Archives par mot-clé : Global Temperature

climate-debate

Weak El Nino Conditions Help Explain Recent Global Warmth

by Dr. Roy Spencer,  January 13, 2020 in WUWT

The continuing global-average warmth over the last year has caused a few people to ask for my opinion regarding potential explanations. So, I updated the 1D energy budget model I described a couple years ago here with the most recent Multivariate ENSO Index (MEIv2) data. The model is initialized in the year 1765, has two ocean layers, and is forced with the RCP6 radiative forcing scenario and the history of El Nino and La Nina activity since the late 1800s.

The result shows that the global-average (60N-60S) ocean sea surface temperature (SST) data in recent months are well explained as a reflection of continuing weak El Nino conditions, on top of a long-term warming trend.

Fig. 1. 1D model of global ocean temperatures compared to observations. The model is forced with the RCP6 radiative forcing scenario (increasing CO2, volcanoes, anthropogenic aerosols, etc.) and the observed history of El Nino and La Nina since the late 1800s. The observations are monthly running 3-month averages and are offset with a single bias to match the model temperatures, which are departures from assumed energy equilibrium in 1765.

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climate-debate

An Exceptional Year? Hardly, Mr McCarthy

by P. Homewood, January 1, 2020 in NotaLotofPeopleKnowThat

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The year as a whole has been remarkably unremarkable, as far as temperatures are concerned, ranking only the 24th warmest on record since 1659, and not as warm as even 1733, 1779, 1834 and 1868:

 

https://www.metoffice.gov.uk/hadobs/hadcet/cet_info_mean.html

A closer look at the years since 1980 confirms that the 10-year average has been falling since 2006:

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climate-debate

Blockbuster: Planetary temperature controls CO2 levels — not humans

by JoNova from Murry Salby, December 27, 2019

Over the last two years he has been looking at C12 and C13 ratios and CO2 levels around the world, and has come to the conclusion that man-made emissions have only a small effect on global CO2 levels. It’s not just that man-made emissions don’t control the climate, they don’t even control global CO2 levels.

Continuer la lecture de Blockbuster: Planetary temperature controls CO2 levels — not humans →

climate-debate

3 degrees C?

by J. Curry, December 23, 2019 in ClimateEtc.

Is 3 C warming over the 21st century now the ‘best estimate’?  A reframing of how we think about climate change over the 21st century, and my arguments for 1 C.

There has been much discussion over on twitter of the new article by David Wallace-Wells:  We’re Getting a Clearer Picture of the Climate Future — and It’s n Not as Bad as it Once Looked.  ‘This article is interesting for several reasons, especially since Wallace-Wells has been ‘alarmist in chief.’

Simply put, it is now becoming more widely accepted that RCP8.5 concentration/emissions scenario is highly implausible.  See my previous post:

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climate-debate

NEWLY PUBLISHED SCIENTIFIC PAPER TEARS GLOBAL WARMING AND THE IPCC TO SHREDS

by Cap Allon, December 11, 2019 in Electroverse

A scientific paper entitled “An Overview of Scientific Debate of Global Warming and Climate Change” has recently come out of the University of Karachi, Pakistan. The paper’s author, Prof. Shamshad Akhtar delves into earth’s natural temperature variations of the past 1000 years, and concludes that any modern warming trend has been hijacked by political & environmental agendas, and that the science (tackled below) has been long-ignored and at times deliberately manipulated.

The published paper –available in full HERE— sets out its intent:

Climate change is NOT a new phenomenon. The palaeo-climatic studies reveal that during the Pleistocene and Holocene periods several warm and cold periods occurred, resulting in changes of sea level and in climatic processes like the rise and fall of global average temperature and rainfall.

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climate-debate

CMIP5 Model Atmospheric Warming 1979-2018: Some Comparisons to Observations

by Roy Spencer, December 12, 2019 in WUWT

I keep getting asked about our charts comparing the CMIP5 models to observations, old versions of which are still circulating, so it could be I have not been proactive enough at providing updates to those. Since I presented some charts at the Heartland conference in D.C. in July summarizing the latest results we had as of that time, I thought I would reproduce those here.

