Archives par mot-clé : Global Temperature

La fin du réchauffement… Pas du changement climatique!

by B. Van Vliet-Lanoë, Jan 1, 2021 in ScienceClimatEnergie


Un hiver froid s’annonce : le premier d’une série qui devrait durer au moins jusqu’en 2053 (Youssef et al., 2009 ; Zharkova et al.  2015 ; Van Vliet, 2019), période où les médias nous assènent une disparition de la banquise estivale, des ours polaires et des phoques ! Ceci est favorisé par l’activité solaire réduite depuis et le minimum solaire actuel (Fig.1). Le cycle solaire suivant (n°25) devrait aussi être faible. Nous y sommes entrés sans un Minimum d’activité aussi profond que celui Dalton (1790-1830) qui a présidé à la « Bérézina ».

 

Fig. 1: Intensité des cycles solaires depuis 1975 et la prédiction du cycle 25 (calculés avec le nombre de taches solaires  2018 * ANRPFD ).  B) évolution de l’extension en km2 des banquises arctique et antarctique depuis 1978 par rapport à la déviation standard 1981-2010 (NSDIC).

UAH Global Temperature Update for December 2020: +0.27 deg. C

by R. Spencer, Jan 2, 2020 in WUWT


The Version 6.0 global average lower tropospheric temperature (LT) anomaly for December, 2020 was +0.27 deg. C, down substantially from the November, 2020 value of +0.53 deg. C.For comparison, the CDAS global surface temperature anomaly for the last 30 days at Weatherbell.com was +0.31 deg. C.

2020 ended as the 2nd warmest year in the 42-year satellite tropospheric temperature record at +0.49 deg. C, behind the 2016 value of +0.53 deg. C.

Cooling in December was largest over land, with 1-month drop of 0.60 deg. C, which is the 6th largest drop out of 504 months. This is likely the result of the La Nina now in progress.

The linear warming trend since January, 1979 remains at +0.14 C/decade (+0.12 C/decade over the global-averaged oceans, and +0.18 C/decade over global-averaged land).

 

The full UAH Global Temperature Report, along with the LT global gridpoint anomaly image for December, 2020 should be available within the next few days here.

The global and regional monthly anomalies for the various atmospheric layers we monitor should be available in the next few days at the following locations:

Lower Troposphere: http://vortex.nsstc.uah.edu/data/msu/v6.0/tlt/uahncdc_lt_6.0.txt
Mid-Troposphere: http://vortex.nsstc.uah.edu/data/msu/v6.0/tmt/uahncdc_mt_6.0.txt
Tropopause: http://vortex.nsstc.uah.edu/data/msu/v6.0/ttp/uahncdc_tp_6.0.txt
Lower Stratosphere: http://vortex.nsstc.uah.edu/data/msu/v6.0/tls/uahncdc_ls_6.0.txt

Greenland Fall Temperatures Unchanged. Proxy Data Show No Warming At 8 Of 9 Antarctic Peninsula Sites Since 1830!

by Kyrie, Dec 29, 2020 in NoTricksZone


Before looking at Antarctica Peninsula, we first take a look at Greenland, which also is considered by the global warming alarmists to be part of the most threatening tipping points. If the ice on Greenland ever melted, like they warn it will, sea levels globally would rise some 6 meters. (Never mind this scenario would take many centuries).

Today we look at the November and autumn trends in Greenland. First we look at November mean temperatures for which the Japan meteorological Agency (JMA) has sufficient data to compute a trend going back to 1999.

 

Four of the 6 stations examined show cooling or no warming trend.

But that’s only for one month, and so doesn’t really tell us a whole lot. So next we look at autumn mean temperatures for these six stations. If autumn is warming then we no that is not ideal for the overall ice formation season.

HadCRUT5 Adjusts Temperatures Upwards Again

by P. Homewood, Dec 16, 2020 in NotaLotofPeopleKnowThat


The Morice paper claims the extra warming has come from an improved representation of Arctic warming and a better understanding of evolving biases in sea‐surface temperature measurements from ships.

