Earth Gauge » Atmosphere

Climate Number: 123 Petagrams of Carbon

kraus — Wed, 25 Aug 2010 20:53:04 +0000

Plants use the sun’s energy to turn carbon dioxide (CO2) in the air into the organic matter, or carbohydrates, that make up their bodies. This process, known as photosynthesis, ultimately feeds the rest of the food chain, with grazers eating the plants and carnivores and omnivores eating the grazers. How much carbon land plants take up each year, as well a how much carbon animals and fungi respirate back into the atmosphere, is important for understanding how much food, fiber and wood can be produced on a global scale. It is also important for predicting the future make-up of the atmosphere and climatic conditions. Estimates show that each year across Earth’s land surfaces, a total of around 123 petagrams (123,000,000,000,000,000 grams) of carbon are taken up by plants. Yet, about the same amount of carbon is respirated back into the air, in addition to the amount of fossilized carbon that goes into the atmosphere after being burnt in cars and power plants. The amount of carbon taken out of the atmosphere varies across the globe, with the Sahara Desert absorbing almost no carbon, while each square meter of the Amazon Rainforest absorbs an average of three kilograms (6.6 pounds) each year.

For comparison: U.S. wheat production is about 2.16 billion bushels per year, for a total weight (assuming 13 percent moisture content) of 58,800,000,000,000 grams (130 billion pounds). This is about 1/2092nd of the total amount of carbon that is taken up by land plants each year. For further comparison, 123 petagrams is about the same weight as a 1.3 million Nimitz Class aircraft carriers.

Seasons: Winter, Spring, Summer, Fall

Sources: Beer, C et al. “Terrestrial Gross Carbon Dioxide Uptake: Global Distribution and Covariation with Climate.” Science 329 (2010): 834-838 and Reich, PB. “The Carbon Dioxide Exchange.” Science 329 (2010): 774-775.

Climate Fact: Heat Waves

kraus — Mon, 23 Aug 2010 14:13:53 +0000

In Brief: Nights are warmer than they were in the early 1970s, which exacerbates the urban heat island effect and heat related health problems.

Heat waves – which in the United States kill up to 1,000 people per year – are defined as prolonged periods of abnormally hot weather. They can occur at any time of the year. What “abnormally hot” weather is will vary from place to place and from season to season, making a standard range of dangerous temperatures difficult to determine. What’s more, people become acclimated to seasonal temperatures. This means that sudden onsets of summer weather early in the year are generally much more dangerous than equivalent temperatures later in the summer. Some basic human physiological limits, however, can provide set temperatures that are dangerous. Heat index temperatures of 130 degrees Fahrenheit or higher are considered extremely dangerous, with heat stroke or sunstroke likely. Temperatures between 105 and 129 degrees are in the danger zone, when sunstroke, muscle cramps, and/or heat exhaustion likely. Heatstroke is possible with prolonged exposure and/or physical activity. When the heat index is between 90 and 105 degrees, extreme caution with the heat is recommended.

Because they are built with heat trapping materials like concrete and asphalt, cities tend to be hotter than surrounding rural areas. This is particularly true at night, when cool temperatures are important for giving the body a break from the heat. Urbanization, in addition to a general warming trend, means that extreme heat events are becoming more common. In North America over the last 50 years, average nighttime low temperatures have risen faster than average daytime high temperatures. There has been a 50 percent increase in the number of unusually warm nights, and nights with temperatures that would have fallen into the top tenth percentile during the 1950s now fall into the top fifteenth percentile. Almost all of this increase has happened since 1975.

Seasons: Spring, Summer, Fall

Sources: Meisner, BN. “Heat Wave.” National Weather Service Southern Region Homepage. NOAA. 15 May 2000. Accessed Online 16 August 2010 and United States Climate Change Science Program. “Weather and Climate Extremes in a Changing Climate.” Synthesis Assessment Product 3.3: GPO. 2008 and American Red Cross. “Talking about Disaster: Guide for Standard Messages.” Available from: and Centers for Disease Control. “Tips for Preventing Heat Related Illness.” Accessed Online 16 August 2010

Climate Trivia: Ocean Acidification

kraus — Fri, 06 Aug 2010 20:32:18 +0000

The oceans are currently absorbing about 22 million tons of carbon dioxide (CO2) each day and have absorbed an estimated 525 billion tons of CO2 over the last 200 years.

