New Research

[knocker]

Regional acceleration in ice mass loss from Greenland and Antarctica using GRACE time-variable gravity data.

 

Abstract

We use GRACE monthly gravity fields to determine the regional acceleration in ice mass loss in Greenland and Antarctica for 2003–2013. We find that the total mass loss is controlled by only a few regions. In Greenland, the southeast and northwest generate 70% of the loss (280∓58 Gt/yr) mostly from ice dynamics, the southwest accounts for 54% of the total acceleration in loss (25.4∓1.2 Gt/yr²) from a decrease in surface mass balance (SMB), followed by the northwest (34%), and we find no significant acceleration in the northeast. In Antarctica, the Amundsen Sea (AS) sector and the Peninsula account for 64% and 17%, respectively, of the total loss (180∓10 Gt/yr) mainly from ice dynamics. The AS sector contributes most of the acceleration in loss (11∓4 Gt/yr²) and Queen Maud Land, East Antarctica is the only sector with a significant mass gain due to a local increase in SMB (63∓5 Gt/yr).

 

http://onlinelibrary.wiley.com/doi/10.1002/2014GL061052/abstract?utm_content=buffer9481f&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Acceleration of snow melt in an Antarctic Peninsula ice core during the twentieth century

 

Over the past 50 years, warming of the Antarctic Peninsula has been accompanied by accelerating glacier mass loss and the retreat and collapse of ice shelves. A key driver of ice loss is summer melting; however, it is not usually possible to specifically reconstruct the summer conditions that are critical for determining ice melt in Antarctic. Here we reconstruct changes in ice-melt intensity and mean temperature on the northern Antarctic Peninsula since AD 1000 based on the identification of visible melt layers in the James Ross Island ice core and local mean annual temperature estimates from the deuterium content of the ice. During the past millennium, the coolest conditions and lowest melt occurred from about AD 1410 to 1460, when mean temperature was 1.6 °C lower than that of 1981–2000. Since the late 1400s, there has been a nearly tenfold increase in melt intensity from 0.5 to 4.9%. The warming has occurred in progressive phases since about AD 1460, but intensification of melt is nonlinear, and has largely occurred since the mid-twentieth century. Summer melting is now at a level that is unprecedented over the past 1,000 years. We conclude that ice on the Antarctic Peninsula is now particularly susceptible to rapid increases in melting and loss in response to relatively small increases in mean temperature.

 

http://www.nature.com/ngeo/journal/v6/n5/full/ngeo1787.html

[knocker]

Arctic sea ice helps remove CO2 from the atmosphere

 

Climate change is a fact, and most of the warming is caused by human activity. The Arctic is now so warm that the extent of sea ice has decreased by about 30 pct. in summer and in winter, sea ice is getting thinner. New research has shown that sea ice removes CO2 from the atmosphere. If Arctic sea ice is reduced, we may therefore be facing an increase of atmospheric concentration of CO2, researchers warn.

 

http://www.sdu.dk/en/Om_SDU/Fakulteterne/Naturvidenskab/Nyheder/2014_09_22_seaice

[knocker]

Global and regional sea level change during the 20th century

 

Abstract

Sea level variations prior to the launch of satellite altimeters are estimated by analysing historic tide gauge records. Recently, a number of groups have reconstructed sea level by applying EOF techniques to fill missing observations. We complement this study with alternative methods. In a first step gaps in 178 records of sea level change are filled using the pattern recognition capabilities of artificial neural networks. Afterwards satellite altimetry is used to extrapolate local sea level change to global fields. Patterns of sea level change are compared to prior studies. Global mean sea level change since 1900 is found to be 1.77 ± 0.38 mm year^−1 on average. Local trends are essentially positive with the highest values found in the western tropical Pacific and in the Indian Ocean east of Madagascar where it reaches about +6 mm year^−1. Regions with negative trends are spotty with a minimum value of about −2 mm year^−1 south of the Aleutian Islands. Although the acceleration found for the global mean, +0.0042 ± 0.0092 mm year^−2, is not significant, local values range from −0.1 mm year^−2 in the central Indian Ocean to +0.1 mm year^−2 in the western tropical Pacific and east of Japan. These extrema are associated with patterns of sea level change that differ significantly from the first half of the analyzed period (i.e. 1900 to 1950) to the second half (1950 to 2000). We take this as an indication of long period oceanic processes that are superimposed to the general sea level rise.

