Climate Change Indicators
Impact of Climate Change Despite the Massive Efforts of Fossil Fuel Industries to Spread Disinformation
The following is a summary of an EPA report titled ‘Climate Change Indicators in the United States’
Two points about the report and the summary:
- What impacts of Climate Change are evident in the US also apply globally, with little or no exception.
- Fire-Earth Moderators have selected those ‘Indicators’ that can be verified independently.
[NOTE: An indicator represents the current state of certain environmental conditions over a given area and a specified period of time. For example, temperature, precipitation, sea level, and greenhouse gas concentrations in the atmosphere.]
Key Findings: Climate Change Indicators in the United States Report
The Greenhouse Effect (All images and captions are sourced from the EPA report)
The Earth receives energy from the sun, then radiates much of this energy back toward space. However, certain gases in the atmosphere, called greenhouse gases, absorb some of the outgoing energy and trap it in the atmosphere. This “greenhouse effect” occurs naturally, but human activities have substantially increased the amount of greenhouse gases in the atmosphere, causing the Earth to trap more heat. This in turn is changing the Earth’s climate.
U.S. Greenhouse Gas Emissions
In the United States, greenhouse gas emissions caused by human activities increased by 14 percent from 1990 to 2008. Carbon dioxide accounts for most of the nation’s emissions and most of this increase. Electricity generation is the largest source of greenhouse gas emissions in the United States, followed by transportation.
Global Greenhouse Gas Emissions
Worldwide, emissions of greenhouse gases from human activities increased by 26 percent from 1990 to 2005. Emissions of carbon dioxide, which account for nearly three-fourths of the total, increased by 31 percent over this period.
Atmospheric Concentrations of Greenhouse Gases
Concentrations of carbon dioxide and other greenhouse gases in the atmosphere have risen substantially since the beginning of the industrial era. Almost all of this increase is attributable to human activities.
Climate or “radiative” forcing is a way to measure how substances such as greenhouse gases affect the amount of energy that is absorbed by the atmosphere. An increase in radiative forcing leads to warming while a decrease in forcing produces cooling. From 1990 to 2008, the radiative forcing of all the greenhouse gases in Earth’s atmosphere increased by about 26 percent.
U.S. and Global Temperature
Average temperatures have risen across the lower 48 states since 1901, with an increased rate of warming over the past 30 years. Average global temperatures show a similar warming trend, and 2000–2009 was the warmest decade on record worldwide. Within the United States, parts of the North, the West, and Alaska have seen temperatures increase the most.
The frequency of heat waves in the United States decreased in the 1960s and 1970s, but has risen steadily since then. The percentage of the United States experiencing heat waves has also increased. The most severe heat waves in U.S. history remain those that occurred during the “Dust Bowl” in the 1930s, although average temperatures have increased since then.
Over the period from 2001 through 2009, between 30 and 60 percent of the United States experienced drought conditions at any given time. However, the data for this indicator have not been collected for long enough to determine whether droughts are increasing or decreasing over time.
U.S. and Global Precipitation
Average precipitation has increased in the United States and worldwide. Since 1901, precipitation has increased at an average rate of more than 6 percent per century in the lower 48 states and nearly 2 percent per century worldwide.
In recent years, a higher percentage of precipitation in the United States has come in the form of intense single-day events [See Hydrokong.] Eight of the top 10 years for extreme one-day precipitation events have occurred since 1990. The occurrence of abnormally high annual precipitation totals has also increased.
Tropical Cyclone Intensity
The intensity of tropical storms in the Atlantic Ocean, Caribbean, and Gulf of Mexico did not exhibit a strong long-term trend for much of the 20th century, but has risen noticeably over the past 20 years. Six of the 10 most active hurricane seasons have occurred since the mid-1990s. This increase is closely related to variations in sea surface temperature in the tropical Atlantic.
Several studies have shown that the amount of heat stored in the ocean has increased substantially since the 1950s. Ocean heat content not only determines sea surface temperature, but also affects sea level and currents.
- Full Report (PDF 14MB)
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