Will 2014 be the hottest year on record?

One commenter said today that any answer to this question other than "we need to wait and see" would be no better than the work of a "non-science charlatan". Well at the risk of being tarred and feathered, I'm going to make a prediction. This year will be recorded as the hottest since 1880.

Appropriately, the climate scientists I spoke to today avoided making a definitive prediction. But there was definitely a consensus among them that 2014 is shaping to be either very hot or the hottest.

This is the first time we have seen such high early year temperatures with an oncoming El Niño. The years 2010 and 1998 began right in the midst of an El Niño event. This saw elevated temperatures from January to June, then a tailing off as a La Nina established itself. The pattern this year is reversed. We are likely to see some degree of El Niño pushing temperatures up in the later months of this year. However we have already seen one of the hottest first six months on record. All temperatures need to do from here is maintain their departure from the average and I'll be proved right... which would be nice if it wasn't entirely meaningless.

My prediction should not be taken seriously. Firstly because it's a guess from a self-confessed non-scientist (I won't accept charlatan, sorry NeverMindTheBollocks). But also because these records and the data they are drawn from have large degrees of uncertainty. The best we can really say of any year is that it was among the hottest.

Further adding to the meaninglessness of this prediction is the inappropriate significance we place on records like this. A hot month, or year, is a tiny slice of data along a much greater timeline. When it comes to climate change, these records are nothing more than milestones along the road - they have no influence on the direction we are going, they simply remind us how far we have come.

Jessica Blunden is a climate scientist at the NOAA. "If we were to maintain the temperature departure from average that we have right now, 2014 would be the hottest year on record," she says. She agrees that El Niño events typically cause increased temperatures, therefore such an event could push the year into record breaking territory.

Blunden also responded to a couple of today's reader questions.

Reader Ed Sulesky sent in this email:

I know other regions have been hot (a friend in Perth, Australia was talking of temps in the 100s in Jan for example), so far here in the Minneapolis/St. Paul area we've hit 90 twice this summer which is unusual & we've had record rain fall & a lot of snow over the winter (with i think 58 days below 32º F).

This past Monday for example it was in the 90s with a heat index over 100, very sauna like. Last week Monday/Tuesday (July 14/15) we had highs in the upper 60s, generally we've been around 80 this summer.

"If you look at global temperatures, in June it was the record hottest," says Blunden. "There were also some regions that were record hottest. But a lot of that is due to weather patterns." She says that individual weather events, such as 90 degree days in Sulesky's hometown, on their own cannot be explained by climate change. "Every place on earth is going to experience climate change in a different way. There are going to be pockets that are hot or cold." But she says the frequency of warmer days will go up as global surface temperatures continue to rise.

Looking at the satellite record RSS

http://woodfortrees.org/plot/rss

which satellite record is in any case used for ocean surface temps

the answer so far is a resounding NO.
So far, as satellites show it, 2014 looks like it is continuing the trend of slight cooling.

If you add all kinds of things to the record, then the result depends on what you add/, of course.

Hadriano23 July 2014 12:45pm

Blunden says the satellite data measures a different part of the atmosphere to the NOAA readings. RSS and UAH readings measure temperatures in the lower and middle troposphere. She says that there is often a time lag between the readings at the surface and further up in the atmosphere. This could explain why June's readings from these sources are not as dramatic as NOAA's findings at the surface.

"Generally when you go up it takes a few months for the emerging El Niño to show up. For June the RSS and UAH said the lower troposhere was the fourth warmest on record."

As far as the commenters claim that the RSS results show a slight cooling trend, Blunden disagrees. Overall she says, the satellite data shows a warming trend.

John Kennedy, a senior climate monitoring and research scientist at the Met Office, says the only thing that can be said is that it's "possible 2014 will be the warmest" year on record.

Kennedy says:

"Our latest ranking diagram [below], which includes 2014 (to May) shows how the average for the year so far compares to the average for other whole years. The size of the coloured bars indicates the 95% uncertainty range on the estimates. You can see that the bar for 2014 is far wider than any other year. That's because we're not even half way through the year yet so we can't form an accurate estimate of the annual average.

