{"id":430588,"date":"2026-03-12T09:58:00","date_gmt":"2026-03-12T08:58:00","guid":{"rendered":"https:\/\/climatescience.press\/?p=430588"},"modified":"2026-03-12T09:58:02","modified_gmt":"2026-03-12T08:58:02","slug":"the-modern-co%e2%82%82-spike-looks-scarier-than-it-really-is","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=430588","title":{"rendered":"The Modern CO\u2082 Spike Looks Scarier Than It Really Is"},"content":{"rendered":"
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Directly splicing the modern Mauna Loa record (~427 ppm in 2025) onto Antarctic ice-core data creates a visually alarming \u201chockey-stick\u201d spike. <\/p>\n\n\n\n

But this comparison is apples- to- oranges because ice- core proxies (especially from low-accumulation sites like Dome C or Vostok) heavily smooth atmospheric signals over 100\u2013300+ years due to firn diffusion. Rapid modern changes get \u201cmuted.\u201d<\/p>\n\n\n\n

Ice cores from Antarctica provide the primary proxy records for past atmospheric CO\u2082 concentrations, extending back up to ~800,000 years. <\/p>\n\n\n\n

However, different drill sites vary significantly in temporal resolution (how finely they capture short-term changes) due to snow accumulation rates, firn diffusion (gas mixing in the porous snow\/ice transition layer before bubbles close off), and site-specific conditions like temperature and wind. <\/p>\n\n\n\n

This leads to varying degrees of smoothing (averaging or damping of rapid fluctuations), with low-accumulation interior sites acting as low-pass filters over centuries, while high-accumulation coastal sites preserve decadal-scale details but shorter records.<\/p>\n\n\n\n

Here\u2019s a comparison of the main sites discussed in paleoclimate literature (e.g., EPICA Dome C, Vostok, Law Dome, and others like WAIS Divide or Siple Dome):<\/p>\n\n\n\n