Wintertemperaturen in den Alpen während der vergangenen 50 Jahre

Der Ski-Tourismus-Forscher Günther Aigner hat ein neues, hochinteressantes Video erstellt. Das Thema sind die Wintertemperaturen in den Alpen während der vergangenen 50 Jahre. Das Video ist in englischer Sprache, da das Thema über die Grenzen des deutschsprachigen Raumes hinaus interessant sein sollte. Unter dem Video gibt es ein Wagenrad-Symbol. Dort können Sie bei Bedarf automatisch generierte deutsche Untertitel anschalten. Die Powerpoint-Folien können Sie hier herunterladen.

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Yale University gab bekannt, dass Sie Facebook beim Suchen nach Klima-Fake News unterstützen wollen. Man darf gespannt sein, was der Fake News-Detektor alles so aufspürt und ob die Klassifizierung stets gerechtfertigt ist.

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NASA’s Goddard Space Flight Center am 20.4.2021:

NASA study predicts less Saharan dust in future winds

During 2020, global average surface temperatures were the hottest on record, tying with 2016 as the warmest recorded year. Last year was also the most active hurricane season to date, with many storms quickly intensifying. Temperature and weather systems each interact with, and are influenced by, a multitude of Earth systems, each affected by the warming climate. One of those is the global transport of massive dust plumes from one continent to another.

In June 2020, a „Godzilla“ dust plume traveled from the Sahara, the planet’s largest, hottest desert, across the Atlantic ocean to North America. While this eye-catching plume made headlines, NASA scientists, using a combination of satellite data and computer models, predict that Africa’s annual dust plumes will actually shrink to a 20,000-year minimum over the next century as a result of climate change and ocean warming.

The Sahara Desert is 3,600,000 square miles (9,200,000 square kilometers) of arid land stretched across the northern half of Africa, coming in just slightly smaller in size than the continental United States. Upwards of 60 million tons of its nutrient-laden mineral dust are lifted into the atmosphere each year, creating a massive layer of hot, dusty air that winds carry across the Atlantic to deliver those nutrients to the ocean and vegetation in South America and the Caribbean.

Recent NASA research outlines the domino-like connections between factors beyond the desert’s borders and the development of dust plumes. These start with temperature differences between the North and South Atlantic, which then impact the region’s consistent east to west winds as well as a tropical band of relatively high rainfall located near the Equator, both of which impact the annual dust plumes. Supported by NASA’s Modeling, Analysis, and Prediction (MAP) Program, and Radiation Sciences Program, the scientists used their new understanding of these relationships to forecast a more substantial reduction in dust activity than previous studies had predicted based on anticipated climate warming.

A Dusty Past

„From ground observations and satellite observations, we see African dust variability,“ said Tianle Yuan, atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. „In fact, it can change quite a bit, from month to month, day to day, year to year, even decade to decade.“

Recent dust estimates are derived from data collected by NASA satellite missions, including Terra, Aqua, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), a joint mission between NASA and the French space agency, Centre National d’Etudes Spatiales.

The researchers were also interested in seeing if the relationship between global average temperature and Saharan dust activity occurred in the past. Geological records going back thousands of years help reveal past precipitation and nutrient levels as the Sahara went through dramatic environmental shifts.

The peak of Saharan dust transport to the eastern side of the Americas took place roughly between 12,000 to 17,000 years ago, at the end of the last Ice Age. Then began the African Humid Period, during which the vast expanse of desert was speckled with lakes, vegetation and human habitation. The increased moisture and plant-life stabilized the ground and minimized dust plumes.

„The Sahara Desert was relatively wet back then,“ said Yuan. North African sediment cores off the coast and pollen records show that there was more rainfall and vegetation present. „Dust was much rarer.“

Though dust transport has increased since then, the research team found that both natural processes and human activity are now likely driving Earth back toward a dust minimum as climate warms.

Sea surface temperatures directly impact wind speeds, so when the northern Atlantic warms relative to the south Atlantic, the trade winds that blow the dust from east to west become weaker. As a result, the slower winds pick up and transport less dust from the Sahara.

