New Research

[knocker]

Trends in the average temperature in Finland, 1847–2013

 

Abstract

The change in the mean temperature in Finland is investigated with a dynamic linear model in order to define the sign and the magnitude of the trend in the temperature time series within the last 166 years. The data consists of gridded monthly mean temperatures. The grid has a 10 km spatial resolution, and it was created by interpolating a homogenized temperature series measured at Finnish weather stations. Seasonal variation in the temperature and the autocorrelation structure of the time series were taken account in the model. Finnish temperature time series exhibits a statistically significant trend, which is consistent with human-induced global warming. The mean temperature has risen very likely over 2 Â°C in the years 1847–2013, which amounts to 0.14 Â°C/decade. The warming after the late 1960s has been more rapid than ever before. The increase in the temperature has been highest in November, December and January. Also spring months (March, April, May) have warmed more than the annual average, but the change in summer months has been less evident. The detected warming exceeds the global trend clearly, which matches the postulation that the warming is stronger at higher latitudes.

 

http://download.springer.com/static/pdf/96/art%253A10.1007%252Fs00477-014-0992-2.pdf?auth66=1419268860_cd94561504f7fb8a9265a897fb764e00&ext=.pdf

[Alan Robinson]

New research?

 

The term is dubious and I rather think it more appropriate to speak of "continuing research". We are overdue an academic revolution as described by Thomas Kuhn.

 

Meanwhile, I still keep my hand-made barograph, and it strikes me that the atmosphere where I live has been extraordinarily passive in 2014. Taking the mean long term atmospheric pressure to be 101.3 kPa (I am a stickler for SI Units) the area between the barograph and 101.3 kPa for the year (integrate from 1st Jan to date) is far less than in recent years.

 

Does anyone know of research into this phenomenon?

[knocker]

Coral reveals long-term link between Pacific winds, global climate

 

BOULDER â€” New research indicates that shifts in Pacific trade winds played a key role in twentieth century climate variation, a sign that they may again be influencing global temperatures.

 

The study, led by scientists at the National Center for Atmospheric Research (NCAR) and the University of Arizona (UA), uses a novel method of analyzing chemical changes in coral to show that weak tropical Pacific trade winds coincided with globally warming temperatures early in the twentieth century. When the natural pattern shifted and winds began to strengthen after 1940, the warming slowed.

 

http://www2.ucar.edu/atmosnews/news/13598/coral-reveals-long-term-link-between-pacific-winds-global-climate

[knocker]

Cold extremes in North America vs. mild weather in Europe: the winter 2013/2014 in the context of a warming world

 

The winter of 2013/2014 had unusual weather in many parts of the world. Here we analyse the cold extremes that were widely reported in North America and the lack of cold extremes in western Europe. We perform a statistical analysis of cold extremes at two representative stations in these areas: Chicago, Illinois and De Bilt, the Netherlands. This shows that the lowest minimum temperature of the winter was not very unusual in Chicago, even in the current warmer climate. Around 1950 it would have been completely normal. The same holds for multi-day cold periods. Only the whole winter temperature was unusual, with a return time larger than 25 years. In the Netherlands the opposite holds: the absence of any cold waves was highly unusual even now, and would have been extremely improbable half-way through the previous century. These results are representative of other stations in the regions. The difference is due to the skewness of the temperature distribution. In both locations, cold extremes are more likely than equally large warm extremes in winter. Severe cold outbreaks and cold winters, like the winter of 2013/2014 in the Great Lakes area, are therefore not evidence against global warming: they will keep on occurring, even if they become less frequent. The absence of cold weather as observed in the Netherlands is a strong signal of a warming trend, as this would have been statistically extremely improbable in the 1950s.

