File Name: global warming and climate change factors and solution writer.zip
The climate of a place, say New York, can be described as its rainfall, changing temperatures during the year and so on. A description of the global climate includes how, for example, the rising temperature of the Pacific feeds typhoons which blow harder, drop more rain and cause more damage, but also shifts global ocean currents that melt Antarctica ice which slowly makes sea level rise until New York will be under water. It is this systemic connectedness that makes global climate change so important and so complicated. Without our atmospheric greenhouse the earth would be very cold.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. Research has also evaluated actions that could be taken—and in some cases are already being taken—to limit the magnitude of future climate change and adapt to its impacts.
In the United States, a series of reports by the U. Internationally, scientific information about climate change is periodically assessed by the Intergovernmental Panel on Climate Change IPCC , most recently in Much has been learned, and this knowledge base is continuously being updated and expanded with new research results.
Our assessment of the current state of knowledge about global climate change, which is summarized in this chapter and described in detail in Part II of the report, leads to the following conclusion. Conclusion 1: Climate change is occurring, is caused largely by human activities, and poses significant risks for—and in many cases is already affecting—a broad range of human and natural systems.
Both our assessment and these previous assessments place high or very high confidence 1 in the following findings:. Earth is warming. Most of the warming over the last several decades can be attributed to human activities that release carbon dioxide CO 2 and other heat-trapping greenhouse gases GHGs into the atmosphere.
The burning of fossil fuels—coal, oil, and natural gas—for energy is the single largest human driver of climate change, but agriculture, forest clearing, and certain industrial activities also make significant contributions. Natural climate variability leads to year-to-year and decade-to-decade fluctuations in temperature and other climate variables, as well as substantial regional differences, but cannot explain or offset the long-term warming trend. Global warming is closely associated with a broad spectrum of other changes, such as increases in the frequency of intense rainfall, decreases in Northern Hemisphere snow cover and Arctic sea ice, warmer and more frequent hot days and nights, rising sea levels, and widespread ocean acidification.
Human-induced climate change and its impacts will continue for many decades, and in some cases for many centuries. Individually and collectively, and in combination with the effects of other human activities, these changes pose risks for a wide range of human and environmental systems, including freshwater resources, the coastal environment, ecosystems, agriculture, fisheries, human health, and national security, among others.
The ultimate magnitude of climate change and the severity of its impacts depend strongly on the actions that human societies take to respond to these risks. The following sections elaborate on these statements and provide a concise, high-level overview of the current state of scientific knowledge about climate change in 12 critical areas of interest to a broad range of stakeholders:.
The research progress in each of these topics is explored in additional detail in Part II of the report, but even those chapters are too brief to provide a comprehensive review of the very large body of research on these issues.
Likewise, this report does not cover all scientific topics of interest in climate change research, only those of most immediate interest to decision makers.
Nevertheless, the laws of physics and chemistry ultimately govern the system, and can be used to understand how and why climate varies from place to place and over time.
The atmospheric concentrations of GHGs have increased over the past two centuries as a result of human activities, especially the burning of the fossil. For additional discussion and references, see Chapter 6 in Part II of the report. Human activities have also increased the number of aerosols small liquid droplets or particles suspended in the atmosphere.
Aerosols have a wide range of environmental effects, but on average they increase the amount of sunlight that is reflected back to space, a cooling effect that offsets some, but not all, of the warming induced by increasing GHG concentrations.
There are many indications—both direct and indirect—that the climate system is warming. The most fundamental of these are thermometer measurements, enough of which have been collected over both land and sea to estimate changes in global average surface temperature since the mid- to late 19th century. A number of inde-.
The black curve shows annual average temperatures, the red curve shows a 5-year running average, and the green bars indicate the estimated uncertainty in the data during different periods of the record.
For further details see Figure 6. Each group uses slightly different analysis techniques and data sources, yet the temperature estimates published by these groups are highly consistent with one another. Surface thermometer measurements show the first decade of the 21st century was 1. This warming has not been uniform, but rather it is superimposed on natural year-to-year and even decade-to-decade variations.
Because of this natural variability, it is important to focus on trends over several decades or longer when assessing changes in the heat balance of the Earth. Physical factors also give rise to substantial spatial variations in the pattern of observed warming, with much stronger warming over the Arctic than over tropical latitudes and over land areas than over the ocean.
Other measurements of global temperature changes come from satellites, weather balloons, and ships, buoys, and floats in the ocean. Like surface thermometer measurements, these data have been analyzed by a number of different research teams around the world, corrected to remove errors and biases, and calibrated using independent observations.
Ocean heat content measurements, which are taken from the top sev-. Up until a few years ago, scientists were puzzled by the fact that the satellite-based record of atmospheric temperature trends seemed to disagree slightly with the data obtained from weather balloon-based measurements, and both seemed to be slightly inconsistent with surface temperature observations.
Recently, researchers identified several small errors in both the satellite and weather balloon-based data sets, including errors caused by instrument replacements, changes in satellite orbits, and the effect of sunlight on the instruments carried by weather balloons.
