Climate is a region’s long-term weather trend. Weather changes hourly, daily, monthly, and annually. However, distinct weather patterns persist over 30 years or longer. A desert may have a rainy week, but it rarely rains. Climate: arid.Climates are mostly consistent, thus living things may adapt. In dry climes, cacti hold onto water, whereas polar bears stay toasty. Climates contribute to Earth’s vast biodiversity.However, climates change slowly over centuries or thousands of years. Climate change requires creatures to adapt or move or face extinction.Changing Earth ClimateEarth’s climate has altered frequently. Earth was warmer 144 to 65 million years ago, according to Cretaceous fossils. Warm-weather fossilized plants and animals have been unearthed at much higher latitudes than they could exist at today. Tropical island breadfruit trees (Artocarpus altilis) grew as far north as Greenland.At least four major ice ages have occurred in the previous 500,000 years. Earth’s temperature dropped, expanding ice sheets and glaciers. The latest Ice Age began two million years ago and peaked 20,000 years ago. Ice caps receded 18,000 years ago. They’re still around. Their presence in Antarctica and Greenland suggests an ice age. Many scientists believe we are in an interglacial phase when rising temperatures have melted the ice caps. Glaciers may advance centuries from now.Climate scientists search several sites for previous climate change. Glaciers leave many clues like inept criminals. As they go, they scratch and scrub rocks. Their sediment is glacial till. Moraines form from this sediment. Glaciers generate drumlins, oval hills. All of these geographic features on areas without glaciers show glaciers were there.Scientists have chemical evidence of ice eras in sediments and rocks. Some rocks are glacial-only. Scientists know glaciers were here because of their presence under the ocean or on land.Fossils provide paleontological evidence. Fossils reveal local animals and flora. Cold-adapted creatures can move closer to the Equator during ice ages. Warm-weather organisms may lose habitat or go extinct.Shorter-term climate changes occur. The Little Ice Age peaked in the 16th and 17th century and lasted a few hundred years. This period had global temperatures 1–1.5 degrees Celsius (2–3 degrees Fahrenheit) lower than now.Though small, a one- or two-degree adjustment had huge impact. Glaciers expanded and swallowed mountain villages. Longer winters limited crop growth. Many northern Europeans left farms and villages to avoid famine.Scientists studied 300-year-old tree rings to learn about the Little Ice Age. Tree rings’ thickness depends on annual growth. Climate change affects this. Drought and cold stunted tree growth. Rings would be closer.Some climate changes are nearly predicted. Warming tropical eastern Pacific Ocean surface waters is one example of normal climate change. El Niño, meaning “The Child,” refers to the warmth that typically begins around Christmas. Trade winds move east-west across the ocean in typical years, pulling warm surface water. A shallow warm water layer forms in the eastern Pacific and warm water builds up in the west. Winds and ocean currents reverse every few years. This is El Niño. Eastern Pacific warm water deepens. This causes drastic climatic change. Australian and southern Asian rain diminishes, and unexpected storms may hit Pacific islands and the west coast of the Americas. Within 1-2 years, El Niño finishes and climate systems revert to normal.Natural Climate Change CausesClimate changes have several causes. Some are due to Earth’s atmosphere. El Niño, caused by winds and ocean currents, is an example of natural atmospheric variations.External forces can also effect natural climate change. Earth’s tilt and orbit around the sun may explain the 100,000-year ice age cycles. Slowly changing planetary parameters determine how much solar energy reaches different parts of the world in different seasons.Climate change may result from huge meteors hitting Earth. The atmosphere would receive millions of tons of debris from a meteor. The debris would obscure some of the sun’s beams, making it cold and dark. Climate change would drastically limit creatures’ survival. Many paleontologists believe a meteor or comet killed the dinosaurs. Climates too cold and gloomy were deadly for dinosaurs. They couldn’t handle the cold, and the dark stunted their food plants.Plate tectonics affects climate. Earth’s continental plates have migrated a lot. The continents formed Pangaea around 200 million years ago. As continents split, ocean currents and their places shifted. Both changes affected climate.Greenhouse gas emissions affect climate change. Carbon dioxide traps solar heat in Earth’s atmosphere, raising surface temperatures. Both land and ocean volcanoes release greenhouse gases, which warm the troposphere if they reach it. If the eruption reaches the stratosphere, particles reflect sunlight back into space, cooling the location.The Human Causes of Climate ChangeBurning fossil fuels for transportation and electricity or employing meat-producing equipment create greenhouse emissions. Cutting down forests for timber or development increases the greenhouse effect because trees absorb CO2. Air-polluting factories do too.Scientists worry that these actions are generating dangerous climate change. Since scientists began recording global temperatures in 1880, they have climbed. Seven of the warmest years of the 20th century were the 1990s. This warming trend may indicate human-caused greenhouse effect increases. Many call this climatic change “global warming.”Industrial and automobile emissions of coal, oil, and natural gas contribute to global warming. Warming also destroys tropical forests. The University of California Riverside and NASA believe human activity has increased atmospheric carbon dioxide by 30% in 150 years.Decomposing plant and animal materials produces more methane, a strong greenhouse gas. Industrial and agricultural development frequently increase methane levels in the atmosphere. As economies flourish, populations consume more commodities and toss away more materials. Decomposing garbage in large landfills releases tons of methane.Chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), and hydrofluorocarbon (HFC) compounds are utilized in refrigeration and aerosol sprays. These substances emit greenhouse gases. Many countries are phasing them out, and some ban their production.Global warmingEarth’s temperature rises with greenhouse gas concentration. Climatologists fear the global temperature will rise so dramatically that ice caps may melt within decades. This would raise sea levels. Many low-lying islands and coastal areas would flood. Hurricanes, typhoons, and tornadoes may increase due to severe climate change. Some locations would get more rain, some less. Croplands could become deserts.Living species’ environments fluctuate with climate. Threatening local animals. Many cultures rely on certain crops for food, clothing, and trade. Climate change may prevent people from growing their staple crops. Some experts worry that tropical diseases like malaria, West Nile virus, and yellow fever will spread to temperate zones as Earth warms.
World Weather is Changing
