Surface Air Temperature Record Research Articles

LiG Metrology, Correlated Error, and the Integrity of the Global Surface Air-Temperature Record

The published 95% uncertainty of the global surface air-temperature anomaly (GSATA) record through 1980 is impossibly less than the 2σ = ±0.25 °C lower limit of laboratory resolution of 1 °C/division liquid-in-glass (LiG) thermometers. The ~0.7 °C/century Joule-drift of lead- and soft-glass thermometer bulbs renders unreliable the entire historical air-temperature record through the 19th century. A circa 1900 Baudin meteorological spirit thermometer bulb exhibited intense Pb X-ray emission lines (10.55, 12.66, and 14.76 keV). Uncorrected LiG thermometer non-linearity leaves 1σ = ±0.27 °C uncertainty in land-surface air temperatures prior to 1981. The 2σ = ±0.43 °C from LiG resolution and non-linearity obscures most of the 20th century GSATA trend. Systematic sensor-measurement errors are highly pair-wise correlated, possibly across hundreds of km. Non-normal distributions of bucket and engine-intake difference SSTs disconfirm the assumption of random measurement error. Semivariogram analysis of ship SST measurements yields half the error difference mean, ±½Δε1,2, not the error mean. Transfer-function adjustment following a change of land station air-temperature sensor eliminates measurement independence and forward-propagates the antecedent uncertainty. LiG resolution limits, non-linearity, and sensor field calibrations yield GSATA mean ±2σ RMS uncertainties of, 1900–1945, ±1.7 °C; 1946–1980, ±2.1 °C; 1981–2004, ±2.0 °C; and 2005–2010, ±1.6 °C. Finally, the 20th century (1900–1999) GSATA, 0.74 ± 1.94 °C, does not convey any information about rate or magnitude of temperature change.

Detecting the causal influence of thermal environments among climate regions in the United States

The quantification of cross-regional interactions for the atmospheric transport processes is of crucial importance to improve the predictive capacity of climatic and environmental system modeling. The dynamic interactions in these complex systems are often nonlinear and non-separable, making conventional approaches of causal inference, such as statistical correlation or Granger causality, infeasible or ineffective. In this study, we applied an advanced approach, based on the convergent cross mapping algorithm, to detect and quantify the causal influence among different climate regions in the contiguous U.S. in response to temperature perturbations using the long-term (1901–2018) climatology of near surface air temperature record. Our results show that the directed causal network constructed by convergent cross mapping algorithm, enables us to distinguish the causal links from spurious ones rendered by statistical correlation. We also find that the Ohio Valley region, as an atmospheric convergent zone, acts as the regional gateway and mediator to the long-term thermal environments in the U.S. In addition, the temporal evolution of dynamic causality of temperature exhibits superposition of periodicities at various time scales, highlighting the impact of prominent low frequency climate variabilities such as El Niño–Southern Oscillation. The proposed method in this work will help to promote novel system-based and data-driven framework in studying the integrated environmental system dynamics.

Rapid Warming Over East Antarctica Since the 1940s Caused by Increasing Influence of El Niño Southern Oscillation and Southern Annular Mode

