Archives par mot-clé : Recent

Radiosonde Temps Show Northern Hemisphere, Tropical Warming Has Mostly Paused Since 1998

by K. Richard, May 22, 2022 in NoTricksZone


A new study indicates nearly all the Northern Hemisphere and Tropical warming in the last 40 years occurred by the late 1990s.

CO2 has risen by about 50 ppm since 1998 (367 to 418 ppm).

Interestingly, upper-air measurements of temperature from balloon-borne sensor radiosonde data, shown below in the image from a new study (Madonna et al., 2022), suggest there was more warming from the early 1980s to late 1990s – when CO2 only rose about 25 ppm (341 to 367 ppm) – than there has been this century.

Radiosonde measurements appear to depict mostly flat temperatures trends since 1998 in both the Northern Hemisphere (25°N to 70°N) and tropics (25°S to 25°N).

 

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Image Source: Madonna et al., 2022

 

Past global photosynthesis reacted quickly to more carbon in the air

by University of Copenhagen, Mar 10, 2022 in ScienceDaily


Ice cores allow climate researchers to look 800,000 years back in time: atmospheric carbon acts as fertilizer, increasing biological production. The mechanism removes carbon from the air and thereby dampens the acceleration in global warming.

Even under ice age conditions will plants, plankton, and other life forms be able to increase production whenever atmospheric carbon concentrations rise. The mechanism will not prevent an ongoing trend of global warming, but at least dampen the acceleration. This conclusion stems from an international collaboration involving the Physics of Ice Climate Earth (PICE) center of Niels Bohr Institute, University of Copenhagen.

“Global biosphere production through photosynthesis is the strongest absorbing flux of atmospheric carbon dioxide. It is therefore essential to understand its natural variability for a better projection of the future carbon cycle,” says Postdoc researcher Ji-Woong Yang, PICE, continuing:

“Nowadays, as we have Earth observation satellites and other advanced equipment, the mechanism of carbon fertilization is well established. However, we were not sure that the same mechanism existed in past periods where the climate was very different and atmospheric carbon concentrations much lower. The new results confirm the existence of the strong correlation and allow us to model future developments with more confidence.”

Eight glacial cycles are covered

In collaboration with Laboratoire des Science du Climat et de l’Environnement, France, the PICE team has studied the ancient air trapped inside tiny air bubbles in an Antarctic ice core. The ice core represents the last 800,000 years of climatic development.

The scientists take advantage of the fact that the oxygen atom does not only exist in the most common form 16O with 8 protons and 8 neutrons but also as the isotopes 17O and 18O. The isotopic composition is a tracer for biosphere productivity. Uniquely, the method will show the global level of biological production in contrast to other methods which give more localized results.

Combining the air bubble measurements with modeling of oxygen behavior in both the biosphere and the stratosphere, the researchers were able to quantify the biosphere productivity evolution under both glacial periods (ice ages) and interglacial periods. In total, eight glacial cycles were covered.

“The results clearly demonstrate that productivity drops during glacial periods and increases during interglacial periods. Further, a strong correlation exists with past atmospheric carbon dioxide concentrations measured from multiple ice cores. In addition, the effect is more prominent during glacial periods where the level of carbon dioxide and the global biosphere productivity start to increase several thousand years before the ice caps begin to melt. This correlation is explained by the strong fertilization effect by atmospheric carbon dioxide,” says Ji-Woong Yang.

Another dot on the graphs (Part II)

by Gavin, Feb 2, 2020 in RealClimate


We have now updated the model-observations comparison page for the 2021 SAT and MSU TMT datasets. Mostly this is just ‘another dot on the graphs’ but we have made a couple of updates of note. First, we have updated the observational products to their latest versions (i.e. HadCRUT5, NOAA-STAR 4.1 etc.), though we are still using NOAA’s GlobalTemp v5 – the Interim version will be available later this year. Secondly, we have added a comparison of the observations to the new CMIP6 model ensemble.

