Correspondences
What is linked, what is not
Each arc joins two phenomena tested on this site. Green and animated: clear link (correlation significant at 5 % after correcting for autocorrelation, or a response outside chance in an event study). Grey: inconclusive test. A statistical link alone does not establish causation.
- Clear link
- Inconclusive
Hypotheses tested
29
Clear links
21
Causation demonstrated
0
Arc width from |r| of the stored result; several tests between the same phenomena are drawn as stacked arcs.
Hypothesis tested: El Niño dries the tropics: fires (Indonesia in 1997–1998, 2015) emit methane, but tropical wetlands, the largest natural source, emit less; La Niña does the opposite (Hodson et al., 2011; Zhang et al., 2018). The sink (OH radical) also responds. The expected net effect is small and of uncertain sign.
Pearson correlation r (lag -4 month(s))
-0.11
95% interval [-0.32; 0.16] (block bootstrap)
Aligned points
500
effective n ≈ 14 (autocorrelation)
p-value
0.728
two-sided, Fisher z transform, effective n
r from 1984 to 2006
-0.11
p = 0.819, n = 266
r from 2007 to 2026
-0.10
p = 0.860, n = 234
Period analysed
1984-07 → 2026-06
computed on Oct 25, 2026 · engine v1.0
Aligned series (standard deviations, after preprocessing)
Show the data as a table
Correlation by lag (month(s))
Show the data as a table
Method and sources
Monthly Niño 3.4 (NOAA PSL); 12-month growth of the deseasonalised trend of global methane (NOAA GML, flask network). Both series are filtered of variations longer than 10 years (running mean removed) to keep the year-to-year fluctuations only. Lags of −12 to +12 months; Bretherton et al. effective size; block bootstrap with 12-month blocks. Same correlation, at the chosen lag, before and from 2007.
Computation parameters
{
"growth": "CH4(t) − CH4(t − 12 months), deseasonalised global trend (NOAA GML)",
"max_lag": 12,
"bootstrap": {
"seed": 20261023,
"block": 12,
"draws": 1000
},
"statistic": "pearson",
"subperiods": "before and from 2007-01 at the lag of the whole period",
"high_pass_months": 120
}Inputs : psl.nino34.anom.monthly (945 pts, run #42) · gml.ch4.global.trend.monthly (516 pts, run #3702)
Reading this result
Unlike CO₂, whose growth clearly follows El Niño, methane responds little: the two effects (fires against wetlands) partly cancel, and the record rise of 2020–2022 came during La Niña, driven by tropical wetlands. A weak or non-significant result is the expected outcome here, not a failure of the test. Without a signal, the chosen lag (that of the largest |r|) has no physical meaning. The 10-year filtering leaves very few independent values (about fifteen): only a strong link could have been detected. Correlation is not causation: common factors (seasons, cycles, trends) or coincidence can produce it. The p-values account for autocorrelation (effective n) but not for preprocessing choices; the confidence interval comes from a block bootstrap. The limits of the source data apply.
SOURCES OF THIS PAGE
- Niño 3.4 SST anomaly (NOAA PSL, ERSSTv5)
-
NOAA PSL, Niño 3.4 index: monthly SST anomaly (5°N–5°S, 170°–120°W) from ERSSTv5, climatology 1991–2020.
· source page ↗
Licence : U.S. Government work, public domain · retrieved on Oct 23, 2026 · SHA-256 879cf3cb31d7… - Global monthly mean CH₄ at the marine surface sites (NOAA GML)
-
Thoning, K., Dlugokencky, E. and Lan, X. (2022). Trends in globally-averaged CH4, N2O, and SF6 determined from NOAA Global Monitoring Laboratory measurements.
· doi:10.15138/P8XG-AA10 · source page ↗
Licence : U.S. Government work, public domain; cite the NOAA GML trend data set · retrieved on Oct 25, 2026 · SHA-256 b51e4a4e6527… - Hodson et al. (2011)
-
Hodson, E. L., Poulter, B., Zimmermann, N. E., Prigent, C., & Kaplan, J. O. (2011). The El Niño–Southern Oscillation and wetland methane interannual variability. Geophysical Research Letters, 38, L08810.
· doi:10.1029/2011GL046861
Licence : Published literature; cited - Zhang et al. (2018)
-
Zhang, Z., Zimmermann, N. E., Calle, L., Hurtt, G., Chatterjee, A., & Poulter, B. (2018). Enhanced response of global wetland methane emissions to the 2015–2016 El Niño-Southern Oscillation event. Environmental Research Letters, 13, 074009.
· doi:10.1088/1748-9326/aac939
Licence : Published literature; cited