- Bishop Hill blog

Lord Donoughue's terrier-like pursuit of the observational evidence that we have experienced warming that is out of the ordinary continues unabated.

Lord Donoughue (Labour): To ask Her Majesty’s Government whether they have identified any observational evidence for statistically significant global warming, either natural or anthropogenic; and, if so, from what sources any such evidence originated.

Baroness Verma (Whip, House of Lords; Conservative): There is considerable observational evidence that the world has experienced statistically significant warming since the end of the 19th century. This is reported in Section 3.2 of the