 

http://onlinelibrary.wiley.com/doi/10.1002/2014JC009900/abstract?utm_content=buffer75a3e&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Intensified Arctic warming under greenhouse warming by vegetation–atmosphere–sea ice interaction (open access)

 

Observations and modeling studies indicate that enhanced vegetation activities over high latitudes under an elevated CO₂ concentration accelerate surface warming by reducing the surface albedo. In this study, we suggest that vegetation-atmosphere-sea ice interactions over high latitudes can induce an additional amplification of Arctic warming. Our hypothesis is tested by a series of coupled vegetation-climate model simulations under 2xCO₂ environments. The increased vegetation activities over high latitudes under a 2xCO₂ condition induce additional surface warming and turbulent heat fluxes to the atmosphere, which are transported to the Arctic through the atmosphere. This causes additional sea-ice melting and upper-ocean warming during the warm season. As a consequence, the Arctic and high-latitude warming is greatly amplified in the following winter and spring, which further promotes vegetation activities the following year. We conclude that the vegetation-atmosphere-sea ice interaction gives rise to additional positive feedback of the Arctic amplification.

 

http://iopscience.iop.org/1748-9326/9/9/094007?utm_content=bufferdd022&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Brief Communication: Trends in sea ice extent north of Svalbard and its impact on cold air outbreaks as observed in spring 2013 (open access)

http://www.the-cryosphere.net/8/1757/2014/tc-8-1757-2014.html?utm_content=bufferb6dd6&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[keithlucky]

A new peered review  paper  over estimated climate sensitivity to CO2 so yet again another IPPC prediction wrong. http://www.cfact.org/2014/09/25/new-peer-reviewed-paper-un-overestimated-climate-sensitivity-to-co2/

Edited September 26, 2014 by keithlucky

[knocker]

A new peered review  paper  over estimated climate sensitivity to CO2 so yet again another IPPC prediction wrong. http://www.cfact.org/2014/09/25/new-peer-reviewed-paper-un-overestimated-climate-sensitivity-to-co2/

 

Did you actually read the paper Keith? Strongly advisable when linking to a poisonous denier site like CFACT  In any case a prediction cannot be wrong prior to the time of prediction.

 

I have actually already posted the paper along with a more reasoned discussion.

 

Lewis and Curry

[knocker]

Alpine glaciers and permanent ice and snow patches in western Canada approach their smallest sizes since the mid-Holocene, consistent with global trends

 

Abstract

Most alpine glaciers in the Northern Hemisphere reached their maximum extents of the Holocene between ad 1600 and 1850. Since the late 1800s, however, glaciers have thinned and retreated, mainly because of atmospheric warming. Glacier retreat in western Canada and other regions is exposing subfossil tree stumps, soils and plant detritus that, until recently, were beneath tens to hundreds of metres of ice. In addition, human artefacts and caribou dung are emerging from permanent snow patches many thousands of years after they were entombed. Dating of these materials indicates that many of these glaciers and snow patches are smaller today than at any time in the past several thousand years. This evidence, in turn, suggests that glacier recession in the 20th century is unprecedented during the past several millennia and that glaciers in western Canada have reached minimum extents only 150–300 years after they achieved their maximum Holocene extents.