Trivia Question: As the oceans absorb more carbon dioxide, they become…

a. more basic (higher pH).
b. more acidic (lower pH).
c. richer in nutrients.
d. warmer.

The correct answer is b. As oceans take CO2 out of the atmosphere, the waters become more acidic. More acidic waters mean there are less carbonate molecules available to organisms that use calcium carbonate to build their bodies, such as coral, oysters and many of the tiny plankton that are at the base of the food chain. One indicator of how this acidification has affected ocean life is the thickness of foraminiferan shells, which are a type of plankton. Samples from the Southern Ocean around Antarctica indicate that foramineferan shells, which are harder to make when there are fewer carbonate molecules, are now one-third thinner than they were in pre-industrial times.

Seasons: Winter, Spring, Summer, Fall

Sources: Hoegh-Guldberg et al. “Coral Reefs Under Rapid Climate Change and Ocean Acidification.” Science 318 (2007): 1737 and “Oceans Becoming More Acidic, Potentially Threatening Marine Life.” Science Daily 23 February 2009. Accessed Online 25 February 2009 and Moy, AD et al. “Reduced calcification in modern Southern Ocean planktonic foraminifera.” Nature Geoscience 2 (2009): doi:10.1038/ngeo460.

Climate Number: 1.52 Teragrams

kraus — Mon, 02 Aug 2010 15:02:40 +0000

While Lake Chad today covers an area of around 115-200 square miles, at the end of the last ice age (12,000 years ago), there was Lake Megachad, which covered an area as large as 154,000 square miles. Rivers flowing into the lake brought in sediments from the surrounding landscape, and the bodies of plankton growing on the lake surface became deposits on the lake bed as they died and sank to the bottom. The lake bed became a nutrient rich sedimentary layer full of minerals such as iron and phosphorous. The lake has shrunk as the climate has changed over the past 10,000 years, and this rich deposit is now dry, easily erodible and exposed to the surface winds that carry it away during dust storms. One particularly rich deposit from Lake Megachad is known as the Bodélé Basin, which is Earth’s largest single source of atmospheric dust. During the winter months, the Bodélé Low Level Jet carries dust plumes from this basin westward across the Sahara and even across the Atlantic Ocean to the Amazon rainforest. This dust is a fertilizer for the rainforest, and helps to sustain the rich ecosystems there that play considerable roles in the global nitrogen and carbon cycles. One key nutrient transported out of the Bodélé Basin is iron. Each year, up to 1.52 teragrams (1.52 trillion grams) of iron travel from the Bodélé Basin across the Atlantic and into the Amazon rainforest. The total amount of dust transported from the Bodélé Basin to the Amazon may be as high as 277 teragrams annually.

For Comparison: 1.52 teragrams is about the same weight as 125,000 Boeing 757-200’s.

Seasons: Winter, Spring, Summer, Fall

Source: Bristow, CS et al. “Fertilizing the Amazon and equatorial Atlantic with West African dust.” Geophysical Research Letters 37 (2010): L14807.

Climate Trivia: Atlantic Hurricane Frequence and ENSO

kraus — Mon, 21 Jun 2010 14:42:52 +0000

Warm ocean surface temperatures in the North Atlantic provide the warm and moist air that fuels hurricanes, which develop out of random disturbances in the tropics that provide the spark for these storms. Warmer waters in the North Atlantic generally mean more fuel for the storms. But did you know that surface temperature conditions in the tropical Pacific Ocean also influence the Atlantic Hurricane season? The El Niño-Southern Oscillation (ENSO) is the periodic shifting of sea surface temperature distributions in the tropical Pacific. During El Niño phases, water temperatures in the eastern tropical Pacific off the coast of South America are warmer than normal. During La Niña phases, water temperatures there are cooler than normal. During ENSO neutral phases, the temperatures are somewhat in between.

Trivia Question: All other things being equal, during what phase of ENSO does the Atlantic Hurricane season tend to be most active?

a. El Niño
b. La Niña
c. Neutral

The correct answer is b. The amount of vertical wind shear over the ocean can make or break a hurricane season. Vertical wind shear is the change in the speed and direction of wind at different levels of the atmosphere. More vertical wind shear, or lots of variation in wind speed across different altitudes, suppresses hurricane activity. Less vertical wind shear, or more even wind patterns across different altitudes, promote hurricane development. La Niña phases work to reduce the amount of vertical wind shear over the North Atlantic, and thus La Niña years tend to be years with more active Atlantic hurricane seasons. La Niña conditions are now present in the tropical Pacific.

