The American Meteorological Society issued its annual report recently on the state of the climate for 2019. The report notes increases in Green House Gases (GHGs) as well as extreme warm days during 2019. A partial summary of the findings in the report includes the following:
“All major greenhouse gases released into Earth’s atmosphere reached new record high concentrations in 2019. The annual global average carbon dioxide concentration at Earth’s surface was 409.8 ± 0.1 ppm, an increase of 2.5 ± 0.1 ppm over 2018, and the highest in the modern instrumental record and in ice core records dating back 800,000 years. Greenhouse gases, along with several halogenated gases, have contributed to a 45% increase in net forcing compared to 1990.
Carbon dioxide is responsible for nearly two-thirds of this increase. A weak El Niño early in the year transitioned to ENSO-neutral conditions by mid-year, yet the annual global surface temperature across land and ocean surfaces was still among the three highest on record. July became the hottest month in records dating to the mid- to late-1800s. Each decade since 1980 is warmer than its preceding decade, with 2010–19being around 0.2°C warmer than 2000–09.In 2019, there were a record high number of extreme warm days (temperatures above the 90th percentile) over global land surfaces. There were also a low number of extreme cool days (temperatures below the 10th percentile) compared to the last 70 years, but there were more cool days compared to the average of just the past decade. A new indicator introduced this year to the report—marine heat waves—indicates that the number of strong marine heatwaves surpassed the number of more moderate marine heat waves for the sixth consecutive year.”
In addition, it is reported that the temperature of the oceans, along with sea levels have continued to rise and that “mean sea level set a new record for the eighth consecutive year, an increase of 6.1 mm from 2018. Record high ocean heat content measured to 700 m depth in 2019 contributed an estimated 4.5 mm of that rise. Since 2004, ocean heat content has been increasing at a rate exceeding 0.20°C per decade near the surface and at a lower but still increasing rate of less than 0.03°C decade in deeper waters below 300 m.”
Moreover, temperatures continued to rise in the Arctic with surface temperatures for 2019 being “… the second highest in the 120-year record, following 2016, with record high temperatures in Alaska and north-west Canada. Mean annual Arctic surface air temperatures over land have increased more than twice as fast as the global mean since the mid-1980s.” As a result of the increased surface temperatures ice melt continues to contribute to rising sea levels. “The Greenland ice sheet and the Arctic-wide mass loss from glaciers and ice caps outside of Greenland are estimated to contribute approximately 0.7 and 0.4 mm yr–1, respectively, to global sea level rise.” Likewise, the Antarctic continent maintained the second highest temperatures recorded since 1980, also contributing to ice melt. “In 2019, global mean sea level set a new record for the eighth consecutive year, an increase of 6.1 mm from 2018.”
While areas of the Northern Hemisphere, such as the United States were cooler on average in 2019, it appears the overall increase of GHGs in the atmosphere and sea level rise, due to ice melt, are trending as predicted by most scientists.