"Another thing to note is that the coloured bars for whole years overlap (e.g. 2005 and 2010), which means that even when we have a whole years data, we can't unambiguously rank a year. Errors in the data will push the observed value away from the true average. Even if 2014 eventually is the warmest (in reality) it won't necessarily end up warmest in the observed data sets. Contrariwise, if 2014 isn't the warmest (in reality) but is close to it, it might end up the highest. Or some mix of the three.

"There are a number of different estimates of global temperature. NOAA NCDC produce their MLOST data set. NASA GISS produce GISTEMP. JMA produce an estimate. The HadCRUT4 data set, which is produced collaboratively by the Met Office Hadley Centre and the Climatic Research Unit at the University of East Anglia, has also been used to make estimates of global average temperature. Estimates from these datasets although similar in their long term and year to year variability, can differ quite markedly over short periods.

This difference in short term results is because of the different ways in which the various agencies make assumptions about temperatures in areas where they do not actually have weather stations. The particular example Kennedy gives is the Arctic where he says HadCRUT4 does not measure temperature. Because this area has warmed more quickly than other areas this may lead to inaccuracies. Possibly explaining why HadCRUT4 does not have this June as a record breaker.

This fog of uncertainty gives the impression that we can't say anything about temperatures, but that's not the case. Longer term changes are larger, relative to the uncertainties, than are the month to month and year to year variations that make headlines.

A number of other commentators have run similar stories to this one. With a consistently strong line from their sources telling them 2014 is on the right track to be the hottest since records began.

• Climate Central: “I agree that 2014 could well be the warmest on record, and/or 2015, depending on how things play out,” said Kevin Trenberth, a climate scientist with the National Center for Atmospheric Research in Boulder.
  
• Mother Jones: Penn State University's Michael Mann said "Global temperature variations can be thought of as waves on a rising tide. The rising tide is global warming, which has raised global temperatures nearly a degree C (1.5 F) over the past century. The waves are the shorter-term natural fluctuations related to phenomena like El Niño (or its flip-side, La Niña), which warm (or cool) the globe, respectively, by 0.1-0.2C."
  
• Washington Post: John Christy, a climate scientist at the University of Alabama, said “The long-term baseline temperature is about three tens of a degree (C) warmer than it was when the big El Niño of 1997-1998 began. With the baseline so much warmer, this upcoming El Niño won’t have very far to go to break that … record.”

Mark McCarthy, a climate scientist at the Met Office, is more cautious than some of his colleagues in making predictions for the rest of the year.

"It's a bit early to say," he says. "For the year so far, the US data says it's third [hottest after 2010 and 1998]. But both those years cooled off a bit because they developed a La Nina in the later half."

Records such as these can be passed off as slightly meaningless by many scientists, but McCarthy says the breaking of new ground, even month by month is "certainly of interest to science". Along with measurements taken throughout the atmosphere oceans and cryosphere, surface temperature is providing scientists with a detailed picture of the warming globe. The surface temperature data set is particularly significant because it dates back for 135 years. Climate science often refers to a 30 years period as the minimum that can be used to assess a trend and many records do not go back that far.

When it get's hot, what do you do? Paint your lawn apparently. Bizarre pictures from California from the Guardian's picture desk.

Results from NOAA show that the warmth in June emerged from the oceans. On land, June was only the 7th warmest June since 1880. But on the ocean it was the first and the ocean-based warming was significant enough to push it into first place overall.

Other highlights from the NOAA report:

• With the exception of February (21^st warmest), every month to date in 2014 has ranked among the four warmest for its respective month.
• June 2014 marked the 38^th consecutive June and 352^nd consecutive month with a global temperature above the 20^th century average.
• The warmth was fairly evenly distributed between the Northern and Southern Hemispheres, with the Northern Hemisphere land-surface temperature sixth highest on record and the Southern Hemisphere land-surface temperature fifth highest.

Japan's Meteorological Agency also publishes world temperature data. Its assessment for June was similar to the NOAA:

The monthly anomaly of the global average surface temperature in June 2014 (i.e., the combined average of the near-surface air temperature over land and the SST) was +0.32°C (the warmest since 1891).

There seems to be little doubt among scientists that this year is on course to become a record breaker (or as near as dammit).

"We can certainly begin to see the evidence piling up that [2014] will be about the hottest year ever," says Piers Forster, a professor of physical climate change at Leeds University. "The ocean surface temperatures are beginning to heat up considerably, consistent with El Nino."

