According to both the National Oceanic and Atmospheric Administration and the National Aeronautics and Space Administration, 2016 was the warmest year globally in 137 years of record keeping and the second warmest for the United States.
When it became apparent that last winter’s El Nino was going to be a huge event, a large spike in global warmth was expected and fully realized.
The last El Nino of such a magnitude was in 1997-1998, which also created a spike that set new global records. The rate of warming on land and in the air after that El Nino slowed, but it didn’t stop.
What is of concern is how much warmer the 2016 global readings were than the 1998 readings. The world’s oceans have been absorbing much of the heat and excess carbon to no good end. Despite that absorption, the global average this past year was 0.5 degrees warmer than during the 1998 spike.
In other words, warming has continued globally since the 1998 spike as a background behind and beyond the record 2016 spike. The rate of warming was slower after last spring through the remainder of the year after El Nino dissipated, exactly as expected.
As I’ve written in earlier articles, it’s highly likely that 2017 will be cooler than 2016 precisely because of the 2016 spike. But 2017 will still be close to recent record years prior to 2016. Here is an overview from NOAA. I’ve chosen NOAA data over NASA just to be "conservative." NASA uses different technologies to map global temperatures and their numbers are higher than NOAA’s. It’s not that I don’t trust NASA’s number, I just chose to use the lower numbers so no one would think I’m loading the dice:
This data has been scrutinized and screened carefully to remove any urban heat biases and other sources of potential contamination. Most climate scientists, physicists, and oceanographers believe anything beyond a 2-degree increase in the global average will have rapidly accelerating negative impacts, including dangerous coastal flooding from rising sea levels. Most of these impacts can be readily calculated using well-understood laws of physics. Even now, Miami has seen a marked increase in tidal flooding in recent years. These sea level increases, when added to storm surge from coastal storms and hurricanes, have already caused major problems, including the impact from Sandy on New York City’s major flooding. Having mentioned the hoped-for ceiling of a still-dangerous 2-degree increase (which would require a concerted effort on the part of all nations to reduce greenhouse emissions), we are already getting close to 1.5 degrees over the 1881-1910 baseline while we’re still early in this century.
Keeping in mind the long shelf life of CO2 in the atmosphere, there is nothing that can be done to magically turn off global warming. However, there are a few possible impacts that may interrupt warming on a regional scale. The most prominent of these possibilities is a weakening of the Atlantic Ocean conveyor current that drives the Gulf Stream. Water with higher salinity has greater density and sinks to the ocean floor. In this great Atlantic circulation, these cold, salty waters flow from the North Atlantic to the warm southern latitudes, forcing upwelling of warmer waters that contribute to the warm Gulf Stream. The warmth provided by this circulation is what makes northwest Europe more habitable, including Great Britain. Edinburgh and Glasgow, Scotland, are slightly north of Moscow. Cambridge, England, is north of Saskatoon, Canada. Get the picture? Without the warmth provided by the Gulf Stream, northwest Europe would be much colder than it is.
However, thanks to melting of freshwater ice, the water in the north Atlantic -- the saltiest ocean -- is becoming less salty. Without this added density, two recent papers offer evidence this conveyor is already slowing down. The dilution of the salinity is related mostly to the Greenland freshwater ice cap’s rapid rate of melt. There is good evidence that rapid shutdowns of this conveyor current have occurred in the earth’s past during periods of natural warming when salinity decreased to a certain threshold. So it is possible in the next century that threshold could again be reached. If that were to happen, there could be regional cooling in northwest Europe, the Canadian Maritime provinces, and parts of the mid-Atlantic in the midst of global warming. I’ll write more on this complex topic in a future article.