On past temperatures and anomalous late‐20th‐century warmth

Mann, Michael; Amman, Caspar; Bradley, R. S.; Briffa, Keith R.; Jones, Philip; Crowley, T. J.; Hughes, Malcolm K.; Oppenheimer, Michael; Overpeck, Jonathan T.; Rutherford, Scott; Trenberth, Kevin E.; Wigley, T. M. L.

doi:10.1029/2003eo270003

Cited by 109 publications

(68 citation statements)

References 31 publications

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“…The two most intense El Niño events in more than a century occurred in 1982-1983 and 1997-1998, while the longest event in the instrumental record was experienced between 1990 and 1995 (Allan and D'Arrigo, 1999;Allan et al, 2003;Folland et al, 2001;Trenberth and Hoar, 1996). The long-term context of these apparently anomalous events is still being debated (Crowley, 2000;Folland et al, 2001;Mann, 2003;Soon and Baliunas, 2003). Recent research has sought to further clarify whether the modern behaviour of ENSO is indeed a manifestation of human-induced global warming (Folland et al, 2001;Timmermann, 2001;Tsonis et al, 2003), or simply an expression of natural decadal or multi-centennial climate variability (Jones and Mann, 2004).…”

Section: Introductionmentioning

confidence: 99%

Classification of synchronous oceanic and atmospheric El Niño-Southern Oscillation (ENSO) events for palaeoclimate reconstruction

Gergis

Fowler

2005

Int. J. Climatol.

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Since the mid-1970s, ENSO has changed in character to a predominance of El Niño conditions, the extreme phase of which appears coincidental with increases in global temperature records. Instrumental time series (<150 years) are too short to adequately address the significance of late twentieth-century ENSO variability, thus, multi-century palaeoclimate reconstructions derived from long proxy records are sought. Despite the global influence exerted by ENSO on society, limited consensus exists within the scientific community as to which index best defines the timing, duration and strength of events. Here we address issues associated with the complexity of ENSO characterisation by comparing the 'event capture' ability of two currently used indices of ENSO. It is suggested that the use of a sole ENSO index is undesirable as a given index is only indicative of one physical aspect of the phenomenon, and as such is unlikely to be representative of the wider interactions experienced in the coupled ocean-atmospheric system. In an attempt to describe more of the nature and evolution of ENSO events, the Coupled ENSO Index (CEI) classification scheme was devised to identify synchronous oceanic (Niño 3.4 SST) and atmospheric (Southern Oscillation Index) anomalies associated with ENSO for the instrumental period . The CEI is of practical relevance to the ENSO community as it provides an amplitude preserving instrumental baseline for the calibration of proxy records to reconstruct both components of the ENSO system. Analysis of the nature of instrumental ENSO events from the CEI suggests that the frequency and intensity of post-1970 ENSO events (when 50% of all extreme events identified occur) appears the most anomalous in the context of at least the past century. It is hoped that the CEI will facilitate palaeo-ENSO research to systematically resolve the long-term context of past ENSO behaviour to assess whether the apparently anomalous nature of late twentieth-century variability is unprecedented within existing palaeoclimate archives.

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Section: Introductionmentioning

confidence: 99%

Classification of synchronous oceanic and atmospheric El Niño-Southern Oscillation (ENSO) events for palaeoclimate reconstruction

Gergis

Fowler

2005

Int. J. Climatol.

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“…Whereas such approaches show that the Atlantic Multidecadal Oscillation (AMO), the North Atlantic Oscillation (NAO), and Atlantic Meridional Overturning Circulation (AMOC) have a substantial influence on Atlantic climate (e.g., ref. 4) they are still unable to capture details that are critical for determining the spatiotemporal distribution of climate oscillations (5,6) and their associated impacts (7). For example, whereas the AMO, which models suggest reflects multidecadal variation in the AMOC (8), is the dominant influence on summer climate in the United Kingdom (9), at higher European latitudes, seasonal terrestrial tree-ring climate records (6,10) are not representative of high-latitude sea surface temperatures (11).…”

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confidence: 99%

“…Similarly, SST, AMO, and AMOC variations are not well represented at high spatiotemporal resolution beyond the instrumental record in North East Atlantic shallow inshore waters (for example 55°50'N 05°50'W). This information is needed to better understand rates of regional climate variability (5).…”

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confidence: 99%

North Atlantic summers have warmed more than winters since 1353, and the response of marine zooplankton

Kamenos

2010

Proc. Natl. Acad. Sci. U.S.A.

