With a ratcheting up of awareness culminating in the Paris climate change conference, 2015 may have been the year that the threat of climate change was finally taken seriously. But a question remains: Who, if anyone, is most deserving of blame, and who should be held responsible?

Today, six of the top 10 greenhouse gas emitters are developing countries, with China the largest contributor at approximately 28 percent of the global total. Yet on the per capita level, the United States and Canada emit more than double the global average.

Pope Francis pointed out in his controversial encyclical on the environment, Laudato Si that, “regarding climate change, there are differentiated responsibilities.” He said greater attention should be given to the needs of the vulnerable in a debate often dominated by more powerful interests, and that in many cases, developed countries have caused harm to less wealthy nations while fueling their own economies.

Although developing nations like China and India are catching up in the emissions race, it was countries such as Great Britain and the United States that have led significant global warming over the past century, producing significant economic development that accrued mainly for their own citizens. From 1850 to the year 2011, the United States alone produced 27 percent of the world’s total carbon dioxide emissions.

The least developed countries, on the other hand, emit the least carbon dioxide. But the effects of climate change — extreme weather, rising seas, higher food costs, increased risk of drought, fire and flood — tend to fall most heavily upon the global poor.

At the United Nations Climate Change conference, held in Paris in December, 196 countries approved a climate accord seeking to hold the increase in global average temperature below 2 degrees Celsius. This is to be achieved through “nationally determined contributions” of emission reductions, created in the context of each country’s individual circumstances. In theory, this should allow developing countries to shoulder less of the burden. Richer countries have also pledged technology and financial resources to help less-advanced countries adopt cleaner energy sources and adapt to climate change.

Individually, the United States has recently begun to take action against companies seen as having irresponsibly hastened climate change or deceived the public about its risks. In late 2015, the New York attorney general launched an investigation into whether oil giant ExxonMobil lied to the public about the risks of climate change in order to increase profits. Just yesterday, the Obama administration filed a lawsuit accusing the German automaker Volkswagen of violating emissions laws.

Yet it’s not just corporations at fault, or even governments. Through our everyday actions, we are all at some level responsible for climate change and its impacts on future generations. The more uncomfortable question is whether some of us are more at fault than others.

What makes climate change a moral issue in the first place? Are developed countries more morally culpable than those still developing, and do ethical standards demand they shoulder a larger emissions-reduction burden than developing nations? Should organizations that deny or misinform the public about climate change be held at fault?

Over the next few days, we’ll hear from: