Climate Feedbacks: An interaction mechanism between processes in the climate system is called a climate feedback, when the result of an initial process triggers changes in a second process that in turn influences the initial one. A positive feedback intensifies the original process, and a negative feedback reduces it.
Climate forcing has to do with the amount of energy we receive from the sun, and the amount of energy we radiate back into space. Variances in climate forcing are determined by physical influences on the atmosphere such as orbital and axial changes as well as the amount of greenhouse gas in our atmosphere.
The (estimated) 1470 Year Climate Cycle - Often quoted as the 1500 year cycle is a popular red herring used by S. Fred Singer and Dennis Avery. It is also a real climate cycle known as Dansgaard-Oeschger (D-O) events. It is of unknown origin.
How the Earth stays warm has to do with the total amount of energy we receive from the sun (around 1366.5 W/m2 when measured in space, and the amount that actually makes it to the surface of Earth is estimated to be around 342 W/m2 on average. Once the energy makes it to the surface, it changes from short wave radiation to longwave radiation which is heat energy. Clouds, dark and light surfaces and greenhouse gases generally regulate the amount of energy that is held within our climate system.
An interesting twist in the argument about what can be projected is the idea that we can only accept the empirical. Another way to state this might be reality vs. modeling. Climate models as we have pointed out are always wrong. It is important to understand the difference between the observations (reality) and the empirical models.
Galactic Cosmic Rays have been considered as a possible relevant cause in our current global warming event. Examinations of claims that galactic cosmic rays are responsible four our current global warming event have been assessed through peer review and peer response. The consensus remains that there is no significant correlation between galactic cosmic rays and climate change, especially in relation to our current warming event.
Greenhouse Gases (GHG's) are the various gases that block outgoing long-wave infrared from easily leaving our atmosphere. The Greenhouse Effect (GHE) is the physical mechanism of this blocking mechanism in our atmosphere that influence how much heat we retain within the atmosphere.
The ice is melting in Greenland. The ice melt rate is also accelerating. What does this mean? That depends on your context in time, your geographic location, and ultimately, why it is happening?
The history of climate science goes back to the early 1900's. This section contains a chronological listing of relevant climate science discoveries and events related to anthropogenic global warming. The information here was compiled by Spencer Weart (see links for reference).
How do we know current global warming is human caused, or man made? Is global warming real, or a hoax? Consider the facts: the climate system is indicated to have left the natural cycle path; multiple lines of evidence and studies from different fields all point to the human fingerprint on current climate change; the convergence of these evidence lines include ice mass loss, pattern changes, ocean acidification, plant and species migration, isotopic signature of CO2, changes in atmospheric composition, and many others. The only identifiable cause explaining these changes with confidence is human influence and increased greenhouse gas emissions. Science has simply not found any other cause factor that can account for the scale of the recent increase in radiative forcing and associated warming.
The International Panel on Climate Change
Most understand the Keeling curve as an upward trend of CO2 in the atmosphere as measured by the Mauna Loa measurements of Charles David Keeling. But there are two Keeling curves and they are related to each other in more than one way. While CO2 increases, it stands to reason that O2 will decrease (C + O2 = CO2). The two curves also have family ties.
Global warming is not only expected to cause a latitudinal shift of the jet-stream, it already has. There has been a measured poleward of the jet-stream in the past 30 years. This is an expected result of global warming.
The Maunder Minimum was a period of low sunspot activity (a quiet sun). This low activity was correlated with a cooling period that caused crops to fail and had many impacts on the human economy.
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.
Methane is a strong Greenhouse gas and human activity has increased methane in our atmosphere around 148% since the beginning of the industrial age. Some evidence indicates regional climate shift based on natural methane release, such as those that may be associated with the demise of the Anastasi or the Inca's. More research is needed on causal relationships. Evidence in the paleo record indicates that methane release concurrent with other contributing factors can have substantial impacts on the earth climate. It is estimated that a warmer world increases the risk of methane release
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.
This section is dedicated to information about the natural cycle in relation to changes in the atmosphere and forcing levels.
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.
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.
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.
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.
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. http://www.jpl.nasa.gov/news/news.cfm?release=2008-066
Pacific / North American Pattern (PNA) – The Pacific/ North American teleconnection pattern (PNA) is one of the most prominent modes of low-frequency variability in the Northern Hemisphere extratropics. The positive phase of the PNA pattern features above-average heights in the vicinity of Hawaii and over the intermountain region of North America, and below-average heights located south of the Aleutian Islands and over the southeastern United States.
Greg Craven has done a very good job of outlining the basic science and risks analysis in a series of videos that he has produced in response to the concerns over the actual science as well as those skeptical of that science. From a risk perspective, he has done a wonderful job in the series. The science has only a few minor representations that are generally slightly out of context. This does not take away from the excellent risk analysis presentation of the arguments.
National and international security concerns regarding global warming.
Information about Solar Irradiance.
Global Temperature: NCAR/UCAR, NCDC, and NASA GISS Analysis: The current analysis uses surface air temperatures measurements from the following data sets: the unadjusted data of the Global Historical Climatology Network (Peterson and Vose, 1997 and 1998), United States Historical Climatology Network (USHCN) data, and SCAR (Scientific Committee on Antarctic Research) data from Antarctic stations. The basic analysis method is described by Hansen et al. (1999), with several modifications described by Hansen et al. (2001) also included. Modifications to the analysis since 2001 are described on the separate Updates to Analysis.
The context of thermal inertia in long-term is different than short-term
This section is dedicated to information about climate tipping points.
Weather intensities are driven by natural variations and overall climate forcing. Forcing agents vary such as surface reflectivity, greenhouse gases and natural variation in atmospheric and ocean cycles as well as longer term forcing agents such as the Milankovitch cycles that drive long term climate change. Even longer term forcing agents have to do with tectonic shifts over millions of years.
What is the difference between weather and climate? Weather is considered short-term variability, while climate is long-term trend based on multiple factors. These factors depend on context. In other words, one persons weather is another persons climate. Generally speaking, in the context of human caused global warming, climate is considered 30+ years of trend with attribution.
Paleoclimatology Records: The Paleo Temperature Record: From the World Data Center for Paleoclimatology: If anyone is not sure if there are enough measurements for us to have a good idea of what the past temperature and atmosphere was, the following list shows the types and disciplines from which paleo data is measured to model the past climate of earth.
Often when someone realizes that climate is an important issue and that human-kind is influencing the climate, the next obvious question arises. What can we do? Here are some simple steps and considerations that we can all do to help.
One of the important questions concerns what we don't know. This section is dedicated to putting what we don't know into perspective with what we know in order to understand what it means.
The Ralph Keeling Curve