In addition to carrying less dust, the weakened winds also allow the band of steady rain that traverses the tropics to drift north over more of the desert, which dampens the dust and keeps it from getting swept away. Less dust in the air, which can reflect sunshine away from Earth’s surface like a sunshield, means more sunlight and heat reach the ocean, warming it further. All together this creates a feedback loop of warm sea surface temperatures leading to reduced dust, and reduced dust in turn contributing to additional warming, combining to impact climate, air quality, and storm and hurricane formation.

From Dust to Dust Impacts

„Dust plays a major role in the Earth system,“ said Hongbin Yu, an atmospheric researcher at Goddard. „A decrease of dust as the climate warms may have profound influences on a variety of phenomena, but these potential impacts may be good or bad.“

On its journey across the Atlantic, Saharan dust sprinkles into the ocean, feeding the marine life, and similarly plant life once it makes landfall. Minerals like iron and phosphorus in the dust act as a fertilizer for the Amazon rainforest, Earth’s largest and most biodiverse tropical forest. Rains wash many of these valuable nutrients from the soil into the Amazon river basin, making the nutrient delivery from Africa important for maintaining healthy vegetation.

Though African dust transport plays an important role in the genesis of soils and sustaining vegetation, Yu says there are some negative effects because the increase in nutrients can lead to harmful algal blooms off the coast of Florida, and coral reef sicknesses and death linked to dust deposition.

Residents in the Caribbean could also see some benefits as less dust means better air quality. Breathing in dust is particularly hazardous for children, the elderly, and those with respiratory conditions such as asthma. That led a team from NASA Earth Applied Sciences Program to develop an early-warning system for Puerto Rico that now provide three days of lead time before a Saharan dust storm reaches the island, giving doctors and public health officials time to prepare and work with meteorologists on air quality alerts. They use data from the Moderate Resolution Imaging Spectroradiometers (MODIS) on NASA’s Terra and Aqua satellites, the Advanced Baseline Imager (ABI) instrument aboard the National Oceanic and Atmospheric Administration (NOAA) Geostationary Operational Environmental Satellite (GOES-16 EAST), and the Visible Infrared Imaging Radiometer Suite (VIIRS) on the joint NASA/NOAA Suomi NPP satellite were employed to help detect the advancing Saharan dust plume before it reached islands like Puerto Rico this past year, so that at-risk communities could prepare for the potentially adverse health effects.

Will the Dust Settle?

„The final piece of the story is looking to the future,“ said Yuan. „We want to know what the Sahara dust will be, given the climate change picture we are painting. But directly predicting dust activity is really hard because it involves a lot of processes.“

With projected global warming, the research team used model data from the Coupled Model Intercomparison Project 5 (CMIP5) that indicate at least a 30% reduction in Saharan dust activity from current levels over the next 20 to 50 years, and a continued decline beyond that.

„The minimum humans experienced during the African Humid Period will likely be surpassed because of climate change,“ Yuan says of the dust levels during the African Humid Period. As the plumes of dust decline, so will their impacts on vegetation an ocean away.

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Keine Dürre in Australien. University of New South Wales am 12.3.2021:

Wettest summer in five years—but is La Nina coming to an end?

With more rain on the horizon in NSW and Queensland, a UNSW climate scientist answers our questions about whether we can expect more wet and cold from La Niña, and what’s in store for next summer.

The Bureau of Meteorology says Australia recorded its wettest and coolest summer in at least five years thanks to La Niña. But the wet and cool conditions are not finished yet, with forecasts of heavy rain to Queensland and NSW over the next week.

What can we expect from La Niña in the future?

Dr. Andrea Taschetto is an Associate Professor and ARC Future Fellow at UNSW Science’s Climate Change Research Center, as well as a chief investigator at the ARC Center of Excellence for Climate Extremes.

„This last summer was particularly unusual. We did receive lots of rain. It was the wettest and coolest summer in the past five years and that was basically because of La Niña,“ she says.

What is La Niña?

