El Niño and the Arctic Report Card

This week, we’re covering the annual American Geophysical Union (AGU) meeting here in San Francisco, where 24,000 scientists are sharing the latest results of their research. On Tuesday we learned more about global El Niño impacts (we recently produced a video about this), and we saw the release of the annual Arctic Report Card.

El Niño Impacts

Four researchers spoke during Tuesday’s AGU sessions about the impacts of El Niño globally, with an obvious focus on the current event. Duane Waliser of NASA’s Jet Propulsion Laboratory looked at the effects of El Niños on atmospheric rivers, the strong weather patterns that bring rain and large storms to our coast. Atmospheric rivers provide 40 percent of California’s annual water supply in about ten storms! And while El Niños don’t increase the number or frequency of atmospheric rivers, they do make them stronger and wetter. However, during El Niño years, warmer weather means that atmospheric rivers deliver less snowfall (and snowpack) to the Sierras.

Will this El Niño be a drought-buster? NOAA’s Martin Hoerling looked at historical data of similarly strong El Niños and finds reason for optimism. While we haven’t seen much rain yet, he says, past drought relief has typically arrived in late December through January and February. So it’s too soon to tell. He did remind us that drought-busting is more than just rainfall: water resources have to be managed very carefully.

Mark Olsen of NASA Goddard uses the Aura satellite (and its OMI instrument mentioned in yesterday’s article) to see how El Niños affects ozone levels. The data show that wind patterns during El Niño change ozone slightly, with varying effects in the Atlantic and southeast Asia that could influence long-term trends in ozone concentration, affecting air quality in those regions.

Finally, Jim Randerson of UC Irvine addressed global fire patterns during El Niño events. Satellite data demonstrate that during El Niños, the number and size of fires increase in tropical forests across Asia and South America. This is due to drying in those areas, Randerson said. “El Niño causes less rain to fall in many areas of the tropics, making forests more vulnerable to human-ignited fires.” The fires are often started for agricultural purposes, and during normal wet years, fires taper out as they reach the damp forest. But as we witnessed in Indonesia this past fall (and will likely see in Central and South America this coming spring and late summer), too-dry forests fuel the fires further. Was El Niño behind the increased wildfires we witnessed in northern California this past summer and fall, as some proposed? Randerson sees no correlation.

Arctic Report Card

Will El Niño affect the Arctic? A reporter posed this question at another press conference on this year’s Arctic Report Card. NOAA’s Jim Overland says there’s a possibility, but not a certainty. Rick Spinrad, NOAA’s chief scientist, considers this ninth annual Arctic Report Card “the key resource in understanding Arctic change.” The report card’s contributors and editors focused on the current certainties and status of the Arctic. Spinrad says, “Warming is happening twice as fast in the Arctic, and we know this is due to human-influenced climate change.” He went on to say that changes in the Arctic, whether severe or subtle, don’t just affect the Arctic, but the entire globe.

So how did the Arctic fare? The news was grim. Jacqueline Richter-Menge noted that the temperature has increased 2.9° Celsius in the Arctic since the beginning of the 20th Century. The maximum sea ice extent occurred on February 25 this year, 15 days earlier than average. The composition of older, thicker ice and younger, thinner ice is also changing. First year ice now makes up 70 percent of sea ice. Melting occurred over 50 percent on the Greenland ice sheet in 2015. It was the second-worst fire season on record in the Arctic, and the tundra vegetation greenness has been browning over the past two to four years, which could have lasting effects on permafrost and temperatures.

North Pacific walruses have seen severe declines, Kit Kovacs told the crowd. And Atlantic fish may be pushing out native Arctic fish in the Barents Sea. Want more bad news? Widespread phytoplankton blooms, increasing Arctic river discharge, and rising sea surface temperatures also made the report card. Any good news? Spinrad was very, extremely, cautiously optimistic about the new Paris Agreement. And Overland mentioned that the tipping point they feared might happen with Arctic sea ice—that it could become so diminished that it would not recover in the winter—doesn’t seem to be a possibility.

Sounds like there’s much room for improvement!