2011: 9th Warmest Calendar Year On Record, Even With A La Niña

NASA’s James Hansen and a few of his colleagues released their assessment of 2011 global temperatures recently.  In short, 2011 was the 9th warmest year in the GISS dataset.

Just as importantly, this situation occurred in the midst of a continuing La Niña event that is of moderate strength.  La Niña is characterized by a general cooling of the tropical Pacific waters near the surface; it is frequently referred to as being the opposite of El Niño.  As La Niñas progress, global temperatures tend to cool from their normal state.  This of course has implications as scientists work to differentiate the effects of natural climate processes and those brought about by humans.  If one year’s temperatures are cooler than the preceding year’s (or are warmer), does that mean that global warming has stopped (as skeptics like to say) or does that mean that there are competing forcings that affect the temperatures recorded?

It is the assessment of an overwhelming majority of climate scientists that global warming has not stopped.  Instead, the 2nd half of 2010 and all of 2011 were dominated by La Niña events.  What does this mean?  It means that if the La Niña events had not occurred (and if there were no El Niños either), in other words purely “normal” conditions, 2011 likely would have been warmer than was recorded.  This should become obvious in the next 6 months to 3 years as this La Niña dissipates and conditions across the globe respond accordingly.  It takes ~6 months for downstream effects to show up in observations after ENSO phases start and after they go away.

Here is Hansen et al.‘s updated figure showing global land-ocean temperatures using an index:

Figure 1.  Global surface air temperature anomalies relative to 1951-1980 base period for annual and 5-year running means. Green vertical bars are 2σ error estimates (Hansen et al., 2010). [Source for all graphs: Hansen]

The last black square on the right hand side of the graph is 2011′s temperature index value: +0.51°C.  You can clearly see where the 9th highest ranking comes from when viewing this graph.  You can further see that 2011 was warmer than 2001, 2004 and 2008 (simply comparing the past 10 years of values), as well as every year prior to 2000 save 1998, the year when the last century’s strongest El Niño occurred.

But I wrote above that large changes can occur year-to-year and this is evidenced by the jagged look to the yearly data in the graph above.  So what happens if the data is analyzed in such a way as to remove the yearly signal?  Furthermore, can the ENSO and solar cycle signals be quieted down to get a better idea of what the global temperatures are likely doing?  Yes they can, as the following graph demonstrates:

Figure 2. Global surface air temperature anomalies relative to 1951-1980 base period for (a) the 12-month running mean, and (b) the 60-month and 132-month running means.

The right panel of Figure 2 demonstrates the results of the removal of the ENSO signal (red line, 60-month running mean) and the solar cycle signal (blue line, 132-month running mean).  The addition of more months into the running mean helps to remove more and more noise (to a limited degree, of course).  What is left behind is increasingly the global warming signal in global temperature data.  A key takeaway is this: the same general result can be seen regardless of the specific temperature dataset employed.

To expand on this topic a little more, here is a graph comparing mean temperature anomalies and the Nino 3.4 index (and index used to characterize the ENSO signal as El Niño or La Niña):

Figure 3. Global monthly and 12-month running mean surface temperature anomalies relative to 1951-1980 base period, and 12-month running mean of the Nino 3.4 index.

Paired with the Nino 3.4 index data, it is very easy to pick out the ENSO influence on the temperature data.  Peaks in global temperature anomalies tend to occur during El Niños while troughs in anomalies tend to occur during La Niñas.  As you can see, claims that global warming has “stopped” in the past couple of years are not likely to be correct since a prolonged La Niña has occurred during that time frame.  One good indicator of whether or not global warming has stopped will be what the global temperature anomaly is ~6 months after the next El Niño peak occurs (likely sometime in the next 3 years).

Another good indicator of whether global warming has stopped or not will be what global temperature anomalies register as the upcoming solar maximum descends from its next peak.  As the following graph illustrates, the peak is likely to occur 3+ years from now:

Figure 4. Solar irradiance from composite satellite-based time series. Data sources: For 1976/01/05 to 2011/02/02 Physikalisch Meteorologisches Observatorium Davos, World Radiation Center and for 2011/02/03 to 2012/01/11 University of Colorado Solar Radiation & Climate Experiment. Data are concatenated using the 2010/02/03 to 2011/02/02 period.