„La Niña events occur when sea surface temperatures of the tropical Pacific, particularly the central and eastern Pacific, gets unusually cold, while the other side of the basin—the Western Pacific which is closer to Australia—gets warmer than average. The warm water near Australia increases moisture to the atmosphere and enhances the chances for more rainfall over northern and eastern Australia.“

„What we are seeing now is actually past the peak of La Niña event and it’s slowly fading. We are expecting that La Niña will fade and go back to normal conditions by April/May this year. Without La Niña we expect to receive normal average rainfall in winter, not exaggerated as we’ve seen during the summer and autumn.“

What causes La Niña?

„La Niña is the cooler phase of a phenomenon called the El Niño-Southern Oscillation (ENSO). The warm phase of ENSO is named El Niño. ENSO is sometimes hard to predict but currently it is possible to predict a La Niña or El Niño nine months in advance. One of the things scientists use to predict La Niña or El Niño is the heat content in the ocean. When the Western Pacific has more heat content than average, then it is more likely that El Niño will develop, and conversely for La Niña.“

What causes the Pacific Ocean to cool during La Niña?

„It is a swing of the so-called Walker circulation in the tropical Pacific. The Walker circulation features trade winds blowing from east to west across the tropical Pacific. This piles up warm water to the western side of the ocean basin, creating a warm pool around the Indonesian seas and off northern Australia. At the same time cold water is upwelled in the east, making the eastern Pacific cool. Surface winds converge in the western Pacific and create lots of convection and rain. When La Niña events occur this Walker circulation gets stronger than normal, so trade winds intensify, making the eastern Pacific cooler, and the water surrounding Australia warmer, favoring more moisture, convection and rainfall for us.“

What makes the oceans warm during El Niño?

„El Niño occurs when this whole circulation weakens. As a consequence, the warm water that is piled up in the west by the winds spreads to the east, thus warming the central and eastern Pacific, and moving the center of convection eastward. With less warm water around Australia and the convective activity away from the western Pacific, there are more chances for dry weather for Australia.“

What’s the prospect for ENSO next summer?

„La Niña and El Niño generally have a three to seven year cycle so we are not expecting to see another event like this develop at the end of the year. Although La Niña can sometimes persist for two years, seasonal forecasting agencies, such as the Bureau of Meteorology, are predicting neutral conditions for the rest of the year and next summer.

The strong La Niña event of 2010/2011 resulted in massive floods in Queensland. The 2010 spring season was the wettest spring in Australia since the 1900s. We simulated a similar event at the time to check how unusual the 2010/11 La Niña was, and we found the warming ocean surrounding the northern parts of Australia was extremely important for that event. It accentuated the chances of having extreme flooding in northeast Australia. Our simulation showed that north-east Australia was three times more likely to experience extreme rainfall during that La Niña than if there hasn’t been a warming of the ocean north of Australia. It was global warming making an appearance on top of La Niña.“

What are the impacts of La Niña?

„The tropical Pacific covers about one third of the tropics, so when ENSO appears it is large enough to impact weather patterns beyond that ocean. It is also often the case that ENSO can combine with other climate phenomena to amplify the impact over Australia. For example, when the east Indian Ocean is warmer than usual at the same time as La Niña, it intensifies rain for south-east Australia. When the Antarctic Oscillation shifts the mid-latitude winds closer to Australia, it can bring more storms and rain to south and east Australia.

Generally during La Niña, there tends to be a higher chance of tropical cyclones around Australian tropics. That didn’t happen this year; there were only three or four tropical cyclones this season. But there were a lot of tropical lows, which are less intense weather systems that can bring significant amounts of rain for northern Australia, and that’s what happened this season.

Another effect of La Niña around Australia is marine heatwaves. Marine heatwaves are extreme ocean temperature events that persist for several days, sometimes months, and can develop due to La Niña in areas like the Ningaloo Reef in Western Australia. These events have massive impact for marine ecosystems, and coastal communities dependant on economic activities such as fishery and oyster farmers.

The impacts of La Nina and El Nino reverberate across the globe. We recently synthesized these complex effects as part of the book El Nino Southern Oscillation in a Changing Climate.“

Are there any positive aspects to La Niña?

