Climate Change and West Coast Marine Ecosystems: some thoughts on uncertainties Nate Mantua, PhD University of Washington Co-Director of JISAO’s Climate Impacts Group School of Aquatic and Fishery Sciences, and USFS PNW Station Nate Mantua, PhD University of Washington Co-Director of JISAO’s Climate Impacts Group School of Aquatic and Fishery Sciences, and USFS PNW Station CERF 2009 Chautauqua Portland, OR - November 3, 2009

Key issues for west coast marine ecosystems All IPCC scenarios point to warming in the future Future warming, like global ocean warming in the past 50 years, will be concentrated in the upper ocean For any given region, there will still be year-to- year and multiyear variations –This is because winds will be important The upper ocean will be become more “acidic”, and ecologically important thresholds are already being crossed in the PNW’s coastal waters All IPCC scenarios point to warming in the future Future warming, like global ocean warming in the past 50 years, will be concentrated in the upper ocean For any given region, there will still be year-to- year and multiyear variations –This is because winds will be important The upper ocean will be become more “acidic”, and ecologically important thresholds are already being crossed in the PNW’s coastal waters

cool-fresh-nutrient rich subarctic waters from northern Japan to California -- coastal upwelling extends this habitat south to Baja California July Sea Surface Temperature SeaWiFS images from NASA’s Goddard Space Flight Center July “ocean color” The subarctic seas of the north and northeast Pacific Ocean

Coastal upwelling Spring and summer winds from the north cause upwelling of cold, nutrient rich waters into the coastal waters of the western US and Baja

Fickle winds can cause large changes in upwelling habitat on short time-space scales 17.5C on July 14 ~11C on July 20 Stonewall Banks Buoy SST June 18 - August July 2005 SST NOAA CoastWatch image Buoy SST plot courtesy of Pete Lawson JuneJulyAugust

El Niño Impacts on the northeastern Pacific Ocean An intense Aleutian Low pressure cell in fall and winter brings warm southerly winds to our region, making for a mild winter and strong coastal downwelling that warms and stratifies the coastal ocean. Sept 1997 El Niño

Sept 1998 La Niña Year-to-Year changes associated with ENSO variations can also be large -- note the 3 to 4ºC (5 to 7ºF) decline in coastal SSTs between Septembers of 1998 and

“Newport Line” (central Oregon coast) upper ocean temperatures Depth in meters El Niño-related warming extends to a depth of ~100 meters (~330 feet) off Newport in 1998, compared with 1999 April 1998 April 1999

West Coast Nekton in Major changes in the distribution of pelagic fish and squid lead to important “top-down” impacts on coastal food-webs too Major changes in the distribution of pelagic fish and squid lead to important “top-down” impacts on coastal food-webs too

A recent visitor that seems to like it here - prior to 1997 they’d never been observed in PNW waters, but were reported to be abundant in California waters in the 1930s. Humboldt Squid, Jumbo flying squid, Diablos rojos (Dosidicus Gigas): a voracious predator that can reach up to 2m in length and weigh up to 45 kg Image from

Cool water, weak stratification subarctic Generally good for NW coho and chinook high nutrients, a productive “subarctic” food-chain with abundant forage fish and few warm water predators; Generally good for NW coho and chinook Warm stratified ocean, few subtropical Generally poor for NW coho and chinook nutrients, low productivity “subtropical” food web, a lack of forage fish and abundant predators: Generally poor for NW coho and chinook Upwelling food webs in our coastal ocean T spinifera

Decadal variations in spring upwelling In the 20th C. springtime upwelling winds varied strongly at interdecadal timescales (partly in step with the PDO) Schwing et al. 2006: GRL In the 20th C. springtime upwelling winds varied strongly at interdecadal timescales (partly in step with the PDO) Schwing et al. 2006: GRL strong weak

Bottom trawl surveys in Pavlov Bay, Alaska (source: Bottsford et al. 1997, Science) Late 1960’s Late 1970’s 1980’s Ecosystem regime shifts - where are the thresholds?

Global warming and Coastal Cooling? oceanic HighThermal Low Because the land warms faster than the ocean, this may intensify the sea level pressure gradient between the oceanic High and Thermal Low over land, which would intensify upwelling winds… which would cool the ocean even more, and further increase the temperature contrast “Thermal Low” Over Warm land “Oceanic High” Over Cooler water H L See Bakun, Patterns in the Ocean, p West coast

IPCC multi-model ensemble summer and winter SLP projections Taken as a group, IPCC climate models project trends to a stronger North Pacific High in summer, and a deeper Aleutian Low in winter 2090s A1B IPCC models JJA DJF H H

More regional climate modeling results are being analyzed now… Salathé, Zhang, Mantua, and Mitchell, in prep 2060s -1990s wrf/echam5_A1B JFM windstressAMJ windstress In this climate model, wintertime Aleutian Low and springtime North Pacific High both intensify in late 21st century …

Climate change and El Niño Trend-ENSO pattern correlation Ratio of ENSO variability La Niña-likeEl Niño-like variability incr. decr. Most (not all) climate models project a trend to El Niño-like SST conditions in the tropical Pacific Most (not all) climate models project a trend to El Niño-like SST conditions in the tropical Pacific different climate models show different changes in ENSO activity different climate models show different changes in ENSO activity IPCC WG1 2007

The future wont likely present itself in a simple, predictable way, as natural variations will still be important for climate change in any location Overland and Wang Eos Transactions (2007) Box1 oCoC Degrees C

55yr trends in Pacific SSTs From there was a near-global warming of SSTs subarctic N. Pacific SSTs had a cooling trend (Figure created by Todd Mitchell, UW-JISAO)

Pressing questions How will sediment budgets change with rising sea levels and altered discharge in western rivers? –And what will be the dynamic response of coastlines and estuaries? What will happen to ENSO, PDO and regional- scale upwelling winds? –Magnitudes and variability across timescales ranging from days to decades … Will future ecosystem responses to radiatively- driven warming look like those caused by wind- driven warming of the past? How will sediment budgets change with rising sea levels and altered discharge in western rivers? –And what will be the dynamic response of coastlines and estuaries? What will happen to ENSO, PDO and regional- scale upwelling winds? –Magnitudes and variability across timescales ranging from days to decades … Will future ecosystem responses to radiatively- driven warming look like those caused by wind- driven warming of the past?