El Niño Southern Oscillation (ENSO), Interdecadal Pacific Oscillations (IPO), and their phase relation with the Southern Annular Mode (SAM) largely control Antarctic climate variability. The relative roles of these climate modes remain elusive, particularly in the backdrop of global warming. In this study, we present a seasonally resolved new ice core (IND33) record of oxygen isotope (δ18O) for the past two centuries (1809–2013 CE) from coastal Dronning Maud Land (DML) to investigate the role of these climate modes in the Antarctic temperature variability and trend. Our investigation based on this record combined with available records from the DML region reveals that ∼32% variability in δ18O records is related to late spring to summer (Nov–Dec–Jan) temperature rather than the mean annual temperature. This indicates that reconstructed annual temperature based on Antarctic ice core δ18O records could be biased toward the temperature of the months/seasons of higher precipitation with low-moderate wind speed, which are suitable for better preservation of the ice core signal. We have reconstructed the DML temperature record of the past two centuries (1809–2019 CE) at an annual resolution based on the δ18O ice core record (1809–1993 CE) combined with the recent ERA5 surface air temperature record (1994–2019 CE). The reconstructed temperature anomaly record reveals a significant cooling trend in the 19th century during 1809–1907 CE with a rate of −0.164 ± 0.045°C decade−1 followed by a warming trend from the mid-20th to early 21st centuries (1942–2019 CE) with a rate of +0.452 ± 0.056°C decade−1. This long-term warming trend since the 1940s coincides with the increase in ENSO events and its strong antiphase relation with SAM, suggesting an increasing influence of SAM–ENSO coupling in modulating the DML temperature in recent decades.

Inhomogeneity of the surface air temperature record from Halley, Antarctica

AbstractCommencing in 1956, observations made at Halley Research Station, Antarctica provide one of the longest continuous series of near-surface temperature observations from the Antarctic continent. Since few other records of comparable length are available, the Halley record has been used extensively in studies of long-term Antarctic climate variability and change. The record does not, however, come from a single location but is a composite of observations from a sequence of seven stations, all situated on the Brunt Ice Shelf, that range from around 10 km to 50 km distance from the coast. Until now, it has generally been assumed that temperature data from all of these stations could be combined into a single composite record with no adjustment. Here, we examine this assumption of homogeneity. Application of a statistical change point algorithm to the composite record detects a sudden cooling associated with the move from Halley IV to Halley V station in 1992. We show that this temperature step is consistent with local temperature gradients measured by a network of automatic weather stations and with those simulated by a high-resolution atmospheric model. These temperature gradients are strongest in the coastal region and result from the onshore advection of maritime air. The detected inhomogeneity could account for the weak cooling trend seen in the uncorrected composite record. In future, studies that make use of the Halley record will need to account for its inhomogeneity.

What could we learn about climate sensitivity from variability in the surface temperature record?

Abstract. We examine what can be learnt about climate sensitivity from variability in the surface air temperature record over the instrumental period, from around 1880 to the present. While many previous studies have used trends in observational time series to constrain equilibrium climate sensitivity, it has also been argued that temporal variability may also be a powerful constraint. We explore this question in the context of a simple widely used energy balance model of the climate system. We consider two recently proposed summary measures of variability and also show how the full information content can be optimally used in this idealised scenario. We find that the constraint provided by variability is inherently skewed, and its power is inversely related to the sensitivity itself, discriminating most strongly between low sensitivity values and weakening substantially for higher values. It is only when the sensitivity is very low that the variability can provide a tight constraint. Our investigations take the form of “perfect model” experiments, in which we make the optimistic assumption that the model is structurally perfect and all uncertainties (including the true parameter values and nature of internal variability noise) are correctly characterised. Therefore the results might be interpreted as a best-case scenario for what we can learn from variability, rather than a realistic estimate of this. In these experiments, we find that for a moderate sensitivity of 2.5 ∘C, a 150-year time series of pure internal variability will typically support an estimate with a 5 %–95% range of around 5 ∘C (e.g. 1.9–6.8 ∘C). Total variability including that due to the forced response, as inferred from the detrended observational record, can provide a stronger constraint with an equivalent 5 %–95 % posterior range of around 4 ∘C (e.g. 1.8–6.0 ∘C) even when uncertainty in aerosol forcing is considered. Using a statistical summary of variability based on autocorrelation and the magnitude of residuals after detrending proves somewhat less powerful as a constraint than the full time series in both situations. Our results support the analysis of variability as a potentially useful tool in helping to constrain equilibrium climate sensitivity but suggest caution in the interpretation of precise results.

