The climate confidence gap

"Ambition" is a constant refrain at climate summits, but new analysis finds little reason to believe most countries will fulfill their aggressive emissions pledges.

Driving the news: The research in Science analyzed countries' net-zero commitments, assigning a "confidence score" of higher, lower, or much lower.

• It's based on whether they're legally binding, have "credible" policy plans, and whether near-term policies put emissions on a downward path.

Threat level: The topline conclusion is that 90% of the 35 targets analyzed are in the "lower" or "much lower" confidence bucket.

• "Looking at policies instead of promises shows that global climate targets may be missed by a large margin," it notes.
• The "lower" club includes the U.S. and China, the world's top two emitters, while the European Union is in the "higher" band.

Why it matters: Reaching net-zero globally around 2050 is a guidepost for hitting increasingly long-shot Paris Agreement goals that hold temperature gains to well under 2°C, and ideally to 1.5°C, compared to preindustrial times.

How it works: The authors looked at future emissions and temperatures under five scenarios.

• They range from only current policies to combining them with varying amounts of faith in net-zero targets and nearer-term Paris pledges ("nationally determined contributions," or NDCs, in Paris-speak).
• The most optimistic case assumes nations fully implement their NDCs and long-term net-zero targets, regardless of how much credibility the authors assigned.

What they found: The most conservative case — looking only at existing policies — sees temperatures rising by a median estimate of 2.6°C (4.7°F) in 2100, with a wide band of uncertainty in both directions.

• When "higher confidence" net-zero targets are tossed in, the median rise is 2.4°C (4.3°F) — way past the Paris targets.

• That most optimistic case sees a median rise of 1.7°C (3.1°F) — not too far off the Paris target.

Of note: The new paper comes as a separate study warns that "the world has eliminated half of its remaining carbon budget to keep warming to 1.5 degrees Celsius compared with preindustrial levels in just the last three years," the Washington Post reports.

What we're watching: How many nations act on the Science paper's easier-said-than-done recommendations.

• The include putting net-zero targets into law — only 12 of 35 assessed are binding — to creating stronger, more detailed, and sector-specific implementation plans.

The bottom line: “Climate change targets are by their nature ambitious — there’s no point in setting a target for a foregone conclusion. But implementation must follow,” co-author Taryn Fransen of the World Resources Institute said in a statement.