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Sunday, January 12, 2014

Papers finding climate models are unable to simulate the Polar Vortex

Global warming alarmists have made the ridiculous claim that the record cold from the 'Polar Vortex' was predicted by climate models as a response to alleged man-made global warming.

However, at least two peer-reviewed publications [noted below] find that climate models have been unable to simulate the behavior of the polar vortex and that little if any confidence should be placed in the model predictions of the polar vortex response to alleged man-made global warming.

In addition, three other peer-reviewed papers find that there is no evidence of any trend over up to the past 142 years in jet stream blocking or location, which in turn controls the polar vortex:

However, there is observational evidence that the polar vortex is related to solar activity, not man-made CO2.

Once again, the global warming apologists are caught hiding behind highly flawed climate models in the face of contradictory real-world data. Dr. Roy Spencer sums it up in a post:

Does Global Warming Theory Predict Record Cold?
January 6th, 2014 by Roy W. Spencer, Ph. D.

NO.

Elementary statistical analysis shows the claim that extreme cold occurs because of warming simply doesn’t stand up to scrutiny.

Excerpt from the paper Stratospheric Polar Vortices:

"A key issue for both the recovery of stratospheric ozone
and the inﬂuence of the stratosphere on tropospheric climate
is how the polar vortices will change, if at all, as greenhouse
gases continue to increase. The stratosphere will cool
because of the direct radiative effect of increased CO2, but
whether the polar vortices will be come stronger or weaker
will likely depend on changes in wave activity entering
the stratosphere. There is currently no agreement between
climate models as to trends in either the wave activity
entering the stratosphere or the strength of the polar vortex,
although the trends are generally small in all models. It is
unclear how much conﬁdence can be put into the model
projections of the vortices given that the models typically
only have moderate resolution and that the climatological
structure of the vortices in the models depends on the tuning
of gravity wave parameterizations. Given the above outstanding
issues, there is need for continued research in the dynamics of
the vortices and their representation in global models."

Abstract from the paper Assessment and Consequences of the Delayed Breakup of the Antarctic Polar Vortex in Chemistry-Climate Models

Title:		Assessment and Consequences of the Delayed Breakup of the Antarctic Polar Vortex in Chemistry-Climate Models
Authors:		Hurwitz, M. M.; Newman, P. A.; Li, F.; Morgenstern, O.; Braesicke, P.; Pyle, J. A.
Affiliation:		AA(NASA Postdoctoral Program, NASA Goddard Space Flight Center, Greenbelt, MD, USA margaret.m.hurwitz@nasa.gov), AB(NASA Goddard Space Flight Center, Code 613.3, Greenbelt, MD, USA paul.a.newman@nasa.gov), AC(Goddard Earth Sciences and Technology Center, University of Maryland, Baltimore County, Baltimore, MD, USA feng.li@nasa.gov), AD(National Institute of Water and Atmospheric Research, Private Bag 50061, Omakau, New Zealand o.morgenstern@niwa.co.nz; NCAS-Climate-Chemistry, Chemistry Department, University of Cambridge, Cambridge, UK peter.braesicke@atm.ch.cam.ac.uk john.pyle@atm.ch.cam.ac.uk), AE(NCAS-Climate-Chemistry, Chemistry Department, University of Cambridge, Cambridge, UK peter.braesicke@atm.ch.cam.ac.uk john.pyle@atm.ch.cam.ac.uk), AF(NCAS-Climate-Chemistry, Chemistry Department, University of Cambridge, Cambridge, UK peter.braesicke@atm.ch.cam.ac.uk john.pyle@atm.ch.cam.ac.uk)
Publication:		EGU General Assembly 2009, held 19-24 April, 2009 in Vienna, Austria http://meetings.copernicus.org/egu2009, p.651
Publication Date:		04/2009
Origin:		COPERNICUS
Bibliographic Code:		2009EGUGA..11..651H