 

http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-14-00036.1

[knocker]

Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure

 

Abstract

Geological data indicate that global mean sea level has fluctuated on 10³ to 10⁶ yr time scales during the last ∼25 million years, at times reaching 20 m or more above modern. If correct, this implies substantial variations in the size of the East Antarctic Ice Sheet (EAIS). However, most climate and ice sheet models have not been able to simulate significant EAIS retreat from continental size, given that atmospheric CO₂ levels were relatively low throughout this period. Here, we use a continental ice sheet model to show that mechanisms based on recent observations and analysis have the potential to resolve this model–data conflict. In response to atmospheric and ocean temperatures typical of past warm periods, floating ice shelves may be drastically reduced or removed completely by increased oceanic melting, and by hydrofracturing due to surface melt draining into crevasses. Ice at deep grounding lines may be weakened by hydrofracturing and reduced buttressing, and may fail structurally if stresses exceed the ice yield strength, producing rapid retreat. Incorporating these mechanisms in our ice-sheet model accelerates the expected collapse of the West Antarctic Ice Sheet to decadal time scales, and also causes retreat into major East Antarctic subglacial basins, producing ∼17 m global sea-level rise within a few thousand years. The mechanisms are highly parameterized and should be tested by further process studies. But if accurate, they offer one explanation for past sea-level high stands, and suggest that Antarctica may be more vulnerable to warm climates than in most previous studies.

 

http://www.sciencedirect.com/science/article/pii/S0012821X14007961

[knocker]

Evidence for a wavier jet stream in response to rapid Arctic warming

 

Letter

New metrics and evidence are presented that support a linkage between rapid Arctic warming, relative to Northern hemisphere mid-latitudes, and more frequent high-amplitude (wavy) jet-stream configurations that favor persistent weather patterns. We find robust relationships among seasonal and regional patterns of weaker poleward thickness gradients, weaker zonal upper-level winds, and a more meridional flow direction. These results suggest that as the Arctic continues to warm faster than elsewhere in response to rising greenhouse-gas concentrations, the frequency of extreme weather events caused by persistent jet-stream patterns will increase.

 

http://iopscience.iop.org/1748-9326/10/1/014005/pdf/1748-9326_10_1_014005.pdf

[knocker]

Recent summer Arctic atmospheric circulation anomalies in a historical perspective

 

Abstract. A significant increase in the summertime occurrence of a high pressure area over the Beaufort Sea, the Canadian Arctic Archipelago, and Greenland has been observed since the beginning of the 2000s, and particularly between 2007 and 2012. These circulation anomalies are likely partly responsible for the enhanced Greenland ice sheet melt as well as the Arctic sea ice loss observed since 2007. Therefore, it is interesting to analyse whether similar conditions might have happened since the late 19th century over the Arctic region. We have used an atmospheric circulation type classification based on daily mean sea level pressure and 500 hPa geopotential height data from five reanalysis data sets (ERA-Interim, ERA-40, NCEP/NCAR, ERA-20C, and 20CRv2) to put the recent circulation anomalies in perspective with the atmospheric circulation variability since 1871. We found that circulation conditions similar to 2007–2012 have occurred in the past, despite a higher uncertainty of the reconstructed circulation before 1940. For example, only ERA-20C shows circulation anomalies that could explain the 1920–1930 summertime Greenland warming, in contrast to 20CRv2. While the recent anomalies exceed by a factor of 2 the interannual variability of the atmospheric circulation of the Arctic region, their origin (natural variability or global warming) remains debatable.

 

http://www.the-cryosphere.net/9/53/2015/tc-9-53-2015.pdf

[Gray-Wolf]

Very interesting Knocks. Makes me think that the synoptics responsible for the loss of all the Paleocryistic ice in the basin were just 'freak' weather adding into AGW warming impacts? Maybe we can 'expect' another good year for the ice after all?

[knocker]

Very interesting Knocks. Makes me think that the synoptics responsible for the loss of all the Paleocryistic ice in the basin were just 'freak' weather adding into AGW warming impacts? Maybe we can 'expect' another good year for the ice after all?

 

I'm no expert on the Arctic GW but it does seem that this could be one of the reasons you get the two or three yearly variations and makes predictions difficult in the short term. To me it just emphasises once again the need to take extended trends.

