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Global warming is transforming the Arctic, and the changes have rippled so widely that the entire biophysical system is shifting toward an "unprecedented state," an international team of researchers concludes in a just-released study.

https://insideclimatenews.org/news/08042019/arctic-climate-change-temperature-permafrost-sea-ice-wildilfe-ecology-study

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Posted (edited)

 

Edited by knocker

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Posted (edited)

 

Edited by knocker

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Summer extremes of 2018 linked to stalled giant waves in jet stream

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29/04/2019 - Record breaking heatwaves and droughts in North America and Western Europe, torrential rainfalls and floods in South-East Europe and Japan - the summer of 2018 brought a series of extreme weather events that occurred almost simultaneously around the Northern Hemisphere in June and July. These extremes had something in common, a new study by an international team of climate researchers now finds: the events were connected by a newly identified pattern of the jet stream encircling the Earth. The jet stream formed a stalled wave pattern in the atmosphere which made weather conditions more persistent and thus extreme in the affected regions. The same pattern also occurred during European heat waves in 2015, 2006 and 2003, which rank among the most extreme heatwaves ever recorded. In recent years, the scientists observed a clear increase of these patterns

https://www.pik-potsdam.de/news/press-releases/summer-extremes-of-2018-linked-to-stalled-giant-waves-in-jet-stream?set_language=en

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Posted (edited)

 

Edited by knocker

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1 hour ago, knocker said:

And the linked paper

The Effects of Heat Advection on UK Weather and Climate Observations in the Vicinity of Small Urbanized Areas

https://link.springer.com/article/10.1007/s10546-017-0263-0

There is also this paper from NOAA

Impacts of Small-Scale Urban Encroachment on Air Temperature Observations

Ronald D. Leeper1,4,*, John Kochendorfer2, Timothy Henderson3, and Michael A. Palecki41 Cooperative Institute for Climate and Satellites (CICS) North Carolina State University (NCSU) Asheville, NC
2 NOAA’s Atmospheric Turbulent Diffusion Division (ATDD) Oak Ridge, TN
3 North Carolina State Climate Office Raleigh, NC
4 NOAA’s National Centers for Environmental Information (NCEI) Asheville, NC

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https://doi.org/10.1175/JAMC-D-19-0002.1

Published Online: 2 May 2019

Abstract

A field experiment was performed in Oak Ridge, TN, with four instrumented towers placed over grass at increasing distances (4, 30, 50, 124, and 300 m) from a built-up area. Stations were aligned in such a way to simulate the impact of small-scale encroachment on temperature observations. As expected, temperature observations were warmest for the site closest to the built environment with an average temperature difference of 0.31 and 0.24 °C for aspirated and unaspirated sensors respectively. Mean aspirated temperature differences were greater during the evening (0.47 °C) than day (0.16 °C). This was particularly true for evenings following greater daytime solar insolation (20+ MJDay−1) with surface winds from the direction of the built environment where mean differences exceeded 0.80 °C. The impact of the built environment on air temperature diminished with distance with a warm bias only detectable out to tower-B’ located 50 meters away.

The experimental findings were comparable to a known case of urban encroachment at a U. S. Climate Reference Network station in Kingston, RI. The experimental and operational results both lead to reductions in the diurnal temperature range of ~0.39 °C for fan aspirated sensors. Interestingly, the unaspirated sensor had a larger reduction in DTR of 0.48 °C. These results suggest that small-scale urban encroachment within 50 meters of a station can have important impacts on daily temperature extrema (maximum and minimum) with the magnitude of these differences dependent upon prevailing environmental conditions and sensing technology.

* Corresponding Author: Ronald D. Leeper, North Carolina State University (NCSU), Cooperative Institute for Climate and Satellites – NC (CICS-NC) at NOAA’s National Centers for Environmental Information (NCEI), 151 Patton Avenue, Asheville, NC, 28801, USA. Phone: +1 828 257-3185; Fax: +1 828 271-4022; E-mail: [email protected]

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Satellites yield insight into not so permanent permafrost

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17 May 2019

Ice is without doubt one of the first casualties of climate change, but the effects of our warming world are not only limited to ice melting on Earth’s surface. Ground that has been frozen for thousands of years is also thawing, adding to the climate crisis and causing immediate problems for local communities.