Seasons: Summer, Fall

Sources: Briggs, WM. “On the Changes in the Number and Intensity of North Atlantic Tropical Cyclones.” Journal of Climate 21 (2008): 1387-1402. Donnely, JP and Woodruff, JD. “Intense hurricane activity over the past 5,000 years controlled by El Niño and the West African monsoon.” Nature 447 (2007): 465-468.

Climate Trivia: Cloud Condensation Nuclei

kraus — Mon, 21 Jun 2010 14:40:09 +0000

The term cloud condensation nuclei (CCN) is a fancy way of describing the tiny particles that even smaller water vapor droplets cling to as raindrops form. Once enough water vapor droplets gather on the nuclei, raindrops fall. This is a critical part of Earth’s water cycle, which moves water from the oceans to the land, making freshwater and life on land possible. Without the nuclei, water vapor would not collect and fall as raindrops.

Trivia Question: Which of the following is a common source of cloud condensation nuclei?

a. Dust storms
b. Ocean salt spray
c. Volcanoes
d. Ocean algae
e. All of the above

The correct answer is e. Dust from dust storms, salt from the ocean, sulfate from volcanic activity, and a substance emitted in large quantities by ocean algae blooms called dimethylsulfide are all crucial sources of cloud condensation nuclei. Any changes in the concentrations of these different nuclei can affect the weather by affecting when and how clouds form and rain falls.

Seasons: Winter, Spring, Summer, Fall

Source: Vakkubam SM et al. “Weak response of oceanic dimethylsulfide to upper mixing shoaling induced by global warming.” PNAS 104 (2007): 16004-16009.

Climate Number: 21 Percent

kraus — Mon, 07 Jun 2010 14:26:10 +0000

Without a steady supply of oxygen in the air around us, we would suffocate. Compared to other planets in our solar system, Earth’s concentration of oxygen in the atmosphere is exceptional. Of the air that goes into your lungs, 78 percent is nitrogen and 21 percent is oxygen. The remaining one percent is a combination of trace gases such as carbon dioxide, water vapor and stable “noble” gases like argon and helium. While lots of oxygen is critical to the survival of complex animal life, including human beings, Earth’s ancient atmosphere was by most estimates almost completely void of oxygen. Instead, the atmosphere was composed almost entirely of carbon dioxide and methane until about 2.4 billion years ago. At this time, bacteria that convert atmospheric carbon into sugars, emitting oxygen as a waste product (called photosynthetic organisms), became a dominant life form. Back then, photosynthetic organisms were the exception and the oxygen they emitted would have been considered a pollutant to other life forms living on Earth. But the photosynthetic organisms reproduced successfully and quickly (in geologic terms) built up the atmosphere we know today. By about 450 million years ago, oxygen concentrations were high enough – about 12.6 percent of the atmosphere – to allow fire to burn through Earth’s early forests. Fire has been part of Earth’s ecosystems ever since.

For Comparison: Venus’ atmosphere has almost no elemental oxygen and is about 96.5 percent carbon dioxide and 3.5 percent nitrogen. The Martian atmosphere is about 95.3 percent carbon dioxide, 2.7 percent nitrogen, 1.6 percent argon and has a trace amount of oxygen (0.13 percent).

Seasons: Winter, Spring, Summer, Fall

Source: Kump, LR. “The rise of atmospheric oxygen.” Nature 451 (2008): 277-278.

Climate Fact: Wheat, Nitrogen and Carbon Dioxide

kraus — Thu, 27 May 2010 18:35:44 +0000

In Brief: Wheat grown under elevated ambient carbon dioxide levels is less nutritious that wheat grown under current levels.