It is important to note that the global temperature response to the solar cycle is delayed by ~18 months.  So in 4-5 years from now, we’ll have a much clearer idea of the effects of global warming in the 1st half of the 2010s were.  That time period will occur after the next solar cycle maximum and after the next El Niño.  It strains credulity to think that global temperatures will be lower after those two milestones than they are today.

My thoughts on this are easily understood: it is more likely that global temperature anomalies will continue to exhibit decadal-scale rises than falls in our future (21st century).  As I’ve stated many times before, it is also likelier that projected temperature increases are underestimated, not overestimated.  We are more likely to read about additional top-10 warmest year on record in our future.  That said, I’d be happy to be wrong about all of this.  The changing environment we’re living in demands changes to the way our societies function.  I don’t believe those changes will be equally catastrophic to everybody around the globe.  But all of us will be affected by this phenomenon in one way or another.  How we decide to handle those changes will be the key.

Climate Change Basics – Energy & Projections

In July, I wrote a post that laid the groundwork for the discussion of climate change basics: Gases, Forcing & Surface Temperature.  This post follows onto that initial post by discussing energy within Earth’s climate system.  As in that post, I will focus on the results in the IPCC’s AR4.  There is a wealth of additional results in the scientific literature since the 2007 Report and I will share some of those in future posts.  In other words, the IPCC information will be used as a baseline.  This post is a little long, but I think it’s worth reading in its entirety.

Energy Content

First, here are two views of the energy content in the climate system.  The first is from the IPCC’s WGI Technical Summary:

Source: IPCC AR4 Figure TS.15.  Energy content changes in different components of the Earth for two periods (1961-2003 (blue) and 1993-2003 (burgundy)).

NASA & NOAA: June 2011 Among Top 10 Warmest On Record

According to data released by NASA and NOAA this month, June 2011 ranked among the top 10 warmest Junes on record: NASA recorded the 8th warmest June in its dataset; NOAA recorded the 7th warmest June in its dataset.  The two agencies have slightly different analysis techniques, which actually helps to reinforce the results from each other.

The details:

June’s global average temperatures were 0.50°C above normal (1951-1980), according to NASA.  The warmest regions on Earth are exactly where climate models have been projecting the most warmth to occur for years: high latitudes (think Arctic & Antarctic Circles).  The past three months have a +0.49°C temperature anomaly.  And the latest 12-month period (Jul 2010 – Jun 2011) had a +0.52°C temperature anomaly.  Additionally, the March-April-May period of 2011 tied for the 7th warmest on record.

According to NOAA, June’s global average temperatures were 0.58°C (1.04°F) above the 20th century mean of 15.5°C (59.9°F).  NOAA’s global temperature anomaly map reinforces the message: high latitudes are warming at a faster rate than the mid- or low-latitudes.  The extreme 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, the leading cause of the warmth we’re now witnessing.

These placements high on the list of recorded temperatures come at a time when the recent strong La Nina is coming to an end (which means anomalously cool Pacific waters return to normal temperatures), and when solar irradiance remains at relatively low levels as the most recent solar cycle continues to ramp up.  Recall that a favorite talking point of Deniers is the sun remains the only important component of climate system drivers.  This has been proven false, as 2010, tied for the warmest year on record with 2005, occurred when solar output was at its most recent minimum.  Humans have become the dominant forcing mechanism – a role that doesn’t look likely to end within the next 50-100 years.

Many future Junes will have the opportunity to pass this year’s values.  That’s because the overwhelming majority of heat that has been absorbed in the climate system has been stored in the world’s oceans:

That heat will eventually be released into the atmosphere, making the surface warmer and warmer year after year, decade after decade.  Right now, the atmosphere is being affected by heat that was absorbed by the ocean 50-100 years ago.  The heat absorbed from 1980-current won’t really impact conditions until 2030-2060.  The heat wave impacting the U.S. this year?  That will likely become commonplace by mid-century.  Think about what kind of extreme weather conditions will occur then.

Climate Change Basics – Gases, Forcing & Surface Temperature

After running across some resources again recently, I thought it would be a good idea to put some posts together that showed the background of many of the common facts I discuss.  In this first post, I wanted to show the relationship between greenhouse gases, radiative forcing and temperatures.  In doing, I will use graphics from the IPCC’s 4th Assessment Report Technical Summary.