In fact it is not scientific to average together Arctic temperatures with the rest of the planet, as it is comparing apples with oranges. It all has to do with latent heat and water vapour, as Tony Heller brilliantly explained:

Sea surface skin temperature

by A. May, Dec 9, 2020 in WUWT


In previous posts, see here and here, I’ve tried to show that because the oceans cover 71% of Earth and they contain 99% of the thermal energy stored on the Earth’s surface, they dominate the speed and magnitude of climate changes. In all my posts the Earth’s surface is defined as everything from the ocean floor to the top of the atmosphere. The details of the calculation of ocean and atmospheric heat content is detailed in this spreadsheet. The ocean’s huge heat capacity prevents large temperature swings and dampens and delays those that do occur.

Attempting to show the direction, speed, and magnitude of climate change by measuring and averaging atmospheric surface temperatures is pointless, in my opinion. The record we have of atmospheric and ocean surface temperatures is too short and far too inaccurate to provide us with useful trends on a climatic (30 years +) time scale. Further, these records are sporadic measurements in a chaotic surface zone that has large temperature swings. In Montana, United States, for example, recent minimum/maximum temperatures have been as low as -70°F (-57°C) and as high as 117°F (47°C). These enormous swings make measuring year-to-year global average differences of 0.1°C exceedingly difficult. Yet, this is the precision demanded if we are to properly characterize a climate that is only warming at a rate of roughly 1.4°C/century, which is 0.014°C per year and 0.14°C/decade.

CO2 Coalition: “The Global Mean Temperature Anomaly Record How it works and why it is misleading”

by D. Middleton,  Dec 8, 2020 in WUWT


Our friends at the CO2 Coalition have published another excellent report.

This white paper by Richard Lindzen and John Christy explores the global mean temperature anomaly record. Their focus isn’t on whether it’s right or wrong; it’s on its significance relative to natural variability and its inherently low signal-to-noise ratio. Here’s the executive summary:

STUDIES AND RESOURCES, WHITE PAPERS AND OTHER PUBLICATIONS

4 DEC, 2020
The Global Mean Temperature Anomaly Record
How it works and why it is misleading

by Richard S. Lindzen and John R. Christy

The CO2 Coalition is honored to present this Climate Issues in Depth paper by two of America’s most respected and prolific atmospheric physicists, MIT professor emeritus Richard Lindzen, who is a longtime member of the Coalition, and University of Alabama in Huntsville professor John Christy.

Professor Lindzen has published over 200 scientific articles and books over a five-decade career. He has held professorships at the University of Chicago, Harvard University and MIT. He is a fellow and award recipient of the American Meteorological Society and the American Geophysical Union. He is also a member of the National Academy of Science and was a lead author of the UN IPCC’s third assessment report’s scientific volume. His research has highlighted the scientific uncertainties about the impact of carbon dioxide emissions on temperature and climate more generally.

Professor Christy, the director of the Earth System Science Center at The University of Alabama in Huntsville, began studying global climate issues in 1987. He has been Alabama’s State Climatologist since 2000 and a fellow of the American Meteorological Society since 2002. He and CO2 Coalition member Dr. Roy W. Spencer developed and have maintained one of the key global temperature data sets relied on by scientists and government bodies, using microwave data observed in the troposphere from satellites since 1979. For this achievement, they were awarded NASA’s Medal for Exceptional Scientific Achievement.

The purpose of this paper is to explain how the data set that is referred to by policy-makers and the media as the global surface temperature record is actually obtained, and where it fits into the popular narrative associated with climate alarm.

Executive Summary
At the center of most discussions of global warming is the record of the global mean surface temperature anomaly—often somewhat misleadingly referred to as the global mean temperature record. This paper addresses two aspects of this record. First, we note that this record is only one link in a fairly long chain of inference leading to the claimed need for worldwide reduction in CO2 emissions. Second, we explore the implications of the way the record is constructed and presented, and show why the record is misleading.