As we’ve discussed previously, the CMIP6 ensemble contains a dozen models (out of ~50) with climate sensitivities that are outside the CMIP5 range, and beyond the very likely constraints from the observations. This suggests that comparisons to the observations should be weighted in some way. One reasonable option is to follow the work of Tokarska et al (2020) and others, and restrict the comparison to those models that have a transient climate response (TCR) that is consistent with observations. The likely range of TCR is 1.4ºC to 2.2ºC according to IPCC AR6, and so we plot both the mean and 95% spread over all all models (1 ensemble member per model) (grey) and the TCR-screened subset (pink).

CMIP6 model means and spreads since 1979 (reader friendly version).

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Climate Change in the Early Holocene

by University of Oxford, Jan 27, 2022 in WUWT

Radiocarbon dating from a prehistoric cemetery in Northern Russia reveals human stress caused by a global cooling event 8,200 years ago Early hunter gatherers developed more complex social systems and, unusually, a large cemetery when faced by climate

Peer-Reviewed Publication

 

16:00 (GMT), Thursday 27 January 2022

Climate change in the Early Holocene

  • Radiocarbon dating from a prehistoric cemetery in Northern Russia reveals human stress caused by a global cooling event 8,200 years ago
  • Early hunter gatherers developed more complex social systems and, unusually, a large cemetery when faced by climate change

New insight into how our early ancestors dealt with major shifts in climate is revealed in research,  published today [27 Jan] in Nature Ecology & Evolution, by an international team, led by Professor Rick Schulting from Oxford University’s School of Archaeology.

It reveals, new radiocarbon dates show the large Early Holocene cemetery of Yuzhniy Oleniy Ostrov, at Lake Onega, some 500 miles north of Moscow, previously thought to have been in use for many centuries, was, in fact, used for only one to two centuries. Moreover, this seems to be in response to a period of climate stress.

Using A Reference Period Outdated 30 Years, Germany’s DWD Weather Service Turns Cooling Into Warming

by Prof. F. Vahrenholt, Jan 8, 2022 in NoTricksZone


Globally, the deviation of the global mean temperature of the satellite-based measurements from the mean of period 1991-2020 rose slightly in December to 0.21 degrees Celsius. The mean temperature increase since satellite measurements began was 0.14 degrees Celsius per decade. The year 2021 was an average year compared to 2010 to 2020, with 0.134 degrees deviation from the thirty-year average. Six years since 2010 were warmer and 5 years were colder.

This is also true for Germany. But the German weather service gives a different impression

How the German DWD Weather Service turned cooling into warming in 2021  

In its press release on Germany’s weather in 2021, the German Weather Service writes: “The mean temperature [Germany] in 2021 was 9.1 degrees Celsius (°C), 0.9 degrees above the value of the internationally valid reference period 1961 to 1990. 2021 was thus the eleventh year in a row that was too warm.”

Why does the DWD use the internationally no longer valid 1961-1990 reference period? It writes itself elsewhere: “To record the climate and its changes, mean values are formed over a period of 30 years…With the end of the year 2020, the reference period for current climatological assessments was replaced by the 1991 to 2020 period.”

Fudging with the reference period

The DWD thus followed the World Meteorological Organization (WMO)recommendation. But in the press release, the DWD still prefers to use the old, outdated period. The 1991 to 202 0reference period differs from the one of 1961 to 1990 by 1.1 degrees. So the DWD should have written : “2021 was 9.1 degrees, 1.3 degrees cooler than 2020 and even -0.2 degrees Celsius below the average from 1991 to 2020. Since 1991 there have only been 9 years colder than 2021.”

But 0.9 degrees more and the eleventh year in a row that is too warm (compared to the colder period of 1961-1990) of course fits much better with the zeitgeist.

Read original in German at Die kalte Sonne

New Study: A ‘Profound’ ~1°C Cooling Trend Across East Antarctica Since 1979 Is ‘Likely To Accelerate’

by K. Richard, July 12, 2021 in NoTricksZone


Except for a few pockets of warming along the West Antarctic coast, surface air temperatures have cooled profoundly across East Antarctica – most of the continent, as well as the surrounding Southern Ocean – in the last 40 years (1979-2018). About 30% of the cooling can be explained by Madden-Julian Oscillation forcing.

