Change & Continuity over Earth time 1,000 BP 10,000 BP 100,000 BP 65 million yrs BP 6 billion yrs BP hours months years decades <100 - 1500 years 100,000 yrs 10’s of million yrs 100’s of milion yrs climate tides seasons El Niño PDO (ocean) Greenland abrupt climate change ice ages Paleocene-E. thermal max Snowball Earth ecology pollination salmon runs salmon (Kodiak Is.) mammals multicellular life humans 112th US Congress Cities Agriculture Climate L2

Evaluating Climate change Climate drivers Sun’s strength and distribution- incoming “radiative forcing” Reflection of incoming light (albedo) “positive feedback” Greenhouse gases- outgoing “radiative forcing” Questions How long? Local or global? How comparable was the climate to present day? Climate L2

Tides ~6-12 hour change Distinct ecological bands Adaptations to different air exposure times Climate L2

Yellowstone cottonwood replacement 1800 1920 1999 Climate L2

Kodiak Island salmon runs marine Karluk Finney et al., 2002 Akalura Frazer = no salmon “control” lake, waterfall at outlet Frazer terrestrial Climate L2 2000 AD - 500 BC 5

Warming events over last 12,000 years relative to today Climate L2

Abrupt climate changes North Atlantic Greenland warmed 8 - 16C within decades, cooled slowly Most linked to changes in ocean heat transport (purple line) Greenland (green line) doesn’t match Antarctica (lower black line) Climate L2

Ice Core Evidence CO2 and temperature: 420,000 BP to present 2050 Ice Core Evidence CO2 and temperature: 420,000 BP to present 2100?? Today This graph covers four glacial cycles. Most data derived from Antarctic ice cores. “ppmv” means parts per million volume – CO2 is a trace gas in the atmosphere. One degree Celsius is 1.8 degrees Fahrenheit. Temperature differential and CO2 fluctuate in lock-step. We were already in a warm (interglacial) period when anthropogenic CO2 emissions began. There was never a CO2 maximum as high as today (370 ppm) over the past 420,000 years. The anthropogenic increase in CO2 from 270 ppm to 370 ppm happened in just 200 years – about 3/100 inch if this graph is projected 5 feet wide, and an instant in geological time. Middle of the road IPCC TAR scenarios put CO2 at ~500ppm by 2050 …By 2100 IPCC TAR projects CO2 between ~500 and ~900ppm depending on our choices (3 minutes) Source: various, (1) Vostok assembled by Davies 2000, (2) GISP2

Glacial sea level ~130 m lower ~18,000 yrs ago Assembly of several climate datasets of ocean temperature Climate: Long range Investigation, Mapping, and Prediction Climate L2

How warm was the last interglacial? Global ice cover is easier to reconstruct than temperature: Less glacial ice ~100,000 years ago than today Due to reduction of Greenland, Antarctic Ice sheets Temperatures warmer at least some places coastal Pacific, Atlantic, Indian Oceans Expansion of forest into tundra in North America & Asia Climate L2

Greenhouse gases Climate L2

Chosing carbon: why is CO2 the focus?

Biodiversity over millions of years: known genera Thousands of genera “Big Five” mass extinctions other mass extinctions Climate L2 Millions of years ago http://en.wikipedia.org/wiki/Extinction_event

Present extinction rates are easier to estimate to past "If we find a mass extinction, we have great difficulty determining whether it was a 'bad weekend' or it occurred over a decade or 10,000 years" Charles Marshall “Present (extinction) rates are higher than during most past mass extinctions.” Climate L2

How does current change compare to past? Questions Local? (temperature, precipitation) Global (greenhouse gases) How comparable to present day (continental drift) If projections are realized of 5C in this century, then the Earth will have warmed ~50x faster than at end of the last ice age Several degrees of global warming would be bigger than any comparable increase over the last 50 million years Climate L2

Change & Continuity over Earth time 1,000 BP 10,000 BP 100,000 BP 65 million yrs BP 6 billion yrs BP hours months years decades <100 - 1500 years 100,000 yrs 10’s of million yrs 100’s of milion yrs climate tides seasons El Niño PDO (ocean) Greenland abrupt climate change ice ages Paleocene-E. thermal max Snowball Earth ecology pollination salmon runs salmon (Kodiak Is.) mammals multicellular life humans 112th US Congress Cities Agriculture Climate L2 16

Future(s) temperature change global economic development regional economic stratification global environmental consciousness regional environmental consciousness and economies 1992 projection Intergovernmental Panel on Climate Change (IPCC) is an international collaboration of about 2,000 climate scientists organized by the World Meteorological Organization and the United Nations Environment Program. No larger effort to organize scientific consensus has ever been undertaken in history. IPCC does not perform research; it synthesizes worldwide research. Working Group I synthesizes research on fundamental climate science, including model forecasts of future change. Future change depends both on the behavior of the climate system and on the anthropogenic GHG emissions. Each color line represents one anthropogenic GHG emissions scenario. Different models forecast different behaviors of the climate system. The error bars on the right show how the outcome of each emission scenario (each color) varies depending on which forecast model. “SRES” is the Special Report on Emission Scenarios, which describes 35 emissions scenarios. Emission scenarios A1F1 – B2 on this graph are six of these 35, and cover a wide variety of world economic scenarios. Dark grey shows the envelope of similar results for all 35 SRES scenarios. Light grey shows a wider uncertainty using IPCC’s simple model calibrated to the climate sensitivities exhibited by the more complex models. The scenarios do not include aggressive GHG regulation. Scenario IS92a is for comparison with the Second Assessment Report. (3 minutes) Climate L2 Source: IPCC 2001

Projected Pacific Northwest Temperature Changes relative to 1970-1999 7.2°F 3.6°F 0°F 10.8°F 14.4°F +2.2ºF (1.1-3.4ºF) +3.5ºF (1.6-5.2ºF) +5.9ºF (2.8-9.7ºF) °C Choice of emissions scenario matters more after 2040s So how is climate in the PNW projected to change? The average warming rate in the Pacific Northwest during the next century is expected to be in the range 0.1-0.6°C (0.2-1.0°F) per decade, with a best estimate of 0.3°C (0.5°F) per decade. For comparison, observed warming in the second half of the 20th century was approximately 0.2°C (about 0.4°F) per decade. The warming trend for the 20th century overall was 0.15°F per decade. In every scenario, the future warming greatly exceeds natural variability. For precipitation this is not the case; the range of simulated precipitation could increase substantially or decrease substantially but the weighted-average annual mean change is small throughout the 21st Century.   Figure: Smoothed traces in temperature for the 39 model simulations, relative to the 1970-99 mean. The smooth curve for each scenario is the Reliability Ensemble Average (REA) value, calculated for each year. The average provided above each box is the REA for that decade; the low and high values represent the lowest and highest value from either scenario (B1 or A1B) 2020s* temperature precipitation low 0.6°C (1.1°F) -9% average* 1.2°C (2.2°F) +1% high 1.9°C (3.4°F) +12% 2040s* temperature precipitation low 0.9°C (1.6°F) -11% average* 2.0°C (3.5°F) +2% high 2.9°C (5.2°F) +12% 2080s* temperature precipitation low 1.6°C (2.8°F) -10% average* 3.3°C (5.9°F) +4% high 5.4°C (9.7°F) +20% Rate of change per decade expected to be 3x greater through mid-21st century, data from Climate Impacts Group Climate L2 18

Future fossil fuel reserves