This is because the record is often treated as a kind of single, direct instrumental measurement. However, as the late Stan Grotch of the Laurence Livermore Laboratory pointed out 30 years ago, it is really the average of widely scattered station data, where the actual data points are almost evenly spread between large positive and negative values.

The average is simply the small difference of these positive and negative excursions, with the usual problem associated with small differences of large numbers: at least thus far, the one-degree Celsius increase in the global mean since 1900 is swamped by the normal variations at individual stations, and so bears little relation to what is actually going on at a particular one.

The U.S. National Temperature Index, is it based on data? Or corrections?

by Andy May, Nov 24, 2020 in WUWT


The United States has a very dense population of weather stations, data from them is collected and processed by NOAA/NCEI to compute the National Temperature Index. The index is an average temperature for the nation and used to show if the U.S. is warming. The data is stored by NOAA/NCEI in their GHCN or “Global Historical Climatology Network” database. GHCN-Daily contains the quality-controlled raw data, which is subsequently corrected and then used to populate GHCN-Monthly, a database of monthly averages, both raw and final. I downloaded version 4.0.1 of the GHCN-Monthly database on October 10, 2020. At that time, it had 27,519 stations globally and 12,514 (45%) of them were in the United States, including Alaska and Hawaii. Of the 12,514 U.S. stations, 11,969 of them are in “CONUS,” the conterminous lower 48 states. The current station coverage is shown in Figure 1.

Figure 1. The GHCN weather station coverage in the United States is very good, except for northern Alaska. There are two stations in the western Pacific that are not shown.

igure 4. The orange line is the uncorrected monthly mean temperature, which is “qcu” in NOAA terminology. The blue line is corrected, or NOAA’s “qcf.”

New Study Finds A Robust Link Between European Temperatures And Solar Activity Via AMO/NAO Modulation

by K. Richard, Oct 22, 2020 in NoTricksZone


European winter temperature variability is “dominated” by the North Atlantic Oscillation (NAO), which is, in turn, modulated by solar activity.

Even proponents of anthropogenic global warming (AGW) agree natural processes (AMO, NAO, ENSO, solar forcing, volcanism) drive temperature variability. But they insist the rising temperature trend is human-caused.

So if we don’t have a regional upward trend, is the non-warming natural or anthropogenic?

Lüdecke et al., 2020 find temperatures across Europe have been oscillating, not rising in linear fashion, for the last century. The timings of the temperature undulations correspond quite closely to natural ocean cycles (the NAO and AMO). The authors detail a non-linear and indirect solar activity impact on these ocean cycles, and ultimately to the European climate.

Why lockdown had little to no effect on global temperatures

by A.N. Archer & J.Weber, Oct 22, 2020 in Phys.Org


Countries across the world took unprecedented action in the first few months of 2020 to control the spread of COVID-19. At its peak, one-third of the world’s population was in lockdown. Around the world, car travel fell by 50%, the number of flights plummeted by 75% and industrial activity fell by around 35%.

With so many cars parked, airplanes grounded and factories closed, global carbon dioxide (CO₂) emissions fell by around 17% compared with the same period in 2019. But greenhouse gases such as CO₂ weren’t the only emissions to fall, and not all pollution heats the planet. Some of the industrial activities that shut down—particularly heavy industry, including steel and cement making—also produced aerosols, which are that linger in the atmosphere for weeks and reflect heat from the Sun.

Previous studies have suggested that if a lot of these industrial processes were to suddenly shut down, it would lead to short-term warming because the atmosphere would lose the reflective effect of aerosols. But as the lockdown cleared skies, temperatures didn’t rocket.

In new research, we show that lockdown had a negligible effect on global temperatures. So what really happened?

The “Warmest September Ever” Is A Myth… Cooler Times Likely Ahead As NASA Foresees Strong La Nina…

by P. Gosselin, Oct 9, 2020 in NoTricksZone


Our friend “SnowFan” here looks at the claims that September 2020 was the warmest ever recorded. It turns out that other measurement advanced satellites don’t agree.

