Global warming is the long-term warming of the planet’s overall temperature. Though this warming trend has been going on for a long time, its pace has significantly increased in the last hundred years due to the burning of fossil fuels.
As the human population has increase so has the volume of fossil fuels burned. The global average surface temperature rose 0. What has scientists concerned now is that over the past 2years, humans have been artificially raising the concentration of greenhouse gases in the atmosphere at an ever-increasing rate, mostly by burning fossil fuels, but also from cutting down carbon-absorbing forests.
Earth has experienced climate change in the past without help from humanity. We know about past climates because of evidence left in tree rings, layers of ice in glaciers, ocean sediments, coral reefs, and layers of sedimentary rocks. The chemical make-up of the ice provides clues to the average global temperature. Temperatures across the globe dipped for two to three years.
Although volcanoes are active around the worl and continue to emit carbon dioxide as they did in the past, the amount of carbon dioxide they release is extremely small compared to human emissions. On average, volcanoes emit between 1and 2million tonnes of carbon dioxide per year. Changes in the brightness of the Sun can influence the climate from decade to decade, but an increase in solar output falls short as an explanation for recent warming.
The total energy the Sun radiates varies over an 11-year cycle. During solar maxima, solar energy is approximately 0. See full list on earthobservatory.
But the current climatic warming is occurring much more rapidly than past warming events. In the past century alone, the temperature has climbed 0. Celsius, roughly ten times faster than the average rate of ice-age-recovery warming.
Most often, global climate has changed because of variations in sunlight. Variations in the Sun itself have alternately increased and decreased the amount of solar energy reaching Earth.
Volcanic eruptions have generated particles that reflect sunlight, brightening the planet and cooling the climate. Volcanic activity has also, in the deep past, increased greenhouse gases over millions of years, contributing to episodes of global warming.
These natural causes are still in play today, but their influence is too small or they occur too slowly to explain the rapid warming seen in recent decades. Based on plausible emission scenarios, average surface temperatures could rise between 2°C and 6°C by the end of the 21st century. The impact of global warming is far greater than just increasing temperatures.
Warming modifies rainfall patterns, amplifies coastal erosion, lengthens the growing season in some regions, melts ice caps and glaciers, and alters the ranges of some infectious diseases. Some of these changes are already occurring. Roughly percent of incoming sunlight is reflected back into space by bright surfaces like clouds and ice.
Of the remaining percent, most is absorbed by the land and ocean, and the rest is absorbed by the atmosphere. The absorbed solar energy heats our planet. As the rocks, the air, and the seas warm, they radiate heat energy (thermal infrared radiation). They radiate in all directions.
The energy that radiates back toward Earth heats both the lower atmosphere and the surface, enhancing the heating they get from direct sunlight. See the Earth Observatorys series Paleoclimatology for details about how scientists study past climates. Earths temperature begins with the Sun.
The paleoclimate record combined with global models shows past ice ages as well as periods even warmer than today. But the paleoclimate record also reveals that the current climatic warming is occurring much more rapidly than past warming events.
We know this because scientists closely monitor the natural and human activities that influence climate with a fleet of satellites and surface instruments. Scientists theorize that there may be a multi-decadal trend in solar output, though if one exists, it has not been observed as yet. When the Suns energy is at its peak (solar maxima), temperatures in both the lower atmosphere (troposphere) and the upper atmosphere (stratosphere) become warmer.
Scientists integrate these measurements into climate models to recreate temperatures recorded over the past 1years. After that point, the decadal trend in global surface warming cannot be explained without including the contribution of the greenhouse gases added by humans.
Each cycle exhibits subtle differences in intensity and duration. To further explore the causes and effects of global warming and to predict future warming, scientists build climate modelscomputer simulations of the climate system. Climate models are designed to simulate the responses and interactions of the oceans and atmosphere, and to account for changes to the land surface, both natural and human-induced.
Though the models are complicate rigorous tests with real-world data hone them into powerful tools that allow scientists to explore our understanding of climate in ways not otherwise possible. Based on a range of plausible emission scenarios, average surface temperatures could rise between 2°C and 6°C by the end of the 21st century. Perhaps the most well known feedback comes from melting snow and ice in the Northern Hemisphere.