 

http://hol.sagepub.com/content/early/2014/09/26/0959683614551214.abstract?utm_content=bufferbb8d1&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Influence of projected Arctic sea ice loss on polar stratospheric ozone and circulation in spring

 

Abstract

The impact of projected Arctic sea ice loss on the stratosphere is investigated using the Whole Atmosphere Community Climate Model (WACCM), a state-of-the-art coupled chemistry climate model. Two 91-year simulations are conducted: one with a repeating seasonal cycle of Arctic sea ice for the late twentieth-century, taken from the fully coupled WACCM historical run; the other with Arctic sea ice for the late twenty-first century, obtained from the fully coupled WACCM RCP8.5 run. In response to Arctic sea ice loss, polar cap stratospheric ozone decreases by 13 DU (34 DU at the North Pole) in spring, confirming the results of Scinocca et al (2009 Geophys. Res. Lett. 36 L24701). The ozone loss is dynamically initiated in March by a suppression of upward-propagating planetary waves, possibly related to the destructive interference between the forced wave number 1 and its climatology. The diminished upward wave propagation, in turn, weakens the Brewer–Dobson circulation at high latitudes, strengthens the polar vortex, and cools the polar stratosphere. The ozone reduction persists until the polar vortex breaks down in late spring.

 

http://iopscience.iop.org/1748-9326/9/8/084016/pdf/1748-9326_9_8_084016.pdf

[knocker]

A couple of papers from September.

 

New research – September 2014

http://agwobserver.wordpress.com/2014/10/01/new-research-september-2014/

[knocker]

Some of this may ring a bell

 

Radiative forcings for 28 potential Archean greenhouse gases

 

Abstract. Despite reduced insolation in the late Archean, evidence suggests a~warm climate which was likely sustained by a stronger greenhouse effect, the so-called faint young sun problem (FYSP). CO₂ and CH₄ are generally thought to be the mainstays of this enhanced greenhouse, though many other gases have been proposed. We present high accuracy radiative forcings for CO₂, CH₄, and 26 other gases, performing the radiative transfer calculations at line-by-line resolution and using HITRAN 2012 line data for background pressures of 0.5, 1, and 2 bar of atmospheric N₂. For CO₂ to resolve the FYSP alone at 2.8 Gyr BP (80% of present solar luminosity), 0.32 bar is needed with 0.5 bar of atmospheric N₂, 0.20 bar with 1 bar of atmospheric N₂, or 0.11 bar with 2 bar of atmospheric N₂. For CH₄, we find that near-infrared absorption is much stronger than previously thought, arising from updates to the HITRAN database. CH₄ radiative forcing peaks at 10.3, 9, or 8.3 W m^−2 for background pressures of 0.5, 1, or 2 bar, likely limiting the utility of CH₄ for warming the Archean. For the other 26 HITRAN gases, radiative forcings of up to a few to 10 W m^−2 are obtained from concentrations of 0.1–1 ppmv for many gases. For the 20 strongest gases, we calculate the reduction in radiative forcing due to overlap. We also tabulate the modern sources, sinks, concentrations, and lifetimes of these gases and summaries the literature on Archean sources and concentrations. We recommend the forcings provided here be used both as a first reference for which gases are likely good greenhouse gases, and as a standard set of calculations for validation of radiative forcing calculations for the Archean.

 

http://www.clim-past.net/10/1779/2014/cp-10-1779-2014.pdf

Edited October 3, 2014 by knocker

[knocker]

The ‘Little Ice Age’ in the Southern Hemisphere in the context of the last 3000 years: Peat-based proxy-climate data from Tierra del Fuego

 

Abstract

The so-called ‘Little Ice Age’ (LIA) of the 15th to 19th centuries ad is well-attested from much of Europe and from some other parts of the Northern Hemisphere. It has been attributed to solar forcing, associated with reduced solar activity, notably during the Spörer, Maunder and Dalton solar minima, although other causes have also been proposed and feature strongly in recent papers. Detection of the LIA in some proxy-climate records from the Southern Hemisphere is less clear, leading to suggestions that the LIA was perhaps not a global phenomenon. Resolving this issue requires more data from the Southern Hemisphere. We present proxy-climate data (plant macrofossils; peat humification) covering the past three millennia from an ombrotrophic mire (peat bog) in Tierra del Fuego, southern South America, but focus our discussion on the period traditionally associated with the LIA. During parts of this time, the mire surface was apparently relatively dry compared with much of its 3000-year record. It was reported earlier that a particularly dry episode in the mire coincided with the 2800 cal. BP ‘solar’ event (since identified as a Grand Solar Minimum), which was attributed to solar-driven changes in atmospheric circulation, and more specifically to a shift in position of the Westerlies. Parts of the LIA record show a similar shift to dryness, and we invoke a similar cause. The shifts to and from dry episodes are abrupt. These new data support the concept of a global LIA, and for at least the intense dry episodes might reinforce the claim for solar forcing of parts of the LIA climate.