Australia’s Air Temperature Trend Reviewed

The hypothesis of an artificially exaggerated temperature trend in the Australian continental surface air temperature record is tested via comparison with four other records of temperature measured in the Australian region. The trends extracted from all five records are consistent, so the hypothesis of bias in the Bureau of Meteorology’s Australian surface air temperature record cannot be sustained and is rejected. Using three different methods of trend estimation applied to five temperature anomaly time series, the anthropogenic contribution to warming of the Australian region since 1950 is determined to have occurred at a rate of 0.12 ± 0.02K per decade, which translates to a total anthropogenic warming contribution of 0.78 ± 0.13K over the period 1950 to 2015.

Australia's Air Temperature Trend Reviewed

The hypothesis of an artificially exaggerated temperature trend in the Australian continental surface air temperature record is tested via comparison with four other records of temperature measured in the Australian region. The trends extracted from all five records are consistent, so the hypothesis of bias in the Bureau of Meteorology’s Australian surface air temperature record cannot be sustained and is rejected. Using three different methods of trend estimation applied to five temperature anomaly time series, the anthropogenic contribution to warming of the Australian region since 1950 is determined to have occurred at a rate of 0.12 ± 0.02K per decade, which translates to a total anthropogenic warming contribution of 0.78 ± 0.13K over the period 1950 to 2015.

Negligence, Non-Science, and Consensus Climatology

The purported consensus that human greenhouse gas emissions have causally dominated the recent climate warming depends decisively upon three lines of evidence: climate model projections, reconstructed paleo-temperatures, and the instrumental surface air temperature record. However, CMIP5 climate model simulations of global cloud fraction reveal theory-bias error. Propagation of this cloud forcing error uncovers a r.s.s.e. uncertainty 1σ ≈ ±15 C in centennially projected air temperature. Causal attribution of warming is therefore impossible. Climate models also fail to reproduce targeted climate observables. For their part, consensus paleo-temperature reconstructions deploy an improper ‘correlation = causation’ logic, suborn physical theory, and represent a descent into pseudo-science. Finally, the published global averaged surface air temperature record completely neglects systematic instrumental error. The average annual systematic measurement uncertainty, 1σ = ±0.5 C, completely vitiates centennial climate warming at the 95% confidence interval. The entire consensus position fails critical examination and evidences pervasive analytical negligence.

Impact of the Atlantic Multidecadal Oscillation (AMO) on deriving anthropogenic warming rates from the instrumental temperature record

Abstract. The instrumental surface air temperature record has been used in several statistical studies to assess the relative role of natural and anthropogenic drivers of climate change. The results of those studies varied considerably, with anthropogenic temperature trends over the past 25–30 years suggested to range from 0.07 to 0.20 °C decade−1. In this short communication, we assess the origin of these differences and highlight the inverse relation between the temperature trend of the past 30 years and the weight given to the Atlantic Multidecadal Oscillation (AMO) as an explanatory factor in the multiple linear regression (MLR) tool that is usually employed. We highlight that robust MLR outcomes require a better understanding of the AMO in general and, more specifically, of its characterization. Our results indicate that both the high and the low end of the anthropogenic trend over the past 30 years found in previous studies are unlikely and that a transient climate response of 1.6 (1.0–3.3) °C best captures the historic instrumental temperature record.

Independent observations corroborate surface air temperature record

One of the most important foundations of scientists' understanding of global climate change is the land surface air temperature record, the long‐term observations of air temperature measured 2 meters above the ground. These observations have been made around the world, for more than a century in some places. The air temperature records have shown a long‐term warming trend due mainly to anthropogenic climate change, and variability seen in the air temperature record is used to guide models of the future climate.