[Gray-Wolf]

For me the thing to hold in mind when thinking about the basin is the massive loss in volume since the 60's? No matter what 'weather' variability does it would be a long ,slow, climb out of the volume well we find ourselves near the bottom of? As such I think we ought to expect low summer extent/area for the foreseeable future and , if Jen Francis work is close to the mark, extreme weather for the N.Hemisphere over late Autumn/winter?

[knocker]

Stable climate and surface mass balance in Svalbard over 1979–2013 despite the Arctic warming

 

Abstract. With the help of the regional climate model MAR (Modèle Atmosphérique Régional) forced by the ERA-Interim reanalysis (MAR_ERA) and the MIROC5 (Model for Interdisciplinary Research on Climate) global model (MAR_MIROC5) from the CMIP5 (Coupled Model Intercomparison Project) database, we have modelled the climate and surface mass balance of Svalbard at a 10 km resolution over 1979–2013. The integrated total surface mass balance (SMB) over Svalbard modelled by MAR_ERA is negative (−1.6 Gt yr^−1) with a large interannual variability (7.1 Gt) but, unlike over Greenland, there has been no acceleration of the surface melt over the past 35 years because of the recent change in atmospheric circulation bringing northwesterly flows in summer over Svalbard, contrasting the recent observed Arctic warming. However, in 2013, the atmospheric circulation changed to a south–southwesterly flow over Svalbard causing record melt, SMB (−20.4 Gt yr^−1) and summer temperature. MIROC5 is significantly colder than ERA-Interim over 1980–2005 but MAR_MIROC5 is able to improve the near-surface MIROC5 results by simulating not significant SMB differences with MAR_ERA over 1980–2005. On the other hand, MIROC5 does not represent the recent atmospheric circulation shift in summer and induces in MAR_MIROC5 a significant trend of decreasing SMB (−0.6 Gt yr^−2) over 1980–2005.

 

http://www.the-cryosphere.net/9/83/2015/tc-9-83-2015.pdf

[knocker]

The global warming hiatus—a natural product of interactions of a secular warming trend and a multi-decadal oscillation

 

Abstract

The globally-averaged annual combined land and ocean surface temperature (GST) anomaly change features a slowdown in the rate of global warming in the mid-twentieth century and the beginning of the twenty-first century. Here, it is shown that the hiatus in the rate of global warming typically occurs when the internally generated cooling associated with the cool phase of the multi-decadal variability overcomes the secular warming from human-induced forcing. We provide compelling evidence that the global warming hiatus is a natural product of the interplays between a secular warming tendency due in a large part to the buildup of anthropogenic greenhouse gas concentrations, in particular CO₂ concentration, and internally generated cooling by a cool phase of a quasi-60-year oscillatory variability that is closely associated with the Atlantic multi-decadal oscillation (AMO) and the Pacific decadal oscillation (PDO). We further illuminate that the AMO can be considered as a useful indicator and the PDO can be implicated as a harbinger of variations in global annual average surface temperature on multi-decadal timescales. Our results suggest that the recent observed hiatus in the rate of global warming will very likely extend for several more years due to the cooling phase of the quasi-60-year oscillatory variability superimposed on the secular warming trend.

 

http://rd.springer.com/article/10.1007%2Fs00704-014-1358-x?utm_content=buffer3a906&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

What this says to me is that if you take each hiatus, and I see no reason why one cannot go back to the end of the 19th century as well, the multi-decadal oscillation has had less impact. Meaning the secular warming is stronger.

[Gray-Wolf]

This is why I worry about a 'shortening' of such periods as the 'edges' (lead in and lead out)  become swamped by the AGW warming? This leaves the 'cold core' of any such phase being the only remnant of past lengthy phases?

 

Eventually I believe the AGW forcing will prove so strong as to impact the very mechanisms driving such 'phases' leading to alterations to global circulation patterns ( air and ocean) and major climate change.

[knocker]

Plus you have to consider regarding the current hiatus that a recent paper concluded that some dimming had occurred because of smaller volcanic eruptions which previously hadn't been considered because it was thought they had no effect.

