If global temperatures continue to rise and reach 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels, people around the world could face multiple impacts of climate change simultaneously. According to a NASA analyzed the impacts of global warming to understand how different climate effects might combine.
An increase in global temperatures of 2 degrees is considered the critical threshold above which the dangerous and cascading effects of human-induced climate change will occur. The researchers found that more than a quarter of the world’s population could experience an additional month of severe heat stress each year compared to the middle of the 20th century (1950-1979).In the American West, extreme fire weather is likely to be more intense and last longer.
To examine the potentially compounding effects of rising temperatures, the study authors worked with a specially crafted set of climate forecasts. The forecasts were originally generated by 35 of the world’s leading climate models specifically.
NASA Earth Exchange (NEX) researchers then took the output from the CMIP6 models and used advanced statistical techniques to “downscale” them, greatly improving the resolution. NEX uses supercomputers at NASA’s Ames Research Center in California’s Silicon Valley to analyze vast amounts of data collected by aircraft and satellites, or in this case, projections made by climate models.
A combination of climate impacts
With the new data set in hand, NEX researchers in Ames analyzed the downscaled projections to assess the changes predicted for six key climate variables. They examined changes in air temperature, precipitation, relative humidity, shortwave and longwave solar radiation, and wind speed at the point where warming exceeds 2°C.
“We wanted to study how these aspects of the environment are projected to change and what their combined impacts might mean for people around the world,” said Taejin Park, the paper’s first author and an Ames-based researcher at the Bay Area Environmental Research Institute (BAERI).
The researchers paid particular attention to two climate indicators: heat stress or the combined effects of temperature and humidity on the human body and fire weather which takes temperature, precipitation, humidity and wind into account. Most regions of the world will experience higher temperature stress, they found, while countries closer to the equator will suffer more days considered extreme.
“Escalating impacts of all climate extremes studied could cause significant damage to communities and economies through fires, floods, landslides and crop failures,” said Ramakrishna Nemani, BAERI principal scientist and co-author of the study.
Democratizing climate data up to the year 2100
The NEX downscaled dataset used for this research provides global, daily climate projections derived from the CMIP6 climate models up to the year 2100. The daily nature of the NEX product is important to capture extremes. When aggregated into a monthly average, Park explained, several days predicted to be dangerously hot and humid could be lost in the numbers, obscuring the risk to human lives.
The level of local and regional detail the resolution of the projections is higher in NEX than most climate projections, which could help policymakers develop targeted climate adaptation and mitigation plans. Raw climate model projections typically provide results for areas of about 120 by 120 miles (200 by 200 kilometers), while the NEX downscaling work increases this resolution to about 15 by 15 miles (25 by 25 kilometers).
Reducing this amount of data is a big job, and the NEX researchers relied on NASA’s powerful Pleiades supercomputer in Ames. The Pleiades help solve some of NASA’s most challenging problems, playing an important role in rocket launches for the Artemis program, fuel-efficient aircraft designs, and studies of Earth’s climate.
NEX scientists hope that downscaled climate projections could help decision-makers prepare and protect their regions from climate impacts. For example, a local politician could choose to build more flood barriers or seek less development in flood-prone areas, said Ian Brosnan, co-author of the paper and chief scientist at NEX. The NEX dataset can also help new commercial and not-for-profit enterprises develop customized climate risk assessments for the private and public sectors.
“NASA’s reduced data is in a really accessible form,” Brosnan said. “People anywhere with some technical ability from college students to experienced climatologists can delve into the information these projections contain.”