After correcting these errors, temperature records based on satellite, weather balloon, and ground-based measurements now agree within the estimated range of uncertainty associated with each type of observation. The long-term trends in many other types of observations also provide evidence that Earth is warming. For example:. Glaciers and ice caps are melting in many parts of the world as described in more detail below ; and. Precipitation, ecosystems, and other environmental systems are changing in ways that are consistent with global warming many of these changes are also described below.
Based on this diverse, carefully examined, and well-understood body of evidence, scientists are virtually certain that the climate system is warming. These proxy data come from ice cores, tree rings, corals, lake sediments, boreholes, and even historical documents and paintings. A recent assessment of these data and the techniques used to analyze them concluded that the past few decades have been warmer than any other comparable period for at least the last years, and possibly for the last 1, years or longer NRC, b.
Careful statistical analyses have demonstrated that it is very unlikely 6 that natural variations in the climate system could have given rise to the observed global warming, especially over the last several decades. However, natural processes produce substantial seasonal, year-to-year, and even decade-to-decade variations that are superimposed on the long-term warming trend, as well as substantial regional differences.
Improving understanding of natural variability patterns, and determining how they might change with increasing GHG emissions and global temperatures, is an important area of active research see the end of this section and Chapter 6.
Large volcanic eruptions, such as the eruption of Mount Pinatubo in , can spew copious amounts of aerosols into the upper atmosphere. If the eruption is large enough, these aerosols can reflect enough sunlight back to space to cool the surface of the planet by a few tenths of a degree for several years. Prior to the satellite era, solar output was estimated by several methods, including methods based on long-term records of the number of sunspots observed each year, which is an indirect indicator of solar activity.
These indirect methods suggest that there was a slight increase in solar energy received by the Earth during the first few decades of the 20th century, which may have contributed to the global temperature increase during that period see Figure 2.
Perhaps the most dramatic example of natural climate variability is the ice age cycle. Detailed analyses of ocean sediments, ice cores, geologic landforms, and other data show that for at least the past , years, and probably the past several million years, the Earth has gone through long periods when temperatures were much colder than today and thick blankets of ice covered much of the Northern Hemisphere including the areas currently occupied by the cities of Chicago, New York, and Seattle.
Through a convergence of theory, observations, and. As discussed in Appendix D , very unlikely indicates a less than 1 in 10 chance of a statement being incorrect. Detailed worldwide records of fossil fuel consumption indicate that fossil fuel burning currently releases over 30 billion tons of CO 2 into the atmosphere every year Figure 2. Tropical deforestation and other land use changes release an additional 3 to 5 billion tons every year.
Precise measurements of atmospheric composition at many sites around the world indicate that CO 2 levels are increasing, currently at a pace of almost 2 parts per million ppm per year. We know that this increase is largely the result of human activities because the chemical signature of the excess CO 2 in the atmosphere can be linked to the composition of the CO 2 in emissions from fossil fuel burning.
Moreover, analyses of bubbles trapped in ice cores from Greenland and Antarctica reveal that atmospheric CO 2 levels have been rising steadily since the start of the Industrial Revolution usually taken as ; see Figure 2. The current CO 2 level ppm as of the end of is higher than it has been in at least , years. For further details see Figures 6. Based on data from Boden et al.
Only 45 percent of the CO 2 emitted by human activities remains in the atmosphere; the remainder is absorbed by the oceans and land surface. The combined impacts of rising CO 2 levels, temperature change, and other climate changes on natural ecosystems and on agriculture are described later in this chapter and in further detail in Part II of the report.
Human activities have led to higher concentrations of a number of GHGs as well as other climate forcing agents. For example, the human-caused increase in CO 2 since the beginning of the Industrial Revolution is associated with a warming effect equivalent to approximately 1.
Although this may seem like a small amount of energy, when multiplied by the surface area of the Earth it is 50 times larger than the total power consumed by all human activities. In addition to CO 2 , the concentrations of methane CH 4 , nitrous oxide N 2 O , ozone O 3 , and over a dozen chlorofluorocarbons and related gases have increased as a result of human activities. Collectively, the total warming associated with GHGs is estimated to be 3. While CO 2 and N 2 O levels continue to rise due mainly to fossil fuel burning and agricultural processes, respectively , concentrations of several of the halogenated gases are now declining as a result of action taken to protect the ozone layer, and the concentration of CH 4 also appears to have leveled off see Chapter 6 for details.
Human activities have also increased the number of aerosols, or particles, in the atmosphere. While the effects of these particles are not as well measured or understood as the effects of GHGs, recent estimates indicate that they produce a net cooling effect that offsets some, but not all, of the warming associated with GHG increases see Figure 2.
Averaged over the globe, it is estimated that these land use and land cover changes have increased the amount of sunlight that is reflected back to. Positive forcing corresponds to a warming effect. See Chapter 6 for further details.
Other human activities can influence local and regional climate but have only a minor influence on global climate. The response of the climate system to GHG increases and other climate forcing agents is strongly influenced by the effects of positive and negative feedback processes in the climate system.
