IPCC Climate Change Report

By Cliff Montgomery – Nov. 7th, 2014Fossilfuel-based power generated without Carbon Capture and Storage (CCS)technology must be “phased out almost entirely by 2100” if human beingsare to avoid a dangerous level of climate change, a panel of experts onthe subject recently declared in a blunt report.TheU.N.-backed Intergovernmental Panel on Climate Change (IPCC) added thatby 2050, the majority of humanity’s electric needs may be met bylow-carbon sources.Otherwise, human beings face a global warming that will be “severe, pervasive and irreversible.”TheUnited Nations stated that denial of the scientific evidence would costeveryone “much more” than it would to make the needed changes.Below, The American Spark offers informative quotes from the IPCC report:Introduction.1: Risk and the management of an uncertain future“Climatechange exposes people, societies, economic sectors and ecosystems torisk. Risk is the potential for consequences when something of value isat stake and the outcome is uncertain, recognizing the diversity ofvalues.“Risksfrom climate change impacts arise from the interaction between hazard(triggered by an event or trend related to climate change),vulnerability (susceptibility to harm), and exposure (people, assets orecosystems at risk).“Hazardsinclude processes that range from brief events, such as severe storms,to slow trends, such as multi-decade droughts or multi-century sea-levelrise. Vulnerability and exposure are both sensitive to a wide range ofsocial and economic processes, with possible increases or decreasesdepending on development pathways.“Risksand co-benefits also arise from policies that aim to mitigate climatechange or to adapt to it. Risk is often represented as the probabilityof occurrence of hazardous events or trends multiplied by the magnitudeof the consequences if these events occur.“Therefore,high risk can result not only from high probability outcomes, but alsofrom low probability outcomes with very severe consequences. This makesit important to assess the full range of possible outcomes, from lowprobability outcomes to very likely outcomes.“Forexample, it is unlikely that global mean sea level will rise by morethan one metre in this century, but the consequence of a greater risecould be so severe that this possibility becomes a significant part ofrisk assessment.“Similarly,low confidence but high consequence outcomes are also policy relevant -for instance the possibility that the response of Amazon forest couldsubstantially amplify climate change merits consideration despite ourcurrently imperfect ability to project the outcome.“Riskcan be understood either qualitatively or quantitatively. It can bereduced and managed using a wide range of formal or informal tools andapproaches that are often iterative. Useful approaches for managing riskdo not necessarily require that risk levels can be accuratelyquantified.“Approachesrecognizing diverse qualitative values, goals, and priorities, based onethical, psychological, cultural, or social factors, could increase theeffectiveness of risk management.Topic 1: Observed Changes and their Causes “Humaninfluence on the climate system is clear, and recent anthropogenicemissions of greenhouse gases are the highest in history. Recent climatechanges have had widespread impacts on human and natural systems.1.1 Observed changes in the climate system “Warmingof the climate system is unequivocal, and since the 1950s, many of theobserved changes are unprecedented over decades to millennia. Theatmosphere and ocean have warmed, the amounts of snow and ice havediminished, and sea level has risen.1.1.1 Atmosphere “Eachof the last three decades has been successively warmer at the Earth’ssurface than any preceding decade since 1850. The period from 1983 to2012 was very likely the warmest 30-year period of the last 800 years inthe Northern Hemisphere, where such assessment is possible (highconfidence) and likely the warmest 30-year period of the last 1400 years(medium confidence).1.1.2 Ocean“Oceanwarming dominates the increase in energy stored in the climate system,accounting for more than 90% of the energy accumulated between 1971 and2010 (high confidence) with only about 1% stored in the atmosphere.“Ona global scale, the ocean warming is largest near the surface, and theupper 75 m warmed by 0.11 [0.09 to 0.13] °C per decade over the period1971 to 2010. It is virtually certain that the upper ocean (0−700 m)warmed from 1971 to 2010, and it likely warmed between the 1870s and1971. It is likely that the ocean warmed from 700 m to 2000 m from 1957to 2009 and from 3000 m to the bottom for the period 1992 to 2005.1.1.3 Cryosphere“Overthe last two decades, the Greenland and Antarctic ice sheets have beenlosing mass (high confidence). Glaciers have continued to shrink almostworldwide (high confidence). Northern Hemisphere spring snow cover hascontinued to decrease in extent (high confidence). There is highconfidence that there are strong regional differences in the trend inAntarctic sea ice extent, with a very likely increase in total extent.1.1.4 Sea level “Overthe period 1901–2010, global mean sea level rose by 0.19 [0.17 to 0.21]m. The rate of sea-level rise since the mid-19th century has beenlarger than the mean rate during the previous two millennia (highconfidence).1.2 Past and recent drivers of climate change “Anthropogenicgreenhouse gas emissions have increased since the pre-industrial eradriven largely by economic and population growth . From 2000 to 2010emissions were the highest in history. Historical emissions have drivenatmospheric concentrations of carbon dioxide, methane and nitrous oxide,to levels that are unprecedented in at least the last 800,000 years,leading to an uptake of energy by the climate system.1.2.1 Natural and anthropogenic radiative forcings “Atmosphericconcentrations of greenhouse gases are at levels that are unprecedentedin at least 800,000 years. Concentrations of CO2, CH4 and N2O have allshown large increases since 1750 (40%, 150% and 20%, respectively).