 

http://hol.sagepub.com/content/early/2014/10/01/0959683614551232.abstract?utm_content=buffere9c57&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Argonne researchers create more accurate model for greenhouse gases from peatlands

 

Scientists at the U.S. Department of Energy’s Argonne National Laboratory have created a new model to more accurately describe the greenhouse gases likely to be released from Arctic peatlands as they warm. Their findings, based on modeling how oxygen filters through soil, suggest that previous models probably underestimated methane emissions and overrepresented carbon dioxide emissions from these regions.

 

http://www.anl.gov/articles/argonne-researchers-create-more-accurate-model-greenhouse-gases-peatlands

[BornFromTheVoid]

Quantifying underestimates of long-term upper-ocean warming

 

The global ocean stores more than 90% of the heat associated with observed greenhouse-gas-attributed global warming1, 2, 3, 4. Using satellite altimetry observations and a large suite of climate models, we conclude that observed estimates of 0–700 dbar global ocean warming since 1970 are likely biased low. This underestimation is attributed to poor sampling of the Southern Hemisphere, and limitations of the analysis methods that conservatively estimate temperature changes in data-sparse regions5, 6, 7. We find that the partitioning of northern and southern hemispheric simulated sea surface height changes are consistent with precise altimeter observations, whereas the hemispheric partitioning of simulated upper-ocean warming is inconsistent with observed in-situ-based ocean heat content estimates. Relying on the close correspondence between hemispheric-scale ocean heat content and steric changes, we adjust the poorly constrained Southern Hemisphere observed warming estimates so that hemispheric ratios are consistent with the broad range of modelled results. These adjustments yield large increases (2.2–7.1 × 1022 J 35 yr−1) to current global upper-ocean heat content change estimates, and have important implications for sea level, the planetary energy budget and climate sensitivity assessments.

 

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2389.html

 

Review of the article here from New Scientist

 

The world is warming faster than we thought

 

[Gray-Wolf]

Well that doesn't sound good BFTV and I can guess that the other side will be thrown into more ranting about 'fudged data' or some such? It makes more sense of the period we have just lived through and really does beg the question " just how much heating ought we expect?" as current GHG forcings max out over the coming years ( esp. if we see 'naturals' swing positive?).

[knocker]

This getting a bit confusing but another new paper supporting this was published at the same time.All a bit different to Cristy's observation of heat disappearing up the chimney.

 

Deep-ocean contribution to sea level and energy budget not detectable over the past decade

 

As the dominant reservoir of heat uptake in the climate system, the world’s oceans provide a critical measure of global climate change. Here, we infer deep-ocean warming in the context of global sea-level rise and Earth’s energy budget between January 2005 and December 2013. Direct measurements of ocean warming above 2,000 m depth explain about 32% of the observed annual rate of global mean sea-level rise. Over the entire water column, independent estimates of ocean warming yield a contribution of 0.77 ± 0.28 mm yr^−1 in sea-level rise and agree with the upper-ocean estimate to within the estimated uncertainties. Accounting for additional possible systematic uncertainties, the deep ocean (below 2,000 m) contributes −0.13 ± 0.72 mm yr^−1 to global sea-level rise and −0.08 ± 0.43 W m^−2 to Earth’s energy balance. The net warming of the ocean implies an energy imbalance for the Earth of 0.64 ± 0.44 W m^−2 from 2005 to 2013.

