According to data released by NASA and NOAA this week, 2012 was the 9th or 10th warmest year (respectively) globally on record. NASA’s analysis produced the 9th warmest year in its dataset; NOAA recorded the 10th warmest year in its dataset. The two agencies have slightly different analysis techniques, which in this case resulted in not only different temperature anomaly values but somewhat different rankings as well.
2012’s global average temperature was +0.56°C (1°F) warmer than the 1951-1980 base period average (1951-1980), according to NASA, as the following graphic shows. The warmest regions on Earth (by anomaly) were the Arctic and central North America. The fall months have a +0.68°C temperature anomaly, which was the highest three-month anomaly in 2012 due to the absence of La Niña. In contrast, Dec-Jan-Feb produced the lowest temperature anomaly of the year because of the preceding La Niña, which was moderate in strength. And the latest 12-month period (Nov 2011 – Oct 2012) had a +0.53°C temperature anomaly. This anomaly is likely to grow larger in the first part of 2013 as the early months of 2012 (influenced by La Niña) slide off. The time series graph in the lower-right quadrant shows NASA’s 12-month running mean temperature index. The recent downturn (2010 to 2012) shows the effect of the latest La Niña event (see below for more) that ended in early 2012. During the summer of 2012, ENSO conditions returned to a neutral state. Therefore, the temperature trace (12-mo running mean) should track upward again as we proceed through 2013.
Figure 1. Global mean surface temperature anomaly maps and 12-month running mean time series through December 2012 from NASA.
According to NOAA, 2012’s global average temperatures were 0.57°C (1.03°F) above the 20th century mean of 13.9°C (57.0°F). NOAA’s global temperature anomaly map for 2012 (duplicated below) reinforces the message: high latitudes continue to warm at a faster rate than the mid- or low-latitudes.
Figure 2. Global temperature anomaly map for 2012 from NOAA.
The two different analyses’ importance is also shown by the preceding two figures. Despite differences in specific global temperature anomalies, both analyses picked up on the same temperature patterns and their relative strength.
The continued anomalous warmth over Siberia is especially worrisome due to the vast methane reserves locked into the tundra and under the seabed near the region. Methane is a stronger greenhouse gas than carbon dioxide over short time-frames (<100y),which is the leading cause of the warmth we’re now witnessing. As I discussed in the comments in post this summer, the warming signal from methane likely hasn’t been captured yet since the yearly natural variability and the CO2-caused warming signals are much stronger. It is likely that we will not detect the methane signal for many more years.
These observations are also worrisome for the following reason: the globe came out of a moderate La Niña event in the first half of the year. During the second half of the year, we remained in a ENSO-neutral state (neither El Niño nor La Niña):
As the second time series graph (labeled NINO3.4) shows, the last La Niña event hit its highest (most negative) magnitude more than once between November 2011 and February 2012. Since then, SSTs peaked at +0.8 in September (y-axis). You can see the effect on global temperatures that the last La Niña had via this NASA time series. Both the sea surface temperature and land surface temperature time series decreased from 2010 (when the globe reached record warmth) to 2012. So the globe’s temperatures were affected by a natural, low-frequency climate oscillation during the past couple of years. And yet temperatures were still in the top-10 warmest for a calendar year in recorded history.
Indeed, this was the warmest La Niña year on record:
Figure 4. Anomalies of annual global temperature as measured by NOAA. Blue bars represent La Niña years, red bars represent El Niño years, and gray bars represent ENSO-neutral years.
This figure shows that 2012 edged out 2011 as the warmest La Niña year on record (since 1950). It also shows a clear trend seen in every temperature record of this length: La Niña years are getting warmer with time (note the difference between 2012 and 1956, for instance). El Niño years are getting warmer with time (note the difference between 2010 and 1958). ENSO-neutral years are getting warmer with time. The globe got warmer throughout the 20th and into the 21st century. Do not pay too much attention to any single year as “evidence” that global warming stopped. As I stated above, natural low-frequency climate oscillations introduce a lot of noise into the temperature signal. Climate is measured over decades and the decadal trend is obvious here: warmer with time.
Skeptics have pointed out that warming has “stopped” or “slowed considerably” in recent years, which they hope will introduce confusion to the public on this topic. What is likely going on is quite different: if an energy imbalance exists (less outgoing energy than incoming) and the surface temperature rise has seemingly stalled, the excess energy has to be going somewhere. That somewhere is likely to be the oceans, and specifically the deep ocean. Before we all cheer about this (since few people want surface temperatures to continue to rise quickly), consider the implications. If you add heat to a material, it expands. The ocean is no different; sea-levels are rising because of heat added to it in the past. The heat that has entered in recent years won’t manifest as sea-level rise for some time, but it will happen. Moreover, when the heated ocean comes back up to the surface, that heat will then be released to the atmosphere, which will raise surface temperatures as well as additional water vapor. Thus, the immediate warming might have slowed down, but we have locked in future warming.
In my previous post on global temperatures, I pointed a few things out and asked some questions. The Conference of Parties summit produced no meaningful climate action. Countries agreed to have something on paper by 2015 and enacted by 2020. If everything goes as planned, significant carbon reductions wouldn’t occur until later in the 2020s – too late to ensure <2°C warming by 2100. If, as is much more likely, everything doesn’t go as planned, reductions wouldn’t occur until later than the 2020s. Additional meetings are scheduled for later this year, but I maintain my expectation that nothing meaningful will come from them. The international process is ill-equipped to handle all the legitimate interest groups in one fell swoop.
The northeast continues to recover from Superstorm Sandy. New York and New Jersey began to plan for infrastructure with increased resilience from the next storm, which will eventually hit the area. Congress took way too long to approve relief money (months, instead of days as it did after Katrina). $60 billion will go a long ways toward assisting the region, especially if people take seriously the threat of living next to the ocean, which has been uncharacteristically quiet for decades.
Paying for recovery is and always will be more expensive than paying to increase resilience from disasters. As drought continues to impact US agriculture, as Arctic ice continues to melt to new record lows, as storms come ashore and impacts communities that are not prepared for today’s high-risk events (due mostly to poor zoning and destruction of natural protections), economic costs will accumulate in this and in future decades. It is up to us how much grief we subject ourselves to. As President Obama begins his second term and climate change “will be a priority in his second term”, he tosses aside the tool most recommended by economists: a carbon tax. Every other policy tool will be less effective than a Pigouvian tax at minimizing the actions that cause future economic harm. It is up to the citizens of this country, and others, to take the lead on this topic. We have to demand common sense actions that will actually make a difference. But be forewarned: even if we take action today, we will still see more warmest La Niña years, more warmest El Niño years, more ENSO-neutral years.