Kentucky

NICKNAMED FOR the bluegrass that covers much of this U.S. state, and known for its whiskey and for the Kentucky Derby that takes place annually at Churchill Downs in Louisville, the Commonwealth of Kentucky was named for the Kentucky River, which was thought to have been named from the Iroquoian word(s) for either “meadowland” or “land of tomorrow.” Kentucky is bounded on the north by the states of ILLINOIS, INDIANA, and OHIO, on the south by TENNESSEE, on the east by VIRGINIA and WEST VIRGINIA, and on the west by MISSOURI.

The Ohio River runs along the entire northern boundary of Kentucky, and the MISSISSIPPI RIVER runs along the western boundary. The total area of Kentucky is 39,728 square mi (102,895 square km). The state ranks 36th in size and 25th in population among the 50 states. Kentucky’s largest cities are Lexington, Louisville, Owensboro, Bowling Green, Covington, Hopkinsville, Frankfurt (the capital), Henderson, Richmond, and Jefferstown.

Approximately 679 square mi (1,758 square km) of Kentucky are covered by water. In addition to the Kentucky, Mississippi, and Ohio, Kentucky’s rivers include the Cumberland and the Green. Most of Kentucky’s lakes were created by damming river waters, including Barkley Lake, Rough River Lake, Green River Lake, Dewey Lake, and Cumberland Lake. Kentucky has a number of significant waterfalls. The average elevation of Kentucky is 750 ft (228 m) above sea level. The highest point in the state is 4,139 ft (1,261 m) above sea level at Black Mountain, and the lowest point is 261 ft (79 m) above sea level at the Mississippi River. The state is approximately 380 mi (611 km) from east to west and approximately 140 mi (225 km) from north to south.

Kentucky’s climate is temperate with annual temperatures ranging from 52 degrees F (11 degrees C) in the northeastern part of the state to 58 degrees F (14 degrees C) in the southwestern section. Temperatures throughout the year range from below freezing in the winter to warm and humid in the summer. Annual precipitation is approximately 45 in (114 cm). Winter snow averages range from 40 in (101 cm) in Kentucky’s highest elevations to 25 in (63 cm) in the northeast, to 10 in (25 cm) in the southwest. Kentucky is frequently beset by storms, particularly from March to September.

The geographic area of Kentucky is varied, encompassing five distinct physiological regions: the Bluegrass Region, the Cumberland Plateau, the Western Coal Field, the Pennyroyal Region, and the Jackson Purchase Region. The north central section of Kentucky falls within the Bluegrass Region, sometimes called the Lexington Plain, which extends into the neighboring state of Ohio.

Much of the Bluegrass Region is filled with rolling meadows and low, steep sandstone hills known as knobs, which are found in the Knobs Region that forms the eastern, southern, and western sections of the Bluegrass Region. The Knobs Region separates the Bluegrass Region from the Cumberland or Mississippian Plateau. The Cumberland Plateau is part of the Appalachian Plateau, which extends along much of the eastern part of the UNITED STATES from NEW YORK to ALABAMA.

In Kentucky, the area is characterized by mountains, plateaus, and valleys that are underlain with sandstone, shale, and limestone. Kentucky’s Cumberland, Pine, and Black mountain ranges are located in the Cumberland Plateau. The section of the plateau known as the Eastern Coal Fields is a mountainous area covered with forests and streams. These mountain ridges are frequently crossed by gaps such as the wellknown Cumberland Gap. Much of the Daniel Boone National Forest lies at the western end of the Eastern Coal Fields.

The northwestern section of Kentucky contains the Western Coal Field, which is a hilly area that lies within the Illinois Basin, extending to the Ohio River on the north and to the Pennyroyal Region on the east, west, and south. The Western Coal Field is named for the large deposits of coal that appear throughout the area. The soil on the borders of the Ohio River is highly fertile. The Pennyroyal Region, sometimes referred to as the Pennyrile Region for the small herb that grows in the area or, alternately, as the Highland Rim, covers a stretch of land between the southern border of Kentucky in the Appalachian Plateau to Kentucky Lake. The southern section of the Pennyroyal Region is made up of flat lands interspersed with occasional rolling hills, while the northern section is comprised mostly of rocky ridges containing numerous underground caves and tunnels. The best known of the caves is Mammoth Cave. A treeless area within the center of the Pennyroyal Region is known as The Barrens.