 

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2387.html

Edited October 6, 2014 by knocker

[knocker]

Concerning the discussion about the above quite a comprehensive review here. Note both studies are consistent.

 

http://www.reportingclimatescience.com/news-stories/article/scientists-find-clues-to-missing-heat-mystery.html

[knocker]

Some further comments.

 

An OHC update

[keithlucky]

New report shows that sea levels have fallen around the coasts of USA http://t.co/BRM6V3OJgT

[knocker]

A framework for benchmarking of homogenisation algorithm performance on the global scale - Paper now published

http://variable-variability.blogspot.co.uk/2014/10/benchmarking-homogenisation-algorithm-global-paper.html

[knocker]

Brazil's Rainforests Are Releasing More Carbon Dioxide Than Previously Thought

 

 

Because of the deforestation of tropical rainforests in Brazil, significantly more carbon has been lost than was previously assumed. As scientists of the Hemholtz Centre for Environmental Research (UFZ) write in the scientific journal Nature Communications, the effect of the degradation has been underestimated in fragmented forest areas, since it was hitherto not possible to calculate the loss of the biomass at the forest edges and the higher emission of carbon dioxide. The UFZ scientists have now closed this knowledge gap. According to their calculations, the forest fragmentation results in up to a fifth more carbon dioxide being emitted by the vegetation.

 

http://www.sciencenewsline.com/articles/2014100717150016.html#footer

[BornFromTheVoid]

New report shows that sea levels have fallen around the coasts of USA http://t.co/BRM6V3OJgT

 

Where does it say that, Keith?

[jonboy]

There are three short animated lectures of which the first two are now available and the last will be later this week discussing the work being undertaken at CERN and in particular relating to the CLOUD experiments (Cosmics Leaving Outdoor Droplets) ie the effect of cosmic rays on cloud formation and its subsequent effect on global temperatures.

http://home.web.cern.ch/about/updates/2014/10/teded-and-cern-team-animate-cosmic-rays

[knocker]

Biogeophysical feedbacks enhance the Arctic terrestrial carbon sink in regional Earth system dynamics

 

Abstract. Continued warming of the Arctic will likely accelerate terrestrial carbon © cycling by increasing both uptake and release of C. Yet, there are still large uncertainties in modelling Arctic terrestrial ecosystems as a source or sink of C. Most modelling studies assessing or projecting the future fate of C exchange with the atmosphere are based on either stand-alone process-based models or coupled climate–C cycle general circulation models, and often disregard biogeophysical feedbacks of land-surface changes to the atmosphere. To understand how biogeophysical feedbacks might impact on both climate and the C budget in Arctic terrestrial ecosystems, we apply the regional Earth system model RCA-GUESS over the CORDEX-Arctic domain. The model is forced with lateral boundary conditions from an EC-Earth CMIP5 climate projection under the representative concentration pathway (RCP) 8.5 scenario. We perform two simulations, with or without interactive vegetation dynamics respectively, to assess the impacts of biogeophysical feedbacks. Both simulations indicate that Arctic terrestrial ecosystems will continue to sequester C with an increased uptake rate until the 2060–2070s, after which the C budget will return to a weak C sink as increased soil respiration and biomass burning outpaces increased net primary productivity. The additional C sinks arising from biogeophysical feedbacks are approximately 8.5 Gt C, accounting for 22% of the total C sinks, of which 83.5% are located in areas of extant Arctic tundra. Two opposing feedback mechanisms, mediated by albedo and evapotranspiration changes respectively, contribute to this response. The albedo feedback dominates in the winter and spring seasons, amplifying the near-surface warming by up to 1.35 °C in spring, while the evapotranspiration feedback dominates in the summer months, and leads to a cooling of up to 0.81 °C. Such feedbacks stimulate vegetation growth due to an earlier onset of the growing season, leading to compositional changes in woody plants and vegetation redistribution.

 

http://www.biogeosciences.net/11/5503/2014/bg-11-5503-2014.pdf