New Research

[knocker]

NOTE. This post is not an attempt to circumvent the locked thread but just a new research paper I think might be of interest.

 

Malcolm

 

 

Amplified mid-latitude planetary waves favour particular regional weather extremes

 

There has been an ostensibly large number of extreme weather events in the Northern Hemisphere mid-latitudes during the past decade¹. An open question that is critically important for scientists and policy makers is whether any such increase in weather extremes is natural or anthropogenic in origin^{2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13}. One mechanism proposed to explain the increased frequency of extreme weather events is the amplification of mid-latitude atmospheric planetary waves^{14, 15, 16, 17}. Disproportionately large warming in the northern polar regions compared with mid-latitudes—and associated weakening of the north–south temperature gradient—may favour larger amplitude planetary waves^{14, 15, 16, 17}, although observational evidence for this remains inconclusive^{18, 19, 20, 21}. A better understanding of the role of planetary waves in causing mid-latitude weather extremes is essential for assessing the potential environmental and socio-economic impacts of future planetary wave changes. Here we show that months of extreme weather over mid-latitudes are commonly accompanied by significantly amplified quasi-stationary mid-tropospheric planetary waves. Conversely, months of near-average weather over mid-latitudes are often accompanied by significantly attenuated waves. Depending on geographical region, certain types of extreme weather (for example, hot, cold, wet, dry) are more strongly related to wave amplitude changes than others. The findings suggest that amplification of quasi-stationary waves preferentially increases the probabilities of heat waves in western North America and central Asia, cold outbreaks in eastern North America, droughts in central North America, Europe and central Asia, and wet spells in western Asia.

 

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2271.html

 

A short discussion of the paper can be found.

 

http://www.realclimate.org/index.php/archives/2014/07/rossby-waves-and-surface-weather-extremes/

Edited July 10, 2014 by knocker

[Gray-Wolf]

I think that the lack of time over the period of extreme weather linked to stationary waves is the only reason we have not yet 'confirmed' their presence? Watch this space?

[knocker]

New study investigates the impact of climate change on malaria

 

Downscaling reveals diverse effects of anthropogenic climate warming on the potential for local environments to support malaria transmission

 

Abstract

The potential impact of climate warming on patterns of malaria transmission has been the subject of keen scientific and policy debate. Standard climate models (GCMs) characterize climate change at relatively coarse spatial and temporal scales. However, malaria parasites and the mosquito vectors respond to diurnal variations in conditions at very local scales. Here we bridge this gap by downscaling a series of GCMs to provide high-resolution temperature data for four different sites and show that although outputs from both the GCM and the downscaled models predict diverse but qualitatively similar effects of warming on the potential for adult mosquitoes to transmit malaria, the predicted magnitude of change differs markedly between the different model approaches. Raw GCM model outputs underestimate the effects of climate warming at both hot (3-fold) and cold (8–12 fold) extremes, and overestimate (3-fold) the change under intermediate conditions. Thus, downscaling could add important insights to the standard application of coarse-scale GCMs for biophysical processes driven strongly by local microclimatic conditions.

 

http://download.springer.com/static/pdf/763/art%253A10.1007%252Fs10584-014-1172-6.pdf?auth66=1405201691_968d7eb4a6c864d8ebe0051949d831cc&ext=.pdf

Edited July 10, 2014 by knocker

[knocker]

Tracking the breakup of Arctic summer sea ice

http://www.eurekalert.org/pub_releases/2014-07/uow-ttb071614.php

[Gray-Wolf]

I seem to remember, post 07' me pointing out the impacts of a well mixed Arctic Ocean only to be met by scorn/denial of the impacts? Why can others be so entrenched as to not accept what must come to pass should such circumstances be allowed to come into play?

[knocker]

Mixing it up: Study provides new insight into Southern Ocean behaviour

 

A new study has found that turbulent mixing in the deep waters of the Southern Ocean, which has a profound effect on global ocean circulation and climate, varies with the strength of surface eddies – the ocean equivalent of storms in the atmosphere – and possibly also wind speeds.

 

It is the first study to link eddies at the surface to deep mixing on timescales of months to decades.

 

This new insight into how the Southern Ocean behaves will allow scientists to build computer models that can better predict how our climate is going to change in the future.

 

http://www.sciencecodex.com/mixing_it_up_study_provides_new_insight_into_southern_ocean_behaviour-137852

[knocker]

Stanford professor finds that wildfires and other burns play bigger role in climate change New study quantifies the degree of contribution to global climate caused by slash-and-burn agriculture and wildfires, and finds bigger than expected impact

 

"We calculate that 5 to 10 percent of worldwide air pollution mortalities are due to biomass burning," Jacobson said. "That means that it causes the premature deaths of about 250,000 people each year."