The Jackson Purchase Region is located at Kentucky’s western tip and is part of the Gulf Plains Region, which extends from the Gulf of Mexico to Illinois. The Jackson Purchase Region stretches to the Kentucky Lake in the east, to Illinois in the north, and to the Mississippi River in the west. Low hills and flooded plains make up the land in the Jackson Purchase Region. The Madrid Fault is located in this area. When earthquakes hit the area in 1811 and 1812, the Mississippi River began to flow backward, creating Reelfoot Lake.

Approximately 40 percent of Kentucky is forested. The coffee tree is the state tree. Kentucky hardwoods include oak, beech, hickory, maple, and walnut. Softwoods include cypress, hemlock, cedar, and pine. Flowering shrubs include buckeye, dogwood, laurel, azalea, rhododendron, redbud, blueberry, pennyroyal, and goldenrod (the state flower). Earlier in Kentucky’s history, bison and elk roamed the forest, but now the woods are filled with fox, groundhog, muskrat, opossum, rabbit, raccoon, squirrel, and deer. In addition to the cardinal, which is the state bird, Kentucky is home to the eagle, egret, mockingbird, yellow-billed sapsucker, crow, kingfisher, and woodpecker. Migratory birds are also frequently seen in the area. Kentucky has four state forests and 59 state parks.

Agriculture dominated Kentucky’s economy until the middle of the 20th century when services and manufacturing gained prevalence. Tobacco, hay, corn, soybeans, wheat, fruit, dairy, and livestock are the major products produced by Kentucky farmers. Industries include motor vehicles (the state’s largest industry), health services, furniture, aluminum ware, brooms, apparel, lumber products, machinery, textiles, and iron and steel products. Kentucky’s most important mineral resources are bituminous coal, petroleum, natural gas, stone, sand and gravel, clay, fluorspar, gemstone, limestone, lead, zinc, and fluorite. Kentucky’s coal mines provide 85 percent of the state’s mineral income.

Kazakhstan

THE REPUBLIC OF Kazakhstan occupies the center of the Eurasian supercontinent, the second largest of the former Soviet republics and today the ninth-largest nation in the world. Most of its vast territory, stretching from the Caspian and Volga lowlands in the west to the ALTAI MOUNTAINS on the borders with CHINA, is flat, covered in arid semidesert or STEPPE. Its people have been nomadic herders for millennia but are now taking the lead in the development of industry, agriculture, and international trade for Central Asia.

Kazakhstan has no coastline, except for 1,174 mi (1,894 km) along the landlocked CASPIAN SEA. Its main trade corridor has therefore been across the land, connecting the commerce of its neighbors (RUSSIA, TURKMENISTAN, UZBEKISTAN, KYRGYZSTAN, and China), starting with the SILK ROAD in the Middle Ages, continuing with the development of railroads in the 20th century, and once again building its transportation links with China today. The Kazakh people are a mixture of Turkic and Mongol nomadic tribes who ruled the region through interlocked, kin-based khanates until gradual annexation by the Russian Empire in the 18th century.

After a brief attempt at autonomy in the 1920s, the region became a Soviet Republic in 1936. The Soviets initiated intense agricultural and industrial development projects in the northern steppes during the 1950s, which brought numerous immigrants—Russians, Ukrainians, Germans, and others—who eventually out-numbered the native peoples. The Kazakhs declared their independence in 1991, and the population has once again shifted, through both mass emigration and a higher birthrate among ethnic Kazakhs.

THREE REGIONS

Geographically, the country is mostly homogeneous, a great flat tableland of lowlands, plains, and plateaus. This can be broken up into three basic regions: the Volga and Caspian lowlands of the west (with the narrow, low Mugodzhar Mountains), the Turgai Plateau, and the Kazakh Steppe. The Turgai Plateau is characterized by a central depression with a chain of small lakes. Most of the area’s rivers flow into these lakes, some of which evaporate and disappear completely during the dry season.