Abstract

Many atmospheric general circulation models (GCMs) and chemistry-climate models (CCMs) are not able to reproduce the observed polar stratospheric winds in simulations of the late 20th century. Specifically, the polar vortices break down too late and peak wind speeds are higher than in the ERA-40 reanalysis. Insufficient planetary wave driving during the October-November period delays the breakup of the southern hemisphere (SH) polar vortex in versions 1 (V1) and 2 (V2) of the Goddard Earth Observing System (GEOS) chemistry-climate model, and is likely the cause of the delayed breakup in other CCMs with similarly weak October-November wave driving. Differences in the models' response to years when the modelled eddy heat flux at 100hPa is relatively weak or relatively strong allow the consequences of the late breakup of the polar vortex to be evaluated. In the V1 model, the delayed breakup of the Antarctic vortex biases temperature, circulation and trace gas concentrations in the polar stratosphere in spring. The V2 model behaves similarly (despite major model upgrades from V1), though the magnitudes of the anomalous effects on springtime dynamics are smaller. As greenhouse gas concentrations continue to rise, the atmospheric temperature structure and resulting zonal wind structure are expected to change. Clearly, if CCMs cannot duplicate the observed response of the polar stratosphere to late 20th century climate forcings, their ability to simulate the polar vortices in future may be poor. Understanding model weaknesses and improving the modelled stratospheric winds will be necessary for accurate predictions of ozone recovery.

Polar Vortex: Global Warming Divides America Over Climate Change Science

When it comes to the polar vortex, global warming has America divided over whether climate change science messed up big time. After all, it seems counter-intuitive that the global temperature average would cause some locations to experience colder-than-usual weather.

As previously reported by The Inquisitr, several years ago NOAA hypothesized that a reduction in Arctic ice and temperature could result in the polar vortex causing cold weather. In contrast, some of the computer models even predict long term stasis or cooling, although the majority definitely favored warming.

To give you an idea how things can vary in the conditions created by the polar vortex, in the past week there were 665 lowest cold records set while 101 locations reported record highs for this time period (my guess is that Florida has some of those). The effects of the polar vortex are only supposed to last until about the middle of this week, but the political effect in the United States may reverberate for some time to come.

As might be expected, Rush Limbaugh, Donald Trump, and Sean Hannity disagree with the various predictions made on behalf of climate change science. But some in the media, including the Huffington Post, claim “this frigid weather is another example of the kind of violent and abrupt climate change that results from global warming.”

Others like Jason Samenow take the stance that global warming is a separate issue from the polar vortex because similar weather conditions “happened before humans dumped billions of tons of carbon dioxide into the atmosphere and will happen again.” Some reports also point out how the last time the polar vortex caused such drastically cold weather was in the 1980s and also how 2013 set record hot temperatures in Australia.

But what does the science say? Regardless of NOAA’s hypothesis related to air temperature and the Arctic ice extent, studies from 2009 and 2010 doubt the ability of computer models to determine if climate change and the break up of a polar vortex are related:

“Clearly, if CCMs [chemistry climate models] cannot duplicate the observed response of the polar stratosphere to late 20th century climate forcings, their ability to simulate the polar vortices in future may be poor.”

…and…

“It is unclear how much confidence can be put into the model projections of the vortices given that the models typically only have moderate resolution and that the climatological structure of the vortices in the models depends on the tuning of gravity wave parameterizations.”

The Polar Vortex, Global Warming, And Politics

When it comes to the American public, Pew Research Center found only 28 percent believe “dealing with global warming” is a top priority, which has gone down from 38 percent in 2007. Interestingly enough, even among Democrats the political support for implementing policies based upon global warming has fallen down to 38 percent.

Perhaps because of the doubts many Americans have been expressing, the White House felt it needed to issue a statement:

“We know that no single weather episode proves or disproves climate change. Climate refers to the patterns observed in the weather over time and space — in terms of averages, variations, and probabilities. But we also know that this week’s cold spell is of a type there’s reason to believe may become more frequent in a world that’s getting warmer, on average, because of greenhouse-gas pollution.”

