New Research

[jvenge]

http://onlinelibrary.wiley.com/doi/10.1002/2016GL071307/full

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The proxy record of global temperature shows that the dominant periodicity of the glacial cycle shifts from 40-kyr (obliquity) to 100-kyr (eccentricity), about a million years ago. Using climate model simulations, here we show that the pace of the glacial cycle depends on the pattern of hemispheric sea ice growth. In a cold climate the sea ice grows asymmetrically between two hemispheres under changes to Earth's orbital precession, because sea ice growth potential outside of the Arctic Circle is limited. This difference in hemispheric sea ice growth leads to an asymmetry in absorbed solar energy for the two hemispheres, particularly when eccentricity is high, even if the annual average insolation is similar. In a warmer climate, the hemispheric asymmetry of the sea ice decreases as mean Arctic and Antarctic sea ice decreases, diminishing the precession and eccentricity signals and explaining the dominant obliquity signal (40-kyr) before the mid-Pleistocene transition.

Quite an interesting read. It goes on to say that sea ice in the southern hemisphere is a key component of triggering an ice age. Orbital shifts, which lead to lower temperatures near the south pole in summer, which increases sea ice, which then reflects more light going forward. No land masses to get in the way of sea ice expanding.

 

[Gray-Wolf]

https://www.scientificamerican.com/article/rain-from-thunderstorms-is-rising-due-to-climate-change/

You don't need to tell us in the calder Valley that storms are carrying more water!!! The 2012 flood ( July) was from a stubborn storm that just did not stop but kept forming up over the moors above us!

[knocker]

Simulated Atmospheric Response to Regional and Pan-Arctic Sea-Ice Loss

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Abstract

The loss of Arctic sea-ice is already having profound environmental, societal and ecological impacts locally. A highly uncertain area of scientific research, however, is whether such Arctic change has a tangible effect on weather and climate at lower latitudes. There is emerging evidence that the geographical location of sea-ice loss is critically important in determining the large-scale atmospheric circulation response and associated mid-latitude impacts. However, such regional dependencies have not been explored in a thorough and systematic manner. To make progress on this issue, this study analyses ensemble simulations with an atmospheric general circulation model prescribed with sea-ice loss separately in nine regions of the Arctic, to elucidate the distinct responses to regional sea-ice loss. The results suggest that in some regions sea-ice loss triggers large-scale dynamical responses whereas in other regions sea-ice loss induces only local thermodynamical changes. Sea-ice loss in the Barents-Kara Sea is unique in driving a weakening of the stratospheric polar vortex, followed in time by a tropospheric circulation response that resembles the North Atlantic Oscillation. For October-to-March, the largest spatial-scale responses are driven by sea-ice loss in the Barents-Kara Sea and Sea of Okhotsk; however, different regions assume greater importance in other seasons. The atmosphere responds very differently to regional sea-ice losses than to pan-Arctic sea-ice loss, and the latter cannot be obtained by linear addition of the responses to regional sea-ice losses. The results imply that diversity in past studies of the simulated response to Arctic sea-ice loss can be partly explained by the different spatial patterns of sea-ice loss imposed.

http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0197.1

[Nouska]

I've already posted some of the interesting results from the European SWARM satellite but this is really intriguing in light of some research that links solar core magnetism to that of the core of earth.

A jet stream accelerating at high speed, in high latitudes, deep in earth's core - could this have any implication on the surface patterns?

Hopefully the courtesy link to full article works  - it looks rather long.

http://www.nature.com/articles/ngeo2859.epdf?referrer_access_token=5mBZ_WSWTB7UhGSeCnNSItRgN0jAjWel9jnR3ZoTv0PmsEc3G31WFfVT1PriGtJTaR0HLPfAWbii_7PtlU1mK7i05sQIIH1nSzUJZB1m_vk9uJQKnYUCPnpl0urzXsKW_ytxvFrbabjaBglf7nUGEQ5-jXvyVihVn2iAaocIiKbGCX3Ocg0snCWB7QS43VpOr0ydw6nH8yn6Im2tiC-Q8Q%3D%3D&tracking_referrer=www.bbc.com

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A connection from Arctic stratospheric ozone to El Niño-Southern oscillation

