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Two large scale circulation patterns, the Arctic Oscillation and the El Niño-Southern Oscillation, have proven useful for predicting winter weather in different areas of the United States. AO: The Arctic Oscillation (AO) is the difference in atmospheric pressure between the Arctic and the mid-latitudes of the Northern Hemisphere. Upper-atmospheric westerly winds and mid-latitude winter storms [...]

In Brief: Warmer winter temperatures are allowing the Purple Finch to winter 433 miles farther north than it did in the 1960s. Observers during recent annual Audubon Christmas Bird Counts are noticing different birds in their local areas during the winter months than observers did in the 1960s. Between 1966 and 2005, significant northward movement [...]

In Brief: Warmer winter temperatures are allowing the American Goldfinch to winter 250 miles farther north than it did in the 1960s. Observers during recent annual Audubon Christmas Bird Counts are noticing different birds in their local areas during the winter months than observers did in the 1960s. Between 1966 and 2005, significant northward movement [...]

In Brief: Warmer winter temperatures are allowing the House Finch to winter 270 miles farther north than it did in the 1960s. Observers during recent annual Audubon Christmas Bird Counts are noticing different birds in their local areas during the winter months than observers did in the 1960s. Between 1966 and 2005, significant northward movement [...]

Temperatures have warmed by an average of two degrees Fahrenheit over Earth’s land surface and 0.6 degrees Fahrenheit over the oceans over the past 50 years. These temperature changes have been accompanied by changes in precipitation and seasonal cycles, including lengthening of the growing/frost-free season in temperate and high latitudes. Together, these factors related to [...]

The September/October Arctic sea ice annual minimum this year was the second lowest minimum on record for the 33 year period of satellite observations. The lowest minimum was recorded in 2007. But how do these ice extents relate to what the sea ice has done over the past several hundred or thousand years? Known relationships [...]

The Great Salt Lake is a prominent feature of the Intermountain West landscape. Geologists who study the region believe that the size of the lake varies on long time scales. Trivia Question: 20,000 years ago, when Earth’s climate was much cooler and a massive ice sheet extended form the Arctic south all the way to [...]

As the Earth warms, a few things happen to the water cycle. Warmer temperatures mean more evaporation from the soil, which can cause land surfaces to dry. They also mean, however, that the air holds more moisture, which can lead to more rainfall in certain regions. The polar regions, for example, are wetter than they [...]

Commercial airline flights spend most the time in the lower reaches of the stratosphere, which is the second layer of the atmosphere beginning at five to six miles up in the air. The air in the stratosphere is thin and cold, making it inhospitable, but it is also less turbulent than the air in the [...]

The Earth holds more heat today than it did in 1950 and the lion’s share of this heat has been absorbed by the world’s oceans. Water has a higher specific heat than air or land surfaces, meaning that it takes more energy to raise the temperature of a certain amount (say, a pound) of water [...]

Paleoclimatology, the study of past climates and past climate changes, provides ample evidence that climate change can happen suddenly. Around 18,700 years ago, a section of the slowly melting Laurentide (North American) Ice Sheet, which at one point extended all the way from the Arctic to the Ohio River, disintegrated around present day Wisconsin. This [...]

In Brief: African aerosols are transported across the Atlantic, affecting the climate of the Amazon rainforest. Dust suspended in the air and smoke from fires make up most of the aerosol concentrations found in the air around us. Aerosols affect how much sunlight reaches the Earth’s surface and how clouds form, which means they can [...]

In Brief: Periods of increased stratospheric aerosol content over the past 50 years likely dampened the  warming trend. Volcanic eruptions can cool the Earth by injecting sulfur up into the stratosphere, the second layer of the atmosphere between five and 30 miles in altitude. The volcanoes increase stratospheric levels of tiny droplets of sulfuric acid, [...]

In Brief: Plants, particularly in the Amazon, influence their climate by moving moisture from the soil into the atmosphere – less when the soil is dry and more when the soil is wet. This helps to maintain both wet and dry rainfall regimes. Every place in the world has its own climate with its own [...]

In Brief: The silt cliffs on the Beaufort and Chuckchi Seas around Alaska are crumbling as water temperatures have warmed and the annual duration of the Arctic Sea Ice has declined. The Arctic, where the temperature rise has been twice the global average, has born some of the most visible impacts of the last 40 [...]

Each year the United States pumps about 28 cubic miles of water out its groundwater aquifers – natural underground storage areas – for irrigation, drinking water, industrial purposes, etc. While about 84.6 percent of these withdrawals are recharged to the aquifers through natural recharge (primarily rainfall) or artificial recharge (recharge to the groundwater from human [...]

In Brief: Earth’s ocean circulation patterns and  climate would be much different without the presence of the Rocky and Andes Mountains, and without the Antarctic Ice Sheet. A system of big warm and cool water ocean currents, which dwarf the flow of even the largest rivers, work to mix heat and nutrients around the globe. [...]

In Brief: Glaciers, a key source of water in the West, are melting more in the summer than they are growing during the winter. The glaciers that make the peaks of the Western United States white year round are located almost exclusively within National Forests and National Parks. In addition to providing scenery and tourist [...]

Yellowstone, America’s first established National Park, has changed as average annual temperatures have warmed by one degree Fahrenheit over the last 40 years. This warming trend has been accompanied by a slight decrease in annual rainfall levels. Related changes include: Tree Cover: As temperatures have warmed since 1970, tree cover in areas that had not [...]

In Brief: Record subtropical Atlantic sea surface temperatures and more acidic ocean waters have in the last 15 years reduced coral reef cover in the Florida Keys National Marine Sanctuary by 180 square miles, an area the size of Miami and Atlanta combined. Florida Keys National Marine Sanctuary, the nation’s second largest marine sanctuary, provides [...]