Answer:
1- One of the most immediate and obvious effects of worldwide warming is the increase in temperatures around the world. The average worldwide temperature has increased by about 1.4 degrees Fahrenheit (0.8 degrees Celsius) over the past 100 years, according to the National Ocean-related and (related to the air outside) Management (NOAA).
The (related to the air outside) carbon dioxide concentration has risen from about 270 parts per million (ppm) before 1700 to about 355 ppm today. Climate changes, including a mean worldwide surface temperature rise of between 2.8 and 5.2°C, have been (described a possible future event) by five independent general circulation models (GCMs) for a doubling of the carbon dioxide concentration. The goals of this paper are to examine plant responses to rising carbon dioxide levels and (related to the Earth's weather) changes and to understand/explain the results of these changes on crop water use and water supplies for the United States.
2- Human activity has increased the direct warming effect of carbon dioxide in the atmosphere by 50 percent above pre-industrial levels during the past 25 years, according to NOAA's 10th Once-a-year (glass building where plants are grown) Gas Index.
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