According to the much ballyhooed data, temperatures in Europe in September this year were on average 0.2 degrees Celsius higher than in the previous record September 2018. The service providing the data is part of the European earth observation program Copernicus.

But the satellite data from the UAH and RSS both agree that this is not really the case!

 

Above the global satellite data from UAH (left) and from RSS (right) in the tables clearly clearly show the monthly deviations from the WMO mean 1981-2010 (UAH) and from the climate mean 1979-1998 (RSS): September 2020 was not the warmest since satellite measurements began in 1979. At UAH, September 2019 was slightly warmer while at RSS even September 2017 was warmer.

Strong La Nina may be in the works

A HISTORY OF CLIMATE FRAUD (I)

by Cap Allon, oct 5, 2020 in Electroverse


Much of the below analysis is courtesy of Kenneth Richard.

The combined Hadley Centre and Climatic Research Unit (HadCRUT) data set –which is featured in IPCC reports– underwent a revision from version 3 to version 4 in March of 2012, about a year before the next IPCC report was due.

At the time (early 2012), the HadCRUT3 was showing a slight global cooling trend between 1998 and 2012, visible in the graph below which uses HadCRUT3 and HadCRUT4 raw data. In conjunction with changing versions, the slight cooling trend had convenientlychanged to a slight warming trend:

 

As recently as 1990, it was widely accepted that the global temperature trend showed a “0.5°C rise between 1880 and 1950”, as reported by NASA (Hansen and Lebedeff, 1987). This rise (as well as the 0.6C rise between 1880 and 1940) can clearly be seen in the NASA GISS graph from 1987:

Study: Global Warming Hiatus (aka “The Pause”) Was Real

by A. Watts, Sep 28, 2020 in WUWT


From the GWPF and the better late than never department: (the paper was published in late 2019 but seems pretty solid, using Oxygen18 isotope analysis) – Anthony

A new analysis of global air temperature by researchers from Tongji University in Shanghai has cast light on the much debated recent hiatus in global temperature.

Writing in the Journal of Earth Science the Chinese scientists say there was a rapid rise in global mean surface air temperature after the late 1970s but that this stalled and there was a relative stagnation and even slight cooling that lasted for about 15 years (1998–2012). They add that even though the slowdown was acknowledged by the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5) and termed as a hiatus (IPCC, 2013) there was a debate in the scientific community about whether there was a hiatus in global warming or not.

The researchers believe that the debate about the global warming hiatus poses a substantial challenge to our understanding of the global climate response to anthropogenic greenhouse gas emissions and natural variability. They say that the disagreements about the recent global warming hiatus mainly arise from different sources, among which differences across observational SAT datasets may be a key contributor to the contradictory conclusions. So they use an alternative set of data.

They use the ratio of two oxygen isotopes in precipitation, oxygen 16 and 18, which is a proxy for the temperature of precipitation and surface temperature. They are particularly interested in what they term a “robust correlation” between precipitation oxygen ratios and surface temperature over mid- and high-latitude regions. Twelve stations were selected of which ten are located in Europe, and the remaining two in Antarctica and North America, respectively. Using the data they constructed a composite isotope index spanning 1970–2016 by combining twelve precipitation oxygen isotope records collected over mid and high-latitude continents. With it they evaluate the recent global warming hiatus.

Continuer la lecture de Study: Global Warming Hiatus (aka “The Pause”) Was Real

Determined Scientists Add Phantom ‘Unprecedented’ Warmth To New Temperature Reconstructions

by K. Richard, Sep 21, 2020 in NoTricksZone


Paleoclimate reconstructions that find no unusual modern warming are nonetheless characterized as showing sharp temperature increases in recent decades anyway.

A new (Li et al., 2020) 1818-2012  temperature reconstruction determined 1955 (6.33 °C) and 2001 (7.17 °C) were the 1st and 5th coldest years in northeastern China in the last 200 years. The two warmest years were 1832 (9.63 °C) and 1900 (9.57 °C).