Imposed and Neglected Uncertainty in the Global Average Surface Air Temperature Index

The statistical error model commonly applied to monthly surface station temperatures assumes a physically incomplete climatology that forces deterministic temperature trends to be interpreted as measurement errors. Large artefactual uncertainties are thereby imposed onto the global average surface air temperature record. To illustrate this problem, representative monthly and annual uncertainties were calculated using air temperature data sets from globally distributed surface climate stations, yielding ±2.7 C and ±6.3 C, respectively. Further, the magnitude uncertainty in the 1961–1990 global air temperature annual anomaly normal, entirely neglected until now, is found to be ±0.17 C. After combining magnitude uncertainty with the previously reported ±0.46 C lower limit of measurement error, the 1856–2004 global surface air temperature anomaly with its 95% confidence interval is 0.8±0.98 C, Thus, the global average surface air temperature trend is statistically indistinguishable from 0 C. Regulatory policies aimed at influencing global surface air temperature are not empirically justifiable.

A perspective on decadal climate variability and predictability

The global surface air temperature record of the last 150 years is characterized by a long-term warming trend, with strong multidecadal variability superimposed. Similar multidecadal variability is also seen in other (societal important) parameters such as Sahel rainfall or Atlantic hurricane activity. The existence of the multidecadal variability makes climate change detection a challenge, since global warming evolves on a similar timescale. The ongoing discussion about a potential anthropogenic signal in the Atlantic hurricane activity is an example. A lot of work was devoted during the last years to understand the dynamics of the multidecadal variability, and external and internal mechanisms were proposed. This review paper focuses on two aspects. First, it describes the mechanisms for internal variability using a stochastic framework. Specific attention is given to variability of the Atlantic Meridional Overturning Circulation (AMOC), which is likely the origin of a considerable part of decadal variability and predictability in the Atlantic Sector. Second, the paper discusses decadal predictability and the factors limiting its realization. These include a poor understanding of the mechanisms involved and large biases in state-of-the-art climate models. Enhanced model resolution, improved subgrid scale parameterisations, and the inclusion of additional climate subsystems, such as a resolved stratosphere, may help overcome these limitations.

Spectral Analysis of the Svalbard Temperature Record 1912–2010

Climate development with possible anthropogenic effects occurs on a background of natural climatic variations, which may be considerable, and especially in the Arctic. Natural climate variations however remain poorly understood, although they remain important for discriminating between natural and anthropogenic influences on current climate change. Using the Svalbard (78°N) surface air temperature record 1912–2010 as an example, we here suggest a road ahead to identify and describe such natural climate variations. By means of Fourier and wavelet analysis the record is decomposed into time-frequency space, to extract information on periodic signals and their amplitude and variation over time. By this we identify several cyclic variations on the time scale investigated. These oscillations are present in the annual record, as well as in seasonal subsets of the record. Using only three oscillations it is possible to hindcast the Svalbard temperature record well. We suggest that such persistent oscillations may be used for forecasting the overall features of future temperature changes for a limited period, about 10–25% of the record length. Our main focus is on identifying the character of recurrent natural temperature variations, but we also comment briefly on possible physical explanations for some of the identified cyclic variations.

Urban heat island effects on estimates of observed climate change

AbstractUrban heat islands are a result of the physical properties of buildings and other structures, and the emission of heat by human activities. They are most pronounced on clear, calm nights; their strength depends also on the background geography and climate, and there are often cool islands in parks and less‐developed areas. Some old city centers no longer show warming trends relative to rural neighbourhoods, because urban development has stabilised. This article reviews the effects that urban heat islands may have on estimates of global near‐surface temperature trends. These effects have been reduced by avoiding or adjusting urban temperature measurements. Comparisons of windy weather with calm‐weather air temperature trends for a worldwide set of observing sites suggest that global near‐surface temperature trends have not been greatly affected by urban warming trends; this is supported by comparisons with marine surface temperatures. The use of dynamical‐model‐based reanalyses to estimate urban influences has been hindered by the heterogeneity of the data input to the reanalyses and by biases in the models. However, improvements in reanalyses are increasing their utility for assessing the surface air temperature record. High‐resolution climate models and data on changing land use offer potential for future assessment of worldwide urban warming influences. The latest assessments of the likely magnitude of the residual urban trend in available global near‐surface temperature records are summarized, along with the uncertainties of these residual trends. Copyright © 2010 John Wiley & Sons, Ltd.This article is categorized under: Paleoclimates and Current Trends > Detection and Attribution