Atmospheric CO2 concentrations rose from 337 ppm in 1979 to 408 ppm in 2018.

But according to graphical illustrations of surface air temperature (SAT) trends from satellite observations documented in a new study (Hsu et al., 2021), nearly the entire continent of Antarctica and much of the surrounding Southern Ocean have undergone about -0.02°C/year (-0.2°C per decade) SAT cooling during this period.

East Antarctica’s temperatures have fallen by about 1°C in the last 40 years, with approximately -0.4°C cooling from 1999-2018 relative to 1979-1998.

Per the authors, one-third of this 40-year cooling trend can be attributed to Madden-Julian Oscillation (MJO) forcing. The MJO influence is “likely to accelerate” the long-term cooling trend for East Antarctica in the coming decades.

Eastern Alps may have been ice-free in the time of Ötzi the Iceman

by C. Rotter, Dec 21, 2020 in WUWT


From The New Scientist

Glaciers in the Ötztal Alps in Austria are currently melting and may be lost within two decades, but this might not be the first time humans have seen this kind of change. A new analysis reveals that glaciers in this region formed just before or perhaps even within the lifetime of Ötzi the Iceman, a mummified body found just 12 kilometres away in 1991.

Pascal Bohleber at the Austrian Academy of Sciences in Vienna and his colleagues drilled 11 metres into the Weißseespitze summit glacier, down to the bedrock, at 3500 metres altitude and collected two ice cores. They then used radiocarbon dating to  analyse microscopic bits of organic material extracted from the ice cores and found that the glacier is 5200 to 6600 years old. Ötzi is thought to have lived between 5100 and 5300 years ago, and his body was found preserved in ice.

The glacier’s age means it formed during a time called the mid-Holocene warm period, when Earth’s climate was warmer than it is now. It is also dome-shaped, which Bohleber says is rare in the Alps and means that the ice has seen very little movement over time, meaning we can use it to study the climate when it formed.

Read more: Ötzi the Iceman’s last journey revealed by moss found in his stomach

“More information on the mid-Holocene warm period, when the glaciers were smaller than today, is direly needed so that we can better predict how the glaciers will respond to the anticipated future climate over the next 50 years,” says Bethan Davies at Royal Holloway, University of London.

Comparing ice cores from different sites tells us quite a bit about the past climate in that region, says Bohleber, but that gets harder as the glaciers thaw. Meltwater makes it more difficult to drill for ice cores and causes the glaciers to slide downhill, exposing the ancient ice to modern contaminants.

Read more: https://www.newscientist.com/article/2263399-eastern-alps-may-have-been-ice-free-in-the-time-of-otzi-the-iceman/#ixzz6hDkuLfkW

See also  in GWPF

New sunspot cycle could be one of the strongest on record, new research predicts

by National Center for Atmospheric Research/University Corporation for Atmospheric Research, Dec 7, 2020 in ScienceDaily


In direct contradiction to the official forecast, a team of scientists led by the National Center for Atmospheric Research (NCAR) is predicting that the Sunspot Cycle that started this fall could be one of the strongest since record-keeping began.

In a new article published in Solar Physics, the research team predicts that Sunspot Cycle 25 will peak with a maximum sunspot number somewhere between approximately 210 and 260, which would put the new cycle in the company of the top few ever observed.

The cycle that just ended, Sunspot Cycle 24, peaked with a sunspot number of 116, and the consensus forecast from a panel of experts convened by the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA) is predicting that Sunspot Cycle 25 will be similarly weak. The panel predicts a peak sunspot number of 115.

New Paleoclimatology Finding Shows Earth’s Climate Was Typically Warmer than Today

by H.S. Sterling, Dec2, 2020 in WUWT


Archaeologists have published a new paper in The HoloceneDOI: 10.1177/0959683620972775 that confirms what previous research has shown: numerous periods during recent history have been as warm as or warmer than the present.