The Ulu-Tau mountains divide this area from the eastern third of the country, the Kazakh Steppe, which is mostly flat with a few scattered massifs. The primary of these elevated areas divides the watershed between the upper Irtysh River valley (whose waters flow across the West Siberian Plain all the way to the Arctic Sea) and Lake BALKASH, one of the largest lakes in the world in area, but not in volume, since it is very shallow. Lake Balkash is also very salty and has very little wildlife. South of these broad semi-desert and steppe plains are the northern edges of one of the great deserts of Central Asia, the Kyzyl Kum. Across this desert runs the other major river of Kazakhstan, the Syr Darya, which flows into the ARAL SEA. To the east and south rise the great mountain chains that divide Central Asia from China, the Altai, and Tian Shan.

Along the northern edges of Kazakhstan, several large cities were developed under the Soviet regime, the mining and industrial heart of Central Asia. Kazakhstan is a leading producer of coal, iron ore, manganese, copper, and many other minerals. It is oil and gas, however, that hold the most promise for the Kazakhs, with reserves estimated to put Kazakhstan into the top 10 oil producers in the world by 2015, especially around the Caspian Sea basin—the Tenghiz field ranks as one of the largest deposits in the world. Agriculture is still a major part of Kazakh economy, chiefly in grain exports and livestock.

Actively courting western investment and friendship, the Kazakhs declared their territory nuclear free in 1995, and the new national capital (Astana, moved in 1998, formerly known as Akmola, then as Tselinograd) lies inside a special economic zone with reduced trade barriers and tax incentives for investors. Russia continues to run the space center Baykonur Cosmodrome (formerly called Leninsk), but the Kazakh government is encouraging greater participation by ethnic Kazakhs.

Kashmir

KASHMIR IS THE name given to the Vale of Kashmir, a valley situated on the Jhelum River between the Pir Panjal range and the main range of the HIMALAYAS. By extension, the name is used to refer to the Indian state of Jammu and Kashmir and to a portion of the old preindependence territory that included what is now called Northern Areas and Azad (Free) Kashmir in PAKISTAN.

In addition, INDIA claims a 14,500-square-mile (37,554-square-km) section of the Tibetan plateau, “Aksai Chin,” as part of the old state of Kashmir. Kashmir was also a state under British soveriegnty until 1947 when the Hindu maharaja of the largely Muslim state attempted to obtain a degree of independence for his land by not joining Hindu India or Muslim Pakistan. The delay led to disputed territory between the two powers. The Indian government claimed that the Hindu ruler of Kashmir state had signed an Instrument of Accession to India, although the original document has never been seen, nor is there any evidence to indicate that the maharaja signed the document on the day cited, as he was being driven from Srinagar to Jammu. The state fell into outside hands, once again having been under the rule of the Moghuls and the Sikhs in previous centuries. Although the United Nations agreed to the suggestion of a plebiscite to which India also agreed, no such vote has ever taken place.

India has claimed territory, the former Gilgit Agency and Baltistan, that is now under Pakistani control and known as the Northern Areas. A small portion of this agency in the extreme north and lying in the watershed draining into CHINA was deeded to China by Pakistan in 1964. At no time did Gilgit Agency come under direct Kashmir rule, because the British kept a civil and military delegation in the agency prior to independence. Because of the continuing disputes of jurisdiction of Kashmir, Pakistan has agitated for a plebiscite, which now seems remote. Armed conflict by India with China and Pakistan has resulted in small wars in 1962 with China and in 1965 and 1971 with Pakistan. A transitory border, “The Line of Control,” was established but another dispute broke out in 1984 when Pakistan issued permits to tourists into territory that India claimed as Kashmir India territory. This dispute revolved around the Siachen glacier, the headwaters for the Nubra River flowing into the Shyok River, a tributary of the Indus.

This continued territorial dispute mars the attributes of Kashmir in its several guises today. Geographically, Jammu is in the Punjab lowlands and is Hindu or Sikh. The Vale of Kashmir is almost all Muslim today, the Hindu castes having left. Territorially, the largest area is Ladakh in the trans-Himalaya Tibetan plateau, where local culture is similar to that of Tibet but where there are a substantial number of Muslims, both Sunni and Shia. These people formerly conducted caravan trade across the infamous “Five Passes” route, that is, five passes over 18,000 ft (5,500 m), on the route from Leh in Ladakh to Sainju Bazaar down on the edge of the Takla Makan Desert bowl of XINJIANG province in western China. This lucrative trading route was the reason for the prosperity of old Kashmir. Its geography created a passland, that is, a state through which passes were essential for its commercial existence.

