Pronounced differences between observed and CMIP5‐simulated multidecadal climate variability in the twentieth century

Kravtsov, Sergey

doi:10.1002/2017gl074016

Cited by 56 publications

(58 citation statements)

References 59 publications

(68 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The externally forced component of the simulated variability accounts for more than 60% of upwelling-favorable meridional windstress increase off Chile, while a negative IPO canonical internal variability pattern has no significant contribution to the meridional windstress positive trend over the same period. In the real world the IPO has a different spatial structure, amplitude and time behaviour to that in CMIP5-class models (Kravtsov, 2017). Analyses of observed decadal trends in SST, wind…”

Section: Discussionmentioning

confidence: 99%

Contributions of Internal Variability and External Forcing to the Recent Trends in the Southeastern Pacific and Peru–Chile Upwelling System

et al. 2020

View full text Add to dashboard Cite

In a warming world context, Sea Surface Temperature (SST) off central-south Peru, northern Chile and further offshore increases at a slower rate than the global average since several decades, i.e. cools, relative to the global average. This tendency is synchronous with an Interdecadal Pacific Oscillation (IPO) negative trend since ∼1980, which has a cooling signature in the southeastern Pacific. Here, we use a large ensemble of historical coupled model simulations to investigate the relative roles of internal variability (and in particular the IPO) and external forcing in driving this relative regional cooling, and the associated mechanisms. The ensemble-mean reproduces the relative cooling, in response to an externally-forced southerly wind anomaly, which strengthens the upwelling off Chile in recent decades. This southerly wind anomaly results from the poleward expansion of the Southern Hemisphere Hadley Cell. Attribution experiments reveal that this poleward expansion and the resulting enhanced upwelling mostly occur in response to increasing greenhouse gases and stratospheric ozone depletion since ∼1980. An oceanic heat budget confirms that the wind-forced upwelling enhancement dominates the relative cooling near the coast. In contrast, a wind-forced deepening of the mixed layer drives the offshore cooling. While internal variability contributes to the spread of tendencies, the ensemble-mean relative cooling in the southeastern Pacific is consistent with observations and occurs irrespectively of the IPO phase, hence indicating the preeminent role of external forcing.

show abstract

Section: Discussionmentioning

confidence: 99%

Contributions of Internal Variability and External Forcing to the Recent Trends in the Southeastern Pacific and Peru–Chile Upwelling System

et al. 2020

View full text Add to dashboard Cite

show abstract

“…This is highly relevant to both decadal predictability of future change and efforts to improve detection and attribution of climate trends that have occurred in the past. Recent studies have highlighted that a large proportion of contemporary climate models exhibit weak multidecadal twentieth century NA climate variability when compared to observations (Cheung et al, 2017;Han et al, 2016;Kravtsov, 2017;Wang et al, 2017;Zhang & Wang, 2013). Further, many models exhibit weaker-than-observed links between the North Atlantic Oscillation (NAO) and low-frequency phenomena such as Atlantic multidecadal variability (AMV; Ba et al, 2014;Keeley et al, 2012;Kim et al, 2018;Omrani et al, 2014;Peings et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Do CMIP5 Models Reproduce Observed Low‐Frequency North Atlantic Jet Variability?

Bracegirdle

Eade

et al. 2018

Geophysical Research Letters

View full text Add to dashboard Cite

The magnitude of observed multidecadal variations in the North Atlantic Oscillation (NAO) in winter is at the upper end of the range simulated by climate models and a clear explanation for this remains elusive. Recent research shows that observed multidecadal winter NAO variability is more strongly associated with North Atlantic (NA) jet strength than latitude, thus motivating a comprehensive comparison of NA jet and NAO variability across the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Our results show that the observed peak in multidecadal jet strength variability is even more unusual than NAO variability when compared to the model‐simulated range across 133 historical CMIP5 simulations. Some CMIP5 models appear capable of reproducing the observed low‐frequency peak in jet strength, but there are too few simulations of each model to clearly identify which. It is also found that an observed strong multidecadal correlation between jet strength and NAO since the mid‐nineteenth century may be specific to this period.

show abstract

“…[16][17][18][19] Irrespective of exact methodology used to infer the internal component of the observed DCV, it appears that climate model simulations tend to underestimate its magnitude and fall short of faithfully replicating its spatial patterns. 15,16,18,[20][21][22][23] These deficiencies may have substantially contributed to climate models' apparent lack of skill in reproducing recent decadal slowdown, or "hiatus" in the near-surface global warming of the Earth, although multiple factors could be at play. [22][23][24][25][26][27] Similar decadal discrepancies between modelled and observed decadal climate trends are ubiquitous throughout the twentieth century.…”

Section: Introductionmentioning

confidence: 99%

Global-scale multidecadal variability missing in state-of-the-art climate models

Kravtsov

Grimm

2018

npj Clim Atmos Sci

Self Cite

View full text Add to dashboard Cite

Reliability of future global warming projections depends on how well climate models reproduce the observed climate change over the twentieth century. In this regard, deviations of the model-simulated climate change from observations, such as a recent "pause" in global warming, have received considerable attention. Such decadal mismatches between model-simulated and observed climate trends are common throughout the twentieth century, and their causes are still poorly understood. Here we show that the discrepancies between the observed and simulated climate variability on decadal and longer timescale have a coherent structure suggestive of a pronounced Global Multidecadal Oscillation. Surface temperature anomalies associated with this variability originate in the North Atlantic and spread out to the Pacific and Southern oceans and Antarctica, with Arctic following suit in about 25-35 years. While climate models exhibit various levels of decadal climate variability and some regional similarities to observations, none of the model simulations considered match the observed signal in terms of its magnitude, spatial patterns and their sequential time development. These results highlight a substantial degree of uncertainty in our interpretation of the observed climate change using current generation of climate models.

show abstract

Pronounced differences between observed and CMIP5‐simulated multidecadal climate variability in the twentieth century

Cited by 56 publications

References 59 publications

Contributions of Internal Variability and External Forcing to the Recent Trends in the Southeastern Pacific and Peru–Chile Upwelling System

Contributions of Internal Variability and External Forcing to the Recent Trends in the Southeastern Pacific and Peru–Chile Upwelling System

Do CMIP5 Models Reproduce Observed Low‐Frequency North Atlantic Jet Variability?

Global-scale multidecadal variability missing in state-of-the-art climate models

Contact Info

Product

Resources

About