Atmospheric carbon dioxide (CO2) is a key plant nutrient, as carbon is the primary building block of all life on Earth. Other building blocks, however, are just as essential. Nitrogen, for example, is the mineral that plants require in the largest quantity. As atmospheric CO2 concentrations have risen from 280 parts per million to 390 over the last few centuries, scientists have started to ask questions about what this change will do to plant growth. More CO2 appears to stimulate growth in some plants, notably parasitic climbing vines, poison ivy and weeds like Canadian Thistle. In other plants, which use different methods to convert carbon into plant matter, more CO2 can also affect a plant’s ability to absorb nitrate, the most common nitrogen compound found in agricultural soils. Experiments done on wheat show that when this crop is grown under CO2 concentrations of twice today’s levels, there is a 7.4 to 11 percent decline in the protein content of the wheat grains, making the grain less nutritious.

Seasons: Winter, Spring, Summer, Fall

Sources: Bloom, AJ et al. “Carbon Dioxide Enrichment Inhibits Nitrate Assimilation in Wheat and Arabidopsis.” Science 328 (2010): 899-903 and Phillips, OL et al. “Increasing dominance of large lianas in Amazonian forests.” Nature 418 (2002): 770-774 and “As CO2 Levels Rise, Plants—and Humans—Respond.” Agricultural Research Magazine. USDA Agricultural Research Service, Nov. & Dec. 2009. Web. Nov. 2009: Vol. 57, No. 10.

Climate Trivia: Substance in the Stratosphere

kraus — Mon, 24 May 2010 13:41:37 +0000

The 1991 eruption of Mt. Pinatubo injected into the atmosphere about 20 million tons of a certain substance, which blocked the incoming sunlight causing a global cooling of one degree Fahrenheit over 18 months.

Trivia Question: What was this substance?

a. Carbon dioxide (CO2)
b. Carbon monoxide (CO)
c. Sulfur dioxide (SO2)
d. Ash

The correct answer is c. The June 15th eruption of Mt. Pinatubo on the island of Luzon in the Philippines injected about 20 million tons of sulfur dioxide into the stratosphere, the second lowest layer of the atmosphere between six and 31 miles in altitude. The U.S. Environmental Protection Agency lists sulfur dioxide as a criteria air pollutant. When it is present in the lower parts of the atmosphere, it makes rain more acidic and can lead to damaged plants, buildings and degraded water quality. After the Pinatubo eruption, plumes of sulfur dioxide circled the Earth in about three weeks and by the end of the year had made it to the poles, forming a “sulfur dioxide envelope” around the Earth. The sulfur dioxide particles in the stratosphere absorbed sunlight, warming that layer of the atmosphere by seven degrees Fahrenheit, but they also prevented the usual amount of sunlight from reaching the Earth’s surface, which caused a surface cooling of one degree Fahrenheit.

Seasons: Winter, Spring, Summer, Fall

Sources: Gu, Lianhong et al. “Response of a Deciduous Forest to the Mount Pinatubo Eruption: Enhanced Photosynthesis.” Science 299 (2003): 2035-2038 and Wolfe, Jason. “Volcanoes and Climate Change.” NASA Earth Observatory 5 September 2000. 16 July 2008

Climate Number: 24.2 Teragrams

kraus — Mon, 10 May 2010 14:13:19 +0000

Since the 1750’s, the amount of methane (CH4) in the atmosphere has increased by 250 percent. Much of this methane is emitted from lakes in northern regions. Glacial movement across the far North (north of 45 degrees) during the last ice age leveled the landscape, carved depressions in the bedrock and deposited ice that formed lakes as it melted. About 40 percent of Earth’s lakes are located north of 45 degrees North. Some of these northern regions have almost half of their surface area covered by lakes. On these lake bottoms, the decomposition of organic matter, much of which comes into lakes as the “active layer” of the surrounding permafrost thaws during the warm months, results in significant releases of methane into the atmosphere. In total, 24.2 teragrams (about 53,000,000,000 pounds) of methane is released from northern lakes each year. As temperatures have warmed over the past few decades, the permafrost “active layer” has become deeper in many areas and the total area covered by permafrost has shrunk. Thawing of Siberia’s Yedoma ice complex, where many of these high latitude lakes occur, could result in a total release of almost 50,000 teragrams of methane.

For Comparison: 24.2 teragrams weighs more than two million Boeing 757-200s.

Seasons: Winter, Spring, Summer, Fall

Source: Walter, KM et al. “Methane bubbling from northern lakes: present and future contributions to the global methane budget.” Philosophical Transactions of the Royal Society: A 365 (2007): 1657-1676.