[Gray-Wolf]

True. and we still don't seem to have a handle on the negative impacts of our pollution ( our dimming/seeding) on just how fast the AGW impact can accrue? I bang on about the results of China's move toward reducing 'dirty emmisions' ( for the same reasons we scrabbled to put in the 'clean air ' acts?). Unlike us they already have our wisdom on the subject and technology 'on the shelf' to put in a near instant 'fix'. This would then give us less than 7 years before we saw a more complete picture of just how strong the AGW forcing is at present?

 

I used to think that the point AGW was powerful enough to over ride other climate forcings was a long way off but with rapid changes ( ongoing) across the Arctic and the prospect of Asia losing some of it's dimming potential has me reconsidering? Is the warming of Pacific showing us that the scale of the particulates /dimming flowing out across the Pacific from Asia is now already lessening ? Both their inclusion of 'renewables' in their energy solutions and the retro fixing of 'scrubbing' technology in cooling towers/smoke stacks must show some impacts?

 

For me I'd always fretted that the naturals had 'flipped' negative at just the wrong time ( when Asia was really ramping up its outputs?) . 

 

Has the noughties suffered a double whamy of pull downs on the rate of atmospheric warming with both the naturals limiting rate of warming but also the explosion of coal use across China over the same time period?

 

If the figure NASA provided us with ( a few years back) of the full impacts over AGW being reduced by up to 50% by the other elements of fossil fuel burning (sulphates and soot) then we will see a step up in its ability to aid warming as the major cities of China 'clean up' their atmosphere's? Should this coincide with the Naturals flipping positive then we may be on the verge of seeing the 'flip side' of the 'slow down' in warming rates over the coming years?

Edited January 13, 2015 by Gray-Wolf

[knocker]

Study shows how meltwater on Greenland's ice sheet contribute to rising sea levels

http://phys.org/news/2015-01-meltwater-greenland-ice-sheet-contribute.html

[knocker]

Was China 6-8 K warmer in winter 6000 years ago?

 

Monckton, Soon, Legates & Briggs have published a paper in the Science Bulletin (formerly Chinese Science Bulletin), which, despite having an impact factor of 1.365, is “one of the world’s top six learned journals of scienceâ€. Allegedly.

 

In their paper, “Why models run hot: results from an irreducibly simple climate model†Monckton et al argue that the climate will only warm slightly over the next century because a process engineer would not design a climate with large net positive feedbacks that give a high climate sensitivity.

 

A couple of parts of the paper concern palaeoclimate data. I want to look at one of these.

 

Some more on this

 

http://climateconomysociety.blogspot.co.uk/2015/01/monckton-soon-legates-and-briggs.html?spref=tw

Edited January 19, 2015 by knocker

[knocker]

Ratios of record high to record low temperatures in Europe exhibit sharp increases since 2000 despite a slowdown in the rise of mean temperatures

 

Abstract

A study has been undertaken to analyze the behavior of record high and low values of temperature since the early 1950s for 30 locations spread across Europe. When establishing the ratios of the number of record Tmax to record Tmin values in each year, it is seen that there is a sharp increase in these ratios in the most recent decade. This seems to be an apparent paradox in view of the slow-down in atmospheric temperatures that has been observed since the early 2000s at both the hemispheric and European scales, but closer analysis suggests that the relationship between the record high:low ratios and mean annual temperatures is not linear but rather a square relationship. It is suggested that the record high to record low ratios in both the Mediterranean region and beyond 60° latitude north, observed in the most recent decade, may be related to an amplification of low-level atmospheric temperatures resulting from shorter snow seasons in the north and enhanced summer dryness in the south.

