Lauren Heerschap, Fort Lewis College, Spring 2016

Do you think Earth is cooler or warmer now, compared to past climates? What are some factors that cause Earth’s climate to change? How do current changes compare to past changes?

Paleoclimatology! – Direct Measurements or Records: Instrumental Record – temperature since about 1860 Historical Records – written records and archeology, ex: Little Ice Age, Medieval Warm Period – Proxy Data: Sedimentary Rock Record – rock types and fossils indicate past environments Tectonic History – distribution of landmasses, mountains, oceans all can affect global climate Isotopes – oxygen (O-16 vs. O-18) derived from corals and sediments indicates “weight” of seawater and general temperature Evidence of Glaciation – erosion and deposition by ice leaves record Ice Cores – trapped gas bubbles show past CO2 and CH4, and also contain ash, pollen, dust that help illustrate climate Tree Rings – dendrochronology, shows drought vs. wet seasons, fire Pollen – palynology, tells what plant species were nearby

Tectonics – arrangement of continental masses and areas of high elevation, mountain building Ocean currents – circulation of cold and warm currents Volcanic activity – release of aerosols, GHGs Atmosphere – amount of GHGs present, methane releases Carbon sequestration or release – times of higher % vegetation, coal formation, limestone formation, weathering Milankovitch cycles – variations in Earth’s orbit, tilt, and axis wobble Solar cycles/forcing – variation in Sun’s energy (minor) Albedo – reflectance of surface leads to feedback loops Anthropogenic forcing – people! Post-Industrial Revolution increases in greenhouse gases, deforestation, agriculture

Ocean currents distribute warm and cold waters throughout the globe

Milankovitch Cycles are variations in Earth-Sun geometry that cause glacial fluctuations

Albedo is a measure of surface reflectance – ocean water absorbs a lot of solar energy, while glaciated areas reflect

Composition of Earth’s Current Atmosphere

Water vapor Carbon dioxide Methane Nitrous oxide Ozone CFC’s Sulfur hexaflouride These gases trap the Earth’s heat, reduce its heat loss, maintain its temperature – like a greenhouse! Earth would be -18 °C on average without these gases! (It’s about 14 °C now…)

March That’s 100 ppm higher than past 400,000 years!

Where does this data come from?

From

RANK 1 = WARMEST PERIOD OF RECORD: 1880–2015 YEAR ANOMALY °C ANOMALY °F (tie) (tie) (tie)2003 & (tie)

record-shattering-global-warm-temperatures-in-2015

These maps show temperatures across the world in the 1880s (left) and the 1980s (right), as compared to average temperatures from 1951 to This difference from average is called an anomaly. The map on the left shows that it was colder in the 1880's in most places. The map on the right shows it was warmer in the 1980s in most places. Earth's average surface temperature has increased almost 1.5°F during the 20th century. Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.3°F-0.4°F per decade. Source: NASANASA 1880s 1980s

warming.com/sea-temperature.html

2007 report by Intergovernmental Panel on Climate Change, a group of 1200 scientists from 120 countries, concluded that there is 90% probability that observed changes in climate are anthropogenic

Milankovitch cycles are modeled to be on cooling trend, not warming trend right now. Solar output is lower now than it has been in decades.

Pre-Industrial CO 2 = 280 ppm Spring 2016 reached 405 ppm Already seeing over 1  C temperature rise Models suggest 4-8  C further rise if CO 2 continues to rise

Shift in world’s climate zones Extinctions, Loss of Biodiversity Melting Ice: Sea Level Rise, Water Resources Displaced coastal/island communities Droughts, Famines Increased storms, hurricanes, floods, landslides Wildfires Ocean Acidification Feedback Loops

IPCC conclusions: – If temperatures rise 2°C above pre- industrial levels, 20-30% of plants and animals may be subject to extinction – If temperatures rise 4°C, 40-70% of species will be at risk

Only melting land ice contributes to sea level rise, not melting sea ice.

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Wildfires >250 acres, rd/news/topstory/2006/wildfire_thr eat.html

Positive (enhance changes) : – Water vapor – Natural GHGs – Albedo & Melting Ice – Methane hydrates – CFCs & ozone layer Negative (dampen changes) : – Aerosols – Black carbon – Cloud cover – Vegetation/Algal Blooms – Cold freshwater influx into oceans

Stabilization

Global: – Intergovernmental Panel on Climate Change (IPCC) provides information to guide policies – first report in 1990 – United Nations Framework Convention on Climate Change (UNFCCC) began in 1992 at Earth Summit in Rio de Janeiro – Kyoto Protocol (1997): GHG emission target limits aiming for below 1990 levels (US did not ratify) – 2014 Agreement with China: office/2014/11/11/fact-sheet-us-china-joint-announcement-climate-change- and-clean-energy-chttps:// office/2014/11/11/fact-sheet-us-china-joint-announcement-climate-change- and-clean-energy-c – Carbon Cap and Trade, Carbon Offsets, Carbon Tax National: US is not unified in efforts, many organizations are involved State: California target of reaching pre-1990 GHG levels by 2020 through renewable electricity sources, carbon trading, strict vehicle emissions standards Local: grassroots efforts aplenty! Individual????

The Ozone Hole “Discovered” in 1985 Linked to CFC release into atmosphere 1987 Montreal Protocol banned these substances Steady “healing” of the layer

What facts support the idea of anthropogenic causes for global warming? Climate skeptics use what counter-arguments against anthropogenic causes? How can people look at the same facts but have differing interpretations? In your opinion, what is the ‘scariest’ consequence of future global warming? Are there any positive aspects of global warming? What is the most important thing humans should do NOW to counteract global warming? Are the environment and the economy inherently at odds with each other?

EPA: and NOAA: IPCC: NASA: