As countries 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, China 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...