As La Niña runs its course and continues to prevent global temperatures from reaching new record highs, there is still much to report about global warming and its effects on the atmosphere and ocean — some good, but mostly bad.
January Global Temperatures Continue To Show Moderation From El Niño Highs
NOAA’s Global Climate Report for January 2018 shows it to be the fifth warmest January on record. New records for warmest January were set in New Zealand, southeastern Australia, the waters between these two countries, a swath from northern Australia through Indonesia and into the Pacific Ocean, the southwest US extending into Baja California, the Atlantic Ocean near Portugal, and much of France and adjacent Italy and Germany.
There were no record cold land areas and just one small record-cold patch of ocean in the south Pacific.
Sea Level Rising At Increasing Rate
Polar ice caps are shrinking at an alarming rate. According to a conservative estimate in Peter Wadhams’s book A Farewell to Ice and my back-of-an-envelope calculation, the volume of ice that disappears annually from Greenland is enough to provide 5 one-inch ice cubes for a hundred trillion scotch-and-sodas. A sobering thought.
Until recently, the best assumption was that the ice melts at a constant rate and the oceans rise accordingly. But a new NASA study finds that sea level rise has accelerated in recent years: The rise in the 2010s is 30% greater than that of the 1980s. The resulting calculation of sea level rise by the year 2100 has now been revised upwards to 26 inches — more than double the previous estimate. And NASA believes this estimate is too low.
One odd effect of melting glaciers is the reverse of what one might expect: The greatest sea level rise will occur farthest from the melting glacier. Here’s why:
The glacier’s mass has a gravitational attraction. When the glacier melts and its water is distributed around the world, the attraction at the glacial source lessens, and the sea level actually falls in the vicinity of the ex-glacier. Most of the rise takes place in the low and mid-latitudes.
Arctic Ice At Record Low For The Time Of Year
Arctic ice extent, as measured by the Danish Meteorological Institute, was a record low for January and the trend is continuing this month. As a result, for the first time in winter, a liquid natural gas tanker traversed the Arctic Ocean without an icebreaker escort.
As we have discussed previously, the open ocean’s low albedo (ability to reflect sunlight) creates a positive feedback effect of melting sea ice that increases the warming. The result so far has been a rise in temperatures near the north pole nearly triple the global average.
However, opening the shipping route will have a negative feedback effect. Shorter shipping trips will use less fossil fuel, with a resulting reduction of carbon emissions. Less carbon dioxide pumped into the atmosphere, less global warming.
Wadhams and others believe that surface ice extent does not accurately measure the volume of ice because the ice thickness is rapidly decreasing. The Arctic is expected to be ice-free in summer by 2030, but the date could be moved up if current projections don’t adequately account for the decrease in ice thickness.
Antarctic Ice Reverses Course
Antarctic ice extent has been steady or increasing slightly for several decades — until 2017. The trend has suddenly reversed in the last two years and January 2018 saw the lowest ice extent ever recorded for that month in what could be an ominous development.
The Antarctic is less well-studied than the Arctic, but there is no reason to doubt the data. The puzzle of why Antarctic ice increased slightly prior to 2017 has been answered several ways.
The simplest is that the thickness has decreased, but wind flows have led to formation of more thin ice at the surface. If Antarctic ice begins to disappear at an increasing rate, sea level projections may have to be revised upwards again. Have another scotch-and-soda while there’s still plenty of ice.
Water Temperatures: Trend Continues
Decoded Science is keeping a careful eye on sea water temperatures, which could provide the first indication of significant climate change.
The overall pattern hasn’t changed much from last month: noticeable La Niña in the tropical Pacific; warm around 40° latitude in both hemispheres. La Niña is expected to wane by spring, possibly by the time of the next Climate Change Checkup. And if current forecasts are correct, there is a good chance of El Niño returning by fall, which would probably make the current period of temperature stability short-lived.
Next Climate Change Checkup will be published after the release of NOAA’s January global temperature analysis, normally around the 18th of the month. NOAA no longer announces the date of release of this report in advance.
Next Weather Around The World will be published on March 6.