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Medieval Warm Period
The Medieval Warm Period (MWP) occurred around one thousand years ago. This is known by examinations of ice core records and multiple proxy models from multiple interrelated disciplines.
Located in Projects & Resources / Environment / Global Warming
Milankovitch Cycles
What are Milankovitch Cycles? Natural global warming, and cooling, is considered to be initiated by Milankovitch cycles. These orbital and axial variations influence the initiation of climate change in long-term natural cycles of 'ice ages' and 'warm periods' known as 'glacial' and 'interglacial' periods. Our current climate forcing shows we are outside of that natural cycle forcing range.
Located in Projects & Resources / Environment / Global Warming
Global Warming Natural Cycle
The idea that Global Warming is a natural cycle is well understood from paleo data covering the past 1 million years. Is there a difference between current climate, and the natural cycle? For the past million years the natural climate has oscillated between warm periods and ice ages. This shifting in and out of warm periods and ice ages is correlated strongly with Milankovitch cycles. In order to understand the difference between natural cycle and human-caused/influenced global warming, one needs to consider changes in radiative forcing and how this affects systems on Earth such as the atmosphere, vegetation, ice and snow, ocean chemistry and ocean heat content overturn cycles and related effects. The current radiative forcing levels are clearly outside of the natural cycle range.
Located in Projects & Resources / Environment / Global Warming
Natural Variation
Natural variation includes internal and external variability influences such as the solar Schwabe cycle, oceanic cycles, seasonal influences based on changes caused by the interaction of the various natural oscillations in the climate system. These variations combined influence regional climate and weather on periodic basis as well as influence weather event patterns.
Located in Projects & Resources / Environment / Global Warming
North Atlantic Oscillation (NAO)
The North Atlantic Oscillation (NAO) is a measure of the strength of the westerlies across the North Atlantic. Originally defined by Sir Gilbert Walker in 1932 as the difference in pressure between Ponta Delgada on the Azores and Stykkisholmur in Iceland.
Located in Projects & Resources / Environment / Global Warming
El Nino Southern Oscillation (ENSO)
ENSO stands for El Niño/ Southern Oscillation. The ENSO cycle refers to the coherent and sometimes very strong year-to-year variations in sea- surface temperatures, convective rainfall, surface air pressure, and atmospheric circulation that occur across the equatorial Pacific Ocean. El Niño and La Niña represent opposite extremes in the ENSO cycle.
Located in Projects & Resources / Environment / Global Warming
Southern Oscillation Index (SOI)
The Southern Oscillation Index (SOI) is one measure of the large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific (i.e., the state of the Southern Oscillation) during El Niño and La Niña episodes. Traditionally, this index has been calculated based on the differences in air pressure anomaly between Tahiti and Darwin, Australia.
Located in Projects & Resources / Environment / Global Warming
Pacific Decadal Oscillation (PDO)
The Pacific Decadal Oscillation is a long-term fluctuation of the Pacific Ocean that waxes and wanes between cool and warm phases approximately every 5 to 20 years. In the cool phase, higher than normal sea-surface heights caused by warm water from a horseshoe pattern that connects the north, west and southern Pacific, with cool water in the middle. During most of the 1980s and 1990s, the Pacific was locked in the oscillation's warm phase, during which these warm and cool regions are reversed.
Located in Projects & Resources / Environment / Global Warming
Rich document 2009 - Sea Level Rise Research Summary (last update 4/2013)
How to reconcile the strict limitations of scientific method with reasonable expectations based on probability and risk have confounded the human-caused global warming (AGW) argument. The reality is sea level will rise. However, there are other oceanic forces that will have economic consequences prior to major sea level rise. Storm strength, droughts, flooding, crop yields and thermal limits are also important considerations. Note: Tad Pfeffer has responded in an update to this report on September 15th regarding SLR above 5 meters: "...we believe it is reasonable to ponder very high rates of SLR in the next century. However, we also believe that it is problematic to project such a ‘hypothesis’ as a supported theory without proper testing by the scientific method."
Located in Projects & Resources / Environment / Global Warming
Rich document Security Implications
What does global warming mean for National Security? The following reports include the Department of Defense, The Center for Strategic & International Studies, The Center for Naval Analysis, and the German Advisory Council. A report from authors including former CIA Director R. James Woolsey; Jay Gulledge, Ph.D., is the senior scientist and program manager for science and impacts at the Pew Center on Global Climate Change and John Podesta, president and CEO of the Center for American Progress outlines three case scenarios and their impacts for national security.
Located in Projects & Resources / Environment / Global Warming