There’s a good chance that 2010 will be the warmest year in the global surface temperature record. So I figured it’s worth keeping an eye on global temperatures this year. I’ll be posting regular updates on this page.
Global temperatures are usually given as anomalies relative to an average because they are easier and more useful to compare than absolute temperatures. Currently the warmest year on record is 2005 (0.62°C above the 20th century average), followed by 1998 (0.60°C). 2009 came in at sixth warmest (0.56°C), the years 2001-2009 all make the top ten, and the top 14 have all occurred since 1995. The 2000s was the warmest decade (0.54°C), followed by the 1990s (0.36°C) and 1980s (0.20°C). The Earth has warmed about 0.18°C/decade in the last quarter-century.
There are four main surface temperature records: the 130-year records of NOAA’s National Climatic Data Center (NCDC) and NASA’s Goddard Institute for Space Studies (GISS), the 160-year record of the University of East Anglia’s Climatic Research Unit (CRU), and the lesser-known 119-year record of the Japan Meteorological Agency (JMA). All temperature statistics cited on this page, unless otherwise stated, I have taken from the NCDC record.
Disclaimer: One year isn’t really important.
Surface temperatures vary from year to year as heat moves between the atmosphere and the oceans (which have a much higher heat capacity). Despite short-term fluctuations due to internal variability, in the long run it’s the overall energy budget, the amount of heat entering and leaving the entire climate system, that counts. (More about this in Part 2 of my series on global warming contrarian arguments.)
So a couple of relatively cool years following a few relatively warm years may signify nothing more than regression to the mean. When trying to discern long-term climatic trends, it is more useful to look at moving averages than at single years. Despite all this, it is still interesting to watch global temperatures, especially in a year that’s expected to be a record-breaker.
The updates below are listed in reverse chronological order.
24 January 2011
My final end-of-year wrapup is here.
24 October 2010
See here for the latest update.
18 July 2010 (a condensed version of this post)
The Earth has just experienced its warmest June on record, 0.68°C warmer than the 20th-century June average of 15.5°C. Most of the globe was warmer than usual, with the highest temperature anomalies seen in eastern and western Asia, eastern North America, western South America, and most of the Atlantic Ocean. The only surface temperatures much cooler than average were in the eastern Pacific and Southern Oceans. The warmest June is particularly notable in that it follows the warmest March, April, and May.
The last four months have not only each been the warmest for their respective month, but all these months were also among the top 20 monthly anomalies of all time. (Currently March is third, April is sixth, May is 16th, and June is 15th.)
Global temperature has remained relatively high despite the recent end of El Niño. As the eastern Pacific continues to cool, La Niña conditions are expected to develop during the southern winter (which, incidentally, would mean wetter weather in Australia). It will be interesting to see if this causes a dramatic drop in global temperature.
In a previous post I compared the record-warm beginning of 2010 to the then-record-warm beginning of 2007 — in the case of 2007, the onset of La Niña caused the Earth to cool rapidly, and I thought this might be an analogue for the current situation. However, comparing the global temperature anomalies for the first half of each year, already we see that this year is already running considerably hotter (0.68°C for January-June 2010 versus 0.60°C for 2007).
Also, the 12-month mean global temperature continues to climb. July 2009 – June 2010 was the third warmest 12-month period in the NCDC record, at 0.63°C above the annual average 13.9°C. The two warmest are the 12-month periods ending in August 1998 and September 1998 (0.64°C and 0.63°C respectively). For July 2010 to break that record, the global monthly anomaly would have to be greater than 0.66°C.
All these numbers come from NCDC, so keep in mind that there are slight differences with other global temperature records such as the one maintained by GISS. Probably the most notable difference for 2010 is that according to GISS, the 12-month mean record has already been broken. But for the sake of consistency I’ll continue to report the NCDC results in future updates.
24 June 2010 (a condensed version of this post)
Although this year’s El Niño has now come to an end, May 2010 was still the warmest May (and 13th warmest month), at 0.69°C above the average 14.8°C. Unusually warm temperatures were seen in eastern Europe, Siberia, eastern North America, and large parts of Africa; meanwhile, the Southern Ocean cooled.
