According to NOAA, 2017 was the third warmest year in 137 years of accurate records, and December was the fourth warmest equivalent month, despite the cooling effect of La Niña.
But let’s start this month’s discussion of global warming and climate change with some definitions.
Global Warming And Climate Change: What’s The Difference?
A reader asked me the above question in a comment on last month’s Climate Change Checkup.
Global warming is simply an increase in temperature averaged over the land and ocean surfaces of the earth. It is generally used in reference to the warming since the industrial revolution, and is, by all credible scientific analyses, most likely caused by the carbon dioxide released when human beings burn fossil fuels. This carbon dioxide traps heat in the atmosphere by absorbing the earth’s infrared radiation while allowing the sun’s radiation, primarily in the visible range, to pass through. It is observed to be about 1 C (1.8 F) in the last century.
Climate change refers to changes in temperature, precipitation, wind, humidity, cloud cover, and other variables over an extended period of time. The terms have been used, even by Decoded Science, somewhat interchangeably. We will try to be more accurate in the future.
What’s The Connection?
The simplest correlation between global warming and climate change, and the one that would be tried first as an assumption, is that everything would move linearly: temperature would increase, in the current case for example, by one degree Celsius everywhere and the resulting climate change would be to basically move everything a little bit poleward.
If the temperature were to change just marginally (one or two, or even three degrees Celsius) around the globe, global warming could be assimilated by human populations with minimal disruptions. But we know, as covered in last month’s Climate Change Checkup, that this assumption of the same linear change everywhere is not correct; the arctic is warming much faster than other parts of the planet. The great danger is that the changes in climate will be neither gradual nor predictable. We may be seeing a possible example in California.
In the last four years, California has had record drought, followed by record rain, followed by drought again, and most recently more heavy rain. This results in a pattern of dry vegetation leading to fires, followed by mudslides on the denuded hills, followed by lush growth, followed by drying out, etc. This could all take place with average temperatures and rainfall staying nearly normal over time. Recognizing the dangerous effects of global warming on climate will be a tricky statistical undertaking.
Decoded Science will pay careful attention to departures of any meteorological quantity from normal over any time period of more than a few months. Consistent departures of any kind could indicate significant climate change as global warming begins to have global impacts.
Water covers approximately 70% of the earth’s surface, and ocean currents have a significant effect on climate. For example, the Gulf Stream, which is a warm water river that crosses the Atlantic, keeps Europe relatively warm.
Decoded Science has been watching sea surface temperatures (SST), and there is something significant to report.
Look at the accompanying chart of current SST. A striking feature is the clustering of warmer than average temperatures near 40 degrees latitude in every ocean in both hemispheres. This anomaly has persisted for many months, but it will take years of data to establish a reliable statistical anomaly, and then a final judgment that something significant is happening on a long-term basis will await a physical explanation. So for now ….. just sayin’.
While we’re looking at the SST chart, it’s worth noting that the obvious La Niña along the equator in the Pacific is rather weak compared to the one that followed the 1998 El Niño. Many models forecast a return to El Niño by fall, and this could lead to another upward surge in global temperatures.
2017 Weather Disasters Costliest Ever By Far
Natural disasters in the US cost $306 billion in 2017, blowing (and burning) away the 2005 record by 42%. Hurricane Harvey was the second costliest storm ever (remember Katrina?) at $125 billion, and Maria was third at $90 billion.
Western wildfires, an annual summer and fall occurrence but this year exacerbated by drought and heat, racked up $18 billion in damages, triple the previous record.
The increase in weather disasters has been linked to slower-moving weather systems that create drought and excessive rain. There is strong statistical and physical evidence that the slowdown in the movement of weather systems is a result of global warming, probably connected to the excessive warming in the arctic.
Why Can’t She Find A Date?
Genetics determines the gender of most animal species. But that’s not the case with Green Sea Turtles. Their sex is determined by the temperature of the developing egg — with 85 degrees F the critical value. A couple of degrees lower and the turtles are all males; above, all females. Recent research shows that global warming is leading to many more females than males being hatched, possibly threatening the survival of the species.
December And Full Year 2017 Temperatures
The lull after the surge in temperatures initiated by the recent El Niño continued in December, which came in fourth warmest behind the previous three Decembers. The full year temperature was third warmest behind 2016 and 2015. Most of the new December warm records were set in the oceans — western North Pacific, western South Pacific, southern Indian, and eastern North Atlantic. The only significant land areas with new records were Alaska and southern China.
There were no new cold records in December; in fact, only a couple of spots were much cooler than average. However, the effect of the modest La Niña can be seen, particularly in the southern hemisphere, where the ocean temperature was only 14th warmest.
Next Climate Change Checkup: after the mid-February release of NOAA’s January data.
Next Weather Around The World: February Sixth.