The following comparisons are for the lower tropospheric (LT) temperature product, with separate results for global and tropical (20N-20S). I also provide trend ranking “bar plots” so you can get a better idea of how the warming trends all quantitatively compare to one another (and since it is the trends that, arguably, matter the most when discussing “global warming”).

From what I understand, the new CMIP6 models are exhibiting even more warming than the CMIP5 models, so it sounds like when we have sufficient model comparisons to produce CMIP6 plots, the discrepancies seen below will be increasing.

Global Comparisons

First is the plot of global LT anomaly time series, where I have averaged 4 reanalysis datasets together, but kept the RSS and UAH versions of the satellite-only datasets separate. (Click on images to get full-resolution versions).

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climate-debate

GLOBAL TEMPERATURES HOLDING STEADY FOR TWO DECADES

by Climate Science, December 13,  2019

Global temperatures have been holding nearly steady for almost two decades according to satellites from the Remote Sensing Systems (RSS) and University of Alabama at Huntsville (UAH).6You will never see that in the mass media.

2018 is the 3rd year in a row of cooling global temperatures – So far 2018 was the third year in a row that the globe has cooled off from its El Nino peak set in 2015.

Norwegian Professor Ole Humlum explained in his 2018 “State of the Climate Report”: “After the warm year of 2016, temperatures last year (in 2018) continued to fall back to levels of the so-called warming ‘pause’ of 2000-2015. There is no sign of any acceleration in global temperature, hurricanes or sea-level rise. These empirical observations show no sign of acceleration whatsoever.”

While 2005, 2010, 2015, and 2016 were declared the “hottest years” or “near -hottest,”  based on heavily altered surface data by global warming proponents, a closer examination revealed the claims were “based on year-to-year temperature data that differs by only a few HUNDREDTHS of a degree to tenths of a degree Fahrenheit – differences that were within the margin of error in the data.” 7

MIT climate scientist Dr. Richard Lindzen ridiculed “hottest year” claims. “The uncertainty here is tenths of a degree. It’s just nonsense. This is a very tiny change period,” Lindzen said. “If you can adjust temperatures to 2/10ths of a degree, it means it wasn’t certain to 2/10ths of a degree.”

In 2015, the Associated Press was forced to issue a “clarification” on “hottest year” claims, stating in part: “The story also reported that 2014 was the hottest year on record, according to the National Oceanic and Atmospheric Administration and NASA, but did not include the caveat that other recent years had average temperatures that were almost as high  – and they all fall within a margin of error that lessens the certainty that any one of the years was the hottest.”

Climatologist Pat Michaels explained that, in any case, the world’s temperature “should be near the top of the record given the record only begins in the late 19th century when the surface temperature was still reverberating from the Little Ice Age.”

“Hottest year” claims are purely political statements designed to persuade the public that the government needs to take action on man-made climate change. In addition, the claims of “hottest year” are based on surface data only dating back to the late 19th century, and also ignore the temperature revisions made by NASA and NOAA that have enhanced the warming trend by retroactively cooling the past. 8

6 The Pause Lives on: Global Satellites: 2016 not Statistically Warmer than 1998 – Climatologist Dr. Roy Spencer – January 4, 2017
7 Dr. David Whitehouse noted the ‘temperature pause never went away’ – January 19, 2017
8 Climate analyst Tony Heller – Real Climate Science – February 14, 2017

climate-debate

2019 the Third Least-Chilly in the Satellite Temperature Record

by Roy Spencer, December 6, 2019 in WUWT

It’s that time of year again, when we are subjected to exaggerated climate claims such as in this Forbes article, 2019 Wraps Up The Hottest Decade In Recorded Human History. Given that the global average surface temperature is about 60 deg. F, and most of the climate protesters we see in the news are wearing more clothing than the average Key West bar patron, I would think that journalists striving for accuracy would use a more accurate term than “hottest”.

So, I am announcing that in our 41-year record of global satellite measurements of the lower atmosphere, 2019 will come in as 3rd least-chilly.

For the decade 2010-2019, the satellite temperatures averaged only 0.15 C higher than in the previous decade (1990-1999). That’s less than a third of a degree F, which no one would even notice over 10 years.