Climate Fact: Temperature and Soil Carbon Release

kraus — Mon, 29 Mar 2010 13:39:56 +0000

In Brief: Compared to the 1980’s, more carbon is now being released into the atmosphere from the soil.

How changes in the carbon cycle affect Earth’s temperature and how Earth’s temperature affects the carbon cycle are two key questions for climate research. In 2008, there was a net release of about 98 petagrams (98 billion metric tons) of carbon from the soil into the atmosphere. Since 1989, there has been a 0.1 billion metric ton increase in this annual amount of carbon released from the soils. A key question is whether this increased release is in the form of newly mobilized “old” carbon that had been stored in the soils or whether the soils are also taking up more carbon from the atmosphere and there is more “new” carbon that is being cycled at a faster rate. “New” carbon being cycled at a faster rate would imply a general acceleration of the carbon cycle.

Seasons: Winter, Spring, Summer, Fall

Source: Bond-Lamberty, B and Thomson, Allison. “Temperature-associated increases in the global soil respiration record.” Nature 464 (2010): 579-582.

Climate Fact: Crops and Cooling

kraus — Mon, 29 Mar 2010 13:35:46 +0000

In Brief: More irrigation likely drove a 3.6 degree Fahrenheit decline in average summertime daily maximum temperatures between 1934 and 2002 at weather stations in heavily farmed areas of California.

Over the past few centuries, large parts of North America were converted from native ecosystems to agricultural and urban landscapes. Agricultural land now covers about 17 percent of America’s surface. One of the most intensively farmed areas is California, which grows about half of America’s domestically consumed produce. As the number of farms in California grew between 1934 and 2002, the amount of irrigated land grew as well. At weather stations located in the State’s agricultural centers, the irrigated proportion of the surrounding landscapes grew from 22.4 to 62.2 percent. Large irrigation systems, which provide vital water to crops in California’s Mediterranean climate where almost no rain falls in the summer, can increase evaporation and cloud cover, ultimately having a cooling affect. Compared to other California weather stations where large increases in irrigation did not occur, daily maximum temperatures decreased by 3.6 degrees Fahrenheit between 1934 and 2002. Because daily minimum temperatures showed little trend at these stations during this period, the average daily temperature range, or the difference between the daily maximum and daily minimum temperature, became smaller.

Seasons: Spring, Summer

Source: Lobell, David B., and Celine Bonfils. “The Effect of Irrigation on Regional Temperatures: A Spatial and Temporal Analysis of Trends in California, 1934-2002.” Journal of Climate 21 (2008): 2063-2071.

Climate Fact: Wind Speed Changes

kraus — Mon, 22 Mar 2010 14:56:52 +0000

In Brief: Higher elevation areas are experiencing the overall global trend of wind speed “stilling” more acutely than surrounding lowlands.

Wind speeds in the mid-latitudes have shown a downward trend over the past 30-50 years, a phenomenon known as “stilling.” Any trends in wind speed have implications for the water cycle, ecosystems and wind energy generation. Wind speeds pick up as the land-surface elevation increases. High elevation areas give birth to the river water that supports about 25 percent of the world’s gross domestic product, and climate changes at high elevations have potential implications for this water. In two high elevation areas, Switzerland and the Loess region of China, the overall trend in wind speed reduction has been more pronounced at higher elevations and during the winter months. For both of these study areas (which have similar climatologies) during the winter months, the wind speed increases by about 11 feet per second for every mile the land surface gains in elevation. Between 1960 and 2006, this wintertime rate of wind speed increase with elevation declined by about one percent. Wind speed is thus another climate variable that is changing faster at higher elevations.

Seasons: Winter, Spring

Source: McVicar, TR. “Observational evidence from two mountainous regions that near-surface wind speeds are declining more rapidly at higher elevations than lower elevations: 1960-2006.” Geophysical Research Letters 37 (2010): L06402.

Climate Trivia: Earth’s Green Season

kraus — Mon, 08 Mar 2010 15:01:01 +0000

In the Northern Hemisphere, deciduous trees are beginning to come out of their dormant season and unfurl their leaves. Soon, the greys and browns that characterize America’s broadleaf forests during winter will be replaced the by the greens of spring and summer. Over the last four decades, there has been a global trend in the length of the “green” season, or the period between when leaves emerge in the spring and when they turn color and drop in the fall.

