A mathematical analysis of the divergence problem in dendroclimatology

Loehle, Craig

doi:10.1007/s10584-008-9488-8

Cited by 56 publications

(47 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another recently described method is based on visual inspection, where both I t and X t are scaled to zero mean and unit variance over some predefined period and then plotted and analyzed (e.g., Esper et al, 2010). Loehle (2009) discusses the special case where the correspondence between I t and X t is non-linear, either within the calibration period or outside of it. It is this latter case that we address below.…”

Section: Discussion Of Model (1)mentioning

confidence: 99%

“…However, as suggested by Loehle (2009), non-linearities may also appear in extreme cases where explanatory variables X t attain values not found during the calibration period. If this is the case, reconstructions will be less accurate during such times.…”

Section: Diagnostic Checks Climate Envelopementioning

confidence: 90%

“…The importance of this test has been stressed by Loehle (2009) within the context of dendroclimatic reconstructions. In addition to evaluation of scatterplots, we propose a second check for linearity, in which model (1) can be estimated with the extension of a quadratic term:…”

Section: Diagnostic Checks Climate Envelopementioning

confidence: 99%

“…A related phenomenon is that some formerly temperature sensitive trees may be losing their ability to reflect high-frequency climate signals in some boreal and alpine forests (e.g., Wilmking et al, 2005;Pisaric et al, 2007;Zhang et al, 2009;Büntgen et al, 2006Büntgen et al, , 2008Büntgen et al, , 2009). These observations have been described as the "Divergence Problem" (DP), which has been discussed in a number of recently published articles (e.g., Jansen et al, 2007;Wilson et al, 2007;D'Arrigo et al, 2008;Wilmking and Singh, 2008;Büntgen et al, 2009;Esper and Frank, 2009;Loehle, 2009). DP has not only led to discussions within the scientific community, but recently also to considerable controversy within the public arena (the "CRU affair", "climategate", the "trick").…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Detecting instabilities in tree-ring proxy calibration

et al. 2010

View full text Add to dashboard Cite

Abstract. Evidence has been found for reduced sensitivity of tree growth to temperature in a number of forests at high northern latitudes and alpine locations. Furthermore, at some of these sites, emergent subpopulations of trees show negative growth trends with rising temperature. These findings are typically referred to as the "Divergence Problem" (DP). Given the high relevance of paleoclimatic reconstructions for policy-related studies, it is important for dendrochronologists to address this issue of potential model uncertainties associated with the DP. Here we address this issue by proposing a calibration technique, termed "stochastic response function" (SRF), which allows the presence or absence of any instabilities in growth response of trees (or any other climate proxy) to their calibration target to be visualized and detected. Since this framework estimates confidence limits and subsequently provides statistical significance tests, the approach is also very well suited for proxy screening prior to the generation of a climate-reconstruction network.Two examples of tree growth/climate relationships are provided, one from the North American Arctic treeline and the other from the upper treeline in the European Alps. Instabilities were found to be present where stabilities were reported in the literature, and vice versa, stabilities were found where instabilities were reported. We advise to apply SRFs in future proxy-screening schemes, next to the use of correlations and RE/CE statistics. It will improve the strength of reconstruction hindcasts.

show abstract

Section: Discussion Of Model (1)mentioning

confidence: 99%

Section: Diagnostic Checks Climate Envelopementioning

confidence: 90%

Section: Diagnostic Checks Climate Envelopementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Detecting instabilities in tree-ring proxy calibration

et al. 2010

View full text Add to dashboard Cite

show abstract

“…Some discussion of this point can be found in Loehle [2009]. But here, we limit ourselves to the illustrative examples of this problem solving.…”

Section: Introductionmentioning

confidence: 99%

A Possible Paleoclimatic Implication of a Recent Change of Correlations Between the Tree-Growth and the Current Warming

Datsenko¹,

Ivashchenko²

2011

Geogr. environ. sustain.

View full text Add to dashboard Cite

ABSTRACT. Recent studies have revealed a reduced sensitivity of tree-growth to temperature at high Northern Hemisphere (NH) latitudes during recent decades. Causes of this reduction are not known, but it seems to be for certain that this reduction has important implications for paleoclimatic reconstructions based on tree-rings because there is a risk that warmer phases of paleoclimates can be essentially underestimated if the problem is not taken into account. We add some more observational evidences of the reduction and argue: it is a signal that temperatures recently have reached above optimum levels for the tree-growth in some areas of NH. If such equally warm, or warmer, phases existed in the past, and if tree-growth responded negatively to temperatures during these phases, it would be necessary to apply separate transfer functions to calibrate tree-ring records in terms of temperature for warmer and colder phases of the past climates.

show abstract

Cellulose microfibril angle variation in Picea crassifolia tree rings improves climate signals on the Tibetan plateau

Bao

et al. 2012

Trees

View full text Add to dashboard Cite

Microfibril angle (MFA) is an important factor in determining the mechanical properties of individual cells and wood as a whole. While some studies have described the variation of MFA within trees, little work has been done on the extent to which MFA is influenced by climate, despite it being known to respond to climatic events. Yearto-year variation in MFA and ring width was measured at high resolution by SilviScan-3 Ò on 30 dated Picea crassifolia trees growing in the northeastern Tibetan plateau. The climate signals registered in MFA and ring width were analyzed using dendroclimatological methods. The response function of MFA accounted for 67% of total variance, of which 60% was explained by climate elements. The response function of ring width explained 57% total variance, 37% of which was explained by climate variables. MFA significantly responded to July-August temperatures, and to precipitation in March, May and September. Over the period 1987-2009 temperatures generally increase and appeared to have a greater influence on MFA. A decrease in the strength of the relationship between MFA and ring width over the period was also observed. MFA offers the potential to build robust climate proxies. The strong climate sensitivity of MFA to increasing temperature or the observed changes in the MFA-ring width relationship may contribute to resolving the ''divergence problem'' in temperature reconstructions. As far as we are aware, this study is the first to show a strong climate response in MFA and suggests that it might be a useful climate proxy.

show abstract

A mathematical analysis of the divergence problem in dendroclimatology

Cited by 56 publications

References 65 publications

Detecting instabilities in tree-ring proxy calibration

Detecting instabilities in tree-ring proxy calibration

A Possible Paleoclimatic Implication of a Recent Change of Correlations Between the Tree-Growth and the Current Warming

Cellulose microfibril angle variation in Picea crassifolia tree rings improves climate signals on the Tibetan plateau

Contact Info

Product

Resources

About