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Assess a paleoclimate claim against the leaf-wax taxonomy

Source: R/assess_claim.R
assess_claim.Rd

Walks the four-level taxonomy from manuscript Section 4.5.6 and reports the highest level a claim survives at. The taxonomy is:

  • Level 1: a leaf-wax delta-2-H change occurred between two intervals. Defensible when the change exceeds analytical uncertainty.

  • Level 2: the wax change is consistent with a directional hydroclimate change. Requires corroborating evidence (multi- proxy concordance, sedimentological context, or biomarker evidence for vegetation stability) supplied via corroborating_proxies.

  • Level 3: the wax change implies a quantitative delta-2-H_precip magnitude. Requires a defended local effective slope and explicit uncertainty propagation through the inversion. When reconstruction is NULL the function calls invert_d2H() itself.

  • Level 4: the magnitude is uniquely attributable to precipitation isotope change rather than to vegetation, source-water seasonality, or evapotranspirative enrichment. Requires independent stationarity evidence for each non- precipitation control over the interval.

Usage

assess_claim(
  record,
  claim,
  reconstruction = NULL,
  longitude = NULL,
  latitude = NULL,
  model_name = "baseline_sp",
  ...
)

Arguments

record

Data frame (or list) with at least d2h_wax and age columns of equal length. d2h_wax_err is optional; defaults to claim$sigma_analytical per row.

claim

Named list specifying the claim. Required fields: level (integer 1-4, the level the user is asserting), interval_baseline (length-2 numeric c(min, max) age window), interval_test (length-2 numeric age window). Optional fields, used by higher levels: sigma_analytical (default 3), rho_t (default 0; from estimate_temporal_autocorrelation()), beta_eff (numeric scalar; required at Level 3+), confidence (default 0.95), magnitude_precip (numeric, the precip-space magnitude the user asserts; required at Level 3+), corroborating_proxies (list, used at Level 2; the test is non-empty + named), vegetation_stationary, seasonal_source_stationary, evapotranspirative_stationary (each a list with value (TRUE) and a non-empty evidence string; required at Level 4).

reconstruction

Optional output of invert_d2H(..., return_full = TRUE) on the record. When NULL and the claim's level is 3 or 4, the function runs the inversion itself.

longitude, latitude

Site coordinates, used only when reconstruction is NULL.

model_name

Model to use when running the inversion (default "baseline_sp").

...

Additional args forwarded to invert_d2H() (e.g., elevation, c4_fraction, pft_*, n_posterior_draws).

Value

A list with elements:

  • highest_level - integer in 0:4. 0 means even Level 1 did not clear.

  • levels - data frame, one row per level, with columns level, passed (logical), summary (one-line reason).

  • details - per-level lists of computed quantities (e.g., delta_wax, threshold, p_exceed, missing fields).

  • claim - the (validated) claim object.

Details

Use this when a colleague claims that a downcore record shows a specific d2H_precip shift and you want a structured check of which levels of the taxonomy that claim actually clears.