The recent events have also caused some to call for politics to get out science. For example, Patrick J. Michaels, the director of the Center for the Study of Science at the Cato Institute, pointed out how Nobel Prize winner Randy Schekman wrote that science journals like “Nature, Cell, and Science are damaging science” by focusing on publishing manuscripts with the “flashiest” headlines. Michaels believes these type of headlines “compel politicians to disburse more money for more research, ultimately buying a beach house for the doom-saying scientists“:

“This creates horrific effects, especially when the issues are policy-related. Summaries of the scientific literature are used to guide policymakers, but if the published research is biased, then so must be the summaries; leaving policymakers no option – not being scientists themselves – but to embrace what is inevitably touted as ‘the best science.’”

Does the cold weather caused by the polar vortex alter your beliefs about global warming or climate change science? Either way, what do you think should be done about the alleged bias in scientific circles?

Saturday, October 25, 2014

New paper explains how Polar Vortex is controlled by natural variability, not CO2

A paper published today in Climate Dynamics finds complex, non-linear, and chaotic interactions of natural gravity waves, the El Nino Southern Oscillation [ENSO], the solar cycle, and the Quasi-Biennial Oscillation [QBO] "combine to affect the polar vortex." The Quasi-Biennial Oscillation [QBO] and ENSO have also been linked to solar activity and may act as potential solar amplification mechanisms which affect the dreaded polar vortex.

Some warmists such as Jennifer Francis and Katherine Hayhoe instead want you to believe that recent record-cold winters due to dips of the polar vortex are your fault, due to your evil CO2 emissions and the CO2 universal control knob of climate. This false assumption has been thoroughly shot down in the peer-reviewed literature by fellow warmists, even including Kevin Trenberth et al. Climate models robustly predict the opposite of fewer jet stream and polar vortex dips due to global warming.

This new paper provides a start to explain how natural forcings and feedbacks [some of which are linked to solar activity] combine chaotically and unexpectedly with "the opposite sign to the forcing" to govern the polar vortex. The paper also joins others finding links between solar activity and the polar vortex.

Excerpts:

"The demonstration that the steady state stratospheric response to a forcing may have the opposite sign to the forcing (Sect. 3.1) has important implications for studies of the mechanisms by which external forcings influence the polar vortex—in principle it could be the case that the direct effect of a forcing has the opposite sign to the long-term mean response. As far as we are aware, this possibility has not been considered in any previous studies of the effect on the [polar] vortex of forcings such as the QBO, ENSO and the solar cycle. Feedbacks may greatly modify the response from what is expected based on simple arguments. It also highlights the difficulties of using diagnostics such as composite differences to understand forcing mechanisms, since these may be dominated by the effects of feedback processes (Watson and Gray 2014). [i.e. chaos]

The implication that the extratropical stratospheric response to an external forcing is affected by the climatology may be relevant for understanding non-linearity in the way different forcings combine to affect the polar vortex, such as the suggested non-linear combined influence of the QBO and ENSO (Garfinkel and Hartmann 2007; Wei et al. 2007) and of the QBO and solar cycle (e.g. Labitzke 1987; Matthes et al. 2004). When one forcing affects the background circulation, this would be expected to change the circulation response to other forcings, and this effect may contribute to the reported non-linearities."

Climate Dynamics [full paper open access]

The stratospheric wintertime response to applied extratropical torques and its relationship with the annular mode

