Deconstructing climate change, and its deniers

I presented these IPCC graphs some time back in Climate change is complex. They underline the fact that climate changes are caused by a number of factors (natural and human-caused) so any successful modelling of global temperature changes needs to take all the factors into account. The graphs show how omission of human caused factors produces model results inconsistent with measured values.

Figure a included all the natural and anthropogenic influences. The black line is the actual measured global temperature anomaly (obtained by subtracting the average temperature for 1901 to 1950). The individual simulations are shown as thin yellow curves. The red line is the multi-model ensemble mean (see Figure 9.5 – AR4 WGI Chapter 9: Understanding and Attributing Climate Change).
Figure b is a similar plot using simulations which consider only the natural influences on climate. The individual simulations are shown as thin blue curves. The thick blue line is the multi-model ensemble mean.

These figures show how simple plots of global temperate over time cannot identify causes – a more complex investigation involving modelling was required. This enabled contributions from non-natural and natural causes to be identified.

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Now the blog Skeptical science has produced a video showing a similar deconstruction of the factors causing global temperature change. The purpose was to show the falseness of recent claims by climate change deniers/contrarians/sceptics of no human contribution to climate change because they have observed no warming in the last 16 years.

Short term temperature changes are the results of several natural and human caused factors. But only the human caused emissions of CO₂ is causing a steady effect which becomes clear when long-term changes are considered (even if not clear in the short term).

(Thanks to Still warming after all these years (again) at Hot Topic).

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Finally, here is another graph which has the climate change deniers/contrarians/sceptics buzzing. It’s from the UK Met Office (see Decadal forecast). The buzz arises from the Met Offices revisions of “near-term’ climate prediction because of improvements in the modelling.

Observed (black, from Hadley Centre, GISS and NCDC) and predicted global average annual surface temperature difference relative to 1971-2000. Previous predictions starting from June 1960, 1965, …, 2005 are shown as white curves, with red shading representing their probable range, such that the observations are expected to lie within the shading 90% of the time. The most recent forecast (thick blue curve with thin blue curves showing range) starts from November 2012. All data are rolling annual mean values. The gap between the black and blue curves arises because the last observed value represents the period November 2011 to October 2012 whereas the first forecast period is November 2012 to October 2013.

Actually, the denier/contrairan/sceptic buzz arises because the revised (improved) predictions are a “little lower” than the previous one. This has caused them (the deniers/contrarians/etc) to claim this proves global warming has stopped, and that human-caused climate change has consequently been proven wrong!
Of course this is wishful, and motivated, thinking on their part. The predictions produced by the Met Office rely on simulations using the best and most up to date models. The models incorporate all the factors known to influence global temperatures – including that caused by human burning of fossil fuels!

It’s a strange old world. The deniers/contrarians/sceptics who wish to deny human contributions to climate change have been sucked in by the Met Office sort term predictions of global temperatures. These deniers/contrarians/etc., are now touting models in support of their claims which in fact are based on the effects of such human contributions.

They are relying on the very thing they wish to deny!

See also:
Updates to our decadal forecast
Has global warming ground to a halt?

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