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Climate Change: Polar Regions
Published in Yeqiao Wang, Atmosphere and Climate, 2020
The start of the post-glacial Holocene period is dated from 11,500 years ago when conditions approached those of today. In the Arctic region, the warmest conditions appear to have occurred in the early Holocene, coincident with the precessional timing of the boreal summer solstice, occurring when the Earth was nearest to the Sun (perihelion), making northern summers relatively warmer. The precession of the equinoxes has a period of approximately 23,000 years; currently, summer solstice occurs at aphelion, when the Earth is most distant from the Sun, making summers relatively cooler. In the early Holocene the distribution of bowhead whale bones indicates at least periodically ice-free summers along the length of the Northwest Passage and the same pattern is repeated much later from approximately A.D. 500-1250.
Global Climate Change
Published in John C. Ayers, Sustainability, 2017
Paleoclimate records from 10,000 to 1 million years ago primarily come from ice cores retrieved from thick continental ice sheets. We are currently in the Pleistocene ice age that started about 2.6 million years ago. Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating on 40,000- and 100,000-year time scales. The ice core records show two dominant climate regimes—glacial and interglacial. The Earth is currently in an interglacial known as the Holocene, which started about 10,000 years ago. All that remains of the continental ice sheets are the Greenland and Antarctic ice sheets and several isolated smaller glaciers. These ice sheets have given us the ice core records that have been so useful for reconstructing the history of climate and atmospheric composition over the last 600,000 years (Petit et al. 1999).
Nature’s Laws of Reciprocity
Published in Cameron La Follette , Chris Maser, Sustainability and the Rights of Nature, 2017
Cameron La Follette , Chris Maser
Although Earth has undergone many periods of significant environmental change, the planet’s environment has been unusually stable for the past 10,000 years. This period of stability—known to geologists as the Holocene—has seen human civilizations arise, develop and thrive. Such stability may now be under threat. Since the Industrial Revolution, a new era has arisen, the Anthropocene, in which human actions have become the main driver of global environmental change. This could see human activities push the Earth system outside the stable environmental state of the Holocene, with consequences that are detrimental or even catastrophic for large parts of the world.3 [Holocene comes from the Greek holos, (“whole”) and cene (“new”). Anthropocene4 comes from the Greek anthropo (“human”) and cene (“new”).]
Apocalypse? No! The need for systems engineering thinking to address global challenges and avert global crises
Published in Civil Engineering and Environmental Systems, 2022
In geological terms, we are in the Holocene, the second epoch of the Quaternary period. There is discussion underway that the end of the twentieth century marks the beginning of a new epoch, the Anthropocene, because the geological column will show not simply the detritus of homo sapiens, but compounds and materials never seen before, and which are the product of human ingenuity and technology. In technological terms, we have progressed through the Immediate (hunter/gatherer) and Urban (trade specialisation) phases of technology and are now leaving the Rational phase (scientifically driven and where production could be mechanised at scale and anything was possible) and we are entering the Systems phase (where the interactions of different physical and social and environmental systems are beginning to be realised actually and conceptually) and where the outcomes are far reaching and often not anticipated. In an anthropological sense, some of the world’s aboriginal peoples still have a systems view of the world, just as in their different ways, all our distant forebears did before a reductionist view took hold.
Effect of Soil-Type and Fines Content on Liquefaction Resistance—Shear-Wave Velocity Correlation
Published in Journal of Earthquake Engineering, 2020
The study site was carefully selected from the knowledge of the local geology preserved in the RADIUS project [1999] and by considering the following criteria: (1) sandy soils must mostly contain 0–35% non-/low plastic FC, given that FC over 30% by weight and/or high plasticity of fines is known to affect liquefaction resistance of fines containing sands. (2) The groundwater level should be high enough to ensure that the data would be obtained under fully saturated conditions. Based on the RADIUS project [1999], the surficial geology of the study area is predominantly composed of quaternary sediments. These sediments are mainly saturated and are formed by sedimentation of the alluvial fan deposits transported by the Gediz River. Geologic age of the deposits was Holocene-age (deposited <10,000 years before present day).
Geological field guides as educational tools: the Coorong, South Australia
Published in Australian Journal of Earth Sciences, 2019
Sea level curve for the past 130,000 years, in relation to Marine Isotope Stages 1 to 5, derived from observations of flights of coral terraces on the uplifting Huon Peninsula, Papua New Guinea; adapted from Lambeck and Chappell (2001). The thickness of the line of the curve is an expression of the degree of uncertainty of the calculated sea-levels. Numbers 1 to 5 refer to episodes of time (stages) defined by marine oxygen isotopes. The Last Glacial Maximum, when sea level was about 120 m lower than at present, is shown within Stage 2. The Last Interglacial warm period (within Stage 5) occurred about 130,000 to 120,000 years ago, when sea level was about 2 m higher than at present. The present interglacial warm period (Stage 1) has existed for little more than the past 10 000 years. The rapid rise in sea level during the transition from Stage 2 to Stage 1 is known as the Postglacial Marine Transgression. The last 10,000 years (approximately) constitutes the Holocene Epoch.