In the Silurian and Devonian (430 to 359 million years ago), North America moved north across the equator, and the cycle of warming and cooling was repeated yet again. Data for Figures 1 and 3 were obtained from the National Oceanic and Atmospheric Administrations National Centers for Environmental Information, which maintains a large collection of climate data online at: www.ncdc.noaa.gov/cag. The event devastated the Southwest, shifting a densely forested landscape to one primarily covered with fast-growing herbs and ferns. Official websites use .gov Data source: NOAA, 20214Web update: April2021, Key Points | Background | About the Data | Technical Documentation. The thicker line is a nine-year weighted average. Average annual preciptiation for the southwestern U.S. Zack also mentioned our good friend El Nio! Lower latitudes receive more heat from the sun over the course of a year; for each degree increase in latitude, there is approximately a 1C (2F) decrease in temperature. Map by NOAA(public domain) modified for the[emailprotected]project. That's at least one part of a very big climate puzzle crossing that barrier that involves both the ocean and atmosphere. Stages in the formation of a thunderstorm. Left (1):Leaves of a seedling. By comparison, the average high and low temperatures for the entire United States are 17C (63F) and 5C (41F), respectively. Maps modified from maps by Wade Greenberg-Brand, originally published inThe Teacher-Friendly Guide to the Earth Science of the SouthwesternUS, after figure 3 in L. Grande (2013) The Lost World of Fossil Lake. Its largely too soon to tell. Dry air is shown in orange. Source:Figure 1 from Erdei et al. The causes of specific weather events such as tornados and severe thunderstorms are incredibly complex, although climate change has enhanced some correlated factors, such as increased wind speed and an unstable atmosphere. Although there has so far been little regional change in the Southwests annual precipitation, the areas average precipitation is expected to decrease in the south and remain stable or increase in the north. Petrified log at Escalante Petrified Forest State Park, Jurassic Morrison Formation, Garfield County, Utah. Map of the modern Yucatn Peninsula region showing the location of the Chicxulub impact crater. See you then! Precipitation accumulation over the past 12 months, shown as a percent of the average mid-August through mid-August total. Go to the full list of resources about the climate of the southwestern U.S. Go to the full list of general resources about climate. Photo by Center for Land Use Interpretation(Creative Commons Attribution-Noncommercial-ShareAlike 3.0 license, image resized). Photo credits: 1916 photo from USGS (public domain), 2013 photo by daveynin (flickr,Creative Commons Attribution 2.0 Generic license, image resized). When you take an already highly variable phenomenon like rainfall, add in uncertain regional climate change impacts, and factor in the sparse data record, it gets difficult to make a strong case about exactly how the monsoon rainfall is changing. The white arrow is pointing to one of the leaflets of a compound leaf. Higher elevations (such as those found in the Rockies and on the Colorado Plateau) are also cooler, with approximately a 1.5C (3F) decrease in mean annual temperature for each 300-meter (1000-foot) increase in elevation. Sun and storm in Weld County, in the Great Plains region of Colorado, 2015. The North American Monsoon is a seasonal change in the atmospheric circulation that occurs as the summer sun heats the continental land mass. Most models predict a decrease in winter and spring precipitation by the middle of the century, and more frequent precipitation extremes during the last half of the century. Its not over yet, but possible that the overall monsoon rainfall in Arizona will end up being the highest on record. NOAA (National Oceanic and Atmospheric Administration). Pangaea began to break up during the Jurassic, rifting apart into continents that would drift toward their modern-day positions. Snowfall will be below normal in most areas that normally receive snow, with the snowiest periods in early to mid-January and early February. The coldest periods will be in late November, mid- and late December, and mid-January. There is some variability in the onset and demise of the monsoon. Note that the southwestern region of the U.S. is covered by a shallow sea. The thunderstorm begins. 