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The Second Warmest Year Ever

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2017 was the 2nd warmest year on record globally, and the 3rd warmest for the contiguous USA.


Figure 1. Data source: NOAA, Climate-at-a-Glance.

Figure 1 shows the average annual temperature for the Earth from 1880-2017. The chart shows the temperature as an anomaly. That means that they calculated the mean annual temperature for the whole series, and then presented the data as a deviation from that mean. Degrees Celsius are on the left vertical axis, and degrees Fahrenheit are on the right. Because the earth contains very hot regions near the equator and very cold polar regions, the actual mean temperature has relatively little meaning, and Climate-at-a Glance does not include it in their chart. (Except where noted, all data is from NOAA, Climate at a Glance.) 2016 was the highest on record, but 2017 was second. The 4 highest readings have all occurred within the last 4 years. You can see that the Earth appears to have been in a cooling trend until around 1910, then a warming trend until mid-Century, then a cooling period until the late 1960s or early 1970s, and then a warming period since 1970. Over the whole series, the warming trend has been 0.07°C per decade, which equals 0.13°F per decade. Since 1970, however, the warming has accelerated to 0.18°C per decade (0.32°F).

(Click on chart for larger view.)

Figure 2. Data source: NOAA, Climate-at-a-Glance.

Figure 2 shows the average yearly temperature for the contiguous United States from 1895 to 2017. In this chart and those that follow, the vertical axes are reversed, with °F on the left vertical axis, and °C on the right. The purple line shows the data, and the blue line shows the trend. 2017 was the 3rd highest in the record at 54.58°F. The 4 highest readings have all come within the last 6 years. Over time, the average temperature has increased 0.15°F per decade. Since 1970, however, the rate has increased to 0.52°F per decade.

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Figure 3. Data source: NOAA, Climate-at-a-Glance.

Figure 3 shows the average temperature across Missouri for 2017. Across the state, it was the 8th warmest year on record, with an average temperature of 57.1°F. In Missouri, the warming trend from 1930-1950 was more moderate than it was nationally, and the trend has been for a 0.1°F increase in temperature each decade. Since 1970, however, the increase has accelerated to 0.4°F per decade.

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Figure 4. Data source: NOAA, Climate-at-a-Glance.

Because conditions in the Northern Rockies and Plains affect how much water flows into the Missouri River, which provides more of Missouri’s water supply than any other source, I have also tracked climate statistics for that region. Figure 4 shows the data. Last year was the 11th warmest in the record at 44.9°F. This region has been warming at a rate of 0.2°F per decade over the whole period, but since 1970, the rate has accelerated to 0.5°F per decade.

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Figure 5. Data source: NOAA, Climate-at-a-Glance.

Because I have been concerned about the water supply in California, I also track the climate statistics for that state. Figure 5 shows the data. Last year was the third warmest year in the record, with an average temperature of 60.3°F. California has been warming at a rate of 0.2°F each decade. Since 1970 the rate of increase has accelerated to 0.5°F per decade.

In all 4 locations the average yearly temperature seems to have increased significantly for several decades, then paused during mid-Century, and then resumed climbing, but at an accelerated rate. There seems to be little doubt that across the country it is warmer than it was. In Missouri, the average yearly temperature has been increasing, but at a rate that is somewhat less than in the other locations I looked at.

Sources:

NOAA National Centers for Environmental information, Climate at a Glance: U.S. Time Series, published January 2018, retrieved on January 15, 2018 from http://www.ncdc.noaa.gov/cag.


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