September Global Land And Sea Temperatures: Hottest Month Yet; Warming Accelerates

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Home / September Global Land And Sea Temperatures: Hottest Month Yet; Warming Accelerates
2015 is easily on a pace to be the hottest year since meteorologists began keeping records. Graphic courtesy of NOAA.

2015 is easily on a pace to be the hottest year since meteorologists began keeping records. Graphic courtesy of NOAA.

NOAA’s National Centers for Environmental Information issued its ‘Global Analysis — September 2015′ report on land and sea temperatures on October 21, 2015.

It was not a shock that the September temperatures were records for the month and that year-to-date figures match the increase.

But the amount of the increase in September temperatures was alarming — a new record departure from average for any month since record-keeping began in 1880.

This will be the next to last monthly report before conferees meet in Paris for the UN-sponsored summit on global warming.

If October is as worrisome as September, it will put added pressure on the conferees to come up with ways to stem the tide — literally and figuratively.

September, 2015 By The Numbers

The average temperature in September over land and sea was 15.9 degrees Celsius (C) or 60.62 degrees Fahrenheit (F). This is a departure of 0.90 C (1.62 F) from the 20th century average.

It is the largest departure of any month in the 1,629-month record.

The new record beat last year’s record September temperature by 0.12 C (0.22 F). This was the fifth consecutive month with a new land and sea record.

Global average sea temperatures, spurred by El Niño, averaged 17.01 C (62.56 F). This was a departure from the 20th century average of 0.81 C (1.46 F). The temperature was 0.25 C (0.45 F) warmer than in 1998, the year of the last comparable El Niño.

Where Was It Hot? And Where Was It Not?

The temperature percentiles for September show record warmth over large areas. Analysis courtesy of NOAA.

The temperature percentiles for September show record warmth over large areas. Analysis courtesy of NOAA.

As the NOAA report notes, “Large regions of Earth’s land surfaces were much warmer than average…” This was also true of ocean surfaces. However, global warming is not spread evenly over the surface of the earth on either a monthly or long-term basis. Some of the notable departures from normal for September were:

  • Much of the tropical Indian Ocean was record warm.
  • Most of the subtropical North Atlantic Ocean was record warm.
  • The subtropical North Pacific Ocean from the coast of Mexico to Hawaii was record warm.
  • The northeast Atlantic south of Iceland was much colder than normal, but not a record as it was last month.
  • The northern half of South America was record warm, but the extreme southern tip of the continent was record cold.
  • Northeast Africa and the Middle East were record warm.
  • The United States had its second warmest September. Nine states recorded their highest September temperature, including some in the northeast. This is a departure from previous months, which featured a dip in the jet stream over eastern North America and correspondingly cool temperatures in the eastern part of the US.
  • After a hot summer, western Europe had a slightly cooler than average September.
  • Northern China and south-central Russia had a much colder than normal September, but not a record..

How Do We Measure The Rate Of Increase Of Temperature?

Decoded Science has consistently pointed out that statistics are slippery things. The data leave no question about the trend of temperature. But the a proper interpretation of the trend is not so simple. It is natural to extrapolate linearly, but nature does not always act in a linear way. For example, the temperature change from 6 am to noon could not be successfully extrapolated in any meaningful way to predict the temperature at midnight. On a scale of years, though, temperature changes tend to be close to linear. The following are linear extrapolations starting with various years:

  • Since 1880, temperatures worldwide have risen at a rate of 0.6 C (1.1 F) per century.
  • Since 1915, the rate has been 0.91 C (1.64 F).
  • Since 1965, the rate has been 1.9 C (3.42 F).
  • Since 1990, the rate has been 2.36 C (4.25 F).
  • Since 2005, the rate has been 2.1 C (3.78 F).
  • Since 2010, the rate has been 3.3 C (5.94 F).
  • Since 2014,the rate has been 11 C (19.8 F).

You read that last one right.

If we extrapolate the increase in September temperatures in the last year averaged over land and sea, in 100 years, September will be almost 20 degrees Fahrenheit hotter. Get your offer in now for a plot of land in northern Canada.

Now you might think I cherry-picked the starting dates to make the point that in general the rate of increase is increasing. Actually, there’s a randomness to the dates: Except for the first one, which is when the record starts, I used dates that would give me a time period that is a factor of 100. That made my calculation easier (I’m running out of envelopes).

To find a time period from which a linear extrapolation might be more useful, 1998 is probably the best place to start. That was the year of the last comparable El Niño. From 1998 to 2015, the September global temperature increased at a rate of 2.24 C (4.02 F) per century. To put it euphemistically, this rate of increase would create significant inconveniences.

The graph of temperature departures from the long-term averages for January through September make it clear that global warming is accelerating. Graphic courtesy of  NOAA.

The graph of temperature departures from the long-term averages for January through September make it clear that global warming is accelerating. Graphic courtesy of NOAA.

Temperatures Year-To-Date

A single month can have, as we have seen, significant departures from the averages.

The first nine months of the year is a better barometer of what’s happening. The first nine months of 2015 were not only the warmest on record for global land and sea temperatures, it was the warmest in both northern and southern hemispheres and land and sea separately in each hemisphere.

2015 is clearly on pace to be the warmest year by a wide margin. These data make it obvious that global warming is accelerating at a pace that is incompatible with comfortable human existence on planet Earth just a few centuries, perhaps only decades, from now.

What Happens Now?

The twenty-first yearly session of the Conference of the Parties to the 1992 United Nations Framework Convention on Climate Change (UNFCCC) and the eleventh session of the Meeting of the Parties to the 1997 Kyoto Protocol — the title mercifully shortened to COP 21 — will convene in Paris on November 30, 2015.

It is painfully obvious that in 23 years nothing much has happened except more uneventful meetings of the parties. This time could be different. There is some sense of urgency among politicians and heads of state. Whether this sense of urgency can be converted into binding action, given the fact that developed countries want to keep their lavish lifestyles and undeveloped countries want to attain those lifestyles, is still doubtful. But there are hopeful signs.

The United States and China recently came to a bilateral agreement on emissions of greenhouse gases. At least the two largest polluters are pledging some reductions, though no one believes they are enough. Clearly the large carbon-emitters need to take the lead, and this agreement is a small step in the right direction.

In another development, Apple, Inc. announced it is building solar plants to supply the power for manufacture of its products. Skeptics say the company is just responding to complaints about its carbon footprint and the solar plants are mostly for publicity. But so what?

The entrepreneurial vitality that created the comfortable lifestyles of advanced countries also has been a primary cause of many environmental problems. That same vitality has also mitigated or solved many of the problems, such as depletion of the ozone layer by chlorofluorocarbons.

Politicians also respond to public pressure. Will there be enough for them to come to binding agreements at COP21, or will they kick the can to the next meeting of the parties?

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