At the landmark Paris climate agreement, nearly every country in the world pledged to a goal to limit warming to well below 2° Celsius (3.6° Fahrenheit) above preindustrial levels by 2100, and work toward a more ambitious goal to limit warming to 1.5°C (2.7°F). The hope is that such a limit will help Earth avoid […]

At the landmark Paris climate agreement, nearly every country in the world pledged to a goal to limit warming to well below 2° Celsius (3.6° Fahrenheit) above preindustrial levels by 2100, and work toward a more ambitious goal to limit warming to 1.5°C (2.7°F). The hope is that such a limit will help Earth avoid the most catastrophic effects of climate change.

However, a recent review suggests that even the more ambitious ceiling of 1.5°C may be too warm for the planet’s polar ice sheets and trigger massive sea level rise.

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  • Ben Matthews@sopuli.xyzEnglish
    4·
    2 months ago

    This study is indeed disturbing, drawing on multiple lines of evidence suggesting melting may happen faster than previously assumed, I’ll study more.

    However, there never was any magic safe (global-average-surface-) temperature level, to save polar ice sheets. Melting, and the penetration of heat, is cumulative, so to a first approximation it is the integral of the warming that counts (maybe we could talk about a heating budget, similar to the concept of carbon-budget to avoid a specific temperature).

    Although diplomats may stress that the concept of safe level is baked into Article 2 of the Climate convention, that orginally applied to “concentrations” not temperature. Back in the day (early 2000s) I among others pushed (this wasn’t easy) to adopt temperature as a goal closer to real impacts, pointing out that required peak+decline concentration pathways.
    Nevertheless we always knew that a stable (higher) temperature does not bring a stable sea-level (on a multi-century timescale) . While for some other types of impacts - e.g. ecosystem adaptation, it may be the rate (derivative) rather than the integral that matters more. The ‘level’ concept was a compromise to coalesce policy (within which - round numbers like 2.0 or 1.5 C also arbitrary).

    Maybe it could help motivate the global debate, to specifically (dis)agree goals of sea-level rise we try to avoid ? That’s a more tangible level ( at least until we get into regional sea-level-rise variations…) , but due to the double integral, it’s harder to implement.