The Earth’s average surface temperature has already risen by approximately 2.1 degrees Fahrenheit (1.2 degrees Celsius) above pre-industrial levels. With 2024 being declared the hottest year on record, future climate predictions remain concerning.

A recent study, published on May 14 in the journal Earth’s Future, investigated the potential consequences if global temperatures were to increase by 2.7 degrees Fahrenheit (1.5 degrees Celsius), even temporarily.

The study suggests that such a temperature increase could permanently alter the intertropical convergence zone (ITCZ), a region near the equator where trade winds from the northern and southern hemispheres converge.

“These impacts that we quantify here will be there for the long term,” said lead author Norman Steinert, a senior climate researcher at the Center for International Climate research in Norway.

The ITCZ significantly influences rainfall patterns, and rising global temperatures could cause it to shift southward. This shift could alter the duration and intensity of wet and dry seasons,particularly in regions of Africa,the Amazon,and Southeast Asia. the resulting excess or lack of rainfall could have devastating consequences for agriculture, ecosystems, and water resources for a significant portion of the world’s population.

Impact on Rainfall Patterns

Several factors influence the ITCZ,including the Atlantic Meridional Overturning Circulation (AMOC),a major ocean current system. Recent studies indicate that this current is weakening, largely due to the effects of climate change.

“Cut emissions as soon as possible.”

The researchers analyzed two different scenarios using eight Earth System Models, which are complex climate simulation tools. one scenario examined how precipitation patterns might change with a 1% annual increase in atmospheric CO2 for 140 years, followed by a decrease at the same rate for another 140 years. climate models are essential tools for understanding long-term climate trends and projecting future scenarios. According to the IPCC, climate models are now able to simulate many aspects of the climate system with a high degree of accuracy.

The second scenario explored a more realistic situation where emissions increase until 2040, followed by aggressive mitigation efforts to reduce global temperatures.

Steinert explained that the assumption is that “we won’t be able or won’t like to live in a warmer world,and would make actual efforts to bring temperatures down again at some point.”

While most projections showed little or no shift in the ITCZ, one idealized scenario and two realistic scenarios indicated a significant shift, perhaps causing major disruptions to rainfall patterns worldwide.

Although the study describes the ITCZ shift as “unlikely” based on the number of models predicting different outcomes, the researchers argue that the already weakened AMOC and the time lag between climate warming and ocean heating could make a shift in the ITCZ more probable.

Reduced rainfall could affect Central and West Africa and parts of Southeast Asia, while northeast Brazil could experience increased flooding. These changes in weather patterns could disrupt the lives of billions and complicate agriculture that relies on consistent conditions. 23% of the world’s population and over 12% of the global land area could be affected.

Steinert noted that the likelihood of this scenario is “a low probability, but plausible outcome,” with the worst impacts potentially unfolding over decades. In several scenarios, the damage was irreversible, at least on human timescales.

Richard Allan, a professor of climate science at the University of Reading in the U.K., who was not involved in the study, called it “an important study.”

Allan also noted that water availability is more complex than the study considered, as the simulations did not account for soil moisture or river flow.

Still,Allan stated,”this storyline could play out in the future,” adding,”As it has such big possibilities for regional water availability,this has got to be taken seriously.”

Steinert suggests that future research should focus on the local, specific outcomes for areas potentially affected by shifting weather patterns due to climate change. However, he emphasizes that the most effective way to avoid these risks is to “cut emissions as soon as possible.”