The Gist
Bordeaux-family reds swing from green and herbal in cool climates to ripe cassis and chocolate in hot climates — same grape, opposite mood. Mocha and dark fruit tell you it's warm; green pepper and cedar tell you it's cool. The climate often lands before the grape does.
Mechanism
In Cabernet-family grapes, the aromatic spectrum from green pepper (cool/underripe) to mocha/chocolate (warm/ripe) is determined by pyrazine degradation and tannin ripeness. Cool climates: pyrazines survive → green pepper, cedar. Warm climates: pyrazines break down → cassis and blackberry emerge. Very warm: anthocyanins concentrate, oak interaction adds chocolate/mocha.
Mocha + cassis + plush tannin = warm climate expression of a Bordeaux variety. Green pepper + cedar + firm acid = cool climate or underripe. This spectrum applies to Cab Sauv, Cab Franc, Merlot, and Carménère — but each variety sits at a different default position on the scale.
Deeper mechanism
Carménère: even in warm Chilean valleys, Carménère retains more residual IBMP than Cab Sauv — so a warm-climate Carménère shows both dark chocolate AND jalapeño simultaneously. This co-occurrence (sweet + green simultaneously) is the tell. Napa Cab: very warm → pyrazines almost entirely degraded → mocha/cassis/cedar profile dominates.
Confusion analysis
Napa Cab vs. Left Bank Bordeaux
Both Cab Sauv, both have graphite/cassis. Bordeaux: earthier, higher acid, green note possible, cedar. Napa: lower acid, richer, mocha/chocolate from warm-climate ripeness. The mocha intensity calibrates climate.
Carménère vs. Cab Sauvignon (Chile)
Both Chilean, both dark. Carménère: jalapeño more pungent (higher residual IBMP), chocolate heavier, tannin softer. Cab S: green note more restrained, graphite/pencil dominant, tannin firmer.
Related varietals
This concept comes up when tasting: Cabernet Sauvignon, Merlot