The Centre for Australian Weather and Climate Research – a partnership between the Bureau of Meteorology and CSIRO – is leading Australia's climate change and weather research

The Centre for Australian Weather and Climate Research – a partnership between the Bureau of Meteorology and CSIRO – is leading Australia's climate change and weather research

Climate questions: Is there an inconsistency between observed and modelled patterns of warming in the lower atmosphere?

It is commonly claimed that a predicted fingerprint of climate change – a warming (or hot spot) in the lower troposphere – is missing from the measurements. Recent reanalysis of the data has established that observations are not inconsistent with the modelled patterns of warming for the troposphere. Thus there is no ‘missing’ hot spot.

  • 1 June 2011 | Updated 22 March 2013
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In brief

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Hot Topics Kevin Hennessy

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There’s no inconsistency between observed and modelled patterns of warming in the lower atmosphere. Global climate models, when driven by increases in greenhouse gases, simulate a warming of the surface and of the lower atmosphere, and in particular a hot spot at about ten kilometres above the surface in the tropics.

Past measurements showed less than expected warming because they were using two sources of information, one from radiosondes that were attached to balloons, and secondly information that comes from satellites. In both cases the data needed to be corrected for different types of instrumentation that we used over time.

Our current understanding is that there is no inconsistency between the observed warming in the lower atmosphere and what is simulated by global climate models.

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Climate models predict that increasing greenhouse gases should warm the lower troposphere slightly more (in relative terms) than the surface.

However, until recently, observed temperature datasets did not show this level of warming in the tropical troposphere.  

Since predicted changes due to increasing greenhouse gases and aerosols explain so many other observed features of 20th century climate change, scientists have sought to understand and reconcile the apparent difference between modelled and observed tropospheric temperature trends.  

There is no reasonable evidence of a fundamental disagreement between the tropospheric temperature trends from models and observations when uncertainties in both are treated comprehensively.

Disclaimer

Based on information written by CSIRO on behalf of the Department of Climate Change http://www.climatechange.gov.au/climate-change/~/media/publications/science/hot-topics-loweratmospher.ashx [external link] and modified to reflect recent research findings. Published with permission of the Department of Climate Change.

References

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Christy JR, Norris WB, Spencer RW, Hnilo JJ. 2007. Tropospheric temperature change since 1979 from tropical radiosonde and satellite measurements [external link]. Journal of Geophysical Research. 112. D06102.

Domingues CM, Church JA, White NJ, Gleckler PJ, Wijffels SE, Barker PM, Dunn JR. 2008. Improved estimates of upper-ocean warming and multi-decadal sea-level rise. Nature. 453. 1090-1094.

Douglass DH, Christy JR, Pearson BD, Singer SF. 2007. A comparison of tropical temperature trends with model predictions [external link]. International Journal of Climatology. 28(13).

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Karl TR, Hassol SJ, Miller CD, Murray WL (eds). 2006. Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. National Oceanic and Atmospheric Administration, National Climatic Data Center. Asheville, NC. 164 pp.

Lanzante JR, Free M. 2008. Comparison of radiosonde and GCM vertical temperature trend profiles: effects of dataset choice and data homogenization, Journal of Climate. 21(20). 5417–5435.

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Santer BD, Thorne PW, Haimberger L, Taylor KE, Wigley TM, Lanzante JR, Solomon S, Free M, Gleckler PJ, Jones PD. 2008. Consistency of modelled and observed temperature trends in the tropical troposphere. International Journal of Climatology. 28(13), 1703-1722.

Sherwood SC, Meyer CL, Allen RJ, Titchner HA. 2008. Robust tropospheric warming revealed by iteratively homogenized radiosonde data. Journal of Climate. 21(20), 5336–5352.

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Thorne et al. 2010. Tropospheric temperature trends: history of an ongoing controversy. WIREs Climate Change. DOI: 10.1002/wcc.80.