One example of a positive feedback is the water vapor feedback. Water vapor is the most important GHG in terms of its contribution to the natural green-. Because the rate of evaporation and the ability of air to hold water vapor both increase as the climate system warms, a small initial warming will increase the amount of water vapor in the air, reinforcing the initial warming—a positive feedback loop.
If, on the other hand, an initial warming were to cause an increase in the amount of low-lying clouds, which tend to cool the Earth by reflecting solar radiation back to space especially when they occur over ocean areas , this would tend to offset some of the initial warming—a negative feedback.
Other important feedbacks involve changes in other kinds of clouds, land surface properties, biogeochemical cycles, the vertical profile of temperature in the atmosphere, and the circulation of the atmosphere and oceans—all of which operate on different time scales and interact with one another in addition to responding directly to changes in temperature.
The collective effect of all feedback processes determines the sensitivity of the climate system, or how much the system will warm or cool in response to a certain amount of forcing. A variety of methods have been used to estimate climate sensitivity, which is typically expressed as the temperature change expected if atmospheric CO 2 levels reach twice their preindustrial values and then remain there until the climate system reaches equilibrium, with all other climate forcings neglected.
Most of these estimates indicate that the expected warming due to a doubling of CO 2 is between 3. Unfortunately, the diversity and complexity of processes operating in the climate system means that, even with continued progress in understanding climate feedbacks, the exact sensitivity of the climate system will remain somewhat uncertain.
Nevertheless, estimates of climate sensitivity are a useful metric for evaluating the causes of observed climate change and estimating how much Earth will ultimately warm in response to human activities. Many lines of evidence support the conclusion that most of the observed warming since the start of the 20th century, and especially over the last several decades, can be attributed to human activities, including the following:.
The vertical pattern of observed warming—with warming in the bottom-most layer of the atmosphere and cooling immediately above—is consistent with warming caused by GHG increases and inconsistent with other possible causes see below. Detailed simulations with state-of-the-art computer-based models of the climate system are only able to reproduce the observed warming trend and patterns when human-induced GHG emissions are included.
In addition, other possible causes of the observed warming have been rigorously evaluated:. As described above, the climate system varies naturally on a wide range of time scales, but a rigorous statistical evaluation of observed climate trends, supported by analyses with climate models, indicates that the observed warming, especially the warming since the late s, cannot be attributed to natural variations.
Satellite measurements conclusively show that solar output has not increased over the past 30 years, so an increase in energy from the Sun cannot be responsible for recent warming. There is evidence that some of the warming observed during the first few decades of the 20th century may have been caused by a slight uptick in solar output, although this conclusion is much less certain.
In the following viewpoint, Canadell argues that recent efforts to improve energy efficiency and increase the use of clean energy have contributed to a stalling in fossil fuel emissions. However, Canadell contends that governments will need to increase their efforts to meet the climate goals established in the Paris Agreement. He compares the successes and shortcomings of China, the United States, India, Australia, and the European Union in reducing emissions. He examines the practice of storing carbon dioxide underground through carbon capture and storage CCS and concludes that thousands of CCS facilities will be necessary to meet climate goals. In the following viewpoint, Thomas argues that politicians use the issue of climate change as an excuse for the government to interfere in the lives of private citizens. Noting that some climate predictions have overestimated the impact of global warming, the author disputes the widely held belief that global temperatures are rising as a result of human activity.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. Research has also evaluated actions that could be taken—and in some cases are already being taken—to limit the magnitude of future climate change and adapt to its impacts. In the United States, a series of reports by the U. Internationally, scientific information about climate change is periodically assessed by the Intergovernmental Panel on Climate Change IPCC , most recently in Much has been learned, and this knowledge base is continuously being updated and expanded with new research results.
What is global warming? What causes global warming? What is climate change? Is it different from global warming? What is a climate change impact?
Climate change includes both global warming driven by human emissions of greenhouse gases , and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change , since the midth century humans have had unprecedented impact on Earth's climate system and caused change on a global scale. Temperature rise on land is about twice the global average increase, leading to desert expansion and more common heat waves and wildfires. It further magnifies risks of flooding, infectious diseases and extreme heat, with the World Health Organization calling climate change the greatest threat to global health in the 21st century.
При чем здесь таблица умножения? - подумала Сьюзан. - Что он хочет этим сказать. - Четыре на шестнадцать, - повторил профессор. - Лично я проходил это в четвертом классе. Сьюзан вспомнила стандартную школьную таблицу.
Выражение его лица тут же смягчилось. - Сьюзан, извини. Это кошмар наяву.
Крошечная сноска гласила: Предел ошибки составляет 12. Разные лаборатории приводят разные цифры. ГЛАВА 127 Собравшиеся на подиуме тотчас замолчали, словно наблюдая за солнечным затмением или извержением вулкана - событиями, над которыми у них не было ни малейшей власти. Время, казалось, замедлило свой бег.
Он должен настичь Дэвида Беккера.
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