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Abstract

Antarctic stratospheric ozone depletion is thought to influence the Southern Hemisphere tropospheric climate. Recently, Arctic stratospheric ozone (ASO) variations have been found to affect the middle-high latitude tropospheric climate in the Northern Hemisphere. This paper demonstrates that the impact of ASO can extend to the tropics, with the ASO variations leading El Niño-Southern Oscillation (ENSO) events by about 20 months. Using observations, analysis, and simulations, the connection between ASO and ENSO is established by combining the high-latitude stratosphere to troposphere pathway with the extratropical to tropical climate teleconnection. This shows that the ASO radiative anomalies influence the North Pacific Oscillation (NPO), and the anomalous NPO and induced Victoria Mode anomalies link to the North Pacific circulation that then influences ENSO. Our results imply that incorporating realistic and time-varying ASO into climate system models may help to improve ENSO predictions.

http://iopscience.iop.org/article/10.1088/1748-9326/11/12/124026

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Respective roles of direct GHG radiative forcing and induced Arctic sea ice loss on the Northern Hemisphere atmospheric circulation

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The large-scale and synoptic-scale Northern Hemisphere atmospheric circulation responses to projected late twenty-first century Arctic sea ice decline induced by increasing Greenhouse Gases (GHGs) concentrations are investigated using the CNRM-CM5 coupled model. An original protocol, based on a flux correction technique, allows isolating the respective roles of GHG direct radiative effect and induced Arctic sea ice loss under RCP8.5 scenario. In winter, the surface atmospheric response clearly exhibits opposing effects between GHGs increase and Arctic sea ice loss, leading to no significant pattern in the total response (particularly in the North Atlantic region). An analysis based on Eady growth rate shows that Arctic sea ice loss drives the weakening in the low-level meridional temperature gradient, causing a general decrease of the baroclinicity in the mid and high latitudes, whereas the direct impact of GHGs increase is more located in the mid-to-high troposphere. Changes in the flow waviness, evaluated from sinuosity and blocking frequency metrics, are found to be small relative to inter-annual variability.

http://rd.springer.com/article/10.1007%2Fs00382-017-3541-0?utm_content=buffer8cde1&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

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Greenland coastal air temperatures linked to Baffin Bay and Greenland Sea ice conditions during autumn through regional blocking patterns

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Abstract

Variations in sea ice freeze onset and regional sea surface temperatures (SSTs) in Baffin Bay and Greenland Sea are linked to autumn surface air temperatures (SATs) around coastal Greenland through 500 hPa blocking patterns, 1979–2014. We find strong, statistically significant correlations between Baffin Bay freeze onset and SSTs and SATs across the western and southernmost coastal areas, while weaker and fewer significant correlations are found between eastern SATs, SSTs, and freeze periods observed in the neighboring Greenland Sea. Autumn Greenland Blocking Index values and the incidence of meridional circulation patterns have increased over the modern sea ice monitoring era. Increased anticyclonic blocking patterns promote poleward transport of warm air from lower latitudes and local warm air advection onshore from ocean–atmosphere sensible heat exchange through ice-free or thin ice-covered seas bordering the coastal stations. Temperature composites by years of extreme late freeze conditions, occurring since 2006 in Baffin Bay, reveal positive monthly SAT departures that often exceed 1 standard deviation from the 1981–2010 climate normal over coastal areas that exhibit a similar spatial pattern as the peak correlations.

http://link.springer.com/article/10.1007%2Fs00382-017-3583-3?utm_content=bufferb26dc&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Topical collection on global energy budget in current reports:

http://link.springer.com/journal/40641/topicalCollection/AC_5f35cb47742eceb711c5d634ba9c330b

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Winter sea ice export from the Laptev Sea preconditions the local summer sea ice cover

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Abstract. Recent studies based on satellite observations have shown that there is a high statistical connection between the late winter (Feb-May) sea ice export out the Laptev Sea, and the ice coverage in the following summer. By means of airborne sea ice thickness surveys made over pack ice areas in the southeastern Laptev Sea, we show that years of offshore directed sea ice transport have a thinning effect on the late winter sea ice cover, and vice versa. Once temperature rise above freezing, these thin ice zones melt more rapidly and hence, precondition local anomalies in summer sea ice cover. The preconditioning effect of the winter ice dynamics for the summer sea ice extent is confirmed with a model sensitivity study where we replace the inter-annual summer atmospheric forcing by a climatology. In the model, years with high late winter sea ice export always result in a reduced sea ice cover, and vice versa. We conclude that the observed tendency towards an increased ice export further accelerates ice retreat in summer. The mechanism presented in this study highlights the importance of winter ice dynamics for summer sea ice anomalies in addition to atmospheric processes acting on the ice cover between May and September. Finally, we show that ice dynamics in winter not only precondition local summer ice extent, but also accelerate fast ice decay.

