A Cap and Capture policy is proposed as part of a comprehensive response to global warming, such as discussed in this Global Warming Action Plan.
In a Cap and Capture policy, greenhouse gas emissions would be capped. The exact level of the cap for each country will be agreed to in an international treaty. The cap could be specified in tons of carbon, or on a percentage basis. In case of a percentage, a country's emissions could be capped at, say, 90% of its emissions of the previous year.
If a country exceeds the agreed emission cap, it should make up for that by means of capture. The amount of capture should also be agreed to in the international treaty. As an example, a country could be allowed to offset its shortfall by means of carbon capture and storage (CCS) of, say, twice the amount of the shortfall. The offset ratio should be punitive, to avoid that countries will start using CCS as a routine way to escape their obligations to reduce their emissions.
A failure to offset a shortfall would result in sanctions, as arbitrated by the WTO. Tariffs could be imposed on products exported from the country that is in breach, up to the cost of CCS (by international tender), with the proceeds of such tariffs used to ensure that such CCS does indeed take place.