Archives par mot-clé : Temperature

Paleoclimatological Context and Reference Level of the 2°C and 1.5°C Paris Agreement Long-Term Temperature Limits

by S. Lüning & F. Vahrenholt, December12, 2017 in FrontEarthSci


The Paris Agreement adopted in December 2015 during the COP21 conference stipulates that the increase in the global average temperature is to be kept well below 2°C above “pre-industrial levels” and that efforts are pursued to limit the temperature increase to 1.5°C above “pre-industrial levels.” In order to further increase public acceptance of these limits it is important to transparently place the target levels and their baselines in a paleoclimatic context of the past 150,000 years (Last Interglacial, LIG) and in particular of the last 10,000 years (Holocene; Present Interglacial, PIG). Intense paleoclimatological research of the past decade has firmed up that pre-industrial temperatures have been highly variable which needs to be reflected in the pre-industrial climate baseline definitions …

See also here

Evolutions récentes du CO2 atmosphérique (3/4)

by J.C. Maurin, 12 novembre 2018 in ScienceClimatEnergie


L’IPCC (GIEC en français) fut créé en 1988 par l’UNEP (United Nations Environment Programme) et le WMO (World Meteorological Organization). Dans les principes régissant les travaux du GIEC (1) on lit : Le GIEC a pour mission d’évaluer … les risques liés au changement climatique d’origine humaine.  Le GIEC respecte son propre principe fondateur : il attribue l’intégralité de la hausse du taux de CO2 depuis 1958 à une cause anthropique. Nous examinerons ici le modèle anthropique du GIEC et nous le confronterons aux mesures contemporaines, puis à un modèle mixte. Cet article fait suite aux deux précédents publiés sur le site SCE au cours des mois de septembre (1/4) et octobre 2018 (2/4).

C.   Modèle anthropique GIEC

C.1   Les contraintes des modèles (Fig. 1)

Le paragraphe A (article 1/4) a montré qu’en 1980 le taux de CO2 atmosphérique était de 338 ppm et le  δ13C de -7.6 ‰. En  2010 le taux de CO2  atmosphérique était de 388 ppm et le δ13C de -8.3 ‰. Il existe une modulation annuelle de ce taux, très marquée dans l’hémisphère Nord.

 

Proof that Corals are Adapting to Warming Temperatures

by Coles et al., November, 11,  2018 in CO2Science


In light of the above findings, Coles et al. state the obvious, that the corals “were able to withstand elevated temperatures (31.4 °C) for a longer period of time in the current 2017 experiment” compared to the 1970 study. Consequently, they conclude that their results “indicate a shift in the temperature threshold tolerance of these corals to a 31-day exposure to 31.4 °C,” which findings “provide the first evidence of coral acclimatization or adaptation to increasing ocean temperatures.” And that observational reality should hold great bearing on the status and health of coral reefs in response to future climate change. If temperatures rise in the future, clearly, as living organisms, corals can (and do!) adapt. Alarmist predictions of their fast and ensuing demise due to global warming should not be taken too seriously.

Holocene temperature in the Iberian Peninsula reconstructed studying insect subfossils

by University of Barcelona, November 9, 2018 in ScienceDaily


Regional differences regarding other reconstructions

The results of the study show a temperature rise in the beginning of the Holocene, reaching the highest values in the Holocene Climate Optimum (about 7,800 years ago). There are also high temperatures until about 6,000 years ago, when a decline of temperature started and led to the lowest values in the first stage of the late Holocene (about 4,200 and 2,000 years ago).

Last, researchers detected a rise of temperatures over the two last millenniums, but they state they have to be careful with these data. “We cannot guarantee the observed rise in the reconstruction results from a temperature rise only, we cannot rule out other variables that can influence at other levels, such as the gradual increase of the anthropic activity in the area, which can change the community of Chironomidae to species that adapt to higher temperatures, but there are also human influence indicators,” says Narcís Prat.

Although these conclusions can coincide with other paleoclimate reconstructions, results also highlight some divergences at a regional level. “These differences can occur due the fact that some indicators point out to different seasonal signs. Therefore, Chironomidae are indicators of temperature in summer, while others such as chrysophites or alkenones are related to winter/spring temperatures,” notes the researcher.

A tool to evaluate climate trends

Another failure of peer review, due to corrupt temperature data from a single station

by Anthony Watts, November 7, 2018 in WUWT


A new study, based on 27 years of data from Mana Pools National Park in Zimbabwe, suggests that temperature increases over the last three decades have already caused major declines in local populations of tsetse flies.

This analysis, published in the journal PLOS Medicine this week, provides a first step in linking temperature to the risk of sleeping sickness in Africa.

My analysis

A model for fly population mortality is only as good as the temperature data used to run the model. It appears they only used one source of temperature data, the only one available to them, the Rekomitjie Research Station.

