Introduction

by John Young

The simplest definition of climate is the average of past weather conditions for a specific date. This is often referred to as “normal climate”. Since weather fluctuates over time spans from minutes to weeks, its statistical properties of variability may also be considered to be a part of climate. So, climate as a whole may be considered to be the distribution of  probabilities of weather variables for a specific date. By definition, “normal seasonal climate” changes during the year.

In a given year, weather conditions which persistently deviate from “normal” climate values are termed “climate variability”. There are many such “natural cycles” which involve energy interactions between he global atmosphere, ocean, and land.. These cycles typically last months to years before reversing. Abnormally warm summers or El Niño anomalies are examples of natural cycles. They typically affect large regions (e.g., eastern North America), but not the entire globe.

When time periods extending to decades are considered, the presence of  long-term trends in deviations from “normal” indicate “climate change”. This change is believed to be non-cyclic, a result of increased greenhouse gases caused by human activity starting in the 20th century. It can be thought of as a drift toward a “new normal” climate, which is warmer than the old normal climate at most locations on the globe.

In a changing climate, the probabilities of extreme events will shift because of:
(a) a trend  in "normal climate" (e.g. "climate warming"), (b) a trend in climate variability (e.g. El Niño years), or (c) change in weather types (e.g. cold surges diminishing). Climate change science aims at understanding and predicting changes in the probabilities of  both  "changing normals" and extreme events. Research on changing climate impacts (e.g. WICCI)  will follow these steps:
(1) attribution of past climate/probability changes;
(2) assessment of predicted climate/probability changes;
(3) risk assessment of environmental vulnerabilities to changing extremes;
(4) policy guidance for adaptation in order to minimize future negative impacts.

Statewide/Regional

• Please note: Graphs of climate variables (such as temperature, precipitation) for the past century are available for  Wisconsin's climate divisions and six of its largest cities.
   
• Midwest Regional Climate Center's Climate Change & Variability in the Midwest
   
• A book entitled "Understanding Climate Change: Climate Variability, Predictability, and Change in the Midwestern United States" has been recently published by Indiana University Press describing contributions by climate and other scientists to a workshop. Two chapters in this book have been prepared by scientists with the UW-Madison's Center for Climatic Research and the State Climatology Office dealing with climate change in Wisconsin.
   
• As part of the "Global Climate Change Impacts in the United States" report issued by the US Global Change Research Program in June 2009 (see next section), a short subsection Regional Climate Impacts: Midwest (including Wisconsin) is available as a 6-page pdf document. 
   
• A report prepared by a group of scientists, including Professor John Magnuson of the University of Wisconsin-Madison, was released in 2003. The title of this report is "Confronting Climate Change in the Great Lakes Region: Impacts on Our Communities and Ecosystems". If projections of increased warming are correct, this report addresses the implications for the Great Lakes and Wisconsin.
  
• Shorter river ice seasons confirm global warming - CNN features UW-Madison research
  

National

• NOAA Climate Services Portal "Science & Information for a Climate-Smart Nation"
  Topic Tabs: /News & Features, /Maps & Data, /Teaching Climate
  at https://www.climate.gov/
• The American Meteorological Society (AMS) posted an Information Statement on Climate Change on 20 Aug 2012.
• The U.S. Global Change Research Program released in June 2009 a report entitled "Global Climate Change Impacts in the United States"
  For executive summary, regional results, and the full report (a 196-page pdf file), go to the website.  This information is also available on Facebook and Twitter.
• The US Climatic Change Science Program released in March 2009 a 13-page guide called Climate Literacy: The Essential Principles of Climate  designed to help the public understand the essential principles of climate sciences, including how climate influences them and how they influence climate.
• Historical trends for seasonal temperature and precipitation across US  from Climate Prediction Center
• National Climatic Data Center's Global Climate Change
  
• The US Environmental Protection Agency (EPA) has produced a module on its  Watershed Academy Web that considers "the effect of climate change on water resources and programs."
• U.S. Department of State's Bureau of International Information Programs recently issued  the following press releases as part of a series about necessary steps needed to address the effects of climate change at regional and local levels.
  • Obama Makes Climate Change a National Priority
  • Knowledge Centers Could Help Regions Cope with Climate Change
  • Drought Information System Offers Early Warning, Knowledge
  • U.S. Agencies Plan National Climate Service Structure, Products
• The US Climatic Change Science Program has the following series of  "Synthesis and Assessment S&A Products" including:
  • "Climate Models: An Assessment of Strengths and Limitations" (in July 2008) that describes computer models created to simulate the Earth's climate and their ability to model current climate change. Press release
  • "Analyses of the effects of global change on human health and welfare and human systems" (in July 2008) that discusses the potential impacts of climate change on human health, human welfare, and communities in the United States.  Press release
  • "Weather and Climate Extremes in a Changing Climate" (in June 2008) that provides a comprehensive analysis of observed and projected changes in weather and climate extremes across North America and the US territories.  Press release
• Scientists at the National Climatic Data Center recently announced that based upon their preliminary analysis of available weather data for 2006, the just completed year was the warmest nationwide since relatively comprehensive records began in 1895. The coterminous US annual average temperature was 55 degrees Fahrenheit, or 2.2 Fahrenheit degrees above the 20th century long term average temperature and 0.07 Fahrenheit degrees above the previous highest nationwide temperature set in 1998. [NOAA News]
  
• NOAA issued its 2005 Annual Greenhouse Gas Index, which is based upon benchmark measurements of atmospheric gases that could affect the planetary climate. For 2005, the index indicated an increase in carbon dioxide and nitrous oxide, little change in methane, and a decrease in two types of chlorofluorocarbons. [NOAA News]
  