Borehole temperatures and tree rings: Seasonality and estimates of extratropical Northern Hemispheric warming

We construct an extratropical reduced temperature–depth profile for land areas north of 20°N latitude from the global borehole temperature database compiled for climate reconstruction. The mean reduced temperature profile compares well with a time series constructed from an initial baseline temperature (0.6° ± 0.1°C) and the last 140 years of gridded annual surface air temperature data diffused into the ground. This analysis yields a root‐mean‐square misfit of only 15 mK and indicates warming of 1.1°C over the past 500 years. In contrast, a tree ring analysis from the same area (Briffa et al., 2001) indicates considerably less warming over the same time period. The recognition that tree rings correlate most strongly with warm season temperatures (April–September), while boreholes reflect annual temperatures, offers an explanation for the discrepancy in warming estimates. This analysis yields a reconstruction of surface temperature over the past 500 years that is consistent with both the borehole and tree ring analysis and also provides an estimate of long‐term cold season temperature. We estimate that continental extratropical Northern Hemisphere annual and cold season (October–March) temperatures have warmed by 0.2° ± 0.1°C and 0.3° ± 0.3°C, respectively, between 1500 and 1856, prior to the start of the instrumental surface air temperature record.

Variable solar irradiance as a plausible agent for multidecadal variations in the Arctic‐wide surface air temperature record of the past 130 years

This letter offers new evidence motivating a more serious consideration of the potential Arctic temperature responses as a consequence of the decadal, multidecadal and longer‐term persistent forcing by the ever‐changing solar irradiance both in terms of total solar irradiance (TSI, i.e., integrated over all wavelengths) and the related UV irradiance. The support for such a solar modulator can be minimally derived from the large (>75%) explained variance for the decadally‐smoothed Arctic surface air temperatures (SATs) by TSI and from the time‐frequency structures of the TSI and Arctic SAT variability as examined by wavelet analyses. The reconstructed Arctic SAT time series based on the inverse wavelet transform, which includes decadal (5–15 years) and multidecadal (40–80 years) variations and a longer‐term trend, contains nonstationary but persistent features that are highly correlated with the Sun's intrinsic magnetic variability especially on multidecadal time scales.

Analysis of mean, maximum, and minimum temperature in Athens from 1897 to 2001 with emphasis on the last decade: trends, warm events, and cold events

The 105-year (1897–2001) surface air temperature record of the National Observatory of Athens (NOA) has been analyzed to determine indications of significant deviations from long-term average features in the city of Athens. The analysis of the whole record reveals a tendency towards warmer years, with significantly warmer summer and spring periods and slightly warmer winters (an increase of 1.23 and 0.34 °C has been observed in the mean summer and mean winter temperature, respectively). The tendency is more pronounced for the summer and spring maximum temperature, but marginal for the minimum temperature of the cold season. On a monthly basis, a statistically significant (at the 95th confidence level) warming trend has been observed in the average maximum temperature of May and June. The trend analysis for the last decade of the record (1992–2001) revealed a significant increase for both warm and cold seasons, yet maximum and minimum temperature. Extreme temperatures (high/low temperatures above/below a certain threshold value) and extreme events (prolonged extreme temperatures) have also been studied. The number of hot days as well as the frequency of occurrence and duration of warm events have significantly increased during the last decade, while a negative trend is observed in the frequency of low temperatures and the duration of cold events especially after 1960.

