Technology/Science
Summers Could Last Half the Year by the End of this Century By Denise Chow
Africa is not specifically referenced in this article but the content is relevant and results can be extrapolated from the presentation and the actual report may be reviewed using the address shown below. Dawn Editors SUMMERS IN THE NORTHERN HEMISPHERE could last nearly six months by the year 2100 if global warming continues unchecked, according to a recent study that examined how climate change is affecting the pattern and duration of Earth's seasons. The study, published last month in the journal Geophysical Research Letters, found that climate change is making summers hotter and longer, while shrinking the three other seasons. Scientists say the irregularities could have a range of serious implications, affecting human health and agriculture to the environment. "This is the biological clock for every living thing," said the study's lead author, Yuping Guan, a physical oceanographer at the State Key Laboratory of Tropical Oceanography at the Chinese Academy of Sciences. "People argue about temperature rise of 2 degrees or 3 degrees, but global warming changing the seasons is something everyone can understand." Guan and his colleagues combed through daily climate data from 1952 to 2011 to pinpoint the start and end of each season in the Northern Hemisphere. They found that over the nearly 60year period, summers grew from an average of 78 to 95 days long. Winters, on average, shortened from 76 to 73 days, and the spring and autumn seasons similarly contracted. On average, the spring seasons shrank from 124 days to 115 days, and autumns shortened from 87 days to 82 days. The scientists used the findings to build a 86
May-June 2021
model to project how the seasons might change in the future. They discovered that if the pace of climate change continues unmitigated, summers in the Northern Hemisphere could last nearly six months, while winters could span less than two months. In their study, Guan and his colleagues measured the start of summer based on the onset of temperatures in the hottest 25 percent during that time period. Winter was defined as the onset of temperatures in the coldest 25 percent, they said. Previous research has shown that climate change is having a profound impact on the planet's seasons — making summers hotter and longer and winters shorter and warmer — but Guan said he was surprised by the dramatic results of his team's future projections. "We first looked at 2050 and then calculated the change for 2100, and it was a big number," Guan said. "For human well-being, I was really hoping these results were wrong." Changes to Earth's seasons carry risks for the environment and human health. Warmer and longer summers, for instance, mean mosquitos and other disease-carrying pests could expand their range and persist in areas where they are not typically found. "You could get to a point where insects like malarial mosquitos that are normally kept out of high-elevation areas because they can't survive overnight could potentially survive longer and at higher altitudes," said Scott Sheridan, a climate scientist at Kent State University in Ohio, who was DAWN www.africabusinessassociation.org
