Do Models Underestimate the Solar Contribution to Recent Climate Change?

Stott, Peter A.; Jones, Gareth S.; Mitchell, J. F. B.

doi:10.1175/1520-0442(2003)016<4079:dmutsc>2.0.co;2

Cited by 93 publications

(87 citation statements)

References 46 publications

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“…The sensitivity to SST also highlights the need for the reliable reconstruction of the historical evolution, especially before 1950. The early 20th-century Arctic warming may be partly due to the increased GHGs, reduced volcanic aerosols, and solar irradiance changes (11,12,(49)(50)(51)(52)(53). However, it remains challenging to quantify their contribution due to limited observations and uncertainties of model response (54).…”

Section: Summary and Discussionmentioning

confidence: 99%

Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability

Tokinaga

Xie

Mukougawa

2017

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

119

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With amplified warming and record sea ice loss, the Arctic is the canary of global warming. The historical Arctic warming is poorly understood, limiting our confidence in model projections. Specifically, Arctic surface air temperature increased rapidly over the early 20th century, at rates comparable to those of recent decades despite much weaker greenhouse gas forcing. Here, we show that the concurrent phase shift of Pacific and Atlantic interdecadal variability modes is the major driver for the rapid early 20th-century Arctic warming. Atmospheric model simulations successfully reproduce the early Arctic warming when the interdecadal variability of sea surface temperature (SST) is properly prescribed. The early 20th-century Arctic warming is associated with positive SST anomalies over the tropical and North Atlantic and a Pacific SST pattern reminiscent of the positive phase of the Pacific decadal oscillation. Atmospheric circulation changes are important for the early 20th-century Arctic warming. The equatorial Pacific warming deepens the Aleutian low, advecting warm air into the North American Arctic. The extratropical North Atlantic and North Pacific SST warming strengthens surface westerly winds over northern Eurasia, intensifying the warming there. Coupled ocean-atmosphere simulations support the constructive intensification of Arctic warming by a concurrent, negative-to-positive phase shift of the Pacific and Atlantic interdecadal modes. Our results aid attributing the historical Arctic warming and thereby constrain the amplified warming projected for this important region. T he Arctic has warmed faster than the global average by a factor of 2 or more since the mid-20th century, a phenomenon known as the Arctic amplification. The recent temperature warming over the Arctic is strongly linked to a drastic reduction in sea ice extent since the 1970s, contributing to the Arctic amplification through positive ice-albedo feedbacks (1-3). A similar rapid warming occurred in the Arctic during the early 20th century (4-8). Compared with the recent warming, the early 20th-century Arctic warming (hereafter referred to as the early Arctic warming) is mysterious as greenhouse gas (GHG) radiative forcing was three to four times weaker than at present (9) and changes in sea ice extent were small (10). The comparison of these two warming epochs suggests that mechanisms other than GHG forcing are important for the early Arctic warming.Several hypotheses have been proposed for the early Arctic warming, including intensified natural forcing due to decreased volcanic aerosols and increased solar radiation (11, 12); increased cloud long-wave emissivity due to sulfate aerosols transported from Central Europe (6, 13); uncertain but possible reduction in the Arctic sea ice extent (4,5,14); variability of the North Atlantic ocean-ice-atmosphere system (15); and atmospheric internal variability (16). Neither coupled ocean-atmosphere models nor atmospheric models driven by historical radiative forcing and observed sea surface tempe...

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Section: Summary and Discussionmentioning

confidence: 99%

Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability

Tokinaga

Xie

Mukougawa

2017

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

119

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“…Detection-attribution studies using climate models have found a feedback amplification of the input centennial TSI variation by a factor of β S ≈ 3 (e.g. Stott et al 2003;Ingram 2006), which would reduce the required TSI change to near 10 W m −2 . However, one should note that some of this amplification may be unreal and due to a metrology factor (discussed in §9), which has been reported as exaggerating the downward drift in GMAST in the middle of the twentieth century.…”

Section: Some Basic Considerationsmentioning

confidence: 99%

Solar change and climate: an update in the light of the current exceptional solar minimum

2009

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“…Recent climate models suggest that reconstructions of Earth's climate would be more compatible with smaller irradiance variations (Feulner 2011;Schmidt et al 2012), but earlier work did indicate that solar influences may have been underestimated (Stott et al 2003). In this Note we examine the TSI reconstructions of S2011 the light of relevant solar and stellar data.…”

Section: Introductionmentioning

confidence: 98%

Confronting a solar irradiance reconstruction with solar and stellar data

Judge

Lockwood

Radick

et al. 2012

A&A

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Context. A recent paper by Shapiro and colleagues (2011, A&A, 529, A67) reconstructs spectral and total irradiance variations of the Sun during the holocene. Aims. In this note, we comment on why their methodology leads to large (0.5%) variations in the solar TSI on century-long time scales, in stark contrast to other reconstructions which have < ∼ 0.1% variations. Methods. We examine the amplitude of the irradiance variations from the point of view of both solar and stellar data. Results. Shapiro et al.'s large amplitudes arise from differences between the irradiances computed from models A and C of Fontenla and colleagues, and from their explicit assumption that the radiances of the quiet Sun vary with the cosmic ray modulation potential. We suggest that the upper photosphere, as given by model A, is too cool, and discuss relative contributions of local vs. global dynamos to the magnetism and irradiance of the quiet Sun. We compare the slow (>22 yr) components of the irradiance reconstructions with secular changes in stellar photometric data that span 20 years or less, and find that the Sun, if varying with such large amplitudes, would still lie within the distribution of stellar photometric variations measured over a 10−20 year period. However, the stellar time series are individually too short to see if the reconstructed variations will remain consistent with stellar variations when observed for several decades more. Conclusions. By adopting model A, Shapiro et al. have over-estimated quiet-Sun irradiance variations by about a factor of two, based upon a re-analysis of sub-mm data from the James Clerk Maxwell telescope. But both estimates are within bounds set by current stellar data. It is therefore vital to continue accurate photometry of solar-like stars for at least another decade, to reveal secular and cyclic variations on multi-decadal time scales of direct interest to the Sun.

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Do Models Underestimate the Solar Contribution to Recent Climate Change?

Cited by 93 publications

References 46 publications

Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability

Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability

Solar change and climate: an update in the light of the current exceptional solar minimum

Confronting a solar irradiance reconstruction with solar and stellar data

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