„About three years ago, south-east Australia experienced a severe drought. The Murray Darling basin catchment area was very low. The amount of rainfall that La Niña brought this time contributed to bringing the Murray Darling basin and soil moisture back to normal. Overall, we need to think that ENSO is not a bad thing, but a natural oscillation of our climate system. It will continue to appear in the future, although research shows that it will likely appear more often in a warming climate.“

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Frédérik Saltré and Corey J. A. Bradshaw, The Conversation (via phys.org):

What was the Medieval warm period?

What was the Medieval warm period? What caused it, and did carbon dioxide play a role?

We are living in a world that is getting warmer year by year, threatening our environment and way of life.

But what if these climate conditions were not exceptional? What if it had already happened in the past when human influences were not part of the picture?

The often mentioned Medieval warm period seems to fit the bill. This evokes the idea that if natural global warming and all its effects occurred in the past without humans causing them, then perhaps we are not responsible for this one. And it does not really matter because if we survived one in the past, then we can surely survive one now.

But it’s just not that simple.

The Medieval climate anomaly

This Medieval period of warming, also known as the Medieval climate anomaly, was associated with an unusual temperature rise roughly between 750 and 1350 AD (the European Middle Ages). The available evidence suggests that at times, some regions experienced temperatures exceeding those recorded during the period between 1960 and 1990.

Despite being predominantly recorded in Europe, south-western North America and in some tropical regions, the Medieval warm period affected both the northern and southern hemispheres. But the temperature increase was not universal, varying across regions of the world, and did not happen simultaneously everywhere.

While the northern hemisphere, South America, China and Australasia, and even New Zealand, recorded temperatures of 0.3-1.0 ℃ higher than those of 1960-1990 between the early ninth and late 14th centuries, in other areas such as the eastern tropical Pacific Ocean, it was much cooler than today.

Weiterlesen auf phys.org

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Geomar-Pressemitteilung vom 20.4.2021:

In der Gemeinschaft sind Bakterien stark gegen Plastik

Forscher*innen schlagen neuen Ansatz bei der Suche nach biologischen Wegen zum Kunststoffabbau vor

Bakterien sind extrem anpassungsfähig. Je mehr Plastik in die Umwelt gelangt, desto wahrscheinlich ist es, dass sie Wege finden, Energie aus den Kunststoffen zu gewinnen und diese dabei abzubauen. Das könnte sich der Mensch zunutze machen. Die Kunst ist, die entsprechenden Bakterien zu finden. In der internationalen Fachzeitschrift Trends in Microbiology schlagen Kieler Forscher*innen jetzt einen neuen Ansatz vor, der die Suche schneller und den Plastikabbau effektiver gestalten soll.

Schon seit Jahrzehnten nutzt die Menschheit die Fähigkeiten von Bakterien, um die Umwelt sauber zu halten. Ein bekanntes Beispiel sind die biologischen Stufen von Kläranlagen. In ihnen zerlegen Bakterien und andere Mikroorganismen organische Schadstoffe im Abwasser in ihre Bestandteile. Doch in der jüngsten Vergangenheit nimmt ausgerechnet die Menge des Mülls aus langkettigen Kohlenstoffverbindungen – landläufig Kunststoff oder auch Plastik genannt – deutlich zu. Bislang sind kaum Bakterien bekannt, die Kunststoffe zerlegen können. Die Suche nach ihnen läuft weltweit aber auf Hochtouren.

Eine Gruppe von Wissenschaftler*innen des GEOMAR Helmholtz-Zentrums für Ozeanforschung Kiel sowie der Christian-Albrechts-Universität zu Kiel schlägt jetzt in der internationalen Fachzeitschrift Trends in Microbiology ein bislang vernachlässigtes Verfahren vor, um schneller und effektiver natürliche Abbau-Methoden für Kunststoffe auf Bakterien-Basis zu finden. „Wir schlagen vor, dass es viel mehr Sinn machen würde, ganze Bakteriengemeinschaften auf ihre Fähigkeiten zu testen anstatt einzelne Bakterienarten zu suchen, die Enzyme produzieren, mit denen sie Kunststoffe zerlegen können“, sagt Dr. Peter Deines vom GEOMAR, Hauptautor der Studie.