In Earth’s cold regions, much of the sub-surface ground is frozen. Permafrost is frozen soil, rock or sediment – sometimes hundreds of metres thick. To be classified as permafrost, the ground has to have been frozen for at least two years, but much of the sub-surface ground in the polar regions has remained frozen since the last ice age.

Permafrost holds carbon-based remains of vegetation and animals that froze before decomposition could set in. Scientists estimate that the world’s permafrost holds almost double the amount of carbon than is currently in the atmosphere.

http://www.esa.int/Our_Activities/Observing_the_Earth/Space_for_our_climate/Satellites_yield_insight_into_not_so_permanent_permafrost

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Weakening of the teleconnection from El Niño‐Southern Oscillation to the Arctic stratosphere over the past few decades: What can be learned from subseasonal forecast models?

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While a connection between the El Niño‐Southern Oscillation (ENSO) and the Northern Hemisphere wintertime stratospheric polar vortex appears robust in observational studies focusing on the period before 1979 and in many modeling studies, this connection is not evident over the past few decades. In this study, the factors that have led to the disappearance of the ENSO‐vortex relationship are assessed by comparing this relationship in observational data and in operational subseasonal forecasting models over the past few decades. For reforecasts initialized in December, the models simulate a significantly weaker vortex during El Niño (EN) than La Niña (LN) as occurred before 1979, but no such effect was observed to have occurred.

The apparent cause of this is the Eastern European and Western Siberian height anomalies present during ENSO. The observed LN events were associated with persistent ridging over Eastern Europe as compared to EN. Although the S2S models are initialized with this ridge, the ridge quickly dissipates. As ridging over this region enhances wave flux entering the stratosphere, the net effect is no robust stratospheric response to ENSO in the observations despite a North Pacific teleconnection that would, in isolation, lead to less wave flux for LN. The anomalies in the Eastern European sector in response to ENSO likely reflect unforced internal atmospheric variability.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JD029961#.XP9Q-rEbx7Q.twitter

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On 24/05/2019 at 15:11, knocker said:

Note the word is in the title..but if you read the paper its stated climate change could alter wind shear which in turn could lead to more powerful hurricanes..and also later on we may experience more intense hurricanes ..shouldn't the title be climate change could or may destroy the barrier?

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1 hour ago, cheeky_monkey said:

Note the word is in the title..but if you read the paper its stated climate change could alter wind shear which in turn could lead to more powerful hurricanes..and also later on we may experience more intense hurricanes ..shouldn't the title be climate change could or may destroy the barrier?

It is destroying and it could eliminate - no inconsistency imo

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Remember that most scientific research, and their predictions, are based on the weight of evidence and probabilities.
They may state something like there being a 99.9% chance that X may lead to Y. In most walks of life, 99.9% is enough for statements of certainty, but scientists like to avoid that. Science isn't based on unending and unquestionable dogma, so nothing is every really set in stone.

This is the same across most, if not all, scientific fields. So it's not the best method to use to dismiss any particular research

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East Asian Monsoon Variability Since the Sixteenth Century

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Abstract

The East Asian Monsoon (EAM) impacts storms, freshwater availability, wind energy production, coal consumption, and subsequent air quality for billions of people across Asia. Despite its importance, the EAM's long‐term behavior is poorly understood. Here we present an annually resolved record of EAM variance from 1584 to 1950 based on radiocarbon content in a coral from the coast of Vietnam. The coral record reveals previously undocumented centennial scale changes in EAM variance during both the summer and winter seasons, with an overall decline from 1600 to the present. Such long‐term variations in monsoon variance appear to reflect independent seasonal mechanisms that are a combination of changes in continental temperature, the strength of the Siberian High, and El Niño–Southern Oscillation behavior. We conclude that the EAM is an important conduit for propagating climate signals from the tropics to higher latitudes.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL081939

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This study aims to estimate the affect of urbanisation on daily maximum and minimum temperatures in the United Kingdom. Urban fractions were calculated for 10 km × 10 km areas surrounding meteorological weather stations. Using robust regression a linear relationship between urban fraction and temperature difference between station measurements and ERA‐Interim reanalysis temperatures was estimated. For an urban fraction of 1.0, the daily minimum 2‐m temperature was estimated to increase by 1.90 ± 0.88 K while the daily maximum temperature was not significantly affected by urbanisation. This result was then applied to the whole United Kingdom with a maximum T min urban heat island intensity (UHII) of about 1.7K in London and with many UK cities having T min UHIIs above one degree.

