If developed countries bear the brunt of the responsibility of creating climate change, yet developing nations face the greatest and most urgent threats from climate impacts, who should pay for climate change? To examine fairness in climate change, BBC News connected Harvard philosopher Michael Sandel with 60 people from 30 countries around the world in a state-of-the-art digital studio to discuss the philosophical issues underlying the world’s response to climate change.

Sandel and others examined several key puzzles, including the issue of responsibility, the idea of carbon trading, and the potential for reduced consumption.

Who is responsible?

Since the Industrial Revolution, the US and the countries that comprise the European Union have contributed more than 50% of the world’s carbon dioxide emissions. So shouldn’t they pay to fix the problem they created? These countries may argue, however, that during much of this period, no one knew the consequences of their actions, Sandel suggests. Does lack of understanding of one’s actions mitigate responsibility for those actions?

Also with the question of responsibility comes current knowledge of our actions. Now we know that emitting carbon dioxide causes climate change. So should China, which emits more than the United States, and is expected to continue to do so, bear the greatest burden of responsibility? What about a per capita solution? China is the world’s top emitter because its population is four times the size of that of the United States, yet on average, each American citizen emits far more than each Chinese citizen. Should each individual bear the responsibility?

Is carbon trading a good idea?

Sandel and his team also considered the “brilliantly innovative” idea of carbon trading, which assigns each country, state, or company an allowance of emissions. To go beyond its allowance, the country must purchase the right to emit from other countries. Sandel states that “[i]f this market-based system works as it’s supposed to, it’s an efficient and cost-effective way of cutting overall emissions. Emissions can be trimmed in countries where it’s cheap to do so, rather than in countries where it’s expensive and difficult.”

However, many question if this solution is appropriate, or if it is simply the environmental version of buying indulgences — the medieval Roman Catholic practice of paying money for reduced punishment for sins.

Should we consume less anyway?

If technology allowed us to erase our impact on the environment, and we could “carry on munching and guzzling and buying more and more at no environmental cost,” should we? Pope Francis writes that we need a complete revolution in our attitude to the environment: “If we approach nature and the environment without this openness to awe and wonder… our attitude will be that of masters, consumers, ruthless exploiters, unable to set limits on [our] immediate needs.”

If this is true, Sandel argues, perhaps a scientific answer to climate change could be a cause of regret, depriving us of the opportunity to adjust our mindset and our relationship with the world around us.