on Orcas? David Horsey, Seattle Post-Intelligencer

Climate Change Science How settled is it? And what might it mean for the northwest? Nate Mantua, Ph.D. Climate Impacts Group School of Aquatic and Fishery Sciences University of Washington Climate Science in the Public Interest Crossroads Lecture Series Orcas Island March 14, 2010

In the news … “CLIMATEGATE!”  In Nov 2009 more than s from the University of East Anglia’s Climate Research Unit are “stolen” by hackers and published on the internet. A few s reveal scandalous bits of text … “use Mike’s Nature trick … to hide the decline” [We] “will keep them out somehow, even if we have to redefine what the peer-reviewed literature is!”

Climate scientists feeling the heat

Climategate raises some serious questions 1.Do the s indicate a broad climate science conspiracy? 2.Do the s undermine the widely held understanding of climate change science? What do we know about climate change, and how do we know it?

Science of climate change  The scientific understanding comes from thousands of peer-reviewed scientific papers  Intergovernmental Panel on Climate Change (IPCC)  Major IPCC reports in 1990, 1996, 2001, 2007  Reports are produced by hundreds of authors  Conclusions (2007 report):  “An increasing body of observations gives a collective picture of a warming world and other changes in the climate system.”  “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.”

Four main points 1.There is a natural Greenhouse Effect 2.Humans are increasing the Greenhouse Effect by adding Greenhouse Gases to the atmosphere 3.Effects of a changing climate are already apparent 4.There is very likely much more global warming to come

Earth’s Natural Greenhouse Effect

Some facts  Earth’s natural greenhouse effect warms surface temperatures by ~33ºC (60 º F)  H 2 O vapor the most powerful greenhouse gas (GG)  other important GG’s are CO 2, CH 4, N 2 O, HFCs, PFCs, and SF 6 …  Human caused emissions of these GG’s are increasing the natural greenhouse effect  Without drastic changes in current emissions trends, GG concentrations will increase dramatically in the next few centuries

Carbon-dioxide concentrations  Seasonal changes driven by the “breathing” of the biosphere have been riding on top of a rising trend source -

Industrial revolution and the atmosphere The current concentrations of key greenhouse gases, and their rates of change, are unprecedented. Carbon dioxideMethane Nitrous Oxide

 Current concentrations are higher than any time in at least the past ~780,000 years  ~70% of CO 2 emissions come from fossil fuel burning From a long term perspective, these changes are enormous CO 2 over the last 160,000 yr 2009

20th century warming was global Globally averaged, the planet is now about 0.75°C warmer than it was in 1860, based upon dozens of high-quality long records using thermometers worldwide, including land and ocean (IPCC 2007).

Olga air temperature since 1891

Race Rocks sea surface temperature since 1921  Surface temperatures for Puget Sound as a whole closely track those at Race Rocks  Note the large year-to-year changes, decadal cycles, and on longer- term warming trend

The South Cascade glacier retreated dramatically in the 20th century Courtesy of the USGS glacier group Length of the Blue Glacier ~ 800 meter recession since the early 1900s, and ~1500 meter recession since the early 1800s

Recent Climate News: Arctic Sea Ice

Source -

Changes in glaciers, corals, tree rings, bore holes and ice cores also indicate a global average temperature change in the 20th century consistent with the thermometers. recent warming is very rapid in the context of past 1200 year N. Hemisphere temperature reconstruction Paleoclimate: New and Independent Evidence From Many Types of Past Data

Human and Natural Drivers of Climate Change Aerosols (like dust and smog) tend to cool the climate; their precise impact is highly uncertain Carbon dioxide is causing the bulk of the forcing. On average, CO 2 lives more than a hundred years in the atmosphere

Natural Climate InfluenceHuman Climate Influence All Climate Influences

Summary of evidence for a human- contribution to recent warming  Rate of warming appears to be unusually rapid  Pattern of change matches that expected from increasing greenhouse gases  Solar, volcanic forcing would have led to cooling in the past ~30 years

What about the future? (one view from Hollywood)