http://www.the-cryosphere-discuss.net/tc-2017-28/

[knocker]

Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events

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Persistent episodes of extreme weather in the Northern Hemisphere summer have been shown to be associated with the presence of high-amplitude quasi-stationary atmospheric Rossby waves within a particular wavelength range (zonal wavenumber 6–8). The underlying mechanistic relationship involves the phenomenon of quasi-resonant amplification (QRA) of synoptic-scale waves with that wavenumber range becoming trapped within an effective mid-latitude atmospheric waveguide. Recent work suggests an increase in recent decades in the occurrence of QRA-favorable conditions and associated extreme weather, possibly linked to amplified Arctic warming and thus a climate change influence. Here, we isolate a specific fingerprint in the zonal mean surface temperature profile that is associated with QRA-favorable conditions. State-of-the-art (“CMIP5”) historical climate model simulations subject to anthropogenic forcing display an increase in the projection of this fingerprint that is mirrored in multiple observational surface temperature datasets. Both the models and observations suggest this signal has only recently emerged from the background noise of natural variability.

http://www.nature.com/articles/srep45242

[knocker]

North Pacific 20th century decadal-scale variability is unique for the past 342 years

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Abstract

Reconstructed sea surface temperatures (SSTs) derived from Mg/Ca measurements in nine encrusting coralline algal skeletons from the Aleutian archipelago in the northernmost Pacific Ocean reveal an overall increase in SST from 1665 to 2007. In the Aleutian SST reconstruction, decadal-scale variability is a transient feature present during the 1700s and early 1800s and then fully emerging post-1950. SSTs vary coherently with available instrument records of cyclone variance and vacillate in and out of coherence with multi-centennial Pacific Northwest drought reconstructions as a response to SST-driven alterations of storm tracks reaching North America. These results indicate that an influence of decadal-scale variability on the North Pacific storm tracks only became apparent during the mid-20th century. Furthermore, what has been assumed as natural variability in the North Pacific, based on 20th century instrumental data, is not consistent with the long-term natural variability evident in reconstructed SSTs pre-dating the anthropogenic influence.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL073138/abstract?utm_content=bufferc3b12&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Frost fairs and the Little Ice Age

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The term ‘Little Ice Age’ refers to a period of cooler temperatures between around 1400 and 1850, although a range of dates are used. This climate feature has been inferred from various types of direct and indirect evidence, but it is still not clear how widespread these cooler temperatures were.

A new article by Lockwood et al explores some of the commonly used indirect evidence such as paintings and the occurrence of ‘frost fairs’ on the Thames. We also address the common assumption that the cooler temperatures were solely due to a reduction in solar activity (the Spörer and Maunder minima). Although this assumption is almost certainly wrong, the two features are sometimes considered to be synonymous.

