. Cory Gardner of banning condoms. On Monday, NextGen contributed $239,000 to the NARAL Pro-Choice Colorado IE Committee, which then paid a consultant for the radio ad, according to The Federalist."

The Gloves Are Off

Condom shortages and other Democratic trouble signs


We’ve got to hand it to NARAL Pro-Choice America (née National Association for the Repeal of Abortion Laws), which has put out the funniest series of political ads at least since one Christine O’Donnell solemnly intoned to the camera: “I am not a witch.”

The NARAL spots—TV and radio—seek to influence the Colorado senate race, in which Republican Rep. Cory Gardner has been slightly favored to unseat Sen. Mark Udall. The incumbent has relied so heavily on the once-fashionable Democratic war-on-women shtick that he’s earned the derisive nickname “Mark Uterus.”

NARAL’s ads send mixed messages, which is to say that they jump around in an abrupt and madcap way between WOW and other themes. The radio spot begins with a conversation between a heterosexual couple. He has returned home to report failure in his mission to purchase condoms. “How did this happen?” she asks.

He replies: “Cory Gardner banned birth control, and now it’s all on us guys. And you can’t find a condom anywhere. And the pill was just the start. The Pell grants my little brother was counting on for college? Cory cut them! Climate change that everyone knows is weirding our weather—Cory flat-out denies it! Sweet pea, Cory denies science!”

Some guys just know how to talk to the ladies.

The TV ad seems to be directed at the gents. It’s divided into two parts, each introduced by a narrator with a high-pitched voice, one of each sex, frantically addressing the viewer as “Guysguysguysguysguys.” The second part is variation on the contraception theme: “If Cory Gardner gets his way, you better stock up on condoms.” The first part claims Gardner “denies climate change” and shows cars being swept away by rising seas.

Guysguysguysguysguys, Colorado is a doubly landlocked state whose lowest point is 3,310 feet above sea level.

The ads’ claims about Gardner are false. An anti-Gardner site quotes the congressman as acknowledging climate change: “I think the climate is changing, but I don’t believe humans are causing that change to the extent that’s been in the news.” As for the assertion that Gardner seeks to ban birth control, that would be true only if “ban” meant “to make available without a prescription.”

We guess the rationale here is to hope either that the massive quantity of arguments will compensate for their poor quality, or that their scattershot variety will somehow yield a broad appeal across liberal constituencies. Maybe they even have some nonliberal constituencies in mind. We were scratching our head wondering why they would make the small concession to reality of acknowledging that Gardner doesn’t want to ban condoms. Then it occurred to us that maybe they imagine there are extremists who do, and are trying to depress turnout.

also today:

Outside Groups Spending Huge Money On Colorado Senate Race

"But Udall supporters are doubling down on the message, with NARAL Pro-Choice Colorado releasing an ad this week warning that if Gardner is elected, it will lead to a shortage of condoms because he will have banned other forms of birth control. (Gardner actually advocates the sale of birth control pills over the counter.)
Media outlets are having a hard time reporting on the new ad with a straight face. 
"National Review mocked it twice, once in a straight news story titled “Udall Going All In on What Hasn’t Been Working” and again in a mock send-up blaming Gardner for banning everything from bread to Ramen noodles — “anything that could hurt an unborn child.”

New paper claims 'evidence of human influence first emerges from sea level rather than temperature'

A new paper and editorial in Nature Climate Change finds 
"natural variability complicates the detection of anthropogenic climate change in the twenty-first century. Now, research shows that evidence of human influence first emerges from sea level rather than temperature rise."
This is a curious move of the goalposts, since the IPCC claims a bogus 95% confidence that "most" of the warming since 1950 is anthropogenic on the basis of temperature rise since 1950, not on the basis of sea level rise, and thus opposite to the claims of this new paper. In addition, this new paper claims climate models predict allegedly anthropogenic "sea level rise signals can arise as early as 2020 over half the global ocean regions."

If that's the case, there's a lot of sea level rise catching up to do, since global sea levels have been naturally rising for ~20,000 years and have decelerated over the past 8,000 years, decelerated over the 20th century, decelerated 31% since 2002 and decelerated 44% since 2004 to less than 7 inches per century. There is no evidence of an acceleration of sea level rise, and therefore no evidence of any effect of mankind on sea levels. Sea level rise is primarily a local phenomenon related to land subsidence, not CO2 levels.

Further, observational data shows 86%-93% of the alleged AGW "missing heat" is still missing and not in the oceans or atmosphere, and missing or non-existent heat cannot cause sea level rise.

