NASA scientists: Expect record-breaking warm years soon
We’re barely out of 2011, and already there’s plenty of discussion about last year’s temperatures and how they fit with the global warming trend.
Over the past few weeks, the major temperature datasets have been giving their assessment of how temperatures behaved last year. First up: the UK’s Met Office, who released preliminary data putting 2011 as the UK’s second warmest year on record – (remember that any one year doesn’t tell us much about the long term trend, as we pointed out at the time, although lots of hot years together do).
Then the global temperature records starting coming, with the US National Oceanographic and Atmospheric Administration (NOAA) releasing their global stats for 2011. Their global temperature dataset put 2011 as the joint eleventh warmest year since records began in 1880. They also highlighted that 2011
“…Marks the 35th consecutive year, since 1976, that the yearly global temperature was above average…Including 2011, all eleven years of the 21st century so far (2001-2011) rank among the 13 warmest in the 132-year period of record. Only one year during the 20th century, 1998, was warmer than 2011.”
Now it is the turn of the other major US global temperature dataset, from NASA’s Goddard Institute for Space Studies (GISS). They put 2011 as the ninth warmest year on record, and also highlighted that
“The first 11 years of the 21st century experienced notably higher temperatures compared to the middle and late 20th century… The only year from the 20th century in the top 10 warmest years on record is 1998.”
The graphs below show the GISS record for global surface air temperature anomaly since records began:
Image - NASA GISTemp LandOcean 2011 (note)
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. Source: NASA GISS.
The UK’s Met Office and Hadley Centre released provisional figures for their HadCRUT3 dataset in November last year also putting 2011 as the eleventh warmest year on record, but have yet to release the definitive data.
The differences in how the three main datasets are constructed are explored in more detail in this blog, and in our global temperature datasets profile.
NASA expects record warm year in two to three years
We all know by now that natural variations in climate affect global temperatures over short timescales, which is why we have to look at longer-term trends in global temperature to get an idea of the impact man-made greenhouse gas emissions are having on global temperatures.
James Hansen and his colleagues at NASA have taken an look at 2011’s global temperatures, taking into account important natural climate fluctuations, and speculate about what global temperatures might do over the next few years.
We should point out, this is not peer-reviewed research – it’s more of a commentary – but it makes for interesting reading if you’re considering the question of whether global warming has ‘stopped’ or not.
The NASA scientists consider the main natural climate fluctuations, including changing climate patterns like El Niño Southern Oscillation (ENSO) and the solar activity cycle. (Volcanic activity can also affect temperatures, but there have been no eruptions on the scale required to impact global climate this year.)
ENSO
The El Ni̱o Southern Oscillation (ENSO) has two phases РEl Ni̱o which involves the spreading of seawater which is warmer than normal across the equatorial Pacific and La Ni̱a, which is the spreading of cooler than normal water over the same region. As the graph below shows, short-term global temperature fluctuations follow the ENSO cycle.
Image - NASA ENSO Temp 2011 (note)
Global monthly and 12-month running mean surface temperature anomalies relative to 1951-1980 base period, and 12-month running mean of the Niño 3.4 index. Source: NASA GISS.
2011 was dominated by a reasonably strong ‘double-dip’ La Niña. The NASA scientists suggest that this cooled the climate, although not as much as might be expected – probably due to the overall warming influence of man-made greenhouse gases. Hansen argues that under the return of El Niño conditions we could expect a warmer global average temperature, saying:
“It’s always dangerous to make predictions about El Niño, but it’s safe to say we’ll see one in the next three years. It won’t take a very strong El Niño to push temperatures above 2010.”
The Sun
Another important factor is solar activity. As the graph below shows, the last few years have seen low solar activity, which has had a small cooling effect on the climate. As solar activity rises again, this won’t be the case.
Image - NASA solar activity 2011 (note)
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.Source: NASA GISS.
The NASA scientists point out that there tends to be a delay of roughly eighteen months between solar cycle changes and its effect on global temperature, so they anticipate that the sun will probably remain a cooling effect in the near future, but this will change to a warming effect over the next 3 – 5 years.
The prospect of enhanced solar activity and an El Niño event over the next few years have led the NASA scientists to suggest that
“…The slowdown of warming is likely to prove illusory, with more rapid warming appearing over the next few years”
Hansen says he expects a record-breaking global average temperature in the next two to three years. We’ll wait and see.