Читать книгу Climate Change For Dummies - Elizabeth May - Страница 69

El Niño is a natural weather cycle that has the power to change global temperatures. It’s been around for hundreds — possibly millions — of years. El Niño involves the tropical Pacific Ocean warming by 0.9 degrees F (0.5 degrees C) or more for about three months at a time. This warmed water eventually loses that heat to the atmosphere, causing the average air temperature (at the surface, or where humanity lives in the lower part of the atmosphere) to go up a few months later, which then alters the overall climate temporarily. The temperature of the ocean then settles back down to normal and returns to its regular cycle of ups and downs.

Scientists don’t yet know whether global warming is affecting these cycles, but global warming and El Niño cycles are very interrelated. Part of the reason scientists can’t distinguish between the impacts of global warming and El Niño on climate is because they’re so linked and because they both influence many different aspects of regional climate that they can actually change one another. A computer model giving future scenarios of climate that includes both El Niño and global warming doesn’t yet exist because of the difficulty that exists between identifying the separations between the two.

Some models say El Niño will become stronger, but others say it’ll weaken. Evidence suggests that El Niño cycles have been stronger and happening more often over the past few decades, and climate models project that climate change will cause sea-surface temperatures to rise in the tropical Pacific Ocean — similar to El Niño conditions. Scientists are working constantly to advance their understanding of the relationship between climate change and El Niño.

Two unknown questions remain: How much temperature rise is the result of El Niño and how much is the result of global warming? Are El Niño temperatures any higher because of global warming?