The route was dangerous with robbers from Shimshall in the Hunza area pillaging pack ponies and Bactrian camels who often died from lardug, high-altitude pulmonary edema. The hybrid Buddhist-Muslim trader community in Leh and along the trading route ensured the viability of the caravans. Between Srinagar and Leh, the Zoji pass was snowed in for six months of the year, thereby disrupting traffic. Another route from Srinagar went north over the Burzil pass down the Astor valley, over the Indus, and north to Gilgit. Because of the narrow defiles north of Gilgit and Hunza and over the crest of the Karakorum range little interregional trade was carried over this route. Transhumants of sheep and goats still migrate seasonally in the Pir Panjal and Himalaya mountains.

The Vale of Kashmir was once a major tourist destination, with houseboats on the Dal and Wular lakes nestling below high mountains with local products for sale. Many Indian films customarily showed Kashmir scenes. Trout fishing on the Liddar River on the Hindu pilgrimage route beyond Pahlgam was famous. Traditional woodworking, silk making, and wool products were highly sought. Agriculture is marginal, with rice, maize, peas, and beans widespread. The cultivation of saffron is a local specialty. Basic foodstuffs are imported from the Punjab. Stone fruits, cherries, peaches, apricots, and walnuts and almonds are exported to the plains of India through the Banihal tunnel, the main supply route from the Vale to India. Wildlife has suffered extreme depredation in recent years because of the prevalence of military weapons among divisive political factions. The noble sambar deer is severely depleted; ibex wild goat and urial wild sheep and blue sheep still remain in places in Ladakh, although markhor seems to have disappeared. Brown bear and Himalayan black bear now have their ranges severely curtailed. The elusive snow leopard still exists in the Markha valley in Ladakh, where a major conservation effort is under way.

In the past three decades, language has changed significantly. Kashmiri, an Indo-Aryan hill language cognate with the hill languages spoken through northern Pakistan to Pashai in Kabul Kohestan in Afghanistan, reports a decline in the number of speakers. Bazaar languages, Punjabi in the Vale of Kashmir, like Pashto in northern Pakistan and Farsi in Kabul Kohestan, have smothered regional languages in everyday usage. English schools are ubiquitous. Two villages in Ladakh sitting on the “Line of Control,” Dah and Hannu, retain pre-Islamic, pre-Buddhist cultural celebrations to this day. Nineteenth-century linguists referred to these villages, and others, as Dardic, although there is no validity to this term today. Eurocentric myths about the “Dards” being the true Aryans still surface today in Ladakh.

Afforestation

Because vegetation and climate are so strongly related, rapid changes in climate will impact plant distributions, alter the makeup of natural communities, and threaten forest sustainability. Due to increases in temperature, the limited availability of water, and other environmental factors, entire forests are disappearing and new ecosystems are taking their place. Deforestation contributes to the increasing amount of carbon dioxide (CO2) in the atmosphere and is influencing climatic change. A pragmatic and economical place to begin restoring the balance of the global carbon cycle is through the process of planting trees on open land, which is known as afforestation.

Need for Afforestation

Forests exert a strong influence on the environmentdue to their ability to slow the rate of greenhouse gas emissions by acting as a sink for CO2. Therefore, they are a critical element in mitigating climate change. Numerous studies have verified that deforestation has an influence on local, regional, and global climates. The rate of deforestation in the Amazon and elsewhere has rapidly increased in recent years. Most of the clearing is due to cattle ranching, leading to a decrease in biodiversity, weakening of the hydrologic cycle, and accelerated global warming.

Additional global warming is due to the disruption of global rainfall patterns through reduced evaporation and transpiration, which will cause a reduction in forest cover and the drying up of forests. Several options for reducing CO2 include curbing deforestation, establishing reforestation and afforestation projects, enhancing management and harvesting techniques, and maximizing urban forests. Protecting existing forests and planting new forests can help reduce the greenhouse effect, and a number of multidisciplinary mitigation options revolving around forests are surfacing as researchers collectively consider the threat of climate change.