First, here is a graphic of changes in greenhouse gases from ice core and modern observational data, spanning the time period of 20,000 years ago through current:

The portion of this graph I’d like to focus on is the upper left quadrant displaying the time series of atmospheric carbon dioxide concentration.  First, note is the transition from ~180ppm 20,000 years ago to between 260 and 280ppm.  This transition helped bring the last interglacial period to an end.  Of greater import is the more recent transition from 280ppm to 380ppm (as of ~2005; current concentrations are ~390ppm).

East Coast Heat Wave Preview Of New Normal

Readers of my posts should know by now I have been moving away from using certain language when discussing climate change effects.  That language includes talking about effects in the far-off future and the uncertainty involved with climate projections (even though they do exist).  This transition has happened rapidly as I have read hundred of journal articles detailing the latest science assessments as well as seminal reports like the IPCC’s in 2007.  Generally speaking, the American public has no idea what is about to hit them.  A solid percentage think climate change is occurring and our species is now the dominant forcing mechanism.  That’s the good news.  The bad news is far too few Americans realize how quickly conditions are changing and what those changing conditions mean for their future.

An article came out today putting some pieces together that I want to comment on.  The article covers the topic of a new paper being published in Climatic Change Letters by a Standford group.  It deals with projections of summer conditions around the globe, using the current heat wave affecting a good portion of the country as context.  That’s not to say this heat wave can be directly and completely attributed to climate change, but that conditions are primed for heat waves like this to occur with climate change affecting baseline conditions.  Unsurprisingly, the group found (among other things) the following:

The Stanford study’s lead author, Noah Diffenbaugh, sought to determine when the current hottest temperatures would become “the new normal.” He says, “According to our projections, large areas of the globe are likely to warm up so quickly that, by the middle of this century, even the coolest summers will be hotter than the hottest summers of the past 50 years.”

Read that again.  The coolest summers in 40 years will be hotter than anything we’ve experienced since the 1960s.  That projection is in line with the findings of numerous other studies: future decades are likelier to be hotter than preceding decades for a long time to come.  Folks across the East Coast and South are experiencing now what will be a typical summer soon.  And what we considered to be summer will have to be revised: the climate doesn’t care about arbitrary astronomical designations of seasons.  An increase in the number of days with 90F+ daily highs occurring in May and April will occur.  The number of days with 100F+ will also increase.  Of more worry is the number of nights with higher minimum temperatures than ever before.

What effects will these higher temperatures have?  Plenty.

[H]eat waves in 2003 killed an estimated 35,000 people in Europe. Last year, a record heat wave in Russia killed 700 people per day. As for agriculture, new research reveals that global warming has hindered crop yields. Higher temperatures cause dehydration and prevent pollination, resulting in a rise in food prices. Other studies suggest that warmer winters keep pests alive longer, allowing them to carry plant diseases, and greenhouse gases affect a plant’s structure, reducing its protection abilities.

Colorado knows all about the problems of warmer winters, as we’ve witnessed millions of acres of forest fall prey to pine beetles, whose offspring are surviving winters that no longer experience 30F below zero temperatures for extended periods.  And contrary to what science-haters say, plants have an optimal range of temperatures, CO2 concentrations, and other environmental conditions.  If they had paid attention to science in school, they might be able to deduce that they already live in their optimal range because of evolutionary processes.  The critical point is those ranges aren’t very large for most plants.  A small numeric change in one or more of those environmental conditions puts plants under tremendous strain.  It doesn’t take much to push them over the edge and get them to experience dramatically slower growth rates.  In short, more CO2 does not equal faster plant growth.

Another projection cited in the article is worthy of further discussion.

U.N. predictions suggest that there may be 50 million environmental refugees by 2020.

That is an interesting projection since:

This past year alone, natural disasters displaced 42 million people, according to the Internal Displacement Monitoring Centre.

The way I read those two sentences is the following: either 8 million more people need to be displaced to hit the U.N. prediction (which shouldn’t be difficult to do in 9 years’ time) or 50 million people need to be displaced in a single year (which shouldn’t be much more difficult than it was to displace 42 million people last year).  My point is that the U.N. needs to take a hard, honest look at the latest science and reissue their prediction, because it already seems out-of-date one decade early.

Scientists and government planners announced in May that heavy rains, deep snowfalls, monster floods and deadly droughts signal a “new normal” of extreme U.S. weather events influenced by climate change.

How many looming threats and even visible evidence are needed before serious action is taken to fight global warming?