Trivia Question: Since 1970, Earth’s “green” seasons have become…

a) longer
b) shorter

The correct answer is a. Earth’s “green” season – the combined average length of both the Northern and Southern Hemisphere green seasons – is now on average 15 days longer than it was in 1970. This trend has been linked to warmer temperatures, milder winters and higher concentrations atmospheric carbon dioxide.

Seasons: Late Winter, Early Spring

Source: Peñuelas, J et al. “Phenology Feedbacks on Climate Change.” Science 324 (2009): 887-888.

Climate Number: Two Tons

kraus — Mon, 01 Mar 2010 14:57:07 +0000

Over the past 250 years, the amount of carbon dioxide (CO2) in the atmosphere has risen from 280 parts per million to almost 400. Plants use sunlight to convert this atmospheric carbon into the sugars and starches that make up their tissues. As the amount of carbon in the atmosphere changes, plant growth patterns change as well. Longer growing seasons, the period of the year when freezing temperatures do not restrict growth, as well as warmer temperatures in general, also affect plant growth. All three of these climate trends (more CO2, longer growing seasons and higher temperatures) have been occurring in the forests of America’s Mid-Atlantic region over the past century. During this period, plant growth in these forests accelerated. Each acre accumulates a certain amount of “biomass” each year, which reflects how much carbon these forests take out of the atmosphere and store in their bodies. Each acre of Mid-Atlantic forest is now accumulating about two more tons of biomass each year than they did in 1900.

For Comparison: Two tons is about the same weight as two mature Hereford bulls.

Seasons: Spring, Summer, Fall

Sources: McMahon, SM et al. “Evidence for a recent increase in forest growth.” Proceedings of the National Academy of Sciences 107 (2010): 3611-3615 and “Forests are Growing Faster, Ecologist Discover; Climate Change Appears to be Driving Accelerated Growth.” Science Daily 2 February 2010. Accessed Online 28 February 2010 )

Climate Fact: Prairie Plant Response to CO2 Enrichment

kraus — Mon, 22 Feb 2010 15:17:11 +0000

Changes in the amount of carbon dioxide (CO2) in the air have been shown to affect plant growth rates, the amount and quality of fruit plants produce and how much water a plant releases through evaporation. A study conducted between 1996 and 2001 in the western Great Plains (parts of Colorado and Wyoming) grew several species of native and invasive prairie plants under both elevated and current CO2 concentrations and temperatures. The plants communities grown under elevated CO2 concentrations and temperatures produced about twice as much plant matter as the communities grown under today’s conditions. This growth, however, was accompanied by a decrease in the amount of nutrients the plant matter held. Also, plant species considered to be of poorer quality for livestock became more prevalent under the elevated CO2 and temperature conditions.

Seasons: Winter, Spring, Summer, Fall

Source: Parton, WJ et al. “Projected ecosystem impact of the Prairie Heating and CO2 Enrichment experiment.” New Phytologist 174 (2007): 823-834.

Climate Fact: Midwinter Storm Track Suppression

kraus — Mon, 22 Feb 2010 15:15:29 +0000

The temperature/pressure difference between the equatorial regions and the poles is at its maximum during the winter months. The energy this difference generates is thought to power the “storm tracks,” or the bands in the mid-latitudes where east to west traveling storms (cyclonic high and low pressure systems) are most common. The storm track over the Pacific brings the western U.S. ample rainfall for much of the fall, winter and spring seasons. One aspect of Northern Hemisphere winter storm behavior that has been somewhat of a mystery is the midwinter suppression of the Pacific storm track. The maximum latitudinal temperature/pressure difference during winter, which means more power for the storms, is reflected in the Atlantic storm track being at its strongest during the winter months. Over the Pacific, however, the midwinter corresponds to an average decrease in the number and strength of these storms by 20 and 14 percent respectively compared to the fall and spring months. One possible explanation for this suppression is a wintertime drop in the number of atmospheric disturbances that make their way from the mountains of central Eurasia to the Pacific. These disturbances can become the storms that move across the Pacific to North America. The sheer size of the Eurasian landmass means that the wintertime high pressure centers that sit in the middle of the continent are strong enough to push the warmer and competing air masses far to the south and away from the mountains where these warmer air masses can generate the disturbances that can ultimately become the Pacific storms.