If you are wondering how your neck of the woods has fared this year, the latest year-to-date plot of 2019 temperature departures from the 30-year average (1981-2010) shows the usual pattern of above- and below-normal, with little visual indication that the global average for 2019 is now running 0.36 deg. C above normal.

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climate-debate

UAH Global Temperature Update for November 2019: +0.55 deg. C

by Roy Spencer, December 2, 2019 in WUWT

The Version 6.0 global average lower tropospheric temperature (LT) anomaly for November, 2019 was +0.55 deg. C, up from the October value of +0.46 deg. C.

The linear warming trend since January, 1979 remains at +0.13 C/decade (+0.11 C/decade over the global-averaged oceans, and +0.18 C/decade over global-averaged land).

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The UAH LT global anomaly image for November, 2019 should be available in 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

 

climate-debate

Three Graphs

by Kip Hansen, November 30, 2019 in WUWT

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Now an annotated version of the second graph:

Here we have the second graph 1850-2015, with the global Average Surface Temperature anomaly (again — baseline 15 CE)  but I have dropped in a smaller window, on the left, bringing forward  the Roman Warm Period and the Medieval Warm Period (MWP) — the years 100-800 CE (same scale) — to illustrate the difference between the peak Global Average Surface Temperature (GAST)  of the Medieval Warm Period to the most current GAST on the graph (2015).

This exposes the ubiquitous trick of the Climate Debate, in which Global Temperatures are [almost] always shown only from the depths of the Little Ice Age (clearly marked on the first graph by Gebbie), resulting in images similar to Gebbie’s Figure 2 — despite the fact that most 2 millennia reconstructions clearly show the Roman and Medieval Warm Periods as generally in the same range as the Modern Warm Period.   Given the acknowledged range of error  in any temperature reconstruction and in modern estimates of global surface temperatures (today, in absolute temperatrures,  around +/- 0.5ºC  or a range of 1ºC)  — there may be little, if any,  significant-to-the-global-environment difference  between the two periods.

The Medieval Warm period did not result in a “Climate Catastrophe”  and the [iffy] little additional 0.2°C  seen today  is very unlikely to spark a modern Climate Catastrophe either.

climate-debate

170 Years of Earth Surface Temperature Data Show No Evidence of Significant Warming

by T. Bjorklund, October 16, 2019 in WUWT

Key Points

1. From 1850 to the present, the noise-corrected, average warming of the surface of the earth is less than 0.07 degrees C per decade.

2. The rate of warming of the surface of the earth does not correlate with the rate of increase of fossil fuel emissions of CO2 into the atmosphere.

3. Recent increases in surface temperatures reflect 40 years of increasing intensities of the El Nino Southern Oscillation climate pattern.

Abstract

This study investigates the relationships between surface temperatures from 1850 to the present and reported long-range temperature predictions of global warming. A crucial component of this analysis is the calculation of an estimate of the warming curve of the surface of the earth. The calculation removes errors in temperature measurements and fluctuations due to short-duration weather events from the recorded data. The results show the average rate of warming of the surface of earth for the past 170 years is less than 0.07 degrees C per decade. The rate of warming of the surface of the earth does not correlate with the rate of increase of CO2 in the atmosphere. The perceived threat of excessive future global temperatures may stem from misinterpretation of 40 years of increasing intensities of the El Nino Southern Oscillation (ENSO) climate pattern in the eastern Pacific Ocean. ENSO activity culminated in 2016 with the highest surface temperature anomaly ever recorded. The rate of warming of the earth’s surface has dropped 41 percent since 2006.