We might want to start paying attention.  The following list contains weather disasters that have costs exceeding $1 Billion – just so far in 2011:

1. 2011 Groundhog Day’s blizzard ($1- $4 billion)
2. April 3 -5 Southeast U.S. severe weather outbreak ($2 billion)
3. April 8 – 11 severe weather outbreak ($2.25 billion)
4. April 25 – 28 super tornado outbreak ($3.5 – $6 billion)
5. Mississippi River flood of 2011 ($9 billion)
6. Texas drought ($1.2 billion)
7. Joplin tornado ($1 – $3 billion)

That’s the fastest that 7 $1 Billion weather disasters have occurred after Jan. 1, in case you were wondering.  I wrote many times in the past couple of years that we couldn’t afford to continue ignoring climate change.  It’s far more expensive to keep burning fossil fuels and living inefficiently than it is to change our habits while we still have the luxury of time to do so.  Moving forward, we are now faced with the dual challenges of changing our habits while simultaneously reacting to the weather disasters we brought on ourselves.

Cross-posted at SquareState.

New Arctic Ice Assessment: Faster Melt = Faster Sea Level Rise

Most of the projections in the science portion of the IPCC’s 2007 4th Assessment Report have been shown many times since its issuance to be too conservative.  Temperatures have risen faster; ice (sea- and land-based) has melted faster; ocean acidification and warming has happened faster, the number of extreme weather events has increased faster, etc.

I’ve written before about most of these.  I will take this space to write once again about polar ice melting faster than projected (according to observations) and the impact that will have on global coastlines.

According to the executive summary of a new assessment of Arctic climate, the international Arctic Monitoring and Assessment Program (AMAP) reports that Arctic temperatures in the past six years were higher than at any time since measurements began in 1880.  Moreover, feedback mechanisms have already started.

What this means is the arctic sea ice area and global sea level projections made by the IPCC just 4 years ago underestimate this year’s conditions, which means they also very likely underestimate future conditions too.  In an updated projection that has deep significance for billions of people worldwide:

The melting of Arctic glaciers and ice caps, including Greenland’s massive ice sheet, are projected to help raise global sea levels by 35 to 63 inches (90-160 centimeters) by 2100, AMAP said, though it noted that the estimate was highly uncertain.

That’s up from a 2007 projection of 7 to 23 inches (19-59 centimeters) by the U.N. panel, which didn’t consider the dynamics of ice caps in the Arctic and Antarctica.

Is the difference between one-half to 2 feet and 3 feet to 5 feet significant?  Only those of us who are sane seem to think so.  This is but one effect of oil corporations continuing to post record profits quarter after quarter, year after year.  How much infrastructure exists near 5ft above sea level worldwide?  How much is that infrastructure worth?  How much cropland exists at those low altitudes?  How many miles of ruined cropland from rising seas only will occur before widespread food shortages occur?  How much is our lifestyles worth; how much do they really cost?

AMAP scientists will discuss their findings in Copenhagen, Denmark starting tomorrow.

My most recent `State of the Poles` post discussed shorter-term influences on sea ice conditions (monthly to seasonal effects).  I’ve stated in that series that a new regime now exists for the Arctic.  Findings like these support that assessment.

For the hard-core curious, the key findings of the report are reprinted below the fold (h/t ClimateProgress)

2010 Warmest Year On Record, Says NASA & NOAA

The news is in and it isn’t good.  Despite a strong La Nina during the second half of the year and cold air able to escape the Arctic and affect Europe and the eastern U.S., 2010 was the warmest year since 1880.

The top-10 warmest years in the NASA record are now:

2010, 2005 (actually 0.018°F less than 2010), 1998, 2002, 2003, 2006, 2007, 2009, 2004 and 2001.

9 out of the 10 warmest years on record have now all occurred since 2002.  The 12 warmest years on record have occurred since 1997.  Global warming has not stopped.  Global warming will not stop unless and until we stop polluting the climate system with greenhouse gas emissions at a tiny fraction of our current pace.

NOAA has put together their annual global report, which acts as confirmation of the NASA result: 2010 is statistically tied with 2005 as the warmest year in their dataset.

To the climate zombies that infest the discussion over what to do about global warming, consider the following: 2010 was “only” 1.12°F (0.62°C) above the 20th century average of 59.0°F.  Our current emissions trajectory is closest to the A1FI emissions scenario in the IPCC’s SRES family.  Results of running that scenario through climate models produced the following results: best estimate temperature rise of 7.2°F with a likely range of 4.3 to 11.5°F (4.0 °C with a likely range of 2.4 to 6.4 °C).