Botany

Botany is the study of plants. Botanists study all aspects of plants, including their environment and how they grow. The discipline is one of the oldest sciences and has been closely associated with agriculture, horticulture, pharmacology, and other disciplines concerned with plants. Botany is related to many other sciences such as soil science, chemistry, geography, mathematics, and physics. All the sciences and businesses that use botanical knowledge benefit from pure botanical research.

Since prehistoric times, people have used plants for medicine, food, building materials, and making other items such as musical instruments. Plant knowledge was universal among cave dwellers or hunter-gatherers, whose folklore was passed on for generations. Medicine men or women practiced the development of remedies for diseases and injuries, as well as intoxicants. When settled farming communities arose about 12,000 years ago, horticultural plant knowledge also began to move toward a body of knowledge.

Ancient civilizations of the Egyptians, Indians, and Babylonians coined names for the plants they knew. The Greeks added to plant name descriptions. Aristotle, his student Theophrastus (An Inquiry into Plants), Galen the physician, and others gave descriptions to plant names. Aristotle sought the unique form or idea that is found in each plant. This basis would eventually aid the development of taxonomy of plants. He believed in the fixity of the species. This view was challenged by Charles Darwin’s theory of evolution of the species, which was a naturalistic explanation for the enormous plant diversity in the plant kingdom.

There are hundreds of thousand of plants in the world. They vary widely, even when related. This creates a major problem for accurate identification. For example, there are a wide variety of plants named in the Bible and in other ancient literature. However, identifying the exact plants named by biblical names is problematic. The same problem occurs when plants are named by other ancient literature; because they were given local names, the specific plants named are hard to precisely identify. For example, in the Hindu Vedas, there is frequent mention of the soma plant that was used as an intoxicant. Today, scholars are not sure which plant is the soma plant because of the absence of a universal, standard terminology of identification.

A standard nomenclature was adopted after the voyages of discovery, when a rich new variety of similar and uniquely new plants confronted botanists. Standardized nomenclature was developed using a taxonomy derived from Latin names. Latin, the language of scholarship until the 20th century, was used to assign a universal name to plants with different common names or national names in the many European languages. The use of Latin, a dead language, prevents changes in names that would occur in a living language, thereby creating lasting scientific precision. The scientific naming has a fixed pattern, in which the first name identifies the genus to which a plant belongs. The second name is the species name, which denominates precisely to which subgroup it belongs. Each genus is a unique class with each of its species being also unique groups. Many plants also have varietal names. For example, the orange tree has a scientific name of Citrus sinensis; Naval and Valencia oranges are varieties.

Blizzards

In high and mid-latitudes, blizzards are some of the most widespread and hazardous weather events. They are most common in Russia and central and northeastern Asia, northern Europe, Canada, the northern United States, and Antarctica. It is predicted that climate change will likely give rise to changes in the number, severity, and geographical occurrence of blizzards. Although it is common for the term blizzard to be employed to refer to any disruptive winter storm, there is a more precise scientific usage. Blizzards are a winter phenomenon occurring when snow is blown along the ground surface by strong winds. In different countries, official definitions of blizzard conditions vary according to high wind speed, high wind chill values, low visibility, the presence of falling or blowing snow, and the length of time the conditions persist. Although no particular temperature threshold is associated with the definitions, blizzard conditions may produce extreme wind chill values through a combination of low temperatures and high wind speeds.

There are significant inter- and intra-annual variations in blizzard frequency and severity that make statistical analysis of past trends problematic. Detailed studies are limited. Nonetheless, at least in North America, historical evidence points to a decline in the frequency and severity of blizzards on the Canadian prairies, and there has been a significant decline in the frequency of blowing snow conditions in the Canadian Arctic. On the other hand, there is evidence for the occurrence of stronger blizzards along Russia’s Pacific Coast.

An increase in the vigor of winter storms in a substantially warmer and energetic atmosphere may result in severe blizzard conditions becoming more frequent. A warmer climate may also be conducive to greater weather extremes. Regional differences in temperature variations in response to climate change (such as between ocean and continents, or between polar and mid-latitudes) may reduce or enhance temperature contrasts and thereby affect the frequency and severity of storms.

