Tuesday, December 11, 2018

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Climate Assessment supports human cause for drastic climate changes


Most people will not argue that our climate is changing. The winters are not as cold or as long, or are marked by extreme conditions. Midwest and Eastern United States jokes about the bi-polar weather are becoming more widespread.

The debate is not about whether the weather is changing, it is about why it is changing. Some politicians and scientists believe that the changes in our world’s climate is simply the natural course of climate evolution on Earth.

Many more scientists and many politicians claim that our climate is changing at an increased rate because of human activity and carbon emissions.

The Trump administration recently released the National Climate Assessment, which is a climate assessment required by Congress every four years and is issued by 13 federal agencies and the U.S. Global Change Research program.

According to the report, the “U.S. average temperature has increased by 1.3°F to 1.9°F since record keeping began in 1895; most of this increase has occurred since about 1970. The most recent decade was the nation’s warmest on record. Because human-induced warming is superimposed on a naturally varying climate, the temperature rise has not been, and will not be, uniform or smooth across the country or over time.”

Journalists and scientists alike have repeatedly reported that the temperature of the planet is increasing at an alarming rate.

Reports about the melting polar caps, the rising sea levels and endangered wildlife as a result are spread in documentaries, news reports, and throughout social media.

This most recent report indicates that the “minimum Arctic sea ice extent (which occurs in early to mid-September) has decreased by more than 40%. This decline is unprecedented in the historical record, and the reduction of ice volume and thickness is even greater. Ice thickness decreased by more than 50% from 1958-1976 to 2003-2008. “

Many people living in the United States may not feel the impact of melting polar caps yet, but other climate changes due to global temperature increases may be more noticeable, such as  “shorter duration of ice on lakes and rivers, reduced glacier extent, earlier melting of snowpack, reduced lake levels due to increased evaporation, lengthening of the growing season, changes in plant hardiness zones, increased humidity, rising ocean temperatures, rising sea level, and changes in some types of extreme weather.”

Increased temperatures lead to a host of changes in different regions of the country.

The climate assessment explains, “A longer growing season provides a longer period for plant growth and productivity and can slow the increase in atmospheric CO2 concentrations through increased CO2 uptake by living things and their environment.”

This longer growing season can increase the growth of beneficial and undesirable plants. 

“In some cases where moisture is limited, the greater evaporation and loss of moisture through plant transpiration (release of water from plant leaves) associated with a longer growing season can mean less productivity because of increased drying and earlier and longer fire seasons,” the assessment reports.

For the Northwestern region of the U.S., the report indicates that the “lengthening of the frost-free season has been somewhat greater in the western U.S. than the eastern U.S., increasing by 2 to 3 weeks in the Northwest and Southwest, 1 to 2 weeks in the Midwest, Great Plains, and Northeast, and slightly less than 1 week in the Southeast. These differences mirror the overall trend of more warming in the north and west and less warming in the Southeast.”

According to the assessment, Natural factors affect the planet’s climate, but since “the beginning of the Industrial Revolution, humans have been increasingly affecting the global climate.”

“The majority of the warming at the global scale over the past 50 years can only be explained by the effects of human influences, especially the emissions from burning fossil fuels (coal, oil, and natural gas) and from deforestation,” the report states.

Trump’s response to the report was to say, ”It’s fine,” and that he didn’t believe in the extreme projections of the report.

Graphic caption: Global annual average temperature (as measured over both land and oceans) has increased by more than 1.5°F (0.8°C) since 1880 (through 2012). Red bars show temperatures above the long-term average, and blue bars indicate temperatures below the long-term average. The black line shows atmospheric carbon dioxide (CO2) concentration in parts per million (ppm). While there is a clear long-term global warming trend, some years do not show a temperature increase relative to the previous year, and some years show greater changes than others. These year-to-year fluctuations in temperature are due to natural processes, such as the effects of El Niños, La Niñas, and volcanic eruptions. (Figure source: updated from Karl et al. 2009). nca2014.globalchange.org