In the next 60 years many parts of the world including Europe, North America and China could see extreme summer temperature shifts. And tropical regions in Africa, Asia and South America could experience the permanent emergence of unprecedented summer heat as early as the next two decades, if atmospheric greenhouse gas concentrations continue to increase.
The alarming new climate study by Stanford University scientists is to be published later this month in the journal Climatic Change.
According to our projections, large areas of the globe are likely to warm up so quickly that, by the middle of this century, even the coolest summers will be hotter than the hottest summers of the past 50 years, said the studys lead author, Noah Diffenbaugh, an assistant professor of environmental Earth system science and fellow at the Woods Institute for the Environment at Stanford. The study is co-authored by Stanford research assistant Martin Scherer.
When scientists talk about global warming causing more heat waves, people often ask if that means that the hottest temperatures will become the new normal, Diffenbaugh said. That got us thinking at what point can we expect the coolest seasonal temperatures to always be hotter than the historically highest temperatures for that season?
To determine the seasonal impact of global warming in coming decades, Diffenbaugh and Scherer analyzed more than 50 climate model experiments including computer simulations of the 21st century when global greenhouse gas concentrations are expected to increase, and simulations of the 20th century that accurately predicted the Earths climate during the last 50 years. The analysis revealed that many parts of the planet could experience a permanent spike in seasonal temperatures within 60 years.