• The US Climatic Change Science Program issued a report in early May 2006 that is the first of 21 "Synthesis and Assessment S&A Products". This first report entitled "Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences" is meant to improve understanding of atmospheric temperature change in the context of global climate change and how humans have an influence upon these temperature trends. [NOAA News]
  
• NOAA working to improve understanding of climatic change [NOAA News]
  
• NOAA documents World's Oceans Warming over the past 40 years [News Release]
  
• American Association of State Climatologists' Policy Statement on Climatic Variability and Change
  
• American Meteorological Society's Policy Statements: On Global Climate Change and Climate Change Research: Issues for the Atmospheric and Related Sciences
  

Global

• The Intergovernmental Panel on Climate Change (IPCC)
  Background -- The IPCC was established as a scientific intergovernmental body by the World Meteorological Organization (WMO) and by the United Nations Environment Programme (UNEP). to provide the decision-makers and others interested in climate change with an objective source of information concerning climate change.
  Commencing in 1990 and into the latest cycle 2013/2014, the IPCC has produced five assessment reports (1990, 1995, 2001, 2007, and 2013/2014). Part 1 of the current Fifth Assessment Report, "The Physical Science Basis”, was released in September 2013. Parts 2-4 will appear in sequence starting in the first half of 2014.
  The previous IPPC Fourth Assessment Report: Climate Change 2007 was presented in four parts from the four working groups:

  1. The previous Intergovernmental Panel on Climate Change IPCC 2007 Report, "The Physical Science Basis" was issued on 2 February 2007 that describes the latest on human-caused global warming and its future worsening. This most authoritative report is based on six years of new observations and analyses.
  2. A second part of the IPCC 2007 Report, " Impacts, Adaptation and Vulnerability" , was issued on 6 April 2007 that describes what the effects of the projected increases in global temperatures during the rest of the century would have upon societies, ecosystems, and the hydrologic cycle. Adaptation and vulnerability of these systems to climatic change are also addressed.
  3. The third part of the IPCC 2007 Report, entitled "Mitigation of Climate Change" was released on 4 May 2007 in Bangkok, Thailand. This part of the IPCC report focuses upon the scientific, technological, environmental, economic, and social aspects of mitigating projected climate change. It is intended as a summary for policy makers. Delegates contend that the technology and money are currently available for aggressive actions to limit emissions of greenhouse gases, improve fuel efficiency, and utilize renewable energy resources such as solar power in order to avoid some increases in global temperatures and associated climate-related disasters.
  4. The fourth and final part of the IPCC 2007 Report was issued in -November 2007 and called "Synthesis Report", serves as a scientific "instant guide" for policy makers.
     Note: the entire current 2013/2014 IPCC 5th Report will be appearing on the IPCC  site later in 2014.  This report and the previous four IPCC Reports are also available from IPCC.  
• Summer 2012 Arctic sea ice sets record low size - In August 2012, scientists from the National Snow and Ice Data Center report that areal extent of sea ice on Arctic Ocean was close to being the smallest since satellite surveillance began in 1979. NOAA ClimateWatch Magazine
• 2010 was one of two warmest in modern times -- Report from NOAA
• Lower Atmosphere is warming -- Scientists from NOAA, the NOAA-funded Cooperative Institute for Climate and Satellites (CICS), the United Kingdom Met Office, and United Kingdom's University of Reading, recently conducted a review of the history of understanding temperature changes and their causes in the scientific literature over the last four decades. These researchers found that the lowest 6 miles of the atmosphere (called the troposphere) has been warming and this warming has been generally consistent with both theoretical expectations and with climate models. NOAA News
  
• The American Meteorological Society's Information Statement on Climate Change [4 pages] was issued on 1 February 2007. This short report summarizes many topics covered in the IPCC report, in a shorter text and without figures.
  
• National Climatic Data Center's Global Climate Change
  
• NOAA documents World's Oceans Warming over the past 40 years [News Release]
  
• Shorter river ice seasons confirm global warming - CNN features UW-Madison research
  
• Global Change Master Directory (NASA)
  
• Climate Variability and Climate Change - Global Hydrology and Climate Center
  
• Goddard Institute for Space Studies Datasets and Images
• NOAA Annual Arctic Report Card A report of the state of the air, ocean and ice in the Arctic basin prepared by an international team and issued by NOAA's Climate Program Office. The 2012 annual update indicates that the region had above-average air and water temperatures in 2012, but nothing that was "remarkable" when compared with those over the last decade. However, record low amounts of Arctic snow cover were reported last June and the smallest areal coverage was found in summer Arctic sea ice in early September.
  
• Climate Change & Increasing Mediterranean Drought Frequency -- Wintertime droughts across the Mediterranean basin increased during the 20th century and computer models support the conclusion that climate change resulting from increased greenhouse gases have been a major factor.
• Global Sea Level Rise Scenarios for the United States National Climate Assessment
  Report report published by NOAA's Climate Program Office indicates that scientists have a very high confidence (greater than 90% chance) that global mean sea level will rise at least 8 inches (0.2 meter) and no more than 6.6 feet (2.0 meters) by 2100.
  

General Information

• NOAA Climate Services Portal
  www.climate.gov
• NOAA Climate Watch Magazine:
  Articles, Images, Videos
• NOAA Climate Attribution from Earth System Research Laboratory
• National Climatic Data Center's Global Warming Frequently Asked Questions
  
• A Paleo Perspective on Global Warming, NOAA's Paleoclimatology Program
  
• NASA Global Climate Change
   
• UW-Madison professor with IES-SAGE cautions that climate change could bring a wave of new health risks.