Further, the highest “continuous high decadal temperatures” recorded were in 1818–1844 and 1856–1873. The post-1950s temperatures were colder than nearly all of the first 100 years of the temperature record.

And yet in spite of the warmer 19th-century temperatures, the authors chracterize the slight temperature rise since the 1950s as heralding  in “unprecedented” warming. They make this claim (of “unprecedented” recent warmth) in both the paper’s textual and graphical abstracts.

 

Image Source: Li et al., 2020

 

Forbes et al. (2020) use thermometer data from an Alaskan airport for the last ~90 years of their temperature record. The instrumentals show surface temperatures cooled -0.7°C in winter (January) and warmed 0.8°C in summer (July) from the 1950s-’80s decades to the 1990s to 2010s.

For the summer temperature record (shown in red below), nearly all the warming occurred during a step-change from the mid-1970s to mid-1980s. Since about 1985, summer temperatures seem to have been stable to slightly declining.

A lack of net overall warming in the last 50 or 60 years does not advance the anthropogenic global warming (AGW) cause, of course.

When will Temperatures start to fall? Part1

by Tony Brown, August 28, 2020 in WUWT


“If Europeans truly mobilize around the delivery of the 2050 goal, every business decision, lifestyle choice, political swing, every hallmark of European culture — from annual ski trips, to Champions League Football matches, to French cheese — will need to be tested against its contribution to climate change.” European Commission ‘Green Deal’ March 2020

This is an article with a simple proposition.  Science tells us that rapidly rising Co2 in turn causes rising temperatures, which has become a very serious problem for humanity.

The three questions I ask, in the expectation that the answer can be provided from main stream published science is;

“Assuming we reach zero carbon emissions by 2030-Extinction Rebellion (XR) requirement,  or 2050 -the aim of most governments under the Paris Accord- 1) how long would it take for Co2 levels to naturally fall below the’ safe upper limits’ of 350ppm espoused by such as James Hansen; 2) for it to fall further to 280ppm -the previous pre industrial level -AND 3) when will temperatures start to fall in turn, to achieve pre industrial levels, said to be 1 to 2 degrees Centigrade below present, according to the IPCC.”

There are all sorts of caveats of course, with methane, water vapour, clouds, feedbacks, ocean response, natural variations etc but having scoured various ‘official’ web sites I can find no definitive estimate. An examination of the Extinction Rebellion web site demonstrates they are anarchists, rather than a serious green organisation. A couple of more reasoned attempts to track the consequences of zero carbon emissions are given in Note 3below the graphic-Figure 1 together with a variety of other useful background information.

Whether the reader personally believes excess Co2 to be a problem is not a matter this article is concerned with.  Let’s take science at face value –our respective Governments  have overwhelmingly agreed that humanity has added some 140ppm of Co2 to the pre industrial 280ppm and that, as a result, temperatures have risen substantially and are at a dangerous level and causing extremes of weather.

Extensively-Referenced Study Of Past Scientists’ Global Temperature Estimates Suggests ‘No Change’ In 100 Years

by K. Richard, August 13, 2020 in NoTricksZone


In the early 1900s, the globally-averaged distribution of calculated surface temperature estimates ranged between 14 and 15°C. For 1991-2018, HadCRUT, Berkeley, and NASA GISS also estimate today’s global temperature is about 14.5°C.

Scientists estimating Earth’s surface temperature has been an ongoing pursuit since the early 19th century.

A new study (Kramm et al., 2020) suggests the generally agreed-upon global temperature from 1877 to 1913 from dozens of calculated results was about 14.4°C.

Problematically, HadCRUT, Berkley, and NASA GISS also indicate the 1991-2018 had a global surface temperature of about 14.5°C.

This would suggest there has been “no change in the globally averaged near-surface temperature over the past 100 years”.