Peter A. G. Watson and Lesley J. Gray

The response of the wintertime Northern Hemisphere (NH) stratosphere to applied extratropical zonally symmetric zonal torques, simulated by a primitive equation model of the middle atmosphere, is presented. This is relevant to understanding the effect of gravity wave drag (GWD) in models and the influence of natural forcings such as the quasi-biennial oscillation (QBO), El Ninõ-Southern Oscillation (ENSO), solar cycle and volcanic eruptions on the polar vortex. There is a strong feedback due to planetary waves, which approximately cancels the direct effect of the torque on the zonal acceleration in the steady state and leads to an EP flux convergence response above the torque’s location. The residual circulation response is very different to that predicted assuming wave feedbacks are negligible. The results are consistent with the predictions of ray theory, with applied westerly torques increasing the meridional potential vorticity gradient, thus encouraging greater upward planetary wave propagation into the stratosphere. The steady state circulation response to torques applied at high latitudes closely resembles the Northern annular mode (NAM) in perpetual January simulations. This behaviour is analogous to that shown by the Lorenz system and tropospheric models. Imposed westerly high-latitude torques lead counter-intuitively to an easterly zonal mean zonal wind (u¯) response at high latitudes, due to the wave feedbacks. However, in simulations with a seasonal cycle, the feedbacks are qualitatively similar but weaker, and the long-term response is less NAM-like and no longer easterly at high latitudes. This is consistent with ray theory and differences in climatological u¯between the two types of simulations. The response to a tropospheric wave forcing perturbation is also NAM-like. These results suggest that dynamical feedbacks tend to make the long-term NH extratropical stratospheric response to arbitrary external forcings NAM-like, but only if the feedbacks are sufficiently strong. This may explain why the observed polar vortex responses to natural forcings such as the QBO and ENSO are NAM-like [Northern annular mode]. The results imply that wave feedbacks must be understood and accurately modelled in order to understand and predict the influence of GWD and other external forcings on the polar vortex, and that biases in a model’s climatology will cause biases in these feedbacks.

Tuesday, January 7, 2014

Record cold from global warming causing 'polar vortex' debunked

The global warming apologists are struggling to explain the record cold on global warming due to an alleged slowdown in the jet stream keeping a 'polar vortex' alive. However, a recent paper finds no evidence of any unusual or unprecedented changes in the latitude or speed of the North Atlantic jet stream over the past 142 years since 1871. Another 2 papers confirm there is no evidence that climate change has slowed the jet stream or increased frequency of jet stream blocking which controls the polar vortex.

Once again, the global warming apologists are caught out again in the face of real-world data. Dr. Roy Spencer sums it up in a post today:

Does Global Warming Theory Predict Record Cold?
January 6th, 2014 by Roy W. Spencer, Ph. D.

NO.

New paper debunks claims that 'Arctic amplification' causes extreme weather

A new paper published in Geophysical Research Letters debunks claims that "Arctic amplification" is causing an increase of extreme weather in North America or the North Atlantic, finding such claims are "an artifact of the methodology" and not real. The paper finds no evidence of an increased frequency of jet stream blocking or a decrease of jet stream speed, a result corroborated by a recent paper finding no significant changes of the jet stream over the past 140 years. The paper debunks claims by climate alarmists such as Heidi Cullen [and Jennifer Francis] that "Arctic amplification" is causing a "constipated jet stream" leading to increased extreme weather in North America.

Wednesday, October 29, 2014

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

1:50 PM 10/29/2014

Contributor

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.

Remainder at the Daily Caller

Related posts debunking claim that AGW caused increased jet stream dips and polar vortex dips [the opposite of alleged "robust" predictions by climate models]

Monday, September 9, 2013

New paper relates natural 60 year climate cycle to the effects of solar activity and cosmic rays

A paper published today in Advances in Space Research finds a possible reason why the effects of solar activity and galactic cosmic rays on the lower atmospheric circulation can vary over time, due to a 60-year natural cycle of the stratospheric polar vortex. According to the authors, "∼60-year oscillations of the amplitude and sign of Solar Activity/Galactic Cosmic Ray effects on the troposphere pressure ...are closely related to the state of a cyclonic vortex forming in the polar stratosphere. The intensity of the vortex was found to reveal a roughly 60-year [cycle] affecting the evolution of the large-scale atmospheric circulation and the character of Solar Activity/Galactic Cosmic Ray effects." The paper is one of the first to connect the effects of solar activity and GCRs with the well-known 60-year climate cycle.