There is evidence from some regions that winter storms have increased in intensity; however, some modeling and empirical studies suggest a decrease in the frequency of winter storms. There may be considerable regional variation in the response to climate change (e.g., blizzards would be less common with declining snowfalls in the Sierra Nevada of California, but possibly more frequent and severe in western Europe). Storm tracks may also shift. Forecasts are speculative, as there is still a need to verify the conclusions derived from empirical studies of past blizzard patterns and projections from climate models.

Types of Blizzards

It is possible for blizzards to occur in conditions of clear skies when no snow is falling if conditions are conducive to the movement of existing surface snow. These are termed ground blizzards. In many storms in continental interiors, it is not uncommon for little new snow to be associated with a blizzard due to a lack of moisture associated with Arctic and Antarctic air masses in winter. In such circumstances, blizzard conditions are largely the result of winds blowing the existing snow cover. 

However, blizzards in some regions (e.g., those in western Europe and the Asian coast of the North Pacific, and “nor’easters” in the northeastern United States) are characteristically accompanied by heavy snowfall. Blizzards are produced by strong winds—katabatic winds (rushing down elevated slopes) and winds generated by steep sealevel pressure gradients associated with storms in high and mid-latitudes latitudes during winter. A single storm can occur over large areas of a continent, and a severe blizzard may persist for a week or more. A blizzard that struck Saskatchewan, Canada, in 1947, lasted 10 days, burying a train in snowdrift a kilometer long. The most severe blizzards occur in Antarctica, with winds exceeding 93 mi. per hour (150 km per hour). At some Antarctic stations, blizzard conditions occur on over half the days of the year.

Historically, high death tolls have been associated with the most severe blizzards. A spring blizzard in the United States in 1888 killed more than 400 people, and 277 died in a storm in 1993. In addition to the risks resulting from high wind chill values and exposure, blizzards generate other hazards. Whiteouts are often associated with blizzards, producing dangerous travel conditions. The blowing snow, limited visibility, absence of shadows, and lack of contrast between objects can cause a loss of depth perception and conditions in which even nearby objects may be rendered invisible. The persistent winds associated with blizzards may cause severe damage to buildings, can block transportation links, and can bury structures in massive snowdrifts. Outdoor activities may come to a standstill. The resulting economic disruption can be massive. Widespread deaths of domestic animals have occurred due to exposure and sources of feed being cut off by blizzards.

A reported 130,000 head of livestock died in Inner Mongolia as a result of a blizzard that began on New Year’s Eve in 2000. However, very disruptive winter storms may not qualify as blizzards; for example, those involving high snowfalls but without an additional defining characteristic. It may be reasonable to assume that in a warmer world there would be fewer blizzards. However, the occurrence of a blizzard is dependent on a specific combination of physical and meteorological factors. A systematic variation in any one or more of these, as influenced by future climate change— for example, storm intensity, shifting storm paths, wind velocity, ambient temperature, the amount of snowfall, and the amount and condition of snow on the ground—may affect the number, intensity, and geographical distribution of blizzards.

Cretaceous Period

The Cretaceous period spanned the time period from 144 to 65 million years ago. It was the final epoch of the dinosaurs. It ended when the dinosaurs became extinct. At its height, the Cretaceous was a period of great warmth. The poles were icefree, and warm ocean currents spread from the equator to the poles. The concentration of carbon dioxide was higher than it is today, causing a greenhouse effect. The abundance of plants was not enough to lower the amount of carbon dioxide in the atmosphere.

The vigor of their growth implies that the Cretaceous climate was warm and wet, although, curiously, rainfall in the tropics was not heavy enough to support rainforests. Plants grew as far north as the Arctic Circle, proving that high latitudes were far warmer than they are today. The climate cooled, however, and rainfall diminished during the Late Cretaceous. The Cretaceous climate reached its nadir 65 million years ago, when a meteor impacted Earth, ejecting debris, dust, and ash into the atmosphere, blocking out sunlight and cooling the Earth.