 

http://rd.springer.com/article/10.1007%2Fs10584-015-1325-2?utm_content=buffer8224f&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Quite an important paper: worth working through:

 

A review of global ocean temperature observations: Implications for ocean heat content estimates and climate change

 

Abstract

The evolution of ocean temperature measurement systems is presented with a focus on the development and accuracy of two critical devices in use today (expendable bathythermographs and conductivity-temperature-depth instruments used on Argo floats). A detailed discussion of the accuracy of these devices and a projection of the future of ocean temperature measurements are provided. The accuracy of ocean temperature measurements is discussed in detail in the context of ocean heat content, Earth's energy imbalance, and thermosteric sea level rise. Up-to-date estimates are provided for these three important quantities. The total energy imbalance at the top of atmosphere is best assessed by taking an inventory of changes in energy storage. The main storage is in the ocean, the latest values of which are presented. Furthermore, despite differences in measurement methods and analysis techniques, multiple studies show that there has been a multidecadal increase in the heat content of both the upper and deep ocean regions, which reflects the impact of anthropogenic warming. With respect to sea level rise, mutually reinforcing information from tide gauges and radar altimetry shows that presently, sea level is rising at approximately 3 mm yr^−1 with contributions from both thermal expansion and mass accumulation from ice melt. The latest data for thermal expansion sea level rise are included here and analyzed.

 

http://onlinelibrary.wiley.com/doi/10.1002/rog.20022/full

Edited January 23, 2015 by knocker

[knocker]

Atmospheric response in summer linked to recent Arctic sea ice loss

 

Since 2007 a large decline in Arctic sea ice has been observed. The large-scale atmospheric circulation response to this decline is investigated in ERA-Interim reanalyses and HadGEM3 climate model experiments. In winter, post-2007 observed circulation anomalies over the Arctic, North Atlantic and Eurasia are small compared to interannual variability. In summer, the post-2007 observed circulation is dominated by an anticyclonic anomaly over Greenland which has a large signal-to-noise ratio. Climate model experiments driven by observed SST and sea ice anomalies are able to capture the summertime pattern of observed circulation anomalies, although the magnitude is a third of that observed. The experiments suggest high SSTs and reduced sea ice in the Labrador Sea lead to positive temperature anomalies in the lower troposphere which weaken the westerlies over North America through thermal wind balance. The experiments also capture cyclonic anomalies over Northwest Europe, which are consistent with downstream Rossby wave propagation.

 

http://onlinelibrary.wiley.com/doi/10.1002/qj.2502/pdf

[knocker]

Winters in Siberian permafrost regions have warmed since millenia

http://www.eurekalert.org/pub_releases/2015-01/awih-wis012415.php

[knocker]

Arctic sea-ice decline erratic as expected

 

Imagine a ball bouncing down a bumpy hill. Gravity will ensure that the ball will head downwards. But, if the ball hits a bump at a certain angle it might move horizontally or even upwards for a time, before resuming its inevitable downward trajectory. This bouncing ball is an analogy for the behaviour of Arctic sea-ice.

Post based on Swart et al., Nature Climate Change

 

http://www.climate-lab-book.ac.uk/2015/arctic-erratic-as-expected/?utm_source=rss&utm_medium=rss&utm_campaign=arctic-erratic-as-expected

[knocker]

The hiatus in global temperature trends: No systematic error in climate models

 

Observations suggest a hiatus in global surface temperature since 1998, whereas most climate models simulate continued warming. What causes this difference? Do climate models respond too sensitively to the increase in greenhouse-gas concentrations such as that of CO₂, and thus overestimate climate change systematically? Or has the discrepancy arisen by chance? A study just published by the Max Planck Institute for Meteorology (MPI-M) gives a clear answer: There is no evidence for systematic model error.

 

http://www.mpimet.mpg.de/en/kommunikation/aktuelles/forschung-aktuell/das-plateau-in-der-globalen-temperatur.html

[knocker]

Evidence from warm past confirms recent IPCC estimates of climate sensitivity

 

New evidence showing the level of atmospheric CO2 millions of years ago supports recent climate change predications from the Intergovernmental Panel on Climate Change (IPCC).

A multinational research team, led by scientists at the University of Southampton, has analysed new records showing the CO2 content of the Earth's atmosphere between 2.3 to 3.3 million years ago, over the Pliocene.

During the Pliocene, the Earth was around 2ºC warmer than it is today and atmospheric CO2 levels were around 350-400 parts per million (ppm), similar to the levels reached in recent years.

 

http://www.eurekalert.org/pub_releases/2015-02/uos-efw020215.php