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A NASA graphic shows how much hotter temperatures were in the 2012-2016 time frame, compared with the 20th-century average. (NASA Graphic)

Today’s outlook for climate trends is a good-news, bad-news situation for the Pacific Northwest.

First, the bad news: NASA and the National Oceanic and Atmospheric Administration say 2016 ranked as the hottest year on record in terms of global mean temperatures.

NOAA said the year’s average temperature across global land and ocean surfaces was 58.69 degrees Fahrenheit, which is 1.69 degrees F above the 20th-century average and 0.07 degrees F above the previous record, set in 2015.

NASA used a slightly different set of figures, including more readings from the Arctic, to determine that last year’s global average was 1.78 degrees above the 20th-century average and 0.22 degrees above 2015. By either measure, the average is the highest since modern recordkeeping began in 1880.

“2016 is remarkably the third record year in a row in this series,” Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies in New York, said in a news release. “We don’t expect record years every year, but the ongoing long-term warming trend is near.”

This year’s average got a boost from an El Niño weather pattern during the early part of the year, NOAA said. El Niño is typically associated with warmer sea surface temperatures in equatorial Pacific waters. We’re currently in the midst of a weak La Niña weather trend, with cooler Pacific Ocean temperatures that should bring down the average.

The long-term warming trend is widely considered an effect of industrial greenhouse-gas emissions, which has sparked concerns about the potential impacts of climate change. Scientists say those impacts could include weather extremes ranging from droughts to floods; continued loss of glacial and polar ice; and sea level rise as well as ocean acidification.

Milder days ahead?

Not even Seattle would be immune from such impacts, but a study conducted by researchers NOAA and Princeton University brought a bit of good news about our region’s climate outlook: Prediction models suggest that the number of days in Seattle with mild weather should increase by the year 2100.

The study, published in the journal Climatic Change, projects that Seattle’s tally of mild days will go from 88 to 97 by the 2081-2100 time frame. A mild day is defined as a day with temperatures between 64 and 86 degrees F, no more than half an inch of rain and a dew point below 68 degrees F, which is indicative of low humidity.

The study was undertaken to put climate trends into a localized, everyday context.

“Extreme weather is difficult to relate to, because it may happen only once in your lifetime,” lead study author Karin van der Wiel, a Princeton researcher at NOAA’s Geophysical Fluid Dynamics Laboratory, explained in a news release. “We took a different approach here and studied a positive meteorological concept, weather that occurs regularly, and that’s easier to relate to.”

Mild weather forecast
This map shows the change in the annual number of mild days across the globe from the period of 1986-2005 to the period of 2081-2100. Bluish areas are expected to experience an increase in mild days, while areas of brown are expected to see a decline in those days. (NOAA / Princeton Graphic / Van der Wiel et al.)

Seattle is a bright spot in the study: The global average of mild days per year is projected to fall 13 percent, from 74 to 64 days. In the United States, the models suggest the mild-day count will decrease from 77 to 68 in Chicago, from 97 to 69 in Miami, and from 83 to 77 in New York City.

The projections indicate that tropical areas in Africa, Asia and Latin America will be hit the hardest, due to rising heat and humidity. Some regions could see 15 to 50 fewer days of mild weather in the course of a year, based on the computer models.

Study co-author Sarah Kapnick, a physical scientist at the NOAA lab, said changes in mild weather are likely to have effects on economic well-being, public health, leisure activities and urban planning.

“We believe improving the public understanding of how climate change will affect something as important as mild weather is an area ripe for more research and more focused studies,” she said.

In addition to Van der Wiel and Kapnick, the authors of “Shifting Patterns of Mild Weather in Response to Projected Radiative Forcing” include Gabriel Vecchi.

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