Atmospheric temperature trends

The lower atmosphere is warming while the upper atmosphere is cooling – a clear fingerprint of the enhanced greenhouse effect from human emissions of carbon dioxide.

The simple explanation is that some of the infrared radiation emitted by the surface, which would have normally reached the upper atmosphere, is absorbed by greenhouse gases in the lower atmosphere. The upper atmosphere therefore receives less energy than before, and so cools. The very warm years (intense reds) in the upper atmosphere are the 1982-83 El Chichón and 1991-92 Pinatubo eruptions respectively.

Changes in global atmospheric temperature at different levels in the atmosphere from 1979 to 2018: surface, TLT, TTT, TMT, TLS. Data from Cowtan & Way, and RSSv4. The colour scale goes from -0.75K to +0.75K, relative to the average of 1981-2010 for each layer separately.

9 thoughts on “Atmospheric temperature trends

  1. Is the simple explanation correct? The infrared radiation emitted by the surface is not absorbed and re-emitted many times until it reaches a height where the concentration of greenhouse gases is so low that it can escape to space. For most wavelengths this is around 5 km. More greenhouse gases increase the height and given the lapse rate warm the atmosphere. However, in the 15μm band the absorption is so strong that it only escapes to space in the stratosphere. Here the lapse rate is negative, so an increase in greenhouse gases gives cooling.

  2. Yes, but the climate models are still a poor match with the empirical temperature regardless. The models only temporarily resemble the empirical temperature data during the peak of a large El Nino, whereas the rest of the time an embarrassing ‘hiatus’ (IPCC) suggest the temperature could drop out the bottom of the climate models projections:

    http://blogs.reading.ac.uk/climate-lab-book/files/2014/01/fig-nearterm_all_UPDATE_2018-panela-1.png

    The models are inaccurate, as are the predictions associated with them (i.e. extreme weather, accelerating sea level rise, etc.).

      1. You’re more than welcome to disagree Ed, but it’s the IPCC you’re disagreeing with it’s not me. The only thing that changed was the 2015-16 El Nino, and temperatures are falling again (how far they continue to fall I don’t hazard to guess):

        ‘Hiatus’ in Warming From Approx. 1998:
        Source: IPCC AR5 report (2013), Working Group I: The Physical Science Basis, Technical Summary, Page 61, Box TS.3 | Climate Models and the Hiatus in Global Mean Surface Warming of the Past 15 Years

        Consequences of inaccurate models are:

        ‘Extreme Weather’:

        Hurricanes – ‘ … low confidence that any reported long-term (centennial) increases in tropical cyclone activity are robust, after accounting for past changes in observing capabilities. More recent assessments indicate that it is unlikely that annual numbers of tropical storms, hurricanes and major hurricanes counts have increased over the past 100 years in the North Atlantic basin.’

        &

        ‘In summary, confidence in large scale changes in the intensity of extreme extratropical cyclones since 1900 is low. There is also low confidence for a clear trend in storminess proxies over the last century due to inconsistencies between studies or lack of long-term data in some parts of the world (particularly in the SH). Likewise, confidence in trends in extreme winds is low, owing to quality and consistency issues with analysed data.’

        Source: IPCC AR5 report (2013), Working Group I: The Physical Science Basis, Chapter 2, Pages 216-217, 2.6.3 Tropical Storms & 2.6.4 Extratropical Storms.

        Drought – ‘In summary, the current assessment concludes that there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century… ‘

        Source: IPCC AR5 report (2013), Working Group I: The Physical Science Basis, Chapter 2, Pages 214, 2.6.2.3 Droughts.

        Floods – ‘In summary, there continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale.’

        Source: IPCC AR5 report (2013), Working Group I: The Physical Science Basis, Chapter 2, Pages 214, 2.6.2.2 Floods.

        Sea Level Rise Acceleration:

        ‘The trend in GMSL [global mean sea level] observed since 1993, however, is not significantly larger than the estimate of 18-year trends in previous decades (e.g., 1920–1950).’

        Source: IPCC AR5 report (2013), Working Group I: The Physical Science Basis, Chapter 3, Page 290, 3.7.4 Assessment of Evidence for Accelerations in Sea Level Rise.

  3. Cooling in the lower stratosphere is largely controlled by ozone levels. For example, Thompson and Solomon (2008) write:

    http://www.atmos.colostate.edu/~davet/ao/ThompsonPapers/ThompsonSolomon_JClimate2008_InPress.pdf
    “The lower stratosphere has cooled by a globally averaged ~0.3-0.5 K/decade since 1979. The global-mean cooling has not occurred monotonically, but rather is manifested as two downward “steps” in temperature, both of which are coincident with the cessation of transient warming after the major volcanic eruptions of El Chichon and Mt. Pinatubo.

    “The lower stratosphere has not noticeably cooled since 1995, which indicates that the trends in this region are not dominantly controlled by the known increases in carbon dioxide over this period. Attribution experiments indicate that the long-term cooling in global-mean lower stratospheric temperatures is driven mainly by changes in stratospheric ozone.”

    Ozone forcing is several times larger than that from increasing GHGs. From Polvani and Solomon (2012)

    https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2012JD017719
    “Confirming and extending earlier studies we find that, over the second half of the 20th century, the model’s lower-stratospheric cooling caused by ozone depletion is several times larger than that induced by increasing greenhouse gases.”

    If you run a trend analysis of the lower stratosphere temps since 1994 (after the Pinatubo drop) you find there is no statistically significant cooling trend over the last quarter century.

Leave a Reply

Your email address will not be published. Required fields are marked *