2021. Wind moves the air, promoting mixing. Arizona's climate is influenced by three main topographical areas: the high Colorado Plateau (about 15202130 meters or 50007000 feet in elevation), the rugged mountains to the west (27403660 meters or 900012000 feet high), and the low southwestern mountains with desert valleys (as low as 30 meters or 100 feet above sea level). Photograph by "Cathy" (Flickr;Creative Commons Attribution-NonCommerical 2.0 Generic license). A couple of field campaigns, including the Arizona-based South-West Monsoon Project (SWAMP, 1993) and the international North American Monsoon Experiment (NAME, 2004), provided a lot of observational data and resulted in a better understanding of the mechanics of the monsoon. The Southwest, already the driest region in the United States, has become even drier since the mid-20th century, particularly on the hottest days . Increased heat in the Pacific Ocean has altered the weather patterns of Pacific storms, decreasing snowfall in the mountains of western Utah and Arizona. Ideas and explanations found in these posts should be attributed to the ENSO blog team, and not to NOAA (the agency) itself. Extent of the Western Interior Seaway during the Cretaceous Period. Photoandreconstructionby National Park Service/NPS (public domain). JulyAugust rainfall anomaly averaged over North American Monsoon region for every year 19502019 (y-axis) versus Nio-3.4 index (x-axis). Did La Nia drench the Southwest United States in early winter 2022/23? The cities of Aspen and Lafayette, Colorado, as well as the state of New Mexico, were early adopters of the 2030 Challenge, an effort to reduce fossil fuel use in buildings so that both new and renovated buildings would qualify as carbon neutral by the year 2030. Modified fromFigure 11 in Kirby et al. Although the mountain building that occurred during this event was mostly far to the east, the Southwest was influenced by both fluctuating sea levels and a few significant tectonic changes. The current drought outlooks expect that the drought in Arizona and New Mexico will improve in the short term, but persist. By the end of the Cretaceous, uplift to the west was great enough that the resulting hills shed large amounts of sand and gravel in an easterly direction, pushing the shoreline eastward until sediment (combined with a worldwide drop in sea level) filled the area formerly occupied by the Western Interior Seaway. Although much of the Southwest falls within the category of an arid zone, using a single label to describe the Southwest's climate would belie its diversity. Since the early 1900s, the Southwest has experienced wetter conditions during three main periods: the 1900s, 1940s, and 1980s. The risk of dangerous wildfires is currently very high in parts of the Southwest. For temperature, the 2020 monsoon was the hottest on record for the Southwest with an average temperature of 77.1 F, significantly beating the previous record of 76.8 F in 2011 (average is 74.3 F). Agriculture accounts for more than half of the Southwests water use, so any major reduction in the availability of water resources will create a serious strain on ecosystems and populations. Digital Encyclopedia of Earth Science: Why talk about climate change? 2. PRI is a registered 501(c)(3) nonprofit organization. By comparison, the average high and low temperatures for the entire United States are 17C (63F) and 5C (41F), respectively. The book was adapted for the web by Elizabeth J. Hermsen, Jonathan R. Hendricks, and Ingrid Zabel in 2022. Acad. Cumbres in the San Juan Mountains receives nearly 7.6 meters (300 inches) of snowfall annually, while Manassa, less than 50 kilometers (30 miles) away in the San Luis Valley, receives only about 63 centimeters (25 inches) of snow a year. As Pangaea reached its greatest size during the early Triassic, the monsoons intensity increased, and the vast dune deserts of the late Permian were replaced by rivers and floodplains. In the Southwest, average precipitation ranges from only 34 centimeters (13.4 inches) in Utah to 39.9 centimeters (15.7 inches) in Colorado, which reflects the area's general aridity. Photo by Eltiempo10 (Wikimedia Commons, Creative Commons Attribution-ShareAlike 4.0 International license, image resized). Scale bar = 5 centimeters (about 2 inches). Southwest Increased heat, drought, and insect outbreaks, all linked to climate change, have increased wildfires. Saguaro and cholla cacti in the Sonoran Desert National Monument, Arizona. Fossils of a cycad (Dioonopsis praespinulosa) from the Paleocene Castle Rock Flora, Colorado. During the Permian, shallow marine waters gave way to lowland coastal areas across portions of the Southwest. Answer: Winter, June, July, and August. During winter months, daytime temperatures may average 70 degrees F, with night temperatures often falling to freezing of slightly below in the lower desert valleys." These changes include the following: The seasonality and transmission frequency of insect-borne diseases and other infectious diseases prevalent in the Southwest, including plague, valley fever, and Hanta, are influenced