"We are not very good at predicting El Niños," says Forster, but the most likely course of events over the coming six months will see a moderate El Niño. Although it is still possible that there could be a massive El Niño or none at all.

He says the warmer ocean surface temperatures recorded by NOAA are due in part to the El Niño-like behaviour of the Pacific Ocean. This has lead to warmer than average temperatures in that part of the sea. However he thinks the effect is compounded by the increased warming of oceans (often used to explain the so-called 'pause' in surface warming)."We've been putting extra warmth into the ocean over the last decade and perhaps a change in circulation means that it beginning to come back to the surface," he said, adding that this was speculation and would need more research to prove.

Chris Brierley, from University College London, agrees with Forster that this year is likely to break records.

"Each of the past 3 decades has been warmer globally than the one before. As we're causing greenhouse gas levels to increase further, I'd expect this decade to be warmer still. An El Niño makes a year warmer than the years surrounding it. Therefore, I'd expect this year to be one of the warmest of this decade and hence the whole record."

Matt Watson, senior lecturer in natural hazards at University of Bristol, also says that heat trapped in the ocean could be being released and this could push 2014 into the top spot.

“It seems pretty likely that 2014 will be one of the hottest for at least 100,000 years. It may even eclipse 1998 and become the hottest. The last two months were the warmest May and June in 134 years of direct measurements (as opposed to proxies used to go back further in time). This is, in part, due to the likely occurrence of El Nino this year, noting, of course, that the last strong El Nino event was in 1997/1998. Whilst the current prognosis for the forthcoming event is of a weak/moderate El Nino, this is still likely to cause a temporary warming that will push 2014 into top spot, not least as climate scientists speculate that the current 'pause' in global warming is due to heat storage in the ocean that could be released during the event."

This graph (see it bigger here) from HADCRUT4's data set breaks down the hottest three years on record month by month and shows 2014's progress against these. So far it has been the fourth hottest on record (although there is enough uncertainty in the data set to make these rankings slightly tenuous). In all of the other hotter years there was a drop away in the later half of the year. This is because they all came on the back of an El Niño event from the year before. The reason 2014 has grabbed attention is because of the potential for an already hot year to be affected by a warming event towards its end. The graph shows that for 2014 to equal the hottest year ever, temperatures could actually drop slightly for the rest of the year.

View image in fullscreen

Tim Osborn, from the University of East Anglia, explains the graph below. He says 2014 is certainly among the hottest years so far but uncertainty in the data make definitive statements impossible.

Black shows 2014 temperature anomalies so far. Black dashed lines are NOT predictions, instead they are examples of the type of temperature anomalies that would be needed during the remainder of the year for 2014 to equal the current warmest (1st) through to current 10th warmest in our 165-year record.

This gives you an idea of the sustained warmth needed for 2014 to be the hottest year on record, in comparison with the three warmest years so far (red lines) and in comparison with the individual monthly records (thin blue line).

Because our estimates of global temperature are not perfect, the annual values have an uncertainty of about +/- 0.1 degC. The uncertainty for single months is greater. So the warmest three years are not statistically distinguishable since they differ by only 0.01 degC (ten times smaller than the uncertainty). The true temperatures (which we don't know but can only estimate) might have been in a different order.

It is likely that situation for 2014 will be the same: regardless of whether our estimate of 2014's global temperature is slightly above or slightly below the current warmest year (2010), the values will probably have overlapping uncertainty ranges. Even when all the data are in, the answers to both your question "Will 2014 be the hottest year on record?" and this question asked in early 2015 "Was 2014 the hottest year on record?" will likely be the same: "Possibly".

Taking a longer-term view is more informative, where a warming trend in unequivocal.

Note: The link to the NOAA report is currently not working. I'm not sure why this is.

Chris Goodall from Carbon Commentary has emailed a reminder that El Niño type effects were already being observed in the NOAA report.

May also be worth noting that the NOAA report mentions the late and diminished Indian monsoon this year. Usually correlated with El Nino and may be very significant for world food supply.

Second, reason that global temperatures were at record high in June is not Land figures but the numbers for Oceans. If I remember correctly from the release June Ocean temperatures were the largest anomaly ever recorded.