 

http://www.eurekalert.org/pub_releases/2014-07/ssoe-spf073114.php

[BornFromTheVoid]

Recent Walker circulation strengthening and Pacific cooling amplified by Atlantic warming

 

An unprecedented strengthening of Pacific trade winds since the late 1990s (ref. 1) has caused widespread climate perturbations, including rapid sea-level rise in the western tropical Pacific2, 3, 4, 5, strengthening of Indo-Pacific ocean currents6, 7, and an increased uptake of heat in the equatorial Pacific thermocline1. The corresponding intensification of the atmospheric Walker circulation is also associated with sea surface cooling in the eastern Pacific, which has been identified as one of the contributors to the current pause in global surface warming1, 8, 9. In spite of recent progress in determining the climatic impacts of the Pacific trade wind acceleration, the cause of this pronounced trend in atmospheric circulation remains unknown. Here we analyse a series of climate model experiments along with observational data to show that the recent warming trend in Atlantic sea surface temperature and the corresponding trans-basin displacements of the main atmospheric pressure centres were key drivers of the observed Walker circulation intensification, eastern Pacific cooling, North American rainfall trends and western Pacific sea-level rise. Our study suggests that global surface warming has been partly offset by the Pacific climate response to enhanced Atlantic warming since the early 1990s.

 

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2330.html

[knocker]

Funny I was just going to post the same.

 

There is a synopsis here.

 

http://phys.org/news/2014-08-atlantic-turbocharges-pacific.html

[knocker]

University of Minnesota researcher finds cooling effect in warming Arctic lakes

 

Scientists have known for a while that warming global temperatures are causing Arctic lakes to release methane, a potent greenhouse gas that leads to even more warming. In a new study published in the journal Nature, a team of researchers including U of M researcher Jacques Finlay, found that Siberian lakes have actually pulled more greenhouse gasses from the atmosphere than they have released into it since the last Ice Age, causing an overall slight cooling effect.

 

http://www.sciencecodex.com/university_of_minnesota_researcher_finds_cooling_effect_in_warming_arctic_lakes-138998

[knocker]

Evidence for an earlier greenhouse cooling effect in the stratosphere before 1980 over the Northern Hemisphere

 

Abstract. This study provides a new look at the observed and calculated long-term temperature changes from the lower troposphere to the lower stratosphere since 1958 over the Northern Hemisphere. The data sets include the NCEP/NCAR reanalysis, the Free University of Berlin (FU-Berlin) and the RICH radiosonde data sets as well as historical simulations with the CESM1-WACCM global model participating in CMIP5. The analysis is mainly based on monthly layer mean temperatures derived from geopotential height thicknesses in order to take advantage of the use of the independent FU-Berlin stratospheric data set of geopotential height data since 1957. This approach was followed to extend the records for the investigation of the stratospheric temperature trends to the earliest possible time. After removing the natural variability with an autoregressive multiple regression model our analysis shows that the period 1958–2011 can be divided into two distinct sub-periods of long-term temperature variability and trends: before and after 1980. By calculating trends for the summer time to reduce interannual variability, the two periods are as follows. From 1958 until 1979, a non-significant trend (0.06 ± 0.06 °C decade^−1 for NCEP) and slightly cooling trends (−0.12 ± 0.06 °C decade^−1 for RICH) are found in the lower troposphere. The second period from 1980 to the end of the records shows significant warming (0.25 ± 0.05 °C decade^−1 for both NCEP and RICH). Above the tropopause a significant cooling trend is clearly seen in the lower stratosphere both in the pre-1980 period (−0.58 ± 0.17 °C decade^−1 for NCEP, −0.30 ± 0.16 °C decade^−1 for RICH and −0.48 ± 0.20 °C decade^−1 for FU-Berlin) and the post-1980 period (−0.79 ± 0.18 °C decade^−1 for NCEP, −0.66 ± 0.16 °C decade^−1 for RICH and −0.82 ± 0.19 °C decade^−1 for FU-Berlin). The cooling in the lower stratosphere persists throughout the year from the tropics up to 60° N. At polar latitudes competing dynamical and radiative processes reduce the statistical significance of these trends. Model results are in line with reanalysis and the observations, indicating a persistent cooling (−0.33 °C decade^−1) in the lower stratosphere during summer before and after 1980; a feature that is also seen throughout the year. However, the lower stratosphere CESM1-WACCM modelled trends are generally lower than reanalysis and the observations. The contrasting effects of ozone depletion at polar latitudes in winter/spring and the anticipated strengthening of the Brewer–Dobson circulation from man-made global warming at polar latitudes are discussed. Our results provide additional evidence for an early greenhouse cooling signal in the lower stratosphere before 1980, which appears well in advance relative to the tropospheric greenhouse warming signal. The suitability of early warning signals in the stratosphere relative to the troposphere is supported by the fact that the stratosphere is less sensitive to changes due to cloudiness, humidity and man-made aerosols. Our analysis also indicates that the relative contribution of the lower stratosphere versus the upper troposphere low-frequency variability is important for understanding the added value of the long-term tropopause variability related to human-induced global warming.