by warming trends. Another player is land-surface feedbackswetter soils provide more moisture to the air through evaporation. The oceans between Gondwana and North America began to close. Topics covered on this page: Present climate of the southwestern U.S.; Present temperature; Present precipitation; Severe weather; Regional climate variation; Past climate of the southwestern U.S.; Paleozoic; Mesozoic; Cenozoic; Future climate of the southwestern U.S.; Resources. A strong difference in air temperature at different heights creates instability; the warmer the air near the surface is relative to the air above it, the more potential (stored) energy the warm air has to move up, and the more potential for a storm. A .gov website belongs to an official government organization in the United States. The monsoon's intensity waned by the early Jurassic, and the rivers and floodplains were replaced by even larger deserts. The inner canyon temperatures are extreme and hot, with a lower elevation of about 2400 feet (732 meters). At the very end of the Cretaceous, the Gulf Coast experienced an enormous disruption when a large asteroid or bolide collided with Earth in what is now the northern Yucatn Peninsula in Mexico. Climate.gov image of original from Albuquerque, NM National Weather Service office. Burning those fossil fuels releases carbon into the atmosphere, which warms the Earth. We are largely unaware of this precipitation because of the Southern California Chamber of Commerce and a lack of rain gauges. The average annual temperature in most of the Southwest is predicted to rise 2.2 to 5.5C (4 to 10F) by 2100. Since then carbon dioxide emissions have been on a downward trend. Not really sure if it's possible to even find that rabbit hole let alone getting to the end of it :) Good luck. Moisture condenses out of the warm air as it comes into contact with cool air, forming clouds. Precipitation forms. Indeed, much of this region has low annual rainfall and seasonally high temperatures that contribute to its characteristic desert climate. Image adapted from an image by Scenarios for Climate Assessment and Adaptation, first published in The Teacher-Friendly Guide to the Earth Science of the Southwestern US. Other elements involved in the ignition and growth of fires and the risks they pose to people living in the Southwest include (but are not limited to) forest management practices, development patterns, and human behavior (intentionally or unintentionally starting fires). Las Cruces is located in the Basin and Range region of New Mexico. Zack and Mike described this years monsoon for southern Arizona as generational, meaning once in a generation. Facebook Tweet In addition, temperature increases and recent drought have resulted in earlier spring snowmelt and decreased snow cover on the lower slopes of high mountains, bringing about more rapid runoff and increased flooding. Lake Powell, the lake created by Glen Canyon Dam, at two points in time about four years apart. Temperature and drought data come from a network of thousands of weather stations overseen by the National Weather Service. Photo of USNM PAL 165239 by Crinoid Type Project (Smithsonian National Museum of Natural History, public domain). However, although climate change is predicted to enhance the intensity of severe weather, there is currently no way to calculate what effect climate change will have on the frequency of specific storm eventsfor example, we might see more powerful tornados, but we do not know if we will see more of them. An official website of the United States government. Convection occurs when buoyant warm air rises (moves up) while denser cool air sinks (moves down). Glaciers in the Colorado Rockies are sustained largely by avalanches and wind-blown snow. Also, the occasional eastern Pacific tropical storm can increase monsoon moisture and rainfall. (2015) . In general, places in the east and south of the UK tend to be drier, warmer, sunnier and less windy than those further west and north. Tornado Alley is identified. PRI's free resource to help you learn about the Earth and its history. contiguous U.S. (CONUS) into the Northern Plains. Unless otherwise indicated, text and images on this website have Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International licenses. Ive summarized their conclusions above, and include the quotes here, but I suggest you head over to the full science report if youre in the mood for some specifics. In New Mexico, for example, the average difference between the daily high and low temperatures ranges from 14 to 19C (25 to 35F). Drier days and higher temperatures will amplify evaporation, increasing the desertification of already arid areas and affecting natural ecosystems as well as increasing pressure on the water supply