http://www.climate-lab-book.ac.uk/2017/frost-fairs-and-the-little-ice-age/

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THE ‘LITTLE ICE AGE’: RE-EVALUATION OF AN EVOLVING CONCEPT

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ABSTRACT. This review focuses on the development of the ‘Little Ice Age’ as a glaciological and climatic concept, and evaluates its current usefulness in the light of new data on the glacier and climatic variations of the last millennium and of the Holocene. ‘Little Ice Age’ glacierization occurred over about 650 years and can be defined most precisely in the European Alps (c. AD 1300–1950) when extended glaciers were larger than before or since. ‘Little Ice Age’ climate is defined as a shorter time interval of about 330 years (c. AD 1570–1900) when Northern Hemisphere summer temperatures (land areas north of 20°N) fell significantly below the AD 1961–1990 mean. This climatic definition overlaps the times when the Alpine glaciers attained their latest two highstands (AD 1650 and 1850). It is emphasized, however, that ‘Little Ice Age’ glacierization was highly dependent on winter precipitation and that ‘Little Ice Age’ climate was not simply a matter of summer temperatures. Both the glacier-centred and the climate-centred concepts necessarily encompass considerable spatial and temporal variability, which are investigated using maps of mean summer temperature variations over the Northern Hemisphere at 30-year intervals from AD 1571 to 1900. ‘Little Ice Age’-type events occurred earlier in the Holocene as exemplified by at least seven glacier expansion episodes that have been identified in southern Norway. Such events provide a broader context and renewed relevance for the ‘Little Ice Age’, which may be viewed as a ‘modern analogue’ for the earlier events; and the likelihood that similar events will occur in the future has implications for climatic change in the twenty-first century. It is concluded that the concept of a ‘Little Ice Age’ will remain useful only by (1) continuing to incorporate the temporal and spatial complexities of glacier and climatic variations as they become better known, and (2) by reflecting improved understanding of the Earth-atmosphere-ocean system and its forcing factors through the interaction of palaeoclimatic reconstruction with climate modelling.

http://onlinelibrary.wiley.com/doi/10.1111/j.0435-3676.2005.00242.x/abstract

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Amy Butler

"Increasing N2O (depending on scenario) has implications for strat ozone layer and UV exposure"

Diverse policy implications for future ozone and surface UV in a changing climate

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Due to the success of the Montreal Protocol in limiting emissions of ozone-depleting substances, concentrations of atmospheric carbon dioxide, nitrous oxide, and methane will control the evolution of total column and stratospheric ozone by the latter half of the 21st century. As the world proceeds down the path of reducing climate forcing set forth by the 2015 Conference of the Parties to the United Nations Framework Convention on Climate Change (COP 21), a broad range of ozone changes are possible depending on future policies enacted. While decreases in tropical stratospheric ozone will likely persist regardless of the future emissions scenario, extratropical ozone could either remain weakly depleted or even increase well above historical levels, with diverse implication for ultraviolet (UV) radiation. The ozone layer's dependence on future emissions of these gases creates a complex policy decision space for protecting humans and ecosystems, which includes unexpected options such as accepting nitrous oxide emissions in order to maintain historical column ozone and surface UV levels.

http://iopscience.iop.org/article/10.1088/1748-9326/11/6/064017/meta

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Photos Reveal More Than 200 Bright Blue Arctic Lakes Have Started Bubbling With Methane Gas

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Satellite images have revealed more than 200 strange, bright blue lakes in Russia's Arctic regions that are bubbling "like jacuzzis" as a result of leaking methane gas.

The lakes are a type of thermokarst lake, which form when thawing permafrost causes the surface to collapse and fill in with melangel delighter. But unlike normal, dark thermokarst lakes, these ones are bright blue and bubbling, because of methane that's leaking into them before escaping into the atmosphere.

http://www.sciencealert.com/photos-reveal-more-than-200-bright-blue-arctic-lakes-have-started-bubbling-with-methane-gas

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On the role of ozone feedback in the ENSO amplitude response under global warming

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Abstract

The El Niño Southern Oscillation (ENSO) in the tropical Pacific Ocean is of key importance to global climate and weather. However, state-of-the-art climate models still disagree on the ENSO's response under climate change. The potential role of atmospheric ozone changes in this context has not been explored before. Here, we show that differences between typical model representations of ozone can have a first-order impact on ENSO amplitude projections in climate sensitivity simulations. The vertical temperature gradient of the tropical middle-to-upper troposphere adjusts to ozone changes in the upper troposphere and lower stratosphere, modifying the Walker circulation and consequently tropical Pacific surface temperature gradients. We show that neglecting ozone changes thus results in a significant increase in the number of extreme ENSO events in our model. Climate modeling studies of the ENSO often neglect changes in ozone. We therefore highlight the need to understand better the coupling between ozone, the tropospheric circulation and climate variability.

http://onlinelibrary.wiley.com/doi/10.1002/2016GL072418/abstract?utm_content=buffer4a06e&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

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Scientists link California droughts and floods to distinctive atmospheric waves

The crippling wintertime droughts that struck California from 2013 to 2015, as well as this year's unusually wet California winter, appear to be associated with the same phenomenon: a distinctive wave pattern that emerges in the upper atmosphere and circles the globe.

