platform.virdocs.com/r/s/0/doc/1941719/sp/244855632/mi/716572953?cfi=%2F4%2F2%5BInvestigation12B%5D%2F34%5Bfig12B_1%5D%2F4&menu-table-of-contents row inves wwwvery regain (you regram (roymay waniterimentos mar comprare cry youying verr ww www in legs to collect sediment cores, rocks, bcean water samples, and ocean equipment with the goal of addressing specific scientific questions. Leg 208 of the program (then known as the Ocean Drilling Program) was scheduled between 6 March to 6 Mav ollect continuous sequences of sediment from the lower Cenozoic (-65 million years ago) to present. The goal was to study the Paleocene-Eocene Thermal Maximum (PETM). 233 x 135 145 154 166 176 188 200 211 222 231 242 255 264 L M was a remarkable period of extreme global warming that occurred about 56 million years ago. Figure 12B-1 provides a temperature record reconstructed from climate proxies, which preserve physical chara + erature. The proxy records compiled to reconstruct Figure 12B-1 include ice cores, fossils, tree rings, and pollen. The temperature during the PETM was 14°C warmer than the average temperature between 19 a. 1 million years before present b. 3 million years before present a. increasing b. decreasing c. stable 3. From the PETM to 400,000 years ago, temperature generally pochronne € 400 d. 500 5. The temperature in the year 2000 was 100 a 2 b. 4 c. 6 d. 8 6. The temperature projected for the year 2100 is a 2.0 b. 4.5 c. 6.0 d. 8.5 121ni 300 200 10000 c. 55 million years before present d. 100 million years before present 2. In general, with the exception of the very recent time period, the temperature in the past 10,000 years has been Figure 128-1. A record of temperature on Earth over the past 500 million years. The timescale (x-axis) depicts years before present, telescoping from millions of years before present on the left to thousands of years before present toward the right. The most recent peak in warming occurred during the transition from the Paleocene to the Eocene period about 56 million years ago. The orange band (between 500 my to 100 my) shows the effect of extreme assumptions in application of the Geostationary Carbon Observatory (GeoCarb) reconstruction. [Glen Fergus 2014, L 12-23 1. Refer to Figure 128-1. When was the last time in the geological record the temperature excursion of +14°C from the 1960-1990 baseline occurred? Temperature in degrees Celsius can be referenced on the left y-axis of the graph a. increased b. decreased c. was stable 4. The last time Earth experienced a surface temperature similar to the PETM occurred at about million years ago. a. 200 b. 300 Temperature of Planet Earth 5043015 years before present C warmer than the 1960-1990 average. °C warmer than the 1960-1990 average. www $3000 800 600 400 200 30 15 20 5 DC) housands of years at p - By understanding an extreme climatic shift in the past, we can understand how the planet may respond to current warming trends. The PETM (about 100,000 years) was a geologically brief interval of widespread warming associated with a huge buildup of atmospheric carbon dioxide and significant ocean acidification. Possible greenhouse gas sources include the release of methane from the decomposition of methane hydrate deposits within ocean floor sediments, carbon dioxide from volcanic activity, and oxidation of organic-rich sediments. Scientists believe the PETM may have resulted from an abrunt release of as much as 2000 eigntons of marine methane. A hydrate is an ice care that contains a molecule of methane Methane houfrates faithin ne spaces in ocean floor soliments) □: A p. 233 > p. 234