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climate-debate

Propagation of Error and the Reliability of Global Air Temperature Projections

by Patrick Franck, September 6, 2019 in Frontierin EarthScience

The reliability of general circulation climate model (GCM) global air temperature projections is evaluated for the first time, by way of propagation of model calibration error. An extensive series of demonstrations show that GCM air temperature projections are just linear extrapolations of fractional greenhouse gas (GHG) forcing. Linear projections are subject to linear propagation of error. A directly relevant GCM calibration metric is the annual average ±12.1% error in global annual average cloud fraction produced within CMIP5 climate models. This error is strongly pair-wise correlated across models, implying a source in deficient theory. The resulting long-wave cloud forcing (LWCF) error introduces an annual average ±4 Wm–2uncertainty into the simulated tropospheric thermal energy flux. This annual ±4 Wm–2 simulation uncertainty is ±114 × larger than the annual average ∼0.035 Wm–2 change in tropospheric thermal energy flux produced by increasing GHG forcing since 1979. Tropospheric thermal energy flux is the determinant of global air temperature. Uncertainty in simulated tropospheric thermal energy flux imposes uncertainty on projected air temperature. Propagation of LWCF thermal energy flux error through the historically relevant 1988 projections of GISS Model II scenarios A, B, and C, the IPCC SRES scenarios CCC, B1, A1B, and A2, and the RCP scenarios of the 2013 IPCC Fifth Assessment Report, uncovers a ±15 C uncertainty in air temperature at the end of a centennial-scale projection. Analogously large but previously unrecognized uncertainties must therefore exist in all the past and present air temperature projections and hindcasts of even advanced climate models. The unavoidable conclusion is that an anthropogenic air temperature signal cannot have been, nor presently can be, evidenced in climate observables.

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climate-debate, to keep an eye on...

Scientists: Climate Records ‘Correlate Well’ With Solar Modulation…A Grand Solar Minimum Expected By 2030

by K. Richard, November 11, 2019 in NoTricksZone

International and NASA solar scientists find their Total Solar Irradiance reconstruction extending to 1700 can “correlate well” with Earth’s global temperature records, including a positive net TSI trend during 1986-2008. A new Grand Solar Minimum is expected to commence during the 2030s.

Surface climate records that have been uncorrupted by coastal (ocean-air)/urbanization biases suggest there has been a long-term oscillation in temperature since 1900, with peaks during the 1920s-1940s and again during recent decades (Lansner and Pepke Pedersen, 2018).

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climate-debate

Scientists: The Entirety Of The 1979-2017 Global Temperature Change Can Be Explained By Natural Forcing

by K. Richard, October 28, 2019 in NoTricksZone

The last 40 years of global temperature changes can be radiatively explained by a natural reduction in cloud cover.

From 1979 to 2011, satellite data provide documentation of a reduction in cloud cover and aerosol depth that allowed an additional 2.3 W/m² of positive shortwave energy to be absorbed by the Earth’s surface rather than reflected to space.

This change in absorbed solar radiation can account for the energy imbalance and warming during this period far better than the much smaller 0.2 W/m² forcing associated with a +22 ppm CO2 change over 10 years (representing just 10% of the overall trend in downwelling longwave).

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climate-debate

Controversy Swirls As Numbers Don’t Add Up… 1.3°C Missing Heat! – Earth Supposed To Be 16°C, But It’s Only 14.68°C

by P. Gosselin, October 19, 2019 in NoTricksZone

Even NASA says it:

Without the Earth’s greenhouse gases (GHG) in the atmosphere, the planet would be on average a frigid -18°C.

But because of the preindustrial 280 ppmv CO2 and other GHGs in our atmosphere, the average temperature of the Earth thankfully moves up by 33°C to +15°C (see chart below), based on the Stefan Boltzmann Law.

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And because CO2 has since risen to about 410 ppmv today, the global temperature supposedly should now be about another 1°C warmer (assuming positive feedbacks) bringing the average earth’s temperature to 16°C.

And once the preindustrial level of CO2 gets doubled to 560 ppm, later near the end of this century, global warming alarmists insist the Earth’s temperature will be near 18°C, see chart above.

So we are now supposed to be at 16°C today and warming rapidly. But what is the globe’s real average temperature today? 15.8C? 16.0C? 16.5°C?

Answer: astonishingly the official institutes tell us it is only 14.7°C!

For example, data from the World Meteorological Organization (WMO) shows us the global absolute temperatures for the previous 5 years:

 

 

Image: www.klimamanifest.ch, data source: WMO in Geneva.

As the image above shows, the global absolute temperature last year was just 14.68°C.

This is 0.32°C COOLER than the 15°C we are supposed to have with 280 ppmv, and a whopping 1.32°C cooler than the 16°C it is supposed to be with the 410 ppmv CO2 we have in our atmosphere today.

So why are we missing over 1.3°C of heat? Why is there this huge discrepancy between scientists?

