There is overwhelming evidence that human activities are changing the climate system. This paper discusses issues and questions relating to the evaluation of justice in relation to climate change and asks questions such as ‘how do we assess the impacts of climate change?’

There are two different approaches to issues of climate justice. Some philosophers have adopted an isolationist approach because it treats the ethical issues posed by climate change in isolation from other issues. While some favour an integrationist approach because it treats the ethical issues in light of a general theory of justice and in conjunction with other issues.

Assessing climate impacts

The questions, ‘what are people’s interests?’ and ‘how can this understanding be used to evaluate the impacts of climate change?’ are helpful to assess climate impacts. These questions are useful to design adaptation policies, to understand what kind of protection people are entitled to and what interests should be prioritised and protected. Persons’ interests include but are not limited to access to food, water, economic security, health and human rights including indigenous and cultural rights. Theories of distributive justice that concern the distribution of burdens and benefits can be applied to assess what is considered fair in evaluating the impacts of climate change.

Intergenerational justice

The question of what climate target to aim for depends on what responsibilities members of one generation have to future generations. The emission of some greenhouse gases can have an impact far into the future. For example, CO2 lasts in the atmosphere for hundreds of thousands of years.

Risk and uncertainty

Climate projections, such as global warming of 1.5ºC, are characterised by risk and uncertainty. Questions to consider include:

• How risk-averse should we be?
• How should policymakers treat risk and uncertainty?

Responsibilities

The paper frames how to assess the question of responsibility regarding climate justice, for instance:

• Climate action – who should engage in mitigation and adaptation, and to what extent?
• Burden-sharing – who should bear the costs of mitigation and adaptation?
• Political action – who has the responsibility to ensure that (a) those designated to engage in mitigation and adaptation do so and (b) those designated to bear any financial burdens discharge their responsibilities?
• For all of the previous questions, what kinds of entities are the duty-bearers? Many will assume that governments have such responsibilities, but what about other actors? Are individuals duty-bearers? For example, do individuals have duties to engage in mitigation? Or does that duty fall exclusively on other actors?

Justice and the greenhouse gas budget

One responsibility is to limit the emission of greenhouse gases. Key questions to consider include:

• How to use the remaining greenhouse gas budget?
• How should it be distributed and among whom?

Justice and climate policies

Questions of justice arise when considering what policies might be adopted to mitigate and adapt to climate change. Including questions on energy sources, population and geoengineering.

1. Mitigation involves either decreasing the emission of greenhouse gases or creating greenhouse gas sinks, which absorb greenhouse gases, or both. Adaptation involves making changes to people's context so that they can cope better with a world undergoing climate change.
   
2. When considering the distribution of responsibilities and the application of principles of distributive justice to the greenhouse gas budget, it matters whether one takes an isolationist or integrationist perspective.
3. It is argued that many of the adverse impacts like displacement, hunger and loss of shelter can accurately be described as threatening human rights. This view maintains that persons have certain human rights—to life, health, water, food, not to be displaced—and that climate change is unjust because it violates these human rights. Others are sceptical of the applicability of human rights, arguing that they are too inflexible and are unable to provide guidance when trade-offs are necessary.
4. Many climate economists employ the ‘social cost of carbon’ which calculates a monetised value of present and future damages caused by the emission of a ton of CO2.
5. Taking climate justice seriously may have major implications for existing economic institutions and ideologies, such as the valorisation of economic growth, as well as for political institutions.
6. Philosophical analysis has its part to play in evaluating the impacts of climate change and without an understanding of climate justice we lack a compass to guide us. Evaluating such claims clearly requires extensive empirical analysis. Only with the help of climate science, history, politics, economics, anthropology, political economy, sociology, science and technology studies, and law can we begin to address such claims.
7. Importantly, justice is not the only relevant value when confronting the challenges of climate change. Justice plays a large role, but many would argue for the relevance of other kinds of moral consideration, including a recognition of the intrinsic value of the natural world.
8. The key issue concerns the relationship between persons' interests and changes in the climate system. Some views argue that if distributive justice is concerned solely with wealth and income, then the loss of a good because of climate changes can be compensated for by a transfer of wealth and/or income.
9. Some, however, would argue that to limit our focus to interests of wealth and income is too narrow. They hold that some persons have deep attachments to certain places, such as the land that they have traditionally inhabited, and that being rooted in a particular place is an integral part of what makes their life go well.
10. The focus of the article has been on the climate impacts on human beings. However, it argues that you can only get the complete picture by including nonhuman animals. If the interests of other creatures are included then this will have implications for the evaluation of climate impacts.