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The last two million years of Earth’s history are characterized by swings from cold, glacial periods to warmer, interglacial periods. These swings are part of a cycle lasting about 100,000 years, controlled by gradual changes in Earth’s orbit and the amount of the sun’s energy received by the Earth. As the last warm interglacial ended [...]

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 [...]

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 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: 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: 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 [...]

In Brief: Warming of the biodiverse Red Sea since the early 1980s has been accompanied by a reduction in coral growth rates. The Red Sea, which separates Africa from the Arabian Peninsula, hosts one of Earth’s most diverse marine ecosystems. The diversity in the Red Sea is particularly impressive because it is one of the [...]

In Brief: Analysis of paleoclimatic data from the last interglacial period (130,000 to 120,000 years ago) suggests that most of the sea level rise came from the Antarctic Ice Sheet. The last interglacial period (LIG), which ran from about 130,000 to 120,000 years ago, was a particularly warm interglacial period with global temperatures about 3.6 [...]

In Brief: Semi-periodic shifts in North Pacific sea surface temperature distributions have been linked survival rates of Coho Salmon off the Pacific Northwest coast. Water conditions along the Pacific Northwest coast are controlled by the Northern California Current (NCC) system, which features a strong alongshore northward flow of warm waters during winter and a southward [...]

The Canadian Arctic Archipelago (CAA), which lies across Baffin Bay from the northwest coast of Greenland, holds about one third of Earth’s ice mass, excluding the giant Greenland and Antarctic Ice sheets. The Archipelago’s 36,500 islands cover 540,000 square miles including Baffin Island, the world’s fifth largest island covering close to 200,000 square miles. The [...]

More acidic waters mean there are fewer carbonate molecules in the water available to the organisms that build their bodies out of calcium carbonate, such as coral, oysters and tiny plankton. All of these organisms are crucial for the health of ocean ecosystems that provide the fish that humans eat. Did you know that… The [...]

How do sea levels vary as the world warms or cools? A warmer planet means more heat is stored in the oceans. More heat causes thermal expansion that pushes ocean waters onto the land. A warmer Earth also means more melting of the ice sheets and alpine glaciers that sit on the land surface, putting [...]

In Brief: The 1783-84 eruption of Iceland’s Laki volcano caused crop failures and a cold summer in North America, while the following winter’s record cold has been linked to El Niño conditions in the tropical Pacific and a strongly negative North Atlantic Oscillation. The eruption of Iceland’s Laki volcano from June 8, 1783 to February [...]

Commonly known as the biological carbon “pump,” oceans take carbon from out of the atmosphere and deposit it down to the depths. This process is dominated by phytoplankton on the surface taking carbon out of the atmosphere to build their bodies, dying and then falling down to the ocean bottom, where the carbon they originally [...]