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climate-debate

Why Haven’t the Tropics Warmed Much? A Tantalizing Piece of Evidence

by Dr. Roy Spencer, Sep. 28, 2019 in WUWT

The radiative resistance to global temperature change is what limits the temperature change in response to radiative forcing from (say) increasing CO2, or the sun suddenly deciding to pump out a 1 percent more sunlight.

If the climate system sheds only a little extra energy with warming, it warms even more until radiative energy balance is restored. If it sheds a lot of energy, then very little warming is required to restore global energy balance. This is the climate sensitivity holy grail, and it will determine just how much warming results from increasing CO2 in the atmosphere.

John Christy and I are preparing a paper based upon Dept. of Energy-sponsored research explaining why the tropical troposphere hasn’t warmed as much in nature as in climate models. (The discrepancy exists for surface temperature trends; for both RSS and UAH tropical tropospheric trends; as well as for global reanalysis datasets). Danny Braswell and I did a lot of research on this subject about 5-10 years ago, and published several papers.

Without going into the gory details of why it is so difficult to measure “feedbacks” (how strong the climate system radiatively resists a temperature change in response to radiative forcing), I’m going to present one graph of new results from our work that suggests where the problem with the models might be.

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climate-debate

The Great Failure Of The Climate Models

by Tyler Durden, 26 August 2019 in ZeroHedge

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Christy is not looking at surface temperatures, as measured by thermometers at weather stations. Instead, he is looking at temperatures measured from calibrated thermistors carried by weather balloons and data from satellites. Why didn’t he simply look down here, where we all live? Because the records of the surface temperatures have been badly compromised.

Globally averaged thermometers show two periods of warming since 1900: a half-degree from natural causes in the first half of the 20th century, before there was an increase in industrial carbon dioxide that was enough to produce it, and another half-degree in the last quarter of the century.

The latest U.N. science compendium asserts that the latter half-degree is at least half manmade. But the thermometer records showed that the warming stopped from 2000 to 2014. Until they didn’t.

In two of the four global surface series, data were adjusted in two ways that wiped out the “pause” that had been observed.

The first adjustment changed how the temperature of the ocean surface is calculated, by replacing satellite data with drifting buoys and temperatures in ships’ water intake. The size of the ship determines how deep the intake tube is, and steel ships warm up tremendously under sunny, hot conditions. The buoy temperatures, which are measured by precise electronic thermistors, were adjusted upwards to match the questionable ship data. Given that the buoy network became more extensive during the pause, that’s guaranteed to put some artificial warming in the data.

The second big adjustment was over the Arctic Ocean, where there aren’t any weather stations. In this revision, temperatures were estimated from nearby land stations. This runs afoul of basic physics.

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climate-debate, to keep an eye on...

A Skeptic’s Guide To Global Temperatures

by Clive Best, August 30, 2019 in ClimateChangeDispatch

Climate change may well turn out to be a benign problem rather than the severe problem or “emergency” it is claimed to be.

This will eventually depend on just how much the Earth’s climate is warming due to our transient but relatively large increase in atmospheric CO2 levels.

This is why it is so important to accurately and impartially measure the Earth’s average temperature rise since 1850. It turns out that such a measurement is neither straightforward, independent, nor easy.

For some climate scientists, there sometimes appears to be a slight temptation to exaggerate recent warming,  perhaps because their careers and status improve the higher temperatures rise.

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climate-debate

More fake five-alarm crises from the IPCC

by Paul Driessen, August 25, 2019

UN and other scientists recently sent out news releases claiming July 2019 was the “hottest month ever recorded on Earth” – nearly about 1.2 degrees C (2.2 degrees F) “above pre-industrial levels.” That era happens to coincide with the world’s emergence from the 500-year Little Ice Age. And “ever recorded” simply means measured; it does not include multiple earlier eras when Earth was much warmer than now.

Indeed, it is simply baseless to suppose that another few tenths of a degree (to 1.5 C above post-Little Ice Age levels) would somehow bring catastrophe to people, wildlife, agriculture and planet. It is equally ridiculous to assume all recent warming has been human-caused, with none of it natural or cyclical.

Moreover, as University of Alabama-Huntsville climate scientist Dr. Roy Spencer has noted, this past July was most likely not the warmest. The claim, he notes, is based on “a limited and error-prone array of thermometers which were never intended to measure global temperature trends.”

