Tropical warming will outlast net-zero emissions, study finds

Wealthy nations emit more but suffer less from warming

A team at the University of Melbourne has published research showing that the unequal impact of the climate crisis on the world’s poorest populations will not be reversed by reaching net-zero greenhouse gas emissions and could persist for centuries. The Pacific island nation of Tuvalu was cited as one of the tropical areas that would lag in benefiting from emissions cuts.

The study, published in the journal Environmental Research Letters and led by Dr. Andrew King, examined three sets of computer modeling experiments of likely temperature changes if global emissions reached net zero. The researchers then overlaid those projections 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 is emitted before the world reaches net zero. Temperatures have already risen more significantly in tropical areas relative to historic levels than at higher latitudes, including in wealthier countries in Europe and North America, the study found.

“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,” King said. “We can’t easily undo all that damage. 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.”

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 cuts emissions. The asymmetry could take “many decades to begin to reverse” even under a scenario of net-negative emissions, in which carbon dioxide is drawn from the atmosphere.

The climate inequality research was released the same day as a separate report from the UN refugee agency and the Peter McMullin Centre on Statelessness, which examined how climate change is increasing the risk of people becoming stateless. The report called on nations to support “the continuity of statehood” for countries facing extreme climate damage and identified Pacific islands losing land to rising seas as among those at risk.

The UN refugee agency estimated about 4.5 million people are stateless but acknowledged the number is probably much larger, as stateless people are “invisible to official statistics,” the report said.

University of Melbourne Associate Professor Radha Govil, a co-author of the statelessness report, said there was a correlation between the regions most affected by climate change and statelessness. The report recommended that countries be helped to digitize citizenship records and that steps be taken to ensure children are afforded citizenship if they are left without parents after a disaster.

The report also flagged that the risks to children increase if mothers are 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, adding that the recommendations could avert the risk of statelessness and get ahead of the problem.