A spokesperson for the World Meteorological Society has told me that the oceans are behaving in the way you would expect during an El Niño (ie warming) but the atmospheric response has not yet kicked into gear. Leading to questions over whether this year's event will be as strong as first predicted. I'm unclear as to whether the ocean temperature anomaly measured by NOAA is the result of this oceanic warming. If anyone can clear this up it would be great.

Nasa also collates world temperature data, albeit in a slightly different manner to NOAA. Reto Reudy, who works on the Nasa records, says that year to year variability is caused by El Niño and volcanic eruptions. But these are only waves on the rising tide of climate change (to borrow from Michael Mann).

Whether this year will top 2010 (2005) will depend on the strength of the El Nino. Needless to say, strong volcanic eruptions could postpone record years temporarily. However, currently more energy enters the atmosphere than leaves it and this imbalance will insure future record years. It causes a general warming trend which will occasionally be overshadowed by short term transitory ups and downs.

We are using the same data as NOAA, what is somewhat different is the procedure to combine them into gridded data and global means.

"This year and next year are shaping up to be among the hottest years on record," says Richard Allan, a climatologist at Reading University. Although he says it is still difficult to predict, mostly because we don't know how big this year's El Niño is going to be. El Niños often do not fully manifest their effect until the year after they begin, meaning 2015 could be hotter than 2014. Generally, he says, El Niños raise the global temperature by 0.1-0.2C.

Other measures, including the Met Office's HadCRUT4 ("had-cru-tee-four") dataset, have not shown the recent months to be quite as extreme as NOAA. NOAA is the only dataset to include measurements from over the Arctic, where temperatures have increased the most. "You can't unequivocally say June was the hottest on record because of uncertainty [in the modelling]." He said HadCRUT4 had seen a hot but not record breaking May. Their results for June were not out yet.

A couple of exceptionally hot months were not enough to make judgements from, says Allan. HadCRUT4 and NOAA both say the first six months of this year were cooler than 1998 and 2010. HadCRUT4 also has the first half of 2007 as hotter than this year. Despite this, he says 2014-15 are looking like being hot, maybe hottest, years.

When asked if climate scientists get sick of being asked about records by headline hungry media, he graciously laughed, and said:

"For a particular month there is very little significance. When you are looking at a [record] year it's a bit more meaningful. But what scientists are interested in is the long term trends."

There have already been commenters below who have pointed to lower levels of warming observed in Antarctica. Allan says there are complex reasons why the continent is insulating itself from the global warming trend. This is partly to do with refrigerative effect of ice, but the depleted ozone layer over the region has also been a factor.

"Regionally you'll get large departures from the global average. But almost all regions have seen some degree of warming."

El Niño is the name given to weather events caused by an enormous swelling up of warm water from the depths of the eastern Pacific Ocean. This event, which occurs every 5 or so years, affects every global weather system. Every continent is influenced differently, but generally El Niño causes a rise in temperatures, which has traditionally seen the global average spike. Conversely, La Nina, El Niño's counter-event, causes a dip in temperatures. The past two years have been La Nina years.

The general increase in global temperatures has meant that 13 of the hottest 14 years on record have occurred since 2000. The only outlier is 1998, which saw an exceptionally intense El Niño event.

For a detailed and brilliant summary of the global reach of El Niño, see my colleagues Suzanne Goldenberg, Graham Readfern and Damian Carrington's article from earlier this year.

Another year and another set of climate records crumble like Californian topsoil. The US National Oceanic and Atmospheric Administration (NOAA) announced this week that last month was the hottest June since weather archives began.

The average global temperature was 16.2C, 0.7C higher than the 20th century average and one-twentieth of a degree higher than the previous warmest June in 2010. May was also a record breaker.

This summer's hot temperatures look likely to be the beginning of an exceptional spell. An El Niño event is pushing warm water to the surface of the Pacific. Recent El Niño years have smashed temperature records. Both 1998 and 2010 were the hottest years since 1880 when climate records began. The effect of El Niño during these years compounded the muffling effect of greenhouse gases and lead to exceptionally hot global temperatures.

Since last El Niño the atmosphere has only trapped more heat. May and June are the latest in a string of 352 months that were above the 20th century average. So does the looming El Niño mean this year is destined to be the hottest ever?

Join in today’s discussion by contributing in the comments below, tweet me or email me. If you are quoting figures or studies, please provide a link to the original source. Follow me on @karlmathiesen for updates throughout the day and later I will return with my own verdict.