Warming temperatures are already melting a growing percentage of Arctic sea ice, exposing dark ocean water during the perpetual sunlight of summer. Snow cover on land is also dwindling in many areas.
In the absence of snow and ice, these areas go from having bright, sunlight-reflecting surfaces that cool the planet to having dark, sunlight-absorbing surfaces that bring more energy into the Earth system and cause more warming. The largest feedback is water vapor. Water vapor is a strong greenhouse gas. In fact, because of its abundance in the atmosphere, water vapor causes about two-thirds of greenhouse warming, a key factor in keeping temperatures in the habitable range on Earth.
But as temperatures warm, more water vapor evaporates from the surface into the atmosphere, where it can cause temperatures to climb further. The question that scientists ask is, how much water vapor will be in the atmosphere in a warming world? Will that trend hold as temperatures continue to warm?
The amount of water vapor that enters the atmosphere ultimately determines how much additional warming will occur due to the water vapor feedback. So far, most of the atmosphere has maintained a near constant balance between temperature and water vapor concentration as temperatures have gone up in recent decades.
If this trend continues, and many models say that it will, water vapor has the capacity to double the warming caused by carbon dioxide alone. The atmosphere responds quickly to the water vapor feedback.
Clouds can become brighter if more moisture converges in a particular region or if more fine particles (aerosols) enter the air. If fewer bright clouds form, it will contribute to warming from the cloud feedback. Clouds, like greenhouse gases, also absorb and re-emit infrared energy. Low, warm clouds emit more energy than high, cold clouds.
However, in many parts of the worl energy emitted by low clouds can be absorbed by the abundant water vapor above them. In a world without low clouds, the amount of emitted infrared energy escaping to space would not be too different from a world with low clouds. High cold clouds, however, form in a part of the atmosphere where energy-absorbing water vapor is scarce.
These clouds trap (absorb) energy coming from the lower atmosphere, and emit little energy to space because of their frigid temperatures. In a world with high clouds, a significant amount of energy that would otherwise escape to space is captured in the atmosphere. If warmer temperatures result in a greater amount of high clouds, then less infrared energy will be emitted to space. As a result, global temperatures are higher than in a world without high clouds.
Scientists arent entirely sure where and to what degree clouds will end up amplifying or moderating warming, but most climate models predict a slight overall positive feedback or amplification of warming due to a reduction in low cloud cover. A recent observational study found that fewer low, dense clouds formed over a region in the Pacific Ocean when temperatures warme suggesting a positive cloud feedback in this region as the models predicted. What is global warming, explained.
The planet is heating up—and fast. Glaciers are melting, sea levels are rising, cloud forests are dying, and wildlife is scrambling to keep pace. Fahrenheit ( degrees Celsius)— even more.
Climate scientists have since the mid-20th century gathered detailed observations of various weather phenomena (such as temperatures, precipitation, and storms) and of related influences on climate (such as ocean currents and the atmosphere’s chemical composition). According to the National Climate Assessment, human influences are the number one cause of global warming, especially the carbon pollution we cause by burning fossil fuels and the pollution.
These greenhouse gases generally include gases like Carbon dioxide, Carbon monoxide, etc. You can read more Article Writing about people, sports, technology many more. But in some parts of the world it is less than this and some more.
The relatively higher level of global warming in recent times poses higher health risks to humans, both directly and indirectly. The gradual increase in the overall temperature of Earth’s atmosphere due to the greenhouse effect. Global Warming – latest news, breaking stories and comment – The Independent.
This effect is caused by increased levels of carbon dioxide, chlorofluorocarbons and other gases in the air, many of them released by human activity. Read this article to learn about the mechanism, effects and control of global warming! In the next article in our AGW series, we will review the analyses and databases that some climate scientists use to promote the concept of man-made global warming.
Rather than taking these scientists’ statements at face value, we will examine the data and form our own conclusions based on the facts. Even a seemingly slight average temperature rise is enough to cause a dramatic transformation of our planet.