 

http://www.atmos-chem-phys.net/14/7705/2014/acp-14-7705-2014.html?utm_content=buffer381ce&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[mikeworst]

Moreover, they found that the total impact from the influence of aerosols on this type of cloud is almost double that estimated in the latest report of the United Nations' Intergovernmental Panel on Climate Change.--Oh dear, adjust those models.  http://www.sciencedaily.com/releases/2014/08/140806024748.htm?utm_source=twitterfeed

[knocker]

Impact of a 30% reduction in Atlantic meridional overturning during 2009–2010

 

Abstract. The Atlantic meridional overturning circulation comprises warm upper waters flowing northward, becoming colder and denser until they form deep water in the Labrador and Nordic Seas that then returns southward through the North and South Atlantic. The ocean heat transport associated with this circulation is 1.3 PW, accounting for 25% of the maximum combined atmosphere–ocean heat transport necessary to balance the Earth's radiation budget. We have been monitoring the circulation at 25° N since 2004. A 30% slowdown in the circulation for 14 months during 2009–2010 reduced northward ocean heat transport across 25° N by 0.4 PW and resulted in colder upper ocean waters north of 25° N and warmer waters south of 25° N. The spatial pattern of upper ocean temperature anomalies helped push the wintertime circulation 2010–2011 into record-low negative NAO (North Atlantic Oscillation) conditions with accompanying severe winter conditions over northwestern Europe. The warmer temperatures south of 25° N contributed to the high intensity hurricane season in summer 2010.

 

http://www.ocean-sci.net/10/683/2014/os-10-683-2014.pdf

Edited August 7, 2014 by knocker

[Gael_Force]

Impact of a 30% reduction in Atlantic meridional overturning during 2009–2010

 

http://www.ocean-sci.net/10/683/2014/os-10-683-2014.pdf

 

A connection?

 

http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3232.1

 

http://www.clim-past-discuss.net/10/2519/2014/cpd-10-2519-2014.pdf

 

http://www.nature.com/ngeo/journal/v7/n4/full/ngeo2094.html

[BornFromTheVoid]

A 10,000 year history of ENSO using clam shells!

 

Holocene history of ENSO variance and asymmetry in the eastern tropical Pacific

 

Understanding the response of the El Niño-Southern Oscillation (ENSO) to global warming requires quantitative data on ENSO under different climate regimes. Here, we present a reconstruction of ENSO in the eastern tropical Pacific spanning the last 10 thousand years (ka) derived from oxygen isotopes in fossil mollusk shells from Peru. We find that ENSO variance was close to the modern level in the early Holocene and severely damped ~4-5 ka. In addition, ENSO variability was skewed toward cold events along coastal Peru 6.7-7.5 ka owing to a shift of warm anomalies toward the Central Pacific. The modern ENSO regime was established ~3-4.5 ka. We conclude that ENSO was sensitive to changes in climate boundary conditions during the Holocene, including, but not limited to insolation.

 

 

An overview of the paper is here, with some interesting findings.

http://phys.org/news/2014-08-clam-fossils-year-history-el.html

[knocker]

A 10,000 year history of ENSO using clam shells!

 

Holocene history of ENSO variance and asymmetry in the eastern tropical Pacific

 

Understanding the response of the El Niño-Southern Oscillation (ENSO) to global warming requires quantitative data on ENSO under different climate regimes. Here, we present a reconstruction of ENSO in the eastern tropical Pacific spanning the last 10 thousand years (ka) derived from oxygen isotopes in fossil mollusk shells from Peru. We find that ENSO variance was close to the modern level in the early Holocene and severely damped ~4-5 ka. In addition, ENSO variability was skewed toward cold events along coastal Peru 6.7-7.5 ka owing to a shift of warm anomalies toward the Central Pacific. The modern ENSO regime was established ~3-4.5 ka. We conclude that ENSO was sensitive to changes in climate boundary conditions during the Holocene, including, but not limited to insolation.