Die klassische Suche nach Bakterien mit bestimmten Fähigkeiten konzentriert sich auf einzelne Arten. Ist eine gefunden, die möglicherweise in der Lage ist, mit einem speziellen Enzym beispielsweise eine Kunststoffsorte zu zerlegen, wird die Erbinformation des Bakteriums nach dem Code für dieses Enzym abgesucht. „Dabei besteht aber die Gefahr, dass man nur schon bekannte Informationen findet und andere wichtige Fähigkeiten übersieht“, sagt Dr. Deines.

Außerdem birgt die Konzentration auf eine einzelne Bakterienart ein Risiko für die spätere Anwendung des Bakteriums und seines Enzyms, zum Beispiel in Bioreaktoren. „Aus der Ökosystembiologie wissen wir, dass Monokulturen nicht sehr widerstandsfähig sind. Tatsächlich haben Bioreaktoren mit nur einer Bakterienart eine hohe Ausfallrate“, berichtet der Kieler Mikrobiologe.

Bei dem von ihm und seinen Kolleg*innen favorisierten Ansatz werden deshalb an Orten, an denen Bakterien sehr wahrscheinlich mit Plastik in Berührung kommen, ganze Bakterienökosysteme beprobt. Das können die Mägen von Fischen, Biofilme auf Großalgen oder das Sediment des Meeresbodens sein. Im Labor werden diese bisher weitgehend unerforschten Bakteriengemeinschaften dann weiterem Plastik ausgesetzt. Zeigt sich, dass eine Gemeinschaft in der Lage ist, den Kunststoff abzubauen, wird sie für den nächsten Schritt ausgewählt.

„Wir schlagen vor, ganze Bakteriengemeinschaften im Labor für einen erhöhten Plastikabbau zu züchten. Diesen Prozess kann man sich ganz ähnlich vorstellen wie die Zucht von bestimmten Merkmalen bei Haustier- oder Pflanzenrassen. Bei dieser Methode müssen wir nicht vorher wissen, was wir suchen, sondern sind völlig ergebnisoffen. Die Gefahr, Fähigkeiten zu übersehen, ist deutlich geringer. Denn ein Bakterium, das alleine nichts mit Plastik anfangen kann, trägt in einer komplexen Gemeinschaft vielleicht doch entscheidend zu dessen Abbau bei“, sagt Dr. Deines. Durch die anschließende künstliche Selektion im Labor haben die mikrobiellen Gemeinschaften die Chance, ihre Fähigkeiten zum Plastikabbau im Laufe mehrerer Generationen zu verbessern. „Hier nutzen wir also einen Ansatz aus der Evolutionsbiologie“, ergänzt er.

Das Kieler Team will die vorgeschlagenen Methoden in nächster Zukunft auch praktisch umsetzen und sich dabei vor allem auf Bakteriengemeinschaften aus dem Ozean konzentrieren. „Letztendlich ist der Ozean die große Senke, in der die meisten Abfälle und Schadstoffe landen. Im Rahmen des Projekts PLASTISEA haben wir schon viele Proben aus dem zentralen Atlantik gewonnen. Diese nutzen wir jetzt, um sowohl auf klassischem Weg, als auch mit der neuen Methode nach Möglichkeiten zu suchen, Plastik auf biologischem Weg abzubauen. Aber natürlich kann man so auch nach Abbaumöglichkeiten für viele andere Schadstoffe suchen“, sagt Co-Autorin Prof. Dr. Hentschel Humeida, Leiterin der Forschungseinheit Marine Symbiosen am GEOMAR.

Originalarbeit:
Borchert, E., K. Hammerschmidt, U. Hentschel, and P. Deines: Enhancing Microbial Pollutant Degradation by Integrating Eco-Evolutionary Principles with Environmental Biotechnology. Trends in Microbiology, https://doi.org/10.1016/j.tim.2021.03.002