The press release was covered in The New Scientist, “Climate change has revealed a huge haul of ancient arrows in Norway,”  and discusses the findings of researchers from the Universities of Cambridge, Oslo, and Bergen. The researchers discovered a “treasure trove” of arrows, arrowheads, clothing, and other artifacts, recently uncovered by a receding ice in a mountainous region of southern Norway. The oldest arrows and artifacts date from around 4100 BC. The youngest artifacts date from approximately AD 1300, at the end of the Medieval Warm Period. Because present temperatures are only now exposing some of the artifacts were deposited when no ice covered the ground, temperatures were clearly warmer during the many periods when artifacts were deposited.

Along with the arrows and other artifacts, the researchers found nearly 300 specimens of reindeer antler and bone exposed by receding ice. Because reindeer presently frequent the area, the archaeologists say they are confident the area has served as an important hunting ground, off and on, for millennia.

The fact that artifacts were found from several different periods separated by hundreds and thousands of years in time indicates the ice and snow in the region has expanded and receded several times over the current interglacial period.

Elsewhere in Norway, scientists also recently uncovered what they have labeled a “Viking highway,” a route the ancient peoples inhabiting the region used to travel regularly. The route had for approximately 2,000 years been covered by snow and ice that expanded as the region’s climate shifted from a relatively warm period, comparable to present temperatures, to a colder period during which “permanent” thick snow and ice cover formed. This erected the equivalent of a “highway closed” sign.

How ancient dust from the sea floor helps to explain climate history

by UNIVERSITY OF OLDENBURG, Nov 11, 2020 in WUWT


During the last Ice Age about 20,000 years ago, iron-containing dust acted as a fertilizer for marine phytoplankton in the South Pacific, promoting CO2 sequestration and thus the glacial cooling of the Earth. But where did the dust come from? Researchers led by Dr. Torben Struve, geoscientist at the University of Oldenburg, Germany, have investigated this open question of climate history, which is also relevant with respect to current climate change.

Using sediment cores from the sea floor, they found that a large part of the dust deposited in the southern South Pacific at that time had travelled an extremely long way. Up to 80 percent of the dust came from what is now north-west Argentina, from where it was transported almost completely around the globe by the prevailing westerly winds. After a voyage of up to 20,000 kilometres, it contributed significantly to the increased input of iron into the glacial South Pacific. The dust input from Australia, which dominates in the South Pacific today, played only a minor role. The research team has published these new insights into the mechanisms of natural iron input into the Southern Ocean in the journal Nature Communications.

“We have analysed the chemical fingerprint of the dust and compared it with geological data from several continents. This was laborious work, like a jigsaw puzzle,” says Struve, a post-doctoral scientist in the research group “Marine Isotope Geochemistry” at the University’s Institute for Chemistry and Biology of the Marine Environment (ICBM). The team included researchers from his group as well as colleagues from the Alfred Wegener Institute – Helmholtz Centre for Polar and Marine Research, Bremerhaven (Germany), and from Columbia University, New York (USA).

Study: Ancient ocean oxygen levels associated with changing atmospheric carbon dioxide


by Texas A&M University, May 24, 2020 in WUWT


A Texas A&M-led study analyzed ocean floor sediment cores to provide new insights into the relationship between deep ocean oxygenation and atmospheric carbon dioxide levels in the 50,000 years before the last ice age

IMAGE: Deep ocean floor sediment cores hold chemical clues to Earth’s past. view more  Credit: Texas A&M University

Why do carbon dioxide levels in the atmosphere wax and wane in conjunction with the warm and cold periods of Earth’s past? Scientists have been trying to answer this question for many years, and thanks to chemical clues left in sediment cores extracted from deep in the ocean floor, they are starting to put together the pieces of that puzzle.

Recent research suggests that there was enhanced storage of respired carbon in the deep ocean when levels of atmospheric carbon dioxide concentrations were lower than today’s levels. But new research led by a Texas A&M University scientist has reached back even further, for the first time revealing insights into atmospheric carbon dioxide levels in the 50,000 years before the last ice age.