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.896

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12 hours ago, tablet said:

This study aims to estimate the affect of urbanisation on daily maximum and minimum temperatures in the United Kingdom. Urban fractions were calculated for 10 km × 10 km areas surrounding meteorological weather stations. Using robust regression a linear relationship between urban fraction and temperature difference between station measurements and ERA‐Interim reanalysis temperatures was estimated. For an urban fraction of 1.0, the daily minimum 2‐m temperature was estimated to increase by 1.90 ± 0.88 K while the daily maximum temperature was not significantly affected by urbanisation. This result was then applied to the whole United Kingdom with a maximum T min urban heat island intensity (UHII) of about 1.7K in London and with many UK cities having T min UHIIs above one degree.

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.896

Yup, it's an anthropogenic effect. But, do you know how much of the UK is cities?

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Breaching a 'carbon threshold' could lead to mass extinction

Daniel Rothman, professor of geophysics and co-director of the Lorenz Center in MIT's Department of Earth, Atmospheric and Planetary Sciences, has found that when the rate at which carbon dioxide enters the oceans pushes past a certain threshold—whether as the result of a sudden burst or a slow, steady influx—the Earth may respond with a runaway cascade of chemical feedbacks, leading to extreme ocean acidification that dramatically amplifies the effects of the original trigger....

...What does this all have to do with our modern-day climate? Today's oceans are absorbing carbon about an order of magnitude faster than the worst case in the geologic record—the end-Permian extinction. But humans have only been pumping carbon dioxide into the atmosphere for hundreds of years, versus the tens of thousands of years or more that it took for volcanic eruptions or other disturbances to trigger the great environmental disruptions of the past. Might the modern increase of carbon be too brief to excite a major disruption?

According to Rothman, today we are "at the precipice of excitation," and if it occurs, the resulting spike—as evidenced through ocean acidification, species die-offs, and more—is likely to be similar to past global catastrophes.

"Once we're over the threshold, how we got there may not matter," says Rothman, who is publishing his results this week in the Proceedings of the National Academy of Sciences. "Once you get over it, you're dealing with how the Earth works, and it goes on its own ride.

The Paper itself

Characteristic disruptions of an excitable carbon cycle

The history of the carbon cycle is punctuated by enigmatic transient changes in the ocean’s store of carbon. Mass extinction is always accompanied by such a disruption, but most disruptions are relatively benign. The less calamitous group exhibits a characteristic rate of change whereas greater surges accompany mass extinctions. To better understand these observations, I formulate and analyze a mathematical model that suggests that disruptions are initiated by perturbation of a permanently stable steady state beyond a threshold. The ensuing excitation exhibits the characteristic surge of real disruptions. In this view, the magnitude and timescale of the disruption are properties of the carbon cycle itself rather than its perturbation. Surges associated with mass extinction, however, require additional inputs from external sources such as massive volcanism. Surges are excited when CO2 enters the oceans at a flux that exceeds a threshold. The threshold depends on the duration of the injection. For injections lasting a time ti≳10,000 y in the modern carbon cycle, the threshold flux is constant; for smaller ti, the threshold scales like ti−1. Consequently the unusually strong but geologically brief duration of modern anthropogenic oceanic CO2 uptake is roughly equivalent, in terms of its potential to excite a major disruption, to relatively weak but longer-lived perturbations associated with massive volcanism in the geologic past.

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Finally out, new @EGU_ESD review: "Climate feedbacks in the Earth system and prospects for their evaluation" Everything you ever wanted to know about all feedback processes in the Earth System, and more...

https://www.earth-syst-dynam.net/10/379/2019/

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https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083978

High Climate Sensitivity in the Community Earth System Model version 2 (CESM2)

The Community Earth System Model Version 2 (CESM2) has a Equilibrium Climate Sensitivity (ECS) of 5.3K. ECS is an emergent property of both climate feedbacks and aerosol forcing. The increase in ECS over the previous version (CESM1) is the result of cloud feedbacks. Interim versions of CESM2 had a land model which damped ECS. Part of the ECS change results from evolving the model configuration to reproduce the long term trend of global and regional surface temperature over the 20th century in response to climate forcings. Changes made to reduce sensitivity to aerosols also impacted cloud feedbacks, which significantly influence ECS. CESM2 simulations compare very well to observations of present climate. It is critical to understand whether the high ECS, outside the best estimate range of 1.5‐4.5K, is plausible.

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