Le 20ème siècle a été anormalement chaud mais le 21ème siècle revient à la normale (1/2)

by Jean Van Vliet, 14 août 2020, in ScienceClimatEnergie


Introduction

Suite à la prise de conscience à la fin du 20ème siècle d’une hausse inhabituelle des températures terrestres, des chercheurs américains ont développé une théorie du réchauffement global basé sur l’effet de serre dû au CO2 [1], en soulignant la responsabilité possible de l’homme dans le réchauffement observé: la poursuite des émissions de CO2 conduirait à une éventuelle catastrophe planétaire. Ces  chercheurs ont présenté leur théorie au Congrès américain [2] et aux médias. Le monde politique international a réagi rapidement à cet alarmisme [3] en permettant à Assemblée Générale de l’ONU de décembre 1988 d’approuver la mise en place du GIEC [4].

Depuis plus de trente ans et malgré le manque persistant de preuve formelle, la peur du réchauffement global anthropique causé par le CO2 est propagée sans relâche par l’ONU et ses satellites PNUE, GIEC et OMM relayés par les ONG environnementales et les médias, suivis plus récemment par une fraction du monde académique occidental. Une puissante industrie des énergies renouvelables a été créée via des subsides et des certificats verts quitte à doubler ou tripler le prix de l’électricité. Cette industrie est prête à exploiter les nouvelles aubaines financières annoncées par l’Accord de Paris et le Green Deal de l’UE. Dans un tel contexte, le but avoué est que l’humanité change radicalement son comportement, fût-ce au prix d’une dictature environnementale: l’alarmisme médiatique est maximal, et même les enfants sont embrigadés dans le débat pour soi-disant “sauver la planète”.

Cette tentative rampante de prise du pouvoir a cependant buté contre un obstacle imprévu depuis le début de 2020, à savoir la pandémie du Coronavirus: le lockdown sanitaire a montré que la société pouvait changer son comportement de manière spectaculaire, mais au prix de conséquences économiques et sociales majeures. A la première attaque de la pandémie succède aujourd’hui une deuxième vague et il semble impossible de prévoir quand nous serons délivrés du virus.

Les ressources des Etats n’étant pas infinies, la question brûlante se pose aujourd’hui  de l’affectation des moyens humains et financiers disponibles en fonction nos priorités: devons-nous avoir davantage peur d’une pandémie et de ses conséquences sociales et économiques incontestables ou devons-nous supputer une explosion incontrôlable de la crise climatique amorcée au 20ème siècle et modifiant de manière drastique et irréversible notre environnement ?

Le but du présent article est d’apporter des éléments de réponse à cette question en examinant, dans une perspective scientifique large et basée sur les observations plutôt que sur les modèles, la “crise climatique” démarrée durant la seconde moitié du 20ème siècle en essayant de tirer des conclusions applicables au 21èmesiècle.

1/ La crise ‘climatique du 20ème siècle

Il existe de nombreuses sources fournissant des historiques de température, mais il existe peu de séries chronologiques comparables à celle de l’Observatoire d’Armagh en Irlande du Nord pour la période 1796-2002 [5]; cette série est disponible sur le site web du Met Office britannique pour la période allant de 2002 à aujourd’hui [6].

Figure 1 : Evolution des températures moyennes annuelles de 1796 à 2019 (courbe bleue) ainsi qu’une courbe lissée correspondant à la moyenne glissante rétrospective sur une période de 11 ans (courbe rouge).

Modern Ancient Temperatures

by W. Eschenbach, July 24, 2020 in WUWT


OK, no need to torture me, I confess it—I’m a data junkie.

And when I see a new (to me at least) high-resolution dataset, my knees get weak. Case in point? The temperature dataset of the Colle Gnifetti ice core. It has a two-year resolution thanks to some new techniques. Better, it stretches clear back to the year 800. And best, it extends up to near the present, 2006. This lets us compare it to modern datasets. The analysis of the ice core dataset is described in Temperature and mineral dust variability recorded in two low-accumulation Alpine ice cores over the last millennium by Pascal Bohleber et al.

Let me start with where Colle Gnifetti is located. Unusual among ice core records, it’s from Europe, specifically in the Alps on the border of Switzerland and Italy.