Interestingly, this helpful photo was also included in the press release from Eurekalert. It is the weather station used to monitor climate at the Rekomitjie Research Station, Zimbabwe. I provide it below, click for full-size. At the scale displayed above, you might not notice some important details about the weather station itself, but I did. Here it is, magnified: …

The Millennial Turning Point – Solar Activity and the Coming Cooling

by Norman Page, November 2, 2018 in WUWT


When analyzing complex systems with multiple interacting variables it is useful to note the advice of Enrico Fermi who reportedly said “never make something more accurate than absolutely necessary”.

My recent paper presented a simple heuristic approach to climate science which plausibly proposed that a Millennial Turning Point (MTP) and peak in solar activity was reached in 1991.

Zharkova et al 2015 DOI:10.10381/srep15683 says ” Dynamo waves are found generated with close frequencies whose interaction leads to beating effects responsible for the grand cycles (350-400 years) superimposed on a standard 22 year cycle. This approach opens a new era in investigation and confident prediction of solar activity on a millenium timescale. ”
Svalgaard concluded in his essay on WUWT 10/27 2018:

The temperature increase since about 1650 is clearly chiefly due to the up- leg in the natural solar activity millennial cycle as shown by Lean 2018 “Estimating Solar Irradiance Since 850 AD” Fig 5

Hothouse claims from ‘Trajectories of the Earth System in the Anthropocene’ are in a virtual world, not the real world

by Albert Parker, November 2, 2018 in WUWT


A recent paper Trajectories of the Earth System in the Anthropocene (Ref. [1] below) claims that even if the CO2 emission reductions called for in the Paris Agreement are met, our Earth may still enter what they call “Hothouse Earth” conditions, a long-term stabilization at temperature 4-5 °C-higher than pre-industrial temperatures, and sea-level 10-60 m-higher than today. They conclude calling for an accelerated transition towards a CO2 emission-free-world-economy. There is, however, very little evidence that the apocalyptic prediction is scientific grounded. Where really measured, the temperatures haven’t increased dramatically, and similarly, the sea-levels haven’t risen dramatically. More importantly, any acceleration of the temperature warming, or any acceleration of the rate of rise of the sea-level, are hard to detect.

Figure 1 –sample long-term-trend thermometer results (Alice Spring, NT, Australia). The temperatures were recorded in the Post Office / City and Airport locations. Data downloaded from www.bom.gov.au/climate/data/.

 

MOVING THE GOALPOSTS, IPCC SECRETLY REDEFINES ‘CLIMATE’

by David Whitehouse, October 29, 2018 in GWPF


The IPCC appears to have secretly changed the definition of what constitutes ‘climate’ by mixing existing and non-existing data

The definition of ‘climate’ adopted by the World Meteorological Organisation is the average of a particular weather parameter over 30 years. It was introduced at the 1934 Wiesbaden conference of the International Meteorological Organisation (WMO’s precursor) because data sets were only held to be reliable after 1900, so 1901 – 1930 was used as an initial basis for assessing climate. It has a certain arbitrariness, it could have been 25 years.

For its recent 1.5°C report the IPCC has changed the definition of climate to what has been loosely called “the climate we are in.” It still uses 30 years for its estimate of global warming and hence climate – but now it is the 30 years centred on the present.

500 Million Years of Unrelatedness between Atmospheric CO2 and Temperature

by Davis W.J., 2017 in CO2Science


Davis, W.J. 2017. The relationship between atmospheric carbon dioxide concentration and global temperature for the last 425 million years. Climate 5: 76; doi: 10.3390/cli5040076.

Writing by way of introduction to his work, Davis (2017) notes that “a central question for contemporary climate policy is how much of the observed global warming is attributable to the accumulation of atmospheric CO2 and other trace greenhouse gases emitted by human activities.” If you talk to a climate alarmist, the answer you receive from such an inquiry will likely be “almost all.” A climate skeptic, on the other hand, will likely respond that the answer is “likely none.”

Hoping to provide some crucial information on this topic, Davis analyzed the relationship between historic temperature and atmospheric CO2 using the most comprehensive assemblage of empirical databases of these two variables available for the Phanerozoic period (522 to 0 million years before present; Mybp). In all, 6680 proxy temperature and 831 proxy CO2 measurements were utilized, enabling what Davis described as “the most accurate quantitative empirical evaluation to date of the relationship between atmospheric CO2concentration and temperature.” Multiple statistical procedures and analyses were applied to the proxy records and the resultant relationship is depicted in the figure below.