New Study: A Massive Cooling Of 2°C In 8 Years (2008-2016) Has Jolted Large Regions Of The North Atlantic

by K. Richard, February 14, 2020 in NoTricksZone


From 2008 to 2016 a widespread cooling ranging from 0.6°C to more than 2.0°C has chilled effectively the entire oceanic region from E. Canada to N. Iceland to S. Europe. The cooling persists year-round and extends from the surface down to depths of 800 m.

 

Image Source: Bryden et al., 2020

A year ago scientists revealed a large swath of the North Atlantic surface had cooled at a rate of -0.78°C per decade between 2004 and 2017 (Fröb et al., 2019).

800,000 Years Ago, a Meteor Slammed Into Earth. Scientists Just Found the Crater.

by M. Weisberger, January 7, 2020 in LiveScience


About 790,000 years ago, a meteor slammed into Earth with such force that the explosion blanketed about 10% of the planet with shiny black lumps of rocky debris. Known as tektites, these glassy blobs of melted terrestrial rock were strewn from Indochina to eastern Antarctica and from the Indian Ocean to the western Pacific. For more than a century, scientists searched for evidence of the impact that created these pitted blobs.

But the crater’s location eluded detection — until now.

Geochemical analysis and local gravity readings told researchers that the crater lay in southern Laos on the Bolaven Plateau; the ancient impact was concealed under a field of cooled volcanic lava spanning nearly 2,000 square miles (5,000 square kilometers), the scientists reported in a new study.

Was the crater buried? On Laos’ Bolaven Plateau, the scientists found a site where fields of volcanic lava might have hidden signs of an older meteor impact. In a region that the researchers targeted as a likely spot for a crater, most of the lava flows were also in the right age range: between 51,000 and 780,000 years old.

In this geological map of the volcanic field’s summit region, the dashed, yellow ellipse marks the buried crater perimeter for the best-fitting gravity model. The dashed, white circle marks the buried perimeter that best fits geological observations. (Image credit: Sieh et al./PNAS 2019)

The study authors peered below the lava’s surface by taking gravity readings at more than 400 locations. Their resulting gravity map showed one area “of particular interest” with a gravitational anomaly, a subsurface zone less dense than the volcanic rock surrounding it. Their measurements hinted at an elliptical, “elongated crater” about 300 feet (100 m) thick, about 8 miles (13 km) wide and 11 miles (17 km) long, according to the study.

Together, all of these clues suggested that “this thick pile of volcanic rocks does indeed bury the site of the impact,” the scientists wrote.

The findings were published online Dec. 30 in the journal Proceedings of the National Academy of Sciences.

Dry Hot North German Summers Were More Common 1000 Years Ago, Scientists Report

by P. Gosselin, June 19, 2019 in NoTricksZone


Dry Summers Like 2018 Were Common in the Middle Ages

Addressing on Abrupt Global Warming, Warming Trend Slowdown and Related Features in Recent Decades

by Indriani Roy, September28,  2018 in FrontiersinEarthScience


  • College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, United Kingdom

The puzzle of recent global warming trend slowdown has captured enough attention, though the underlying cause is still unexplained. This study addresses that area segregating the role of natural factors (the sun and volcano) to that from CO2 led linear anthropogenic contributions. It separates out a period 1976–1996 that covers two full solar cycles, where two explosive volcanos erupted during active phases of strong solar cycles. The similar period also matched the duration of abrupt global warming. It identifies that dominance of Central Pacific (CP) ENSO and associated water vapor feedback during that period play an important role. The possible mechanism could be initiated via a preferential alignment of NAO phase, generated by explosive volcanos. Inciting extratropical Rossby wave to influence the Aleutian Low, it has a modulating effect on CP ENSO. Disruption of Indian Summer Monsoon and ENSO during the abrupt warming period and a subsequent recovery thereafter can also be explained from that angle. Interestingly, CMIP5 model ensemble, and also individual models, fails to comply with such observation. It also explores possible areas where models miss important contributions due to natural drivers.