Surface air temperature and its changes over the past 150 years

We review the surface air temperature record of the past 150 years, considering the homogeneity of the basic data and the standard errors of estimation of the average hemispheric and global estimates. We present global fields of surface temperature change over the two 20‐year periods of greatest warming this century, 1925–1944 and 1978–1997. Over these periods, global temperatures rose by 0.37° and 0.32°C, respectively. The twentieth‐century warming has been accompanied by a decrease in those areas of the world affected by exceptionally cool temperatures and to a lesser extent by increases in areas affected by exceptionally warm temperatures. In recent decades there have been much greater increases in night minimum temperatures than in day maximum temperatures, so that over 1950–1993 the diurnal temperature range has decreased by 0.08°C per decade. We discuss the recent divergence of surface and satellite temperature measurements of the lower troposphere and consider the last 150 years in the context of the last millennium. We then provide a globally complete absolute surface air temperature climatology on a 1° × 1° grid. This is primarily based on data for 1961–1990. Extensive interpolation had to be undertaken over both polar regions and in a few other regions where basic data are scarce, but we believe the climatology is the most consistent and reliable of absolute surface air temperature conditions over the world. The climatology indicates that the annual average surface temperature of the world is 14.0°C (14.6°C in the Northern Hemisphere (NH) and 13.4°C for the Southern Hemisphere). The annual cycle of global mean temperatures follows that of the land‐dominated NH, with a maximum in July of 15.9°C and a minimum in January of 12.2°C.

Simulation of 20th century temperature trends

Results are reported from simulations with an atmospheric general circulation model (GCM) covering the 20th century. These results focus primarily on the continental surface air temperature (SAT) record, with some discussion of large spatial scale precipitation averages as well. These experiments were conducted using the Max Planck Institute for Meteorology ECHAM3 GCM configured at triangular‐21 truncation, giving a spatial resolution of approximately 5.5°. The surface boundary conditions for the model were constructed by forming decadal climatologies of sea surface temperature (SST) data from the Global SST Atlas (GOSSTA) data set. No changes in greenhouse gas concentrations were made during the experiments. The GCM was then integrated for 5 years with each climatology. Because the high southern latitudes are poorly sampled and show considerable high‐amplitude variability in the GOSSTA data, two complete experiments were conducted. In one experiment the time‐varying GOSSTA data were prescribed globally (the GLBL simulation), in the other, SSTs in the high southern latitudes were held at the 1950–1969 climatology (the NO_SH simulation). The results show both GCM simulations reproduce important features of the observed 20th century global temperature record, suggesting that the low‐frequency variability in global average SAT is modulated to an important degree by variability in SSTs. In the model results, the changes in SST are transmitted to the atmosphere via latent heat flux, i.e., by changes in the flux of water through the hydrologic cycle. The most notable difference between the GLBL and NO_SH SAT records is that during the 1920–1940 period the NO_SH results agree more closely with observations, while the GLBL results are superior from the 1950s forward. At least in part, these differences appear to be linked to differences in simulated sea‐ice extent in the two simulations. Analyses of large‐scale averages in continental precipitation show good model‐observation agreement in the tropics (±30° latitude) and in the extratropical southern hemisphere; however, the upward trend in extratropical NH continental precipitation seen in the observed record is not reproduced in either simulation.

An analysis of a 34-year air temperature record from Fossil Bluff (71°S, 68°W), Antarctica

An analysis of a long-term surface air temperature record for Fossil Bluff in the George VI Sound, West Antarctic Peninsula (WAP) documents in detail some important aspects of the climate of this area for the first time. The analysis identifies the close dependency of air temperatures on latitude in the WAP but reveals that the strength of this dependency is greatest in winter. This result along with others leads to the Fossil Bluff climate regime being characterized as ‘continental’ rather than ‘maritime’ as found further north. The WAP as a whole displays large interannual temperature variability but this is greatest in Marguerite Bay rather than the Fossil Bluff area. Evidence is also provided for secular climatic change appearing in summer throughout the WAP over the last few decades. The representativeness of existing Antarctic Peninsula annual air temperature climatologies, based mainly on snow temperature measurements, for the winter and summer periods is also noted.