The sun was not the reason the Cretaceous period had a warmer climate than today; it produced 1–2 percent less heat. Earth was warmer during the Cretaceous period because the atmosphere contained 3–6 times more carbon dioxide than in the current era. Carbon dioxide formed from the decay of large amounts of dead plants.

Moreover, the Cretaceous, particularly the mid-Cretaceous, was a period of extreme volcanism, with the eruption of volcanoes releasing carbon dioxide into the atmosphere. The weathering of carbonaceous rocks also liberated carbon dioxide.

All of this carbon dioxide created a greenhouse effect, in which carbon dioxide trapped sunlight as heat, warming the atmosphere. A reservoir of heat, the ocean displayed the consequences of the greenhouse effect in its warmth, particularly in the tropics. During the Cretaceous period, tropical waters were between 82 and 111 degrees F (28 and 44 degrees C). At 30 degrees latitude, ocean temperatures dipped to 68 degrees F (20 degrees C). At 60 degrees latitude, ocean temperatures were 54 degrees F (12 degrees C), and at 90 degrees latitude, temperatures were a cold 40 degrees F (4.5 degrees C). Polar temperatures, thus, though cold, were nonetheless above freezing and the poles did not have ice, at least not during the Late Cretaceous, though climatologists are less certain about the earlier periods of the Cretaceous. As is true today, the Cretaceous period oceans were cooler at lower depths, yet even at great depths they were warmer than today’s oceans.

Secrets in Plants

Plants absorbed carbon dioxide during the Cretaceous, though they may not have absorbed as much of the gas as they do today, accounting for the greenhouse effect during the Cretaceous. The tropics were drier during the Cretaceous than they are today, and so did not support a rainforest. The absence of a rainforest may have meant that Cretaceous plants were not numerous enough and did not grow vigorously enough to absorb as much carbon dioxide as today. Although this may have been true of the tropics, high latitudes had forests where today there is only tundra. These forests must have taken carbon dioxide out of the atmosphere, but on balance, plants did not remove carbon dioxide in sufficient quantities during the Cretaceous to reduce the greenhouse effect.

Plants reveal that the Cretaceous had a tropical climate, even at high latitudes. The plant Heilungia grew in Alaska. Although it is extinct, its relatives grow in Mexico and the Caribbean, suggesting that Alaska had a tropical climate during the Cretaceous. Temperatures must have varied little, staying around 80 degrees F (27 degrees C) year-round at high latitude. Rainfall must have exceeded 80 in. (203 cm) a year.

The fact that Alaska had swamps during the Cretaceous also suggests that rainfall was abundant. Moreover, plants grew in profusion and density in Alaska, implying high rainfall and warm temperatures. Tree rings were wide, suggesting a warm, wet climate. Conifers grew at lower latitudes, implying that the climate was less moist and that the climate became drier toward the equator, the opposite of conditions today. 

In Siberia, plants grew in the Arctic Circle. Summer temperatures averaged 70 degrees F (21 degrees C), whereas winter temperatures averaged only 43 degrees F (6 degrees C). Arctic Siberia therefore had seasons, with summer 27 degrees F (15 degrees C) warmer than in winter. The difference between summer and winter temperatures during the Cretaceous is less than the seasonal difference today at high latitudes. The climate was warm enough this far north to permit plant growth for more than seven months each year.

Autumn was brief, with the transition from summer to winter coming rapidly. South of Siberia, in what is Czechoslovakia today, temperatures averaged 68 degrees F (20 degrees C). Summer temperatures averaged 82 degrees F (28 degrees C), whereas winter temperatures averaged 52 degrees F (11 degrees C).

Enigma

The climate of the Late Cretaceous is an enigma. The oceans remained warm and the poles ice-free, but on land, temperatures and rainfall decreased. The final blow came at the end of the Cretaceous 65 million years ago, when a meteor hit Earth, ejecting debris into the atmosphere and blocking out sunlight, cooling the Earth. The meteor impact ended the Cretaceous, temperatures continued to decrease, falling low enough to cause ice ages, the last of which ended only 10,000 years ago. As the concentration of carbon dioxide diminished and ice collected at the poles, tundra replaced forests at high latitudes. Rainfall increased in the tropics, giving rise to the rainforests.