for agriculture and cities. In southern New Mexico, Pleistocene fossil mammals are found that now live at higher elevations in the mountains of northern New Mexico, indicating cooler temperatures and more available moisture in the area during the late Pleistocene. Drought continues to be quite severe over the southern Plains in Texas and Oklahoma due to hot and dry conditions. These changes threaten economic productivity, public health, and the sustainability of Indigenous communities. Large portions of the Southwest have experienced drought conditions since weekly Drought Monitor records began in 2000. Fossil ammonoid (Nigericeras scotti) from the Late Cretaceous Greenhorn Limestone, Baca County, Colorado. Water vapor animation for the afternoon of August 22, 2018 showing the monsoon circulation and thunderstorm formation (dark blue, green, dark red). While the state is generally arid, its high western mountains experience more precipitation each year than the desert southwest and the high northeastern plateau do. Changes in atmospheric pressure during the late fall and winter can lead to an accumulation of haze. This chart shows annual values of the Palmer Drought Severity Index, averaged over six states in the Southwest (Arizona, California, Colorado, Nevada, New Mexico, and Utah). Climate changepast, present & future: a very short guide. Fossil plants, Late Cretaceous Fruitland Formation, San Juan Basin, New Mexico. The last glacial advance of the modern ice age peaked some 18,000 years ago. Some areas were more than2F warmer than average (see Figure 1). . . During the Paleocene to Eocene, the Southwests climate was warm and wet, and large mammals roamed the forested landscape. One especially alarming detail about the Calf Canyon fire is that it was originally set in January 2022. The average amount of precipitation for the United States is 85.6 centimeters (33.7 inches). This circulation brings thunderstorms and rainfall to the monsoon region, providing much of their annual total precipitation. Branches and leaves of an ancient conifer (Walchia dawsonii), Permian Hermit Shale, Arizona. I did a quick comparison of the average JulyAugust rainfall in the monsoon region with the Nio-3.4 index, using 70 years of records. | View Google Privacy Policy. 2021. 94, 95, 96 Each assessment has consistently identified drought, water shortages, and loss of ecosystem integrity as major challenges that the Southwest confronts under climate change. Likewise, its not yet clear how the monsoon is changing in the warming climate, or how it will in the future. Moving westward, Colorado's foothills and mountainous areas experience an overall cooler climate and higher levels of precipitation. In general, it is expected that high alpine glaciers in the Colorado Rockies will disappear as the climate continues to warm. Accessed March 2021. https://droughtmonitor.unl.edu/DmData/DataTables.aspx. The strengthened Gulf Stream carried more warm, moist air with it into the northern Atlantic, which caused increased snowfall in high latitudes, leading to accelerating cooling. Precipitation, while sparse, peaks in the summer during the monsoonal storms, and again in the winter from storms originating in the Pacific Ocean. Right (2):Crown of leaves from a mature plant. Warm, moist air from the south occasionally but infrequently moves into Colorado during the summer. Like the Inside Passage, the weather in Southwest Alaska is heavily influenced by ocean currents and maritime conditions. Regional overview Southwest. (2019)Biology Letters15: 20190114(Creative Commons Attribution 4.0 International license, images cropped, reconfigured, resized, and relabeled). The continued growth of Pangaea created an intense monsoonal climate, similar to that of Asia today, that affected large parts of the continent. The Southwest experiences nearly every variety of extreme weather; heat snaps and cold waves, droughts, floods, blizzards, and even tornados are all considerations for residents of the southwestern states. Photo by Lane Pearman (flickr, Creative Commons Attribution 2.0 Generic license, image cropped and resized). Figures 2 and 3 show two ways of measuring drought in the Southwest: the Drought Monitor and the Palmer Drought Severity Index. This figure uses the U.S. Drought Monitor classification system, which is described in the table in the Droughtindicator. Alaska weather and daylight varies wildly by region and season, from short-sleeves in summer to down jackets in winter; from 7 rainy days in May in Southcentral to 17 rainy days in the Inside Passage. Image above: Sun and storm in Weld County, in the Great Plains region of Colorado, 2015. North America's position near the equator kept its climate relatively warm.
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