Season: Winter

Source: Penny, S et al. “The Source of the Midwinter Suppression in Storminess over the North Pacific.” Journal of Climate 23 (2010): 634-648.

Climate Fact: North American and Eurasian Snow

kraus — Mon, 22 Feb 2010 15:13:48 +0000

Snow is both a product of the weather and a weather maker. It has long been recognized that snow exhibits a cooling effect on local and regional scales. Snow reflects more sunlight than bare ground, meaning that it absorbs less energy. More snow cover also means soils stay moist for longer following the spring melting than they otherwise would. More soil moisture means that more of the sun’s energy that would have been spent heating the ground is instead spent evaporating water. In North America, lots of snow over the continent affects the storm track, or the latitudinal band where travelling cyclonic high and low pressure systems are most common. More specifically, the cold temperatures the snow cover induces eventually force the storm track over North America to veer south. As it does this, the storm track downstream in Eurasia veers north, allowing warmer air masses to penetrate further into the continent than they otherwise would. The presence of these warmer air masses generally means less snow there. Thus, years of above average snow cover in North America tend to be years of below average snow cover in Eurasia.

Seasons: Winter, Spring

Source: Sobolowski, S et al. “Modeled Climate State and Dynamic Responses to Anomalous North American Snow Cover.” Journal of Climate 23 (2010): 785-799.

Climate Trivia: Ocean vs. Atmosphere Carbon Stocks

espinoza — Mon, 08 Feb 2010 13:56:38 +0000

Carbon is a critical element in the Earth system. Carbon molecules are constantly moving from different states and from reservoir to reservoir. One reservoir is the terrestrial biosphere (the life systems that exist on land), which holds carbon primarily in the form of plant matter and soil. The atmosphere holds carbon in the form of carbon-dioxide gas (CO2) and methane. The oceans also hold carbon, primarily in the form of dissolved CO2 and calcium carbonate. The amount of reactive carbon – carbon in forms that can readily change its chemical state and move from one reservoir to another – in each of these reservoirs is markedly different. The ocean is by far the largest of these three carbon reservoirs.

Trivia Question: The ocean’s carbon reservoir is about how many times the size of the atmosphere’s carbon reservoir?

a. Two times
b. Ten times
c. 25 times
d. More than 60 times

The correct answer is d. The oceans hold more than 60 times the amount of reactive carbon that the atmosphere does.

(Source: Riebesell, U et al. “Sensitivities of marine carbon fluxes to ocean change.” Proceedings of the National Academy of Sciences 49 (2009): 20602-20609)

Climate Trivia: Earth’s Largest Dust Source

espinoza — Mon, 08 Feb 2010 13:50:31 +0000

At any given time, there is about 22 million tons of dust suspended in the atmosphere around us. Dust has important effects on Earth’s climate. It absorbs and scatters incoming radiation, affecting how much sunlight reaches the Earth’s surface and how much is reflected back into space. How much sunlight reaches the Earth’s surface helps drive surface temperatures and rainfall patterns. Dust also serves as a fertilizer – dust from barren regions can travel thousands of miles and fertilize plants that grow in lush regions. The Amazon rainforest is one such lush region that is stimulated by fertilizing dust from afar.

Trivia Question: What region is Earth’s largest single source of atmospheric dust?

a. The Great Basin
b. The Gobi Desert
c. The Sahara Desert
d. The Atacama Desert

The correct answer is c. More dust comes out of Africa’s Sahara Desert than any other region on Earth. The Bodélé Depression in Chad (central Africa) may be Earth’s largest single dust “hot spot.” About half of the dust emitted from the Sahara comes from this 8650 square mile barren lake bed. Each year, about 100 dust plumes rise from the depression. Each plume contains about 700,000 tons of dust.

(Source: Grini, A et al. “Model simulations of dust sources and transport in the global atmosphere: Effects of soil erodibility and wind speed variability.”Journal of Geophysical Research – Atmospheres. 110 (2005): D02205 and Washington, R. et al. “Dust as a tipping element: The Bodélé Depression, Chad.” Proceedings of the National Academy of Sciences 49 (2009): 20564-20571)