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better to know...?, climate-debate

Greenland’s ‘Record Temperature’ denied – the data was wrong

by Anthony Watts, August 12, 2019 in WUWT

From the “But, but, wait! Our algorithms can adjust for that!” department comes this tale of alarmist woe. Greenland’s all-time record temperature wasn’t a record at all, and it never got above freezing there.

First, the wailing from news media:

NYT: https://www.nytimes.com/2019/08/02/climate/european-heatwave-climate-change.html

WAPO: https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/06/10/greenland-witnessed-its-highest-june-temperature-ever-recorded-on-thursday/

Climate Progress: https://thinkprogress.org/greenland-hits-record-75-f-sets-melt-record-as-globe-aims-at-hottest-year-e34e534e533e/

Polar Portal: http://polarportal.dk/en/news/news/record-high-temperature-for-june-in-greenland/

Now from the Danish Meteorological Institute (DMI), via the news website The Local, the cooler reality:

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climate-debate

Evidence that ERA5-based Global Temperatures Have Spurious Warming

by Dr. Roy Spencer, August 6, 2019 in GlobalWarming

“Reading, we have a problem.”

As a followup to my post about whether July 2019 was the warmest July on record (globally-averaged), I’ve been comparing reanalysis datasets since 1979. It appears that the ERA5 reanalysis upon which WMO record temperature pronouncements are made might have a problem, with spurious warmth in recent years.

Here’s a comparison of the global-average surface air temperature variations from three reanalysis datasets: ERA5 (ECMWF), CFSv2 (NOAA/NCEP), and MERRA (NASA/GSFC). Note that only CFSv2 covers the full period, January 1979 to July 2019:

ERA5 has a substantially warmer trend than the other two. By differencing ERA5 with the other datasets we can see that there are some systematic changes that occur in ERA5, especially around 2009-2010, as well as after 1998:

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climate-debate

July 2019 Was Not the Warmest on Record

by Roy Spencer, August 2, 2019 in GlobalWarming

July 2019 was probably the 4th warmest of the last 41 years. Global “reanalysis” datasets need to start being used for monitoring of global surface temperatures. [NOTE: It turns out that the WMO, which announced July 2019 as a near-record, relies upon the ERA5 reanalysis which apparently departs substantially from the CFSv2 reanalysis, making my proposed reliance on only reanalysis data for surface temperature monitoring also subject to considerable uncertainty].

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See also here

climate-debate, to keep an eye on...

1970s: Earth Warmed 0.6°C From 1880-1940 And Cooled -0.3°C From 1940-1970. Now It’s 0.1°C And -0.05°C.

by K. Richard, July 25, 2019 in NoTricksZone

About 45 years ago, the “consensus” in climate science (as summarized by Williamson, 1975) was quite different than today’s version.

1. The Medieval Warm Period was about 1°C warmer than present overall while the “largely ice-free” Arctic was 4°C warmer, allowing the Vikings to navigate through open waters because there was “no or very little ice” at that time.
2. The island of Spitsbergen, 1237 km from the North Pole and home to over 2000 people, “benefited” because it warmed by 8°C between 1900 and 1940, resulting in 7 months of sea-ice free regional waters. This was up from just 3 months in the 1800s.
3. Central England temperatures dropped -0.5°C between the 1930s to the 1950s.
4. Pack-ice off northern and eastern iceland returned to its 1880s extent between 1958 and 1975.
5. In the 1960s, polar bears were able to walk across the sea (ice) from Greenland to Iceland for the first time since the early 1900s. (They had somehow survived the 7 months per year of sea-ice-free waters during the 1920s-1940s).

 

 

Image Source: National Academy of Sciences,  Understanding Climatic Change
climate-debate

GLOBAL TEMPERATURE FALLING AGAIN

by Clive Best, July 27, 2019 in GWPF

The global averaged surface temperature for June 2019 was 0.62C, back down to where it was before the 2015/16 El Nino.