In addition, a paper published today in the Journal of Atmospheric and Oceanic Technology finds that the long-term ocean heat content trend is less than previously believed due to sampling biases. The authors "concluded that Argo-period climatologies [only available since 2004] should be used to accurately assess the long-term trend of the climate indicators such as OHC [ocean heat content]."

And what do ARGO-period ocean heat observations show? A tiny increase in ocean heat content, or even a decrease of ocean heat content [before Josh Willis "corrected the ocean cooling" by throwing away the ARGO float data he thought was too cold]

ARGO data before "correction" to remove cooling

Even with the biased and artificially warmed long-term ocean heat content data, the record only shows a very tiny 0.09C ocean warming over the past 55 years.

Thus, sea level rise and ocean heat content have "paused" right along with the "pause" in global surface temperatures. It will likely be many years [if ever] before a clear "signal" of anthropogenic global warming is detected in sea level rise acceleration, ocean heat content acceleration, surface temperature rise, or a tropospheric "hot spot," all of which still remain missing in the 21st century.

Excerpt from Nature Climate Change:

Time of emergence for regional sea-level change

Nature Climate Change
Published online
Determining the time when the climate change signal from increasing greenhouse gases exceeds and thus emerges from natural climate variability (referred to as the time of emergence, ToE) is an important climate change issue1. Previous ToE studies were mainly focused on atmospheric variables234567. Here, based on three regional sea-level projection products available to 2100, which have increasing complexity in terms of included processes, we estimate the ToE for sea-level changes relative to the reference period 1986–2005. The dynamic sea level derived from ocean density and circulation changes alone leads to emergence over only limited regions. By adding the global-ocean thermal expansion effect, 50% of the ocean area will show emergence with rising sea level by the early-to-middle 2040s. Including additional contributions from land ice mass loss, land water storage change and glacial isostatic adjustment generally enhances the signal of regional sea-level rise (except in some regions with decreasing total sea levels), which leads to emergence over more than 50% of the ocean area by 2020. The ToE [time of emergence of an anthropogenic "signal"] for total sea level is substantially earlier than that for surface air temperature and exhibits little dependence on the emission scenarios, which means that our society will face detectable sea-level change and its potential impacts earlier than surface air warming.

Wednesday, October 29, 2014

New paper finds sunshine has controlled maximum temperatures and temperature ranges in China since 1962

A paper published today in the Journal of Geophysical Research Atmospheres finds that daily [diurnal] temperature range in China decreased from 1962 to 2011, and that this decrease was due to a decrease in maximum temperatures related to a decrease of sunshine durations over this period. 

These changes are indicative that sunshine durations, rather than increased greenhouse gases, were the "control knob" which decreased maximum temperatures and decreased daily temperature ranges throughout China, and opposite of the predictions of AGW theory and climate models. 

The authors examined 479 weather stations in China from 1962-2011 and find 
"Results showed that DTR [daily temperature range] decreased rapidly (0.291 C/decade) from 1962 to 1989 due to slightly decreased Tmax [maximum temperatures] and significantly increased Tmin [minimum temperatures], but the decrease in DTR [daily temperature range] has stopped since 1990 as Tmax [maximum temperatures] and Tmin  [minimum temperatures] kept pace with each otherDuring 1990-2011, DTR [daily temperature range] remained trendless, with slight increase in the 1990s and slight decrease after 2000. During the whole study period from 1962 to 2011, DTR [daily temperature range] decreased at a rate of 0.157 C/decade nationally."
"Seasonally, DTR [daily temperature range] decreases were greatest in winter and lowest in summer, and the magnitudes of decrease reduced from the north to south of China. 
"The changes in DTR [daily temperature range] were closely correlated with changes in sunshine duration (SD) in China except the Tibetan Plateau, suggesting that SD [sunshine duration] decrease is an important contributor to the decrease of DTR [daily temperature range] through its influence on Tmax [maximum temperatures]."
In addition, the authors find that "the most arid region of China" experienced "increasing of precipitation," the opposite of the debunked CAGW meme of "dry gets drier and wet gets wetter." 
"In addition to the contribution of SD [sunshine duration] decrease, the increasing of precipitation played an important role in DTR [daily temperature range] decrease in Northwest China, the most arid region of China."
Similar to the findings of this paper, examination of the raw global temperature data [prior to tampering] shows a significant increase in minimum temperatures over the period 1962-1989, and then leveling off 1989-present. However, over the entire period 1940-present, there is no trend in minimum, maximum, or average global temperature anomalies. 

