Poor populations in the tropics may be most vulnerable to predicted temperature variability.| Sebastian Bathiany, Wageningen University
Poor tropical regions that are most vulnerable to extreme climatic events such as heat waves will likely experience the largest variations in monthly temperatures over the next decades, according to a new analysis.
The study published in the May 2 issue of Science Advances highlights the unequal impact of climate change between tropical countries in places such as the Amazon and Southern Africa — which have contributed the least amount to greenhouse gas emissions — and wealthier countries at mid- and high-latitudes.
The predicted variability in temperature across much of the developing as well as the developed world could have considerable social, economic and ecological consequences that enhance the inequality in the impacts of a changing climate, according to the authors.
"[This] global pattern of temperature variability ... will likely have negative impacts in the poorest countries," said Sebastian Bathiany, corresponding author from Wageningen University in Netherlands. "It was an eye-opener to see how clear the relation was between a country's wealth and the predicted changes in temperature variability."
Most climate modeling studies that analyze temperature variability have focused only on changes in global mean temperature or changes at high- and mid-latitudes. To understand how climate change will affect natural, social and economic systems, however, researchers need to know more about how climate variability will change across all regions.
Bathiany and his colleagues focused on how unusually high or low temperatures affect changes in average monthly temperature over decades and centuries. As these unusual events become more common in the future, "predicting temperature based on previous experience then becomes more difficult and it will become more difficult to adapt to climate change because it is hard to plan for such short-term anomalies," said Bathiany.
According to Bathiany, societies and ecosystems can adjust somewhat to slowly changing temperatures, but not intense climatic events like heat waves or cold snaps that differ greatly from normal conditions. With that in mind, the researchers used 37 climate simulations to analyze monthly temperature variabilities at a local scale to identify hotspots — regions of relatively large variability — where many different climate models agree on the largest magnitude changes.
They then created a timeline of relative changes from 1850 to 2100 based on the 37 climate models, and until 2300 using nine of the models. The climate models consistently projected several hotspots that are likely to experience increases in temperature variation over the upcoming decades — namely Amazonia, Southern Africa, Australia, India and Southeast Asia.
"We were particularly surprised how well the models actually agree on the hotspot regions and the underlying mechanisms," Bathiany said.
On a countrywide scale, the magnitude of the typical monthly temperature variability in these regions will increase by roughly 10% until 2100. In the warmest season, this would lead to a 15% increase in temperature variability per degree of global warming in Amazonia and Southern Africa and up to a 10% increase in variability in the region of western and north-central Africa known as the Sahel, India and Southeast Asia.
The Amazon is a particular hotspot of concern, the authors said. In the central Amazon, temperature variability could increase by 40% until 2100, according to the model average. Some individual models show much larger values.
Outside of these tropical regions, the projections show that temperature variability will decrease on average.
The authors said their findings help anticipate how climate change will affect different regions — some more than others — in the future and provide regions with reasons to prepare for impacts.
"I believe that the most developed nations have a responsibility to support the poorer nations not only because they can cope less easily with climate change, but also because the impacts of changes in climate variability can be more damaging in these countries," Bathiany said.