Stratospheric Polar Vortex as a Possible Reason for Temporal Variations of Solar Activity and Galactic Cosmic Ray Effects on the Lower Atmosphere Circulation

S. Veretenenko ^,,
M. Ogurtsov

Ioffe Physical-Technical Institute, Russian Academy of Sciences, Politekhnicheskaya 26, 194021, St.Petersburg, Russia

Abstract

Possible reasons for a temporal instability of long-term effects of solar activity (SA) and galactic cosmic ray (GCR) variations on the lower atmosphere circulation were studied. It was shown that the detected earlier ∼60-year oscillations of the amplitude and sign of Solar Activity/Galactic Cosmic Ray effects on the troposphere pressure at high and middle latitudes (Veretenenko and Ogurtsov, Adv.Space Res., 2012) are closely related to the state of a cyclonic vortex forming in the polar stratosphere. The intensity of the vortex was found to reveal a roughly 60-year periodicity affecting the evolution of the large-scale atmospheric circulation and the character of Solar Activity/Galactic Cosmic Ray effects. An intensification of both Arctic anticyclones and mid-latitudinal cyclones associated with an increase of GCR fluxes at minima of the 11-year solar cycles is observed in the epochs of a strong polar vortex. In the epochs of a weak polar vortex SA/GCR effects on the development of baric systems at middle and high latitudes were found to change the sign. The results obtained provide evidence that the mechanism of solar activity and cosmic ray influences on the lower atmosphere circulation involves changes in the evolution of the stratospheric polar vortex.

Keywords

solar activity;
galactic cosmic rays;
the lower atmosphere circulation;
climate variability

Figures and tables from this article:

: Fig. 1. a) Distribution of mean monthly temperatures in the stratosphere of the Northern hemisphere at the level 20 hPa in January 2005. The asterisk shows the temperature minimum in the vortex center. b) Distribution of magnitudes of temperature gradient at the level 20 hPa in January 2005. The black curve connects the points of the maximal value of temperature gradient at given latitude.; Figure options

: Fig. 2. a) Time variations of the correlation coefficients between yearly values of troposphere pressure at high latitudes (60-85°N) and SA/GCR characteristics for 15-yr sliding intervals: solid and dashed lines show R(SLP,Rz) andR(GPH700,NM), respectively. b) Anomalies (deviations from the climatic mean) of the mean yearly difference of zonal gp heights ΔH between the latitudes 40 and 65°N for the 500 hPa level. c) Anomalies (deviations from the climatic mean) of mean yearly stratospheric temperature at the 50 hPa level in the high-latitudinal region 60-90°N. d) Annual frequencies of occurrence (number of days during a year) of the main forms of the large-scale circulation according to Vangengeim-Girs classification (15-yr running averages). The vertical dashed lines show the years of the correlation reversals. The thick lines at the panels b) and c) show the 3^rd order polynomial fits of the data.; Figure options

: Fig. 3. Distribution of the correlation coefficients R(GPH700, NM) between tropospheric pressure and GCR intensity (left) and their statistical significance (right) for the periods of a strong (a) and weak (b) polar vortex. Curves 1 and 2 indicate the climatic positions of Arctic fronts in January and July, respectively. Similarly, curves 3 and 4 indicate the climatic positions of polar fronts. The confidence levels are shown in grayscale: 0.9 (black areas), 0.95 (dark grey areas), 0.97 (grey areas), 0.98 (light grey areas) and 0.99 (white inner area).; Figure options

: Fig. 4. a) Yearly values of the NAM/AO index (Li and Wang, 2003); b) the Fourier spectrum of the NAM/AO index; c) yearly values of sunspot numbers. Grey lines show the linear trends; thick solid (a) line shows the 6th order polynomial fit of the NAM/AO indices; dashed line (b) shows the 6th order polynomial fit of sunspot numbers in the maxima of the 11-year solar cycle.; Figure options