Multiple extreme weather events also characterized 2010 and continue to do so in early 2011.  From a heat wave worse than any seen in the past few thousand years across eastern Europe and Russia that claimed many lives and spawned massive wildfires to related Pakistani floods that affected tens of millions of people to floods in Australia that cover more area than several countries in Europe, loaded die are starting to land.  The costs of these disasters already reach into the tens to hundreds of billions of dollars.  If these kinds of horrific events are already occurring with only 1.12°F warming, what will happen when the globe warms by an average of 4.3°F, 7.2°F, or even 11.5°F?  It can be summed up simply: stress will move beyond impacting disparate societies; our civilizations will be stressed to breaking points, to say nothing of ecosystems across the planet.

Cross-posted at SquareState.

NOAA Data Agrees With NASA Data: November Among Warmest Ever

NOAA released their November Global Analysis about a week ago.  That was a couple of weeks after NASA released their November analysis.  I’m not sure if this was due to data quality control issues, but the result is in line with NASA’s: November 2010 was very warm globally.  NOAA’s methodology differs from NASA’s, which makes comparison between the two a good exercise.

According to NOAA, November 2010 was the 2nd warmest in their dataset (131 years long), slightly behind November 2004.  NASA, in contrast, reported that November 2010 was the warmest in their dataset.  Neither is more correct than the other.  If a large discrepancy in analyzed temperatures appeared between the two, there would be cause for concern.  But both methodologies are producing quite similar results, especially over climatic time periods of multiple decades.

Some numbers:

NOAA recorded a +1.24°F (+0.69°C) temperature anomaly over land and ocean in November 2010.  They recorded a +1.30°F anomaly during November 2004.  2010′s global temperature anomaly “suffered” from La Nina, which cooled the tropical Pacific.  Largely as a result of this, global ocean temperatures were +0.70°F, which tied 1987 and 2008 for the 10th warmest in the NOAA record.  Land temperatures were an astounding +2.74°F warmer than usual.  That beat out 2004′s +2.41°F anomaly.

I want to draw attention to the Northern Hemispheric land temperature anomalies for November 2010.  The previous record was observed in 2001: +2.84°F.  November 2010 set a new record: +3.55°F!  That is neither beating the previous record by a slim margin nor is it indicative of the climate zombies’ favorite mantra, “global cooling”.  You don’t set hemispheric-wide temperature records for an entire month when the globe is cooling, not when the records only last a handful of years.

The global ocean temperatures are worth mentioning again.  Even with a moderate to strong La Nina in place in the previous handful of months affecting the Pacific Ocean, the 10th warmest ocean temperature anomalies on record were observed.  Put another way: the relatively strong signal of El Nino/La Nina is likely now being dominated by the growing signal of global warming.  Will fluctuations occur from year to year?  Of course they will.  Novembers between 2007 and 2010 are a good example.  A relatively wide range of global ocean temperature anomalies were recorded.  But each of them were larger than the similar measurements during the 1990s except for 1997 and 1998, when the strongest El Nino on record occurred.

NOAA also released seasonal and year-to-date numbers.  From September through November, global temperature anomalies were +1.04°F, the 6th warmest in their records.  From January through November, global temperature anomalies were +1.15°F, the warmest on record (beating out 2005′s +1.12°F).  Land temperatures are the warmest in the NOAA record and ocean temperatures are the 3rd warmest.  Doesn’t look like there’s much cooling, does it?

Lastly, I want to make mention of a topic I wrote about recently: for all the temperature records we’re already seeing being broken in recent years, we haven’t seen anything yet.  The vast majority of the heat accumulated by the globe so far as a result of global warming has been stored by the ocean, specifically the deep ocean.  The heat accumulated thus far therefore has not had a chance yet to affect atmospheric temperatures.  As the 21st century progresses, the heat will get that opportunity.  Warm deep water will upwell along continental coastlines, shifting local climates, until enough heat is released back into the atmosphere that the global climate shifts.  Unfortunately for the globe, past warming episodes have tended to occur quite quickly, on the order of tens of years.  That has been a shocking discovery made recently by climate scientists.  Warmer oceans and a warmer atmosphere will induce a higher frequency of severe weather events.  It won’t take much of an increase in the number of those events to cause real problems for governments around the world.  And until we get our greenhouse pollution under control, that’s the future we face: decades to centuries of a warmer climate and more extreme weather events.