 

 

An overview of the paper is here, with some interesting findings.

http://phys.org/news/2014-08-clam-fossils-year-history-el.html

 

Yes indeed leading to more interesting questions.

[knocker]

A global temperature conundrum: cooling or warming climate?

http://www.news.wisc.edu/23050

[Gael_Force]

A global temperature conundrum: cooling or warming climate?

http://www.news.wisc.edu/23050

 

 

An interesting diagram from the supplemental material.

 

 

That might tie in with the change in warm Atlantic current that is in the link further up the page.

 

http://www.pnas.org/content/early/2014/08/07/1407229111

[knocker]

Spatial distribution of Northern Hemisphere winter temperatures during different phases of the solar cycle

 

Abstract

Several recent studies have found variability in the Northern Hemisphere winter climate related to different parameters of solar activity. While these results consistently indicate some kind of solar modulation of tropospheric and stratospheric circulation and surface temperature, opinions on the exact mechanism and the solar driver differ. Proposed drivers include, e.g., total solar irradiance (TSI), solar UV radiation, galactic cosmic rays and magnetospheric energetic particles. While some of these drivers are difficult to distinguish because of their closely similar variation over the solar cycle, other suggested drivers have clear differences in their solar cycle evolution. For example, geomagnetic activity and magnetospheric particle fluxes peak in the declining phase of the sunspot cycle, in difference to TSI and UV radiation which more closely follow sunspots. Using 13 solar cycles (1869–2009) we study winter surface temperatures and North Atlantic oscillation (NAO) during four different phases of the sunspot cycle: minimum, ascending, maximum and declining phase. We find significant differences in the temperature patterns between the four cycle phases, which indicates a solar cycle modulation of winter surface temperatures. However, the clearest pattern of the temperature anomalies is not found during sunspot maximum or minimum, but during the declining phase, when the temperature pattern closely resembles the pattern found during positive NAO. Moreover, we find the same pattern during the low sunspot activity cycles of 100 years ago, suggesting that the pattern is largely independent of the overall level of solar activity.

http://onlinelibrary.wiley.com/doi/10.1002/2013JD021343/abstract?utm_content=buffer8efe4&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

An interesting diagram from the supplemental material.

 

 

That might tie in with the change in warm Atlantic current that is in the link further up the page.

 

http://www.pnas.org/content/early/2014/08/07/1407229111

 

Recent tweet from Michael Mann

 

New @PNASnews (http://www.pnas.org/content/early/2014/08/07/1407229111.full.pdf+html â€¦) supports our hypothesis (http://www.meteo.psu.edu/holocene/public_html/Mann/articles/articles/MannetalGRL09.pdf â€¦) mid-Holocene warmth may have been overestimated...

[lorenzo]

Impact of a 30% reduction in Atlantic meridional overturning during 2009–2010

 

http://www.ocean-sci.net/10/683/2014/os-10-683-2014.pdf

 

Fascinating reading that one, have you found the paper by Buchan et al quoted in the conclusion?

[Gael_Force]

Fascinating reading that one, have you found the paper by Buchan et al quoted in the conclusion?

 

That one is paywalled -  http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-13-00104.1

 

There is also this paper by one of the authors, Joël Hirschi.

 

http://onlinelibrary.wiley.com/doi/10.1029/2011GL048978/full

[knocker]

It's pretty mind boggling really.

 

New research – July 2014

http://agwobserver.wordpress.com/2014/07/31/new-research-july-2014/

[Gray-Wolf]

It's pretty mind boggling really.

 

New research – July 2014

http://agwobserver.wordpress.com/2014/07/31/new-research-july-2014/

 

Indeed! It's always a case of 'where to begin?'........ maybe we should let someone else wade through it and 'cherry pick' that which suits our viewpoint and then post it into a blog for us so we can grab the soundbites we like. Nah! that'd be plain stupid..................................

[knocker]

Another conundrum

 

Snow has thinned on Arctic sea ice

 

From research stations drifting on ice floes to high-tech aircraft radar, scientists have been tracking the depth of snow that accumulates on Arctic sea ice for almost a century. Now that people are more concerned than ever about what is happening at the poles, research led by the University of Washington and NASA confirms that snow has thinned significantly in the Arctic, particularly on sea ice in western waters near Alaska.

 

http://www.washington.edu/news/2014/08/13/snow-has-thinned-on-arctic-sea-ice/