: Fig. 5. a) Anomalies of sea-level pressure and surface temperature in the Arctic region, the temperature data are given according to Frolov et al. (2009). The thick lines show 15-year running averages. b) Time variations of the correlation coefficients between yearly values of troposphere pressure at high latitudes and SA/GCR characteristics for 15-year sliding intervals; solid and dashed lines show R(SLP,Rz) and R(GPH700,NM), respectively. Vertical dashed lines show the transitions between positive and negative phases of the Arctic Oscillation.; Figure options

: Fig. 6. The Fourier spectra of SLP (a) and temperature (b) anomalies in the Arctic region, the frequency of occurrence of the C-type meridional circulation (c) and correlation coefficients R(SLP,Rz) between SLP at high latitudes (60-85°N) and relative sunspot numbers (d). Confidence levels are calculated for a red noise with AR(1) coefficient =0.3 (a), 0.65 (b) and 0,4 (c).

Tuesday, September 16, 2014

New paper debunks claims that global warming causes colder winters & more snow

Not from anthropogenic global warming

A paper published today in Geophysical Research Letters debunks claims that anthropogenic global warming causes colder winters, more snow, jet stream dips, or the dreaded 'polar vortex'. Instead, the authors find climate models predict the opposite pattern of a poleward jet stream shift [i.e. fewer jet stream dips] from CO2 direct radiative forcing:

"The direct radiative forcing of CO2 drives a weak poleward jet shift in both hemispheres"

The paper goes on to claim

"the indirect (Sea Surface Temperature) component of the CO2 forcing dominates the total response and drives a zonally asymmetric response in the Northern Hemisphere. Hence, understanding the Sea Surface Temperature-mediated component of atmospheric CO2 forcing appears crucial to unlocking the mechanisms that contribute to forced extratropical circulation changes."

The major problem with this assumption of "indirect CO2 forcing" on sea surface temperatures is that longwave IR radiation from greenhouse gases cannot significantly heat the oceans, and ocean heat capacity is 1000 times greater than the atmosphere, therefore the ocean wags the tail of the atmosphere. These major physical bugaboos & false assumptions built into all climate models are perhaps the primary reason why 93% of Trenberth's missing CO2 heat is still missing from the oceans.

The response of mid-latitude jets to increased CO2: Distinguishing the roles of sea surface temperature and direct radiative forcing

Kevin M. Grise and Lorenzo M. Polvani

In Coupled Model Intercomparison Project Phase 5 (CMIP5) models, the zonal-mean tropospheric circulation shifts robustly poleward in the Southern Hemisphere (SH) extratropics in response to increased atmospheric CO2 concentrations. However, in the Northern Hemisphere (NH) extratropics, the circulation response to CO2 is largely absent in the zonal mean, and is instead characterized by complex regional anomalies. This study decomposes the atmospheric circulation response to CO2 forcing in CMIP5 models into two components: a direct component due to CO2 radiative forcing and an indirect component associated with sea surface temperature (SST)-mediated changes. The direct radiative forcing of CO2 drives a weak poleward jet shift in both hemispheres, whereas the indirect (SST) component of the CO2 forcing dominates the total response and drives a zonally asymmetric response in the NH. Hence, understanding the SST-mediated component of atmospheric CO2 forcing appears crucial to unlocking the mechanisms that contribute to forced extratropical circulation changes.

Record cold from global warming causing 'polar vortex' debunked

Climate models robustly predicted the opposite of what has caused the record cold US weather

Scientific workshop concludes there is no proof of a link between Arctic climate change and the polar jet stream

New paper debunks claims that 'Arctic amplification' causes extreme weather

Papers finding climate models are unable to simulate the Polar Vortex

Record cold from global warming causing 'polar vortex' debunked

New paper relates natural 60 year climate cycle to the effects of solar activity and cosmic rays

'Polar vortex' that caused record cold is related to solar activity, not man-made CO2

Freezing Is the New Warming

The Polar Vortex bankrupts renewable energy company

New consensus rediscovers 'polar vortex' jet stream dips are due to global cooling