November 2010 = Warmest Average November Globally

A rather stunning piece of news was released by NASA earlier this week that received absolutely no attention by corporate stenographers.  According to NASA, global average temperatures for November 2010 were higher than any other November in recorded history.  Furthermore, the likelihood that 2010 will end up as the warmest calendar year on record to date increased.  Recent months have seen consecutive 12-month periods rank as the hottest on record already.  But people tend to think along calendar date lines, so perhaps 2010 ranking at or near the top of the recorded history list will help spur folks to action.

Let’s start with November 2010 by itself.  November’s global average temperatures were 0.74C above normal (1951-1980), according to NASA.  The warmest regions on Earth are exactly where climate models have been projecting the most warmth to occur for years: high latitudes (think Arctic & Antarctic Circles).  The past three months have a +0.63C temperature anomaly.  And the latest 12-month period (Dec.2009-Nov.2010) had a +0.65C temperature anomaly, the warmest on record.

Now let’s look at year-to-date values.  The two warmest years in the NASA dataset were 2005 and 1998.  January-November average surface temperatures for 2010 were +0.66C above normal (1951-1980).  January-November 2005 saw +0.63C and January-November 1998 saw +0.57C above normal.  Regions experiencing abnormally warm or cool conditions in any of these years changes somewhat, of course.  But for the most part, the same regions are staying warmer during these record years and they’re getting warmer than they were one or two decades ago.

As if record global warmth wasn’t enough, coincident climate signals that provide monthly-to-seasonal and multi-year forcing on the climate system aren’t at cause.  What am I talking about?  Well, there was a moderate-to-strong El Nino earlier this year, but it ended by July 2010.  El Nino forcing typically takes 3-6 months to be seen in global surface temperatures.  Moreover, a moderate-to-strong La Nina has developed this fall.  We should be seeing a general cooling trend already as a result and we’re not.  Global temperature anomalies have instead been increasing since July, which means these temperature anomalies are responding to a forcing that is stronger than the weakening El Nino and strengthening La Nina.

Furthermore, the sun is still just coming out of what was an extended solar minimum.  The intensity of the current solar cycle (#24), as measured by sunspots and solar flux, is less than what was predicted by space agencies a few months ago.  The solar cycle operates on an approximate 11-year cycle.  Since we remain near the minimum of that cycle, the relative weakness of solar output is also clearly being dominated by a stronger forcing mechanism here on Earth.

For additional context, think of what global temperatures are likely to be in 2013 or 2014 as the solar cycle continues to ramp up.  Then add on another El Nino event, even one of moderate strength.  With the failure of the U.S. political system to come up with common-sense strategies of dealing with global warming, it’s not as if the U.S.’s greenhouse gas pollution will be decreasing between now and then.  It’s also not likely that the global pollution emissions will be lower in 2013 than they were in 2010, absent another economic disaster.  Warmer and warmer we go…

Cross-posted at SquareState.

Jan-Aug 2010 Hottest On Record: NASA & NOAA

You have likely heard or read by now that the first 8 months of global temperature in 2010 were the warmest of any such period in recorded history.  Unlike earlier months this year, I’ve started to see more coverage of this in the corporate media.  Unfortunately, the coverage I have seen has been short and lacking in critical context.  Most of the coverage has actually been of anecdotal situations, like the record-shattering 2010 Russian heat wave.  Stories about the above-average Atlantic hurricane season and the Pakistani floods leaving tens of millions displaced have typically not included much, if any, notation that record heat has been recorded across the globe.

NOAA recorded the 3rd warmest August on record; the 2nd warmest Jun-Aug on record; and Jan-Aug 2010 tied the same time period from 1998 as the warmest on record.  The most intense El Nino in recorded history occurred in 1997-1998, which helped push global temperatures to record levels.  The El Nino of 2009-2010 wasn’t nearly as strong, but added to the background warming brought about by global warming to match the warmest Jan-Aug in modern history.

August 2010

NASA’s global analysis reported a +0.67°C (+1.206°F) surface temperature anomaly for August 2010 (over the 1951-1980 base period).  August 2010 had the 7th highest anomaly of Augusts in the NASA dataset, according to NASA’s GISS dataset.

NOAA’s global analysis reported a +0.6°C (+1.08°F) surface temperature anomaly for August 2010.  According to the NOAA methodology, the two warmer Augusts observed were in 1998 (+1.3°F) and 2009 (+0.62°C  or +1.12°F).