Figure 1. Location of the ice cores in the study.

This is good because some of the longest thermometer-based temperature records are in Europe.

One interesting thing about the site is that usually, ice core drilling occurs at the literal ends of the earth, in Antarctica and Greenland and the like. But this site is not far from the foot of the Margherita Hut, which is at over 4500 metres elevation.

 

Further Reading: It’s instructive to compare the listed temperatures with the data in A Chronological Listing of Early Weather Events.

Decadal Climate Prediction? Might As Well Throw A Dice!

by P. Homewood, July 12, 2020 in NotaLotofPeopleKnowThat


https://hadleyserver.metoffice.gov.uk/wmolc/

The WMO has collated global temperature projections from twelve different organisations, covering this year and the next five years. They were produced in 2019.

It is totally clear that there is very little agreement between any of them, other than a warm Arctic.

An unkind person might call them a waste of space!

Sunny May–But Only The 48th Warmest

by P. Homewood, June 3, 2020 in NotaLotofPeopleKnowThat


While we’re on with Harrabin’s hysterics about May’s sunny weather being due to climate change, it is appropriate to point out to him that last month was far from being the hottest on record in England:

https://www.metoffice.gov.uk/hadobs/hadcet/data/download.html

 

In fact there have been 47 hotter Mays since 1659. The hottest was 1833, and the five hottest were all pre 1850.

See also:  UAH Global Temperature Update for May 2020: +0.54 deg. C

New Study: Arctic Waters Were 4°C Warmer Than Today And Nearly Sea-Ice Free Year-Round ~4100 Years Ago

by Brice et al., May 28, 2020 in NoTricksZone


Today, the region north of Svalbard is encrusted with sea ice for all but a few weeks per year and summer sea surface temperatures (SSTs) hover near 0°C.  Scientists (Brice et al., 2020) have determined this same region had sea ice-free conditions last about 10 months per year while SSTs reached 4°C just ~4100 years ago.

In early September, 2019, Arctic explorers once again needed to be rescued from the “disappearing” sea ice that had captured their ship in central Svalbard. This region is presently free of sea ice for only a few weeks per year (late August).

Image Source: electroverse.net

Tendencies, variability and persistence of sea surface temperature anomalies

by Bulgin et al., May 14, 2020 in Nature OPEN ACCESS


Abstract

Quantifying global trends and variability in sea surface temperature (SST) is of fundamental importance to understanding changes in the Earth’s climate. One approach to observing SST is via remote sensing. Here we use a 37-year gap-filled, daily-mean analysis of satellite SSTs to quantify SST trends, variability and persistence between 1981–2018. The global mean warming trend is 0.09 K per decade globally, with 95% of local trends being between −0.1 K and + 0.35 K. Excluding perennial sea-ice regions, the mean warming trend is 0.11 K per decade. After removing the long-term trend we calculate the SST power spectra over different time periods. The maximum variance in the SST power spectra in the equatorial Pacific is 1.9 K2 on 1–5 year timescales, dominated by ENSO processes. In western boundary currents characterised by an intense mesoscale activity, SST power on sub-annual timescales dominates, with a maximum variance of 4.9 K2. Persistence timescales tend to be shorter in the summer hemisphere due to the shallower mixed layer. The median short-term persistence length is 11–14 days, found over 71–79% of the global ocean area, with seasonal variations. The mean global correlation between monthly SST anomalies with a three-month time-lag is 0.35, with statistically significant correlations over 54.0% of the global oceans, and notably in the northern and equatorial Pacific, and the sub-polar gyre south of Greenland. At six months, the mean global SST anomaly correlation falls to 0.18. The satellite data record enables the detailed characterisation of temporal changes in SST over almost four decades.

