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Measuring how much energy is in Earth’s climate system involves measuring things like surface temperatures, ocean temperatures, the planet’s ice volume, sea level and the persistence and frequency of certain weather events like heavy rains. Sustained changes in the amount of energy in Earth’s climate system and corresponding changes in things like temperature, ice volume [...]

Volcanoes are openings in the Earth’s crust that allow magma and gases to erupt into the surrounding atmosphere. Large volcanic eruptions, particularly eruptions in the tropics like Mt. Pinatubo, which blew in 1991, have noticeable effects on global temperature. Trivia Question: Following periods of frequent volcanic eruptions, what does Earth’s climate tend to do? a.   [...]

The extent of the Arctic sea ice, which is usually gauged by its annual minimum extent in September, has been declining by 11.2 percent per decade since 1979. Large-scale effects of this decline impact Earth’s climate, primarily through increased absorption of sunlight by the open oceans. Local effects have also been documented. As ice has [...]

Discussions of climate and climate variability often focus on temperature trends at the Earth’s surface, which is where humans spend most of their time. But the atmosphere holds onto little energy compared to the oceans – the top few feet of the ocean holds as much heat as the entire atmosphere above it! Transfers and [...]

In Brief: The recent weakness in the East African long rains has been linked to persistently elevated temperatures in the western tropical Pacific. Rains in East Africa primarily fall during the long rains (March through May) and the short rains (October through December). Understanding how climate and climate change influence these rains is particularly important [...]

In Brief: Variability in North Pacific atmospheric circulation systems affects the timing and strength of the upwelling that occurs along the California Coast, impacting the productivity of the waters there. Earth’s ocean is mixed by a complex system of currents. Downwellings occur when currents move water from the surface to the depths and upwellings occur [...]

In Brief: Variations in Earth’s orbit, combined with other processes such as vegetation shifts, control glacial/interglacial cycles. For at least the past two million years, Earth has moved between interglacial phases, like the past 10,000 years when ice cover was confined to the polar regions, and glacial phases, when large ice sheets extend into the [...]

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, [...]