Spatiotemporal change of diurnal temperature range and its relationship with sunshine duration and precipitation in China

Xiangjin Shen et al

We examined the spatiotemporal variation in diurnal temperature range (DTR) and discussed the reasons for the changes of DTR in China based on data from 479 weather stations from 1962 to 2011. Results showed that DTR decreased rapidly (0.291 C/decade) from 1962 to 1989 due to slightly decreased Tmax and significantly increased Tmin, but the decrease in DTR has stopped since 1990 as Tmax and Tmin kept pace with each other. During 1990-2011, DTR remained trendless, with slight increase in the 1990s and slight decrease after 2000. During the whole study period from 1962 to 2011, DTR decreased at a rate of 0.157 C/decade nationally. Spatially, decreases in DTR were greatest in Northeast China and lowest in Southwest China with a transect running from northeast to southwest showing the decreasing trends change from high to low. Seasonally, DTR decreases were greatest in winter and lowest in summer, and the magnitudes of decrease reduced from the north to south of China. The changes in DTR were closely correlated with changes in sunshine duration (SD) in China except the Tibetan Plateau, suggesting that SD decrease is an important contributor to the decrease of DTR through its influence on Tmax. In addition to the contribution of SD decrease, the increasing of precipitation played an important role in DTR decrease in Northwest China, the most arid region of China. It appeared that changes of cloud cover (CC) were not the reasons for DTR changes in the past 50 years as CC has decreased during the study period.

White House sued about claims that man-made global warming caused polar vortex and record-cold winter

Excerpt from The Daily Caller:

Lawsuit: White House Won’t Show Evidence To Back Up ‘Polar Vortex’ Claims

A free-market think tank is suing the White House Office of Science and Technology Policy over its withholding of documents linked to the claim that global warming caused last winter’s polar vortex.
The free-market Competitive Enterprise Institute filed a lawsuit on Wednesday demanding documents related to the White House’s polar vortex video. The suit comes after CEI previously petitioned the White House to correct the video, which was criticized by climate scientists and ran counter to peer-reviewed studies.
But the White House said the video, in which White House science czar John Holdren connected global warming to the harsh winter, was based on Holdren’s “personal opinion” and exempt from data quality laws. When CEI tried to obtain federal documents related to the video, officials said they were part of the “deliberative process” and exempt from records requests.
“If this video really represented Dr. Holdren’s personal opinion, then it’s bad enough that OSTP spent taxpayer dollars to produce and post it on the White House web site,” said CEI general counsel Sam Kazman. “But for the agency to refuse to disclose documents related to the video in order to protect what it claims are internal deliberations is doubly ridiculous.”
The White House released its polar vortex video last January. In the video, Holdren claimed a “growing body of evidence suggests that the kind of extreme cold being experienced by much of the United States as we speak is a pattern that we can expect to see with increasing frequency as global warming continues.”
The idea is that melting Arctic ice sheets weakens the swirling mass of cold air in the polar region, called the polar vortex. As the vortex weakens, its pattern becomes more erratic and pushes cold air farther south. But the video was quickly debunked by climate scientists and peer-reviewed studies showing the polar vortex is not a product of global warming (or climate change, or whatever).
“While perhaps it could be argued that Holdren’s statement is not an outright lie, it is, at its very best, a half-truth and even a stretch at that,” wrote scientists Pat Michaels and Chip Knappenberger with the libertarian Cato Institute. “For in fact, there is a larger and faster growing body of evidence that directly disputes Holdren’s contention.”
“It’s an interesting idea, but alternative observational analyses and simulations with climate models have not confirmed the hypothesis, and we do not view the theoretical arguments underlying it as compelling,” five top climate scientists wrote in a letter published in Science Magazine in the wake of Holdren’s claims.
Studies done before Holdren’s claim that global warming is causing frigid winters also cast doubt on the integrity of the White House polar vortex video.
Research by Colorado State University’s Elizabeth Barnes in 2013 found that claims that “amplified polar warming has led to the increased occurrence of slow-moving weather patterns and blocking episodes, is unsupported by the observations.”
A study published before Barnes’s by Australian scientists James Screen and Jan Simmonds found that statistically significant changes in the jet stream depended largely on the methodology used by scientists. Screen and Simmonds noted their findings have “different and complex possible implications for midlatitude weather, and we encourage further work to better understand these.”
A recent study from Japanese scientists, however, claims that melting Arctic ice will bring colder winter with it. The study found that severe winters happening in Europe and Asia have doubled due to melting ice sheets.
Despite the conflicting evidence on the Arctic’s role in cold winters, the White House has not backed off from its claims that global warming is driving frigid weather. Even though Holdren purportedly espoused his opinion in the video, that has not been disclosed nor has the video been changed.
“Perhaps OSTP should give us a new video titled ‘The Holdren Document Vortex Explained in 2 Hours,’” Kazman quipped.