Egalement voir ici

PAGES2K: North American Tree Ring Proxies

by Steve McIntyre, October 24, 2018 in ClimatAudit


The PAGES (2017) North American network consists entirely of tree rings. Climate Audit readers will recall the unique role of North American stripbark bristlecone chronologies in Mann et al 1998 and Mann et al 2008 (and in the majority of IPCC multiproxy reconstructions).  In today’s post, I’ll parse the PAGES2K North American tree ring networks in both PAGES (2013) and PAGES (2017) from two aspects:

Conclusions

  • ex post screening based on recent proxy trends necessarily biases the resulting data towards a Hockey Stick shape – a criticism made over and over here and at other “ske;ptic” blogs, but not understood by Michael (“I am not a statistician”) Mann and the IPCC paleoclimate “community”;

  • the PAGES 2017 North American tree ring network has been severely screened ex post from a much larger candidate population: over the years, approximately 983 different North American tree ring chronologies have been used in MBH98, Mann et al 2008, PAGES 2013 or PAGES 2017. I.e. only ~15% of the underlying population was selected ex post – a procedure which, even with random data, would impart Hockey Stick-ness to any resulting composite

  • despite this severe ex post screening (in both PAGES 2013 and PAGES 2017), the composite of all data other than stripbark bristlecones had no noticeable Hockey Stick-ness and does not resemble a temperature proxy.

Evidence of the Medieval Warm Period in Australia, New Zealand and Oceania

by S. Lüning, January 9, 2018 in WUWT


The climate of the pre-industrial past is of greatest importance to the ongoing climate discussion. Current climate can only be understood when interpreting it in the paleoclimatological context of the past few thousand years. Until not too long ago it was thought that the pre-industrial climate was monotonous and constant. This idea was e.g. promoted by Mann et al. whose famous hockey stick curve featured prominently in the IPCC report of 2001. Over the last 15 years, however, a large number of studies changed this view by providing robust evidence for the existence of significant natural climate variability. Of particular interest are the past 1000 years which commenced with the generally warm ‘Medieval Climate Anomaly’ (MCA, aka ‘Medieval Warm Period’, MWP), that eventually passed into the ‘Little Ice Age’ (LIA), before returning to the warm climate of the current ‘Modern Warm Period’ of the 20th and early 21st centuries.

There have been controversial debates about the existence of the MWP, …

Higher sea surface temperature in the northern South China Sea during the natural warm periods of late Holocene than recent decades

by Hong Yan et al., November 2014, in ChineseSciBull


The large-scale syntheses of global mean temperatures in IPCC fourth report suggested that the Northern Hemisphere temperature in the second half of the 20th century was likely the highest in at least the past 1,300 years and the 1990s was likely the warmest decade. However, this remains debated and the controversy is centered on whether temperatures during the recent half century were higher than those during the Medieval Climate Anomaly (MCA, AD 800–1300) and the Roman Warm Period (RWP, BC 200–AD 400), the most recent two natural warm periods of the late Holocene. Here the high resolution sea surface temperatures (SSTs) of two time windows around AD 990 (±40) and AD 50 (±40), which located in the MCA and RWP respectively, were reconstructed by the Sr/Ca ratio and δ 18O of Tradacna gigas shells from the northern South China Sea. The results suggested that the mean SSTs around AD 990 (±40) and AD 50 (±40) were 28.1 °C and 28.7 °C, 0.8 °C and 1.4 °C higher than that during AD 1994–2005, respectively. These records, together with the tree ring, lake sediment and literature records from the eastern China and northwest China, imply that the temperatures in recent decades do not seem to exceed the natural changes in MCA, at least in eastern Asia from northwest China to northern SCS.

September 2018 Global Surface (Land+Ocean) and Lower Troposphere Temperature Anomaly Update

by Bob Tisdale, October 18, 2018 in WUWT


This post provides updates of the values for the three primary suppliers of global land+ocean surface temperature reconstructions—GISS through September 2018 and HADCRUT4 and NOAA NCEI (formerly NOAA NCDC) through August 2018—and of the two suppliers of satellite-based lower troposphere temperature composites (RSS and UAH) through September 2018. It also includes a few model-data comparisons.

This is simply an update, but it includes a good amount of background information for those new to the datasets. Because it is an update, there is no overview or summary for this post. There are, however, simple monthly summaries for the individual datasets. So for those familiar with the datasets, simply fast-forward to the graphs and read the summaries under the headings of “Update”.

Reliable? CRU, NASA, BEST, NOAA Land Temp Data Conflict By Up To 90% (0.8°C), Spawning ‘Large Uncertainty’

by K. Richard, October 8, 2018 in NoTricksZone


A new paper documents “remarkably different” land temperatures from one instrumental data set to another. In some regions there is as much as an 0.8°C conflict in recorded temperature anomalies for CRU, NASA, BEST, and NOAA. The relative temperature trend differences can reach 90% when comparing instrumental records. Consequently, the uncertainty in instrumental temperature trends — “0.097–0.305°C per decade for recent decades (i.e., 1981–2017)” —  is as large or larger than the alleged overall warming trend itself for this period.