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Category Archives: Climate
Who conducts the National Climate Assessment?
The U.S. National Climate Assessment is mandated by the Global Change Research Act of 1990. The assessment has been conducted about every four years since 2000 and is an authoritative scientific analysis of climate change risks, impacts, and responses in the U.S. The resulting report, mandated by Congress, explains how climate change affects every region of the U.S.
The nation completed its fifth National Climate Assessment (NCA5) in November 2023. The assessment results from an extensive process that includes internal and external review from federal agencies, the public, and external peer review by a panel of experts. The National Oceanic and Atmospheric Administration (NOAA) is the administrative agency for NCA5 and certifies that the report meets the standards required by the Information Quality Act and Evidence Act. Continue reading
Has the EPA rolled back regulations on greenhouse gas emissions?
On June 11, Environmental Protection Agency Administrator Lee Zeldin proposed repealing all “greenhouse gas” (their quotes, not ours) emission standards for the power sector under Section 111 of the Clean Air Act.
This proposal is based upon the false assertion that “emissions from fossil fuel-fired power plants do not contribute significantly to dangerous air pollution.” This assertion flies in the face of centuries of evolving understanding of the influence that carbon dioxide, the primary by-product of such combustion, has on the radiation balance of Earth’s atmosphere. Continue reading
Category: Climate, Meteorology
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Is there scientific consensus on global warming?
Global warming refers to the recent rise in Earth’s average temperature caused by human activities that emit higher levels of greenhouse gases like carbon dioxide and methane. Scientists understand the physics and chemistry of how these gases warm the atmosphere.
The global average temperature has increased about 1.7°F since 1970. During this same period, temperatures have risen around 2.5°F in the contiguous United States and 4.2°F in Alaska. The 10-year period 2014–2023 was the warmest decade on record. Such warming has, of course, altered average weather conditions, including temperature, precipitation, humidity, wind patterns, atmospheric pressure, and ocean temperatures and so global warming is nearly synonymous with climate change. Although it is difficult to directly attribute specific weather events to global warming/climate change, data analysis indicates that global warming is linked to more extreme weather events such as droughts and floods. There has also been an increase in days with temperatures above 90°F and heat waves. Heat waves, defined as periods of unusually hot weather lasting two or more days, have become more frequent in major cities across the United States, rising from an average of two heat waves per year in the 1960s to over six per year in the 2020s. Continue reading
What is the status of the ozone hole?
This year is the 40th anniversary of the discovery of ozone hole. On 16 May 1985, British Antarctic Survey scientists published research that revealed a significant drop in ozone levels above Antarctica, referred to as the “ozone hole.” Stratospheric ozone loss has also been observed over the Arctic.
Ozone (O3) is a molecule formed by three oxygen atoms. In the lower troposphere O3 is considered a pollutant, as it can cause respiratory problems when breathed. Ozone in the stratosphere absorbs UV rays from the sun, protecting life on Earth from harmful radiation that can cause skin cancer and other health problems.
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Is there a windiest time of year in Madison?
With the pollen season peaking in southern Wisconsin one may wonder if there actually is a windiest time of year in Madison. Of course, a windy day can come along just about any time of year (the record gust of 83 mph in Madison occurred in June 1975) but the climatology suggests that March and April are the windiest months of the year with average wind speeds of 11.3 and 11.4 mph, respectively. November through February are not far behind logging a four-month average of 10.5 mph.
The fact that it’s windier during the cold season is not surprising as that time of year is characterized by the highest frequency of mid-latitude cyclone activity. Mid-latitude cyclones are large in scale, covering several states simultaneously, and are often associated with very large differences in sea-level pressure over small distances. It is these pressure differences that drive the wind. Continue reading
Category: Climate, Seasons, Severe Weather
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