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Modeling and measurements show that Atlantic marine temperatures are rising; however, the low temporal resolution of models and restricted spatial resolution of measurements (i) mask regional details critical for determining the rate and extent of climate variability, and (ii) prevent robust determination of climatic impacts on marine ecosystems. To address both issues for the North East Atlantic, a fortnightly resolution marine climate record from 1353-2006 was constructed for shallow inshore waters and compared to changes in marine zooplankton abundance. For the first time summer marine temperatures are shown to have increased nearly twice as much as winter temperatures since 1353. Additional climatic instability began in 1700 characterized by ∼5-65 year climate oscillations that appear to be a recent phenomenon. Enhanced summer-specific warming reduced the abundance of the copepod Calanus finmarchicus, a key food item of cod, and led to significantly lower projected abundances by 2040 than at present. The faster increase of summer marine temperatures has implications for climate projections and affects abundance, and thus biomass, near the base of the marine food web with potentially significant feedback effects for marine food security.coralline algae | rhodolith | maerl | seasonal P rior to instrumentally derived temperature records that began in the 1850s, knowledge of seasonal and regional-scale marine temperature changes at high latitudes is limited. Thus at present, hemispheric Atlantic climatic patterns are deduced from multiproxy and instrumental networks using statistical (1, 2) and modeling (3) approaches. Whereas such approaches show that the Atlantic Multidecadal Oscillation (AMO), the North Atlantic Oscillation (NAO), and Atlantic Meridional Overturning Circulation (AMOC) have a substantial influence on Atlantic climate (e.g., ref. 4) they are still unable to capture details that are critical for determining the spatiotemporal distribution of climate oscillations (5, 6) and their associated impacts (7). For example, whereas the AMO, which models suggest reflects multidecadal variation in the AMOC (8), is the dominant influence on summer climate in the United Kingdom (9), at higher European latitudes, seasonal terrestrial tree-ring climate records (6, 10) are not representative of high-latitude sea surface temperatures (11). Limited spatiotemporal resolution, absent proxy validation and organism effects have restricted the distribution of current inshore proxy-derived sea surface temperature (SST) records (12-16). Therefore to date, we have a poor understanding of season specific temperature variability. Similarly, SST, AMO, and AMOC variations are not well represented at high spatiotemporal resolution beyond the instrumental record in North East Atlantic shallow inshore waters (for example 55°50'N 05°50'W). This information is needed to better understand rates of regional climate variability (5).Marine responses to such climate fluctuations are reflected in the productivity of marine ecosystems f...

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“…Even though paleoclimatic proxies, surface thermometers, satellites, and weather balloons are recording global warming, interpretations of these instrumental records have sometimes been contentious (4,5). Having measures of warming that are not based on the interpretations of these data allows independent testing of different external and internal factors influencing the climate.…”

mentioning

confidence: 99%

Human-modified temperatures induce species changes: Joint attribution

Root

MacMynowski

Mastrandrea

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

185

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Average global surface-air temperature is increasing. Contention exists over relative contributions by natural and anthropogenic forcings. Ecological studies attribute plant and animal changes to observed warming. Until now, temperature-species connections have not been statistically attributed directly to anthropogenic climatic change. Using modeled climatic variables and observed species data, which are independent of thermometer records and paleoclimatic proxies, we demonstrate statistically significant ''joint attribution,'' a two-step linkage: human activities contribute significantly to temperature changes and human-changed temperatures are associated with discernible changes in plant and animal traits. Additionally, our analyses provide independent testing of grid-box-scale temperature projections from a general circulation model (HadCM3).climate change ͉ double attribution ͉ global warming ͉ plant animal impacts ͉ regional climate change T he Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) Working Group I concluded that humans are changing the climate by injecting greenhouse gases and aerosols into the atmosphere (1). One line of evidence that was examined included temperature trends produced by the HadCM3 general circulation model (GCM) in response to three different scenarios: (i) only natural climatic forcings (hereafter called NF), (ii) only greenhouse gas and aerosol forcings (anthropogenic forcings, AF), and (iii) a coupling of both natural and anthropogenic forcings (combined forcings, CF). Stott and colleagues (2) compared surface-air temperature data from all three model runs to observed global surface-air temperatures. Results for the CF yield the closest match with observed temperatures over the 20th century, AF produce a good fit, but NF results are notably less skillful. Stott (3) has extended these methods to a regional analysis that yields similar results, further confirming the importance of AF for credible simulation of historical observed temperatures.Even though paleoclimatic proxies, surface thermometers, satellites, and weather balloons are recording global warming, interpretations of these instrumental records have sometimes been contentious (4, 5). Having measures of warming that are not based on the interpretations of these data allows independent testing of different external and internal factors influencing the climate. For instance, results from biological metaanalyses, which examined numerous studies to determine the occurrence of a biotic signal consistent with climatic change, indicated that ''. . . a significant impact of recent climatic warming is discernible in the form of long-term, large-scale alterations of animal and plant populations' ' (ref. 6, p. 59). The vast majority (Ϸ80%) of species exhibiting changes are shifting in the manner expected with increasing temperature (6). What has been lacking thus far, however, is statistical evidence that attributes a significant portion of the changes seen in plants and animals (6-8) directly to ...

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On past temperatures and anomalous late‐20th‐century warmth

Cited by 109 publications

References 31 publications

Classification of synchronous oceanic and atmospheric El Niño-Southern Oscillation (ENSO) events for palaeoclimate reconstruction

Classification of synchronous oceanic and atmospheric El Niño-Southern Oscillation (ENSO) events for palaeoclimate reconstruction

North Atlantic summers have warmed more than winters since 1353, and the response of marine zooplankton

Human-modified temperatures induce species changes: Joint attribution

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