In 2015, sweltering heat smashed temperature records around the globe. That year's extreme heat, though, will soon be typical, says a new study. Today’s record heat, it suggests, soon will become the “new normal.”
Global temperatures are increasing in part because people are dumping greenhouse gases into the atmosphere. That has helped fuel global warming. The phrase the “new normal” is one that climate scientists have used to describe what will happen in the future. It is when hot days and nights that are rare today become common.
Sophie Lewis led the new study. She is a climate scientist at the Australian National University in Canberra. She and her colleagues started by giving the informal phrase a more formal definition: a time when at least half of the following 20 years surpass the record of the past. Then they applied their new definition to several computer simulations of future climate.
The outcome depends on how much more carbon dioxide, a main greenhouse gas, human activities (such as burning coal and oil) dump into the atmosphere. If humans keep pumping a lot of this CO2 into the atmosphere, 2015 could become the “new normal” as soon as the 2020s. But even if there’s a sharp drop in CO2 releases, 2015’s heat will seem typical by 2040. The team published its estimates online November 4 in the Bulletin of the American Meteorological Society.
When 2015’s record heat is common, extremely hot years will be beyond anything humans have encountered so far, the researchers predict. That extreme heat could lead to more deadly heat waves, wildfires and other climate-related disasters.
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atmosphere The envelope of gases surrounding Earth or another planet.
carbon The chemical element having the atomic number 6. It is the physical basis of all life on Earth. Carbon exists freely as graphite and diamond. It is an important part of coal, limestone and petroleum, and is capable of self-bonding, chemically, to form an enormous number of chemically, biologically and commercially important molecules.
carbon dioxide (or CO2) A colorless, odorless gas produced by all animals when the oxygen they inhale reacts with the carbon-rich foods that they’ve eaten. Carbon dioxide also is released when organic matter (including fossil fuels like oil or gas) is burned. Carbon dioxide acts as a greenhouse gas, trapping heat in Earth’s atmosphere. Plants convert carbon dioxide into oxygen during photosynthesis, the process they use to make their own food.
climate The weather conditions prevailing in an area in general or over a long period.
colleague Someone who works with another; a co-worker or team member.
global warming The gradual increase in the overall temperature of Earth’s atmosphere due to the greenhouse effect. This effect is caused by increased levels of carbon dioxide, chlorofluorocarbons and other gases in the air, many of them released by human activity.
greenhouse A light-filled structure, often with windows serving as walls and ceiling materials, in which plants are grown. It provides a controlled environment in which set amounts of water, humidity and nutrients can be applied — and pests can be prevented entry.
greenhouse gas A gas that contributes to the greenhouse effect by absorbing heat. Carbon dioxide is one example of a greenhouse gas.
simulation A model, often made using a computer, of some conditions, functions or appearance of a physical system. A computer program does this by using mathematical operations that can describe the system and how it might vary in response to various situations or over time.
society An integrated group of people or animals that generally cooperate and support one another for the greater good of them all.
Journal: S.C. Lewis, A.D. King and S.E. Perkins-Kirkpatrick. Defining a new normal for extremes in a warming world. Bulletin of the American Meteorological Society. Published online November 4, 2016. doi: 10.1175/BAMS-D-16-0183.1.