Tropics to be among last to benefit from net zero emissions, research finds

Temperatures have risen more significantly in tropical areas relative to historic levels than at higher latitudes, including in wealthier countries in Europe and North America. Dr Andrew King and colleagues at the University of Melbourne examined three sets of computer modelling experiments of the likely temperature changes if global emissions reached net zero, and overlaid the results with countries' gross domestic product.

"If we follow a path that is close to net zero, then the inequality we see in present day warming persists indefinitely," King said. "The wealthier countries that have caused more of the problem are not those that are the most exposed, even beyond net zero. The regions that have not caused the warming are those that experience the most warming."

King said the fate of the planet's poorest regions, which tend to be concentrated closer to the equator, would depend on how much greenhouse gas was emitted before the world reached net zero, the implicit goal of the 2015 Paris agreement. "Even when we get to net zero, we have still emitted an enormous amount of carbon into the atmosphere and its effects will continue for centuries. We can't easily undo all that damage," he said. "Getting to net zero sooner means we are less likely to have that long-term warming after net zero. We need to get to net zero sooner to limit that inequality."

The research found the disparity could take "many decades to begin to reverse" if carbon dioxide were drawn from the atmosphere under a "net-negative emissions" plan. King said tropical ecosystems, such as some coral reefs, had mostly evolved to exist in a narrower temperature range than ecosystems at higher latitudes and would continue to be heavily affected for longer as the world cut emissions.

The second report, commissioned by the UN refugee agency and released with the Peter McMullin Centre on Statelessness, called on nations to support "the continuity of statehood" for countries facing extreme climate damage. It said those at risk included Pacific islands that were losing land to rising seas. The agency estimated about 4.5 million people were stateless but said it accepted the number was probably much larger, as stateless people were "invisible to official statistics".

The report said the climate crisis risked creating more stateless people through displacement after climate-driven disasters such as fire, flood and sea level rise. University of Melbourne Associate Prof Radha Govil, a co-author of the report, said there was a correlation between the regions most affected by climate change and statelessness.

The report recommended countries be helped to digitise citizenship records, and that steps be taken to ensure children left without parents after a disaster were afforded citizenship. It said the risks to children were increased if mothers were not given the same rights as fathers to confer their own nationality to their children.

"The recommendations we have set out are absolutely doable," Govil said. "They can stave off this risk of statelessness and get ahead of this problem."

Editor's Summary

Research in Environmental Research Letters finds that warming inequality between the tropics and higher latitudes will persist after emissions reach net zero, and that the poorest, least responsible regions face the longest exposure. A parallel report from the UN refugee agency warns that climate-driven displacement and sea level rise threaten the statehood of vulnerable countries and could increase statelessness, and sets out measures on citizenship records and children's nationality.