The Earth has just experienced its warmest March, April, and May on record. The year-to-date (January-May) has been the warmest such period on record, at 0.68°C above average. So will 2010 break the record for the warmest January-December period? It’s still too early to tell, as we’re not even halfway through the year yet.
The last 12 months (June-May) were the sixth warmest 12-month period on record with a mean temperature anomaly of 0.62°C. The current record is 0.64°C, held by August 1998. However, the 12-month mean should continue to climb in the coming months…
In summary, this year is breaking all the temperature records, and it might just break the biggest one of all: the Earth’s warmest year on record.
19 May 2010
The global temperature for this April was 0.76°C above average. Similarly to this March, it’s both the warmest April on record and one of the warmest months of all time (the fifth highest global temperature anomaly after February 1998, January 2007, March 2010, and February 2002).
Temperatures were particularly warm in North America, northern Africa, Europe, Russia, India, and the equatorial Atlantic; but cooler than average in China. Also, several records were broken in Australia: May 2009-April 2010 was the warmest 12-month period on record in the states of Victoria and Tasmania, and the third warmest for Australia overall.
The year-to-date has been 0.69°C above average, but it’s worth keeping in mind that there are still two-thirds of the year to go. For instance, the opening months of 2007 also saw record-breaking warmth during an El Niño, but later in the year the Earth’s surface cooled rapidly as the Pacific shifted to a La Niña phase.
5 May 2010
El Niño now appears to be over. During April, the Southern Oscillation Index (SOI) flipped from a negative value (El Niño phase) to a positive one (La Niña). Currently models are projecting neutral conditions for the southern winter. However, global temperature tends to lag ENSO by about four months, so we may yet see a record-breaking year.
17 April 2010
The recent volcanic eruption in Iceland is not expected to affect global temperature as the ash did not rise high enough to get into the stratosphere.
16 April 2010
19 March 2010
NCDC have just updated their temperature data to include February 2010. It turns out the Southern Hemisphere just had its warmest February on record, 0.63°C above the 20th century average. However, there were again unusually low temperatures in northern land areas, particularly the US, Europe, and Russia. Although unfortunately this happened to be where the weather most affects public opinion, it did not stop the global temperature being 0.60°C above average, the sixth warmest on record. January 2010, also 0.60°C above average, was fourth warmest. Thus the year to date is actually shaping up to be a relatively warm one.
9 March 2010
The Arctic Oscillation has again returned to neutral.
16 February 2010
The Arctic Oscillation, after returning to a neutral phase in mid-January, is strongly negative again in mid-February – so expect more reports of cold weather in the Northern Hemisphere!
13 February 2010
By definition, global climate is climate averaged out over the entire Earth. Global warming means that the average global surface temperature is rising. Nevertheless, whenever a particular region experiences a cold snap (incidentally, I wrote the first draft of this sentence on a relatively cold day), contrarians are quick to point to this as evidence against global warming. Recently they have been pointing to a cold spell in parts of North America and Eurasia. However, most of them fail to mention that this is part of the Arctic Oscillation (AO), which as of December was in a strong negative phase not seen for decades, moving heat to Arctic regions.
Expectations as of early 2010
Greenhouse gas levels are increasing every year, so in the long run the planet should be getting warmer. But on this timescale, greenhouse gases are not the only influence on climate. The global energy imbalance varies periodically with the 11-year solar cycle, and right now solar activity is coming out of its lowest minimum for decades.
Another cause of short-term climatic variation is the El Niño Southern Oscillation (ENSO). 1998 was exceptionally warm due to an exceptionally strong El Niño phase. Conversely, the rapid cooling from January 2007 to January 2008 was probably due to a strong La Niña phase. Interestingly, GISS scientists have speculated that the current El Niño, expected to continue during early 2010 (before returning to a neutral phase in the southern winter), may set a new global temperature record. The UK’s Met Office agrees, and their “experimental” decadal forecast predicts that about half of the years in the coming decade will be warmer than 1998.