As nations wrangle over climate pledges, how enforceable are they?

When all is said and done at the UN climate talks, and the ink on the COP26 agreement is dry, one awkward question will remain: how enforceable will the deal be anyway?

In the last year, countries have announced a flurry of net-zero emissions pledges. The United States promised net zero by 2050, and Saudi Arabia targeted 2060, and India 2070. Many other countries submitted formal pledges - known as “nationally determined contributions” or NDCs - to cut emissions this decade, ahead of this month’s UN climate conference in Glasgow.

Whether those goals are legally binding is for individual countries to decide.

The 2015 Paris Agreement, a legally binding international treaty, commits its nearly 200 signatory countries only to hold global warming to “well below 2 degrees Celsius and aim for 1.5C. But the accord left it up to countries to set their own national contributions towards the overall Paris targets, and doesn’t require they meet them.

“The NDCs are voluntary measures,” said Lakshman Guruswamy, an international environmental law expert at the University of Colorado-Boulder. “There’s no way of implementing, imposing, or trying to enforce a non-binding agreement.”

Countries including Britain and New Zealand, and the 27-country EU, have fixed individual emission-cutting targets into their own laws. Most nations have not.

International treaties tend not to threaten penalties and instead rely on other political strategies and pressure tactics to ensure cooperation.