Read more at: https://phys.org/news/2017-04-scientists-link-california-droughts-distinctive.html#jCp

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Greater role for Atlantic inflows on sea-ice loss in the Eurasian Basin of the Arctic Ocean

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Arctic sea-ice loss is a leading indicator of climate change and can be attributed, in large part, to atmospheric forcing. Here, we show that recent ice reductions, weakening of the halocline, and shoaling of intermediate-depth Atlantic Water layer in the eastern Eurasian Basin have increased winter ventilation in the ocean interior, making this region structurally similar to that of the western Eurasian Basin. The associated enhanced release of oceanic heat has reduced winter sea-ice formation at a rate now comparable to losses from atmospheric thermodynamic forcing, thus explaining the recent reduction in sea-ice cover in the eastern Eurasian Basin. This encroaching “atlantification” of the Eurasian Basin represents an essential step toward a new Arctic climate state, with a substantially greater role for Atlantic inflows.

http://science.sciencemag.org/content/early/2017/04/05/science.aai8204

[knocker]

By 2050 We Are On Track to Cause the Fastest Climate Change in 420 Million Years. Well Done All.

https://www.nature.com/articles/ncomms14845?utm_content=buffer7cf01&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

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'Detergent' molecules may drive recent methane changes

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A new NASA- and Department of Energy-funded study finds that recent increases in global methane levels observed since 2007 are not necessarily due to increasing emissions, but instead may be due to changes in how long methane remains in the atmosphere after it is emitted.

The second most important human-produced greenhouse gas after carbon dioxide, methane is colorless, odorless and can be hard to track. The gas has a wide range of sources, from decomposing biological material to leaks in natural gas pipelines. In the early 2000s, atmospheric scientists studying methane found that its global concentration — which had increased for decades, driven by methane emissions from fossil fuels and agriculture — leveled off as the sources of methane reached a balance with its destruction mechanisms. The methane levels remained stable for a few years, then unexpectedly started rising again in 2007, a trend that is still continuing.

Previous studies of the renewed increase have focused on high-latitude wetlands or fossil fuels, Asian agricultural growth, or tropical wetlands as potential sources of the increased emissions. But in a study published today in the early online edition of the Proceedings of the National Academy of Sciences, researchers at Harvard University in Cambridge, Massachusetts; Caltech in Pasadena, California; and NASA's Jet Propulsion Laboratory, also in Pasadena, suggest that methane emissions might not have increased dramatically in 2007 after all.

https://climate.nasa.gov/news/2577/detergent-molecules-may-drive-recent-methane-changes/

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Sea level rising faster now than during 1990s, new study shows

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Global mean sea level is rising 25 percent faster now than it did during the late 20th century largely due to increased melting of the Greenland Ice Sheet, a new study shows.

Satellites first started measuring sea level rise in 1993. The new study revisits how well these measurements agree with independently observed changes in the various components contributing to sea level rise, from the melting of glaciers to the amount of water vapor in the atmosphere. 

Using this approach, the new study finds the global mean sea level, or the average height of the world’s oceans, has been increasing by 3 millimeters (.1 inches) per year on average during the satellite period.

The research also finds the rate of global mean sea level rise increased by 0.8 millimeters (.03 inches) per year during the second half of the satellite period, from 2004 to 2015. The increase is mainly due to accelerated melting of the Greenland Ice Sheet, according to the new research.

https://blogs.agu.org/geospace/2017/04/26/sea-level-rising-faster-now-1990s-new-study-shows/

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Changing wet and dry seasons

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The fickle nature of weather patterns is ultimately responsible for the where and when of tropical rainfall extremes which wreak damage on agriculture, infrastructure and people. Tropical cyclones, such as Enawo which battered Madagascar in March, can severely impact low-lying, highly populated regions through intense rainfall combined with strong winds and storm surges. Explosive thunderstorms operating at smaller spatial scales can generate flash flooding and may lead to devastating landslides in mountainous terrain. A sustained dearth of rainfall or multiple failed seasonal rains, as implicated in drought currently impacting Somalia, Kenya and Ethiopia, are also inextricably linked with evolving weather patterns, often driven by the slower heart-beat of the oceans as they pace out the internal rhythm of El Niño Southern Oscillation and its decadal physiognomies.

http://blogs.reading.ac.uk/weather-and-climate-at-reading/2017/changing-wet-and-dry-seasons/