The global averaged surface temperature for June 2019 was 0.62C using my spherical triangulation method merging GHCNV3 with HadSST3. This is a further drop of 0.04C from May 2018. The discrepancy with GHCNV4 is however growing. V4C calculated in exactly the same way gives a June temperature of 0.75C, a rise of 0.03C,  and 0.13C warmer than V3. This difference is statistically significant.

climate-debate

Climate: about which temperature are we talking about?

by S. Furfari and H. Masson, July 26, 2019 in ScienceClimateEnergie

Is it the increase of temperature during the period 1980-2000 that has triggered the strong interest for the climate change issue? But actually, about which temperatures are we talking, and how reliable are the corresponding data?

1/ Measurement errors

Temperatures have been recorded with thermometers for a maximum of about 250 years, and by electronic sensors or satellites, since a few decades. For older data, one relies on “proxies” (tree rings, stomata, or other geological evidence requiring time and amplitude calibration, historical chronicles, almanacs, etc.). Each method has some experimental error, 0.1°C for a thermometer, much more for proxies. Switching from one method to another (for example from thermometer to electronic sensor or from electronic sensor to satellite data) requires some calibration and adjustment of the data, not always perfectly documented in the records. Also, as shown further in this paper, the length of the measurement window is of paramount importance for drawing conclusions on a possible trend observed in climate data. Some compromise is required between the accuracy of the data and their representativity.

2/ Time averaging errors

If one considers only “reliable” measurements made using thermometers, one needs to define daily, weekly, monthly, annually averaged temperatures. But before using electronic sensors, allowing quite continuous recording of the data, these measurements were made punctually, by hand, a few times a day. The daily averaging algorithm used changes from country to country and over time, in a way not perfectly documented in the data; which induces some errors (Limburg, 2014) . Also, the temperature follows seasonal cycles, linked to the solar activity and the local exposition to it (angle of incidence of the solar radiations) which means that when averaging monthly data, one compares temperatures (from the beginning and the end of the month) corresponding to different points on the seasonal cycle. Finally, as any experimental gardener knows, the cycles of the Moon have also some detectable effect on the temperature (a 14 days cycle is apparent in local temperature data, corresponding to the harmonic 2 of the Moon month, Frank, 2010); there are circa 13 moon cycle of 28 days in one solar year of 365 days, but the solar year is divided in 12 months, which induces some biases and fake trends (Masson, 2018).

3/ Spatial averaging

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Figs. 12, 13 and 14 : Linear regression line over a single period of a sinusoid.

 

Conclusions

 

  1. IPCC projections result from mathematical models which need to be calibrated by making use of data from the past. The accuracy of the calibration data is of paramount importance, as the climate system is highly non-linear, and this is also the case for the (Navier-Stokes) equations and (Runge-Kutta integration) algorithms used in the IPCC computer models. Consequently, the system and also the way IPCC represent it, are highly sensitive to tiny changes in the value of parameters or initial conditions (the calibration data in the present case), that must be known with high accuracy. This is not the case, putting serious doubt on whatever conclusion that could be drawn from model projections.

  2. Most of the mainstream climate related data used by IPCC are indeed generated from meteo data collected at land meteo stations. This has two consequences:(i) The spatial coverage of the data is highly questionable, as the temperature over the oceans, representing 70% of the Earth surface, is mostly neglected or “guestimated” by interpolation;(ii) The number and location of theses land meteo stations has considerably changed over time, inducing biases and fake trends.

  3. The key indicator used by IPCC is the global temperature anomaly, obtained by spatially averaging, as well as possible, local anomalies. Local anomalies are the comparison of present local temperature to the averaged local temperature calculated over a previous fixed reference period of 30 years, changing each 30 years (1930-1960, 1960-1990, etc.). The concept of local anomaly is highly questionable, due to the presence of poly-cyclic components in the temperature data, inducing considerable biases and false trends when the “measurement window” is shorter than at least 6 times the longest period detectable in the data; which is unfortunately the case with temperature data

  4. Linear trend lines applied to (poly-)cyclic data of period similar to the length of the time window considered, open the door to any kind of fake conclusions, if not manipulations aimed to push one political agenda or another.

  5. Consequently, it is highly recommended to abandon the concept of global temperature anomaly and to focus on unbiased local meteo data to detect an eventual change in the local climate, which is a physically meaningful concept, and which is after all what is really of importance for local people, agriculture, industry, services, business, health and welfare in general.