GEOL 1302, Week 2 Notes
GEOL 1302, Week 2 Notes GEOL 1302
Popular in Intro To Global Climate Change
Popular in Geology
This 4 page Class Notes was uploaded by Theresa Nguyen on Monday September 5, 2016. The Class Notes belongs to GEOL 1302 at University of Houston taught by yunsoo choi in Fall 2016. Since its upload, it has received 50 views. For similar materials see Intro To Global Climate Change in Geology at University of Houston.
Reviews for GEOL 1302, Week 2 Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/05/16
Chapter 2: Is the Climate Changing? Temperature Anomaly Instead of analyzing temperature directly, climate scientists instead analyze temperature anomalies. A temperature anomaly is the difference between the actual temperature and a reference temperature, usually the reference temperature is an average over a previous multi-decadal period. Recent climate change – Global average T Past Decade warmest on record From 1906 to 2005: dT = 0.74 degrees Celsius Two distinct warming periods: 1910 – 1945 and 1976 – 2005 Rate of warming past 50 yrs = 1.3 degrees Celsius per century - 2x the past 100 years Recent climate data – Zonal temperature Warming not uniform Land areas warmed more than oceans Arctic more than rest of Earth Temperature measurement network No single dataset ever considered definitive Network of thermometers not designed for climate monitoring Network has undergone many changes over the years (types of thermometers, location of stations, environment around station, observing practices, etc) Scientists know about these problems had have worked hard to take them into account Uncertainty in the observed warming is result of both adjustments and some uncertainties that cannot be adjusted for Warming from 1906 to 2005 is 0.74 degrees Celsius + or – 0.18 degrees Celsius - Therefore, warming likely between 0.56 degrees Celsius and 0.92 degrees Celsius Foolish to rely entirely on this single data source to determine how much Earth has warmed. Ice – Sea Ice Extent Sea ice loss measured from satellite reports clear melting in Arctic (but little sea-ice loss in Antarctic (not shown). - This confirms global distribution of polar warming. Arctic sea-ice anomaly for July. - Anomaly is the percent deviation from the 1981-2010 mean area of 9.7 million km2. Ice – Greenland ice sheet Between 2002 – 2009 Greenland 1,600 billion tons of ice (~200 billion tons/yr). - Provides more confidence that warming is indeed occurring. Ocean Temperatures Sea surface temperatures already included in the Land-Ocean surface temperature record. Ocean temperature anomaly in degrees Celsius for top 700 m of the ocean. - Anomalies are calculated relative to 1957-1990 Ocean Heat Content Monthly ocean heat content anomaly for top 700 m of the ocean. - Anomalies are calculated relative to 1957-1990 Monthly ocean heat content anomaly for top 2000 m of the ocean. - Anomalies are calculated relative to 1957-1990 Sea-Level Anomaly Average rate of 1.5 mm yr 1900-2000 (15 cm). - This is faster than 19th century. Past 40 years rate 1.8 mm per year (25% due to thermal expansion). Past 10 years rate of 3.1 mm per year (50% due to thermal expansion). - Interconnected. Is today’s climate changing Yes. Evidence is so strong, IPCC calls it unequivocal. - Meaning it is beyond doubt. Great consistence among various datasets (surface T, satellite, ice loss, heat content of oceans, sea-level rise). Even with uncertainty or errors in some measurements, they are independent measurements. - No single problem could push all measurements in the same direction. These datasets are only a small part of the mountain of evidence. Decreased snow cover, thawing of permafrost, few extreme cold events, more extreme hot events, increased extreme precipitation events, shorter winters, and thousands of biological and ecological changes (poleward expansion of species ranges, earlier spring flowering and insect emergence, change in migration patterns, etc.) Contrary data are rare, regional limited, and vastly outnumbered by evidence of warming. Should be no question in your mind that Earth’s climate is warming. What is not evidence of climate change Climate change is a shift in statistics of the atmosphere… Therefore, a single odd weather event is almost never evidence of climate change. A single extreme hot summer, even if it were hotter than any other summer in the past 100 years, might occur in a stable climate. If hot summers were to begin happening regularly, then that would be indicative of climate change. Also important not to draw conclusions from regional climate extremes. - Regions hotter than average may be cancelled out by other with lower than average temperatures. Cooling over past 70 Myr Reconstructed temperature of the polar regions over the past 70 million years. - The harp temperature spike 55 Mya represents the PaleoceneeEocene Thermal Maximum. - Time series is from ocean isotopes, sensitive to both temperature and sea-level. - About 35 million years ago, Antarctic Ice sheet began to form, causing some variation here. Past 1,000 years Average northern hemisphere anomaly based on multiple proxy records and modern surface thermometer record. - Anomalies calculated relative to 1961-1990 average. - Dessler 2012 F2.12. Chapter Summary The most well studied and reliable source of temperature data for past century is surface thermometer network. - Shows global annual average warming of 0.74°C over 20th century with uncertainty of 0.18°C. Scientists have large number of independent measurements with confirm warming seen by surface thermometer network (satellite T, ice measurement, ocean heat, seal level, etc). Due to overwhelming evidence, scientific community has concluded that Earth is warming (beyond doubt). - Scientists have also concluded that previous decade (2000-2010) is very likely the hottest of past 400 years. Earth’s climate has varied widely over 4.5 Byr history. - Geologic record has climate both much warmer and cooler than today’s climate. Over past few million years Earth has osscilated between ice ages (5- 8°C cooler) and interglacial periods. - Currently in interglacial.
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'