Long-term temperature trends for the US and North America

The start of the new year is a good time to check out the long-term temperature trends across the United States and North America.

The data below from NOAA was <a href="https://science2017.globalchange.gov/chapter/6/" target=n>released</a> in the latest National Climate Assessment.

<strong>Changes in US average temperature from the 1901-1960 period to the 1986-2016 period. </strong>

<img src="https://vortex.accuweather.com/adc2004/pub/includes/columns/climatewx/2018/590x419_01012048_screen-shot-2018-01-01-at-3.26.35-pm.png"/>

You can clearly see that the annual average temperature has warmed over 1 degree Fahrenheit for a large portion of the country. The exception is the Deep South and Mississippi Valley, especially during the summer months.

<strong>
Long-term (going back to 480 AD) pollen-based temperature reconstruction of North America.</strong>

<img src="https://vortex.accuweather.com/adc2004/pub/includes/columns/climatewx/2018/590x453_01012056_screen-shot-2018-01-01-at-3.28.36-pm.png"/>

Note the sharp increase in temperature starting around the industrial revolution.

<strong>The chart below shows years with more record-high temperatures and years with more record-low temperatures for the U.S. </strong>

<img src="https://vortex.accuweather.com/adc2004/pub/includes/columns/climatewx/2018/590x437_01012100_screen-shot-2018-01-01-at-3.29.33-pm.png"/>

Note the clear increase in years with more record highs vs. record low since the start of this century.
<strong>

Warming trend assessment. Is this natural or influenced by humans?</strong>

<img src="https://vortex.accuweather.com/adc2004/pub/includes/columns/climatewx/2018/590x229_01012105_screen-shot-2018-01-01-at-3.30.51-pm.png"/>

A large portion of the U.S. and southern Canada have a detectable human influenced temperature increase that is consistent with modeling. The exception is the southeastern U.S.

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