The scientific approach What are the consequences of increasing nature’s greenhouse effect? To answer this question, scientists are using climate system simulation models and future greenhouse gas emission scenarios

Karl & Trenberth (2003) Science

What ’ s in the pipeline and what could come?  If GHGs were kept fixed at current levels, a committed 0.6°C of further warming would be expected by More warming would accompany more emission. 1.8 o C o F 2.8 o C o F 3.4 o C o F CO2 Eq o C o F

A1B ( ) scenario: Global mean warming 2.8 o C; Much of land area warms by ~3.5 o C Arctic warms by ~7 o C; get less warming for lower emissions (IPCC 2007)

Projections of Future Changes in Climate Drying in much of the subtropics, more rain in higher latitudes and in the wet tropics, continuing the broad pattern of rainfall changes already observed. (IPCC 2007)

21 st Century PNW Temperature and Precipitation Change Scenarios Projected changes in temperature are large compared to historic variability Changes in annual precipitation are generally small compared to past variations, but some models show large seasonal changes (wetter autumns and winters and drier summers)

springtime snowpack will decline in the warmest locations +2.3C, +4.5% winter precip ºF (2.3 º C) & + 4.5% winter precipitation + 4.1°F + 4.5% winter precip Figure courtesy of Alan Hamlet, UW Climate Impacts Group

The coldest locations are less sensitive to warming + 4.1°F + 4.5% winter precip Figure courtesy of Alan Hamlet, UW Climate Impacts Group

Runoff patterns are temperature and elevation dependent Oct Feb Jun Skagit Puyallup Skokomish Oct Feb Jun Puget Sound Precip Oct Feb Jun 1900’s a warmer climate

Cool water, weak stratification subarctic high nutrients, a productive “subarctic” food-chain with abundant forage fish and few warm water predators Warm stratified ocean, few subtropical nutrients, low productivity “subtropical” food web, a lack of forage fish and abundant predators Recently, warm ocean years have generally been poor for NW chinook, coho and sockeye, but good for Puget Sound pink and chum salmon. Upwelling food webs in our coastal ocean

From the Seattle Post-Intelligencer, October 20, 2005 In the ocean, species distributions change with temperature 134 lb marlin caught 40 mi. west of Westport, WA, Sept 2, 2005 Photo obtained from the Seattle Times web-archives

West Coast Fish in  Major changes in the distribution of pelagic fishes 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

New predator-prey interactions  A black bear with a salmon near Tofino, Vancouver Island  A black bear with a humboldt squid, also near Tofino, Vancouver Island

House et al. (2002) GCB Land-use change 200 Pg C (42%) Fossil emission 280 Pg C (58%) Atmospheric accumulation 190 Pg C (40%) Terrestrial sink 166 Pg C (35%) Ocean sink 124 Pg C (26%) SourcesSinks Ocean Acidification: the other CO 2 problem Ocean pH has already dropped by 0.1 units (30% more acidic); increased CO 2 uptake is expected to reduce upper ocean pH by ~0.5 units by 2100, which would be the largest change in pH to occur in the last million years CO 2 + H 2 O HCO H +

Reduced calcification rates for calcifying (hard-shelled) organisms physiological stress Shifts in phytoplankton diversity and changes in food webs Reduced tolerance to other environmental fluctuations for changes to fitness and Potential survival, but this is poorly understood What are the biological implications of ocean acidification? Barrie Kovish Pacific Salmon Coccolithophores Vicki Fabry Pteropods Copepods (Slide provided by Dick Feely, NOAA)

Concluding thoughts  Greenhouse Effect physics are real, robust, and well- understood  There is plenty of uncertainty about future climate, but it cuts both ways  impacts of increasing concentrations of greenhouse gases may be less, or may be more, extreme than scientific mainstream has reported  The northwest has key vulnerabilities to climate (and ocean chemistry) change  Our snowpack is extremely valuable, and it is highly sensitive to winter temperatures  Ocean acidification poses great risks to ocean ecosystems

More information The UW Climate Impacts Group  The US National Academy of Sciences  NOAA Climate Services  The Intergovernmental Panel on Climate Change 