 …

Earth’s Mean Temperature Falling, Planetary Alignment Suspected As Driver Of The 11-Year Solar Cycle

by F. Vahrenholt, May 9, 2020 in NoTricksZone


The global mean temperature in April 2020 was again significantly lower than in February and March, at 0.38°C above the average from 1981 to 2010. The average temperature increase on the globe from 1981 to February 2020 was 0.14°C per decade. The further development promises to be interesting, especially since a number of research institutes expect a higher probability of a cooling La Nina in the Pacific towards the end of the year. March’s solar activity was very low with a sunspot number of 1.5.  Activity in April rose slightly to 5.4. The first sunspots of the new cycle are showing.

What causes the sun to have an 11-year cycle?

Since the Dessau pharmacist Heinrich Samuel Schwabe discovered in 1843 that the sunspots of the sun increase and decrease in an 11-year cycle, science has been puzzling over the reason why this cycle lasts 11 years and why the solar magnetic field also changes its polarity in this rhythm: the north pole becomes the south pole and vice versa.

In July last year, scientists at the Helmholtz Centre in Dresden Rossendorf made a little-noticed but exciting discovery. Every 11.07 years, the planets Venus, Earth and Jupiter are aligned quite precisely. At this point in time, their gravitational force acts jointly in one direction on the Sun.

Image: NASA Earth Observatory. Public Domain

NOAA Satellite records second largest 2-month temperature drop in history

by Anthony Watts, May 1, 2020 in WUWT


UPDATE: Changed emphasis from Northern Hemisphere extratropics to entire Northern Hemisphere (h/t John Christy)

In April, 2020, the Northern Hemisphere experienced its 2nd largest 2-month drop in temperature in the 497-month satellite record.

The Version 6.0 global average lower tropospheric temperature (LT) anomaly for April, 2020 was +0.38 deg. C, down from the March, 2020 value of +0.48 deg. C.

The Northern Hemisphere temperature anomaly fell from +0.96 deg. C to 0.43 deg. C from February to April, a 0.53 deg. C drop which is the 2nd largest 2-month drop in the 497-month satellite record. The largest 2-month drop was -0.69 deg. C from December 1987 to February 1988.

The linear warming trend since January, 1979 has now increased to +0.14 C/decade (but remains statistically unchanged at +0.12 C/decade over the global-averaged oceans, and +0.18 C/decade over global-averaged land).

Global Mean Temperature Flattens the Past

by Andy May, May3, 2020 in WUWT


Introduction

There have been recent discussions about ‘flattening the curve’ and some curves are easier to flatten than others. The Pages 2K Consortium calculates global mean temperature in a manner that flattens the long-term trend and makes present day temperatures appear warmer relative to past temperatures. Across the globe, temperature reconstructions show cooling millennial temperature trends with one exception, the Pages 2K global mean.

Millennial Temperature Trends Show Global Cooling

Global mean surface temperature anomalies were recently calculated by the Pages 2K Consortium led by Nuekom, 2019. Their statistical means are a conglomeration of seven different averaging methods for 7000 proxy records over the past 2000 years. The median across all global mean methods is plotted as a dashed line in Figure 1 and compared to Pages 2K’s published regional reconstructions. All means demonstrate similar trends as the median and will be simply be referred to as the global mean(s).

Regional temperature reconstructions are chosen that utilize similar proxy datasets used in the global mean calculation. The Arctic reconstruction by McKay incorporates a balance of proxy records consisting of ice cores, tree rings, lake and marine sediments north of 60 deg N. The Northern Hemisphere (NH) European reconstruction by Luterbacher is tree ring proxy based. And Stenni’s Antarctic reconstruction uses predominantly ice core isotopes.

The Pages 2K global mean appears to be reasonable compared to regional reconstructions from Present through the Little Ice Age (LIA) until about 1250 AD. Although it is difficult to see how the mean compares to regional reconstructions during the Present when using a 1961-1990 baseline as all reconstructions converge creating the “hockey stick” effect. Pre-1250 AD, the global mean appears to parallel NH Europe temperatures largely ignoring the Antarctic.

 

Figure 1: Top graph are surface temperature reconstructions with a 50-year loess filter plotted with Pages 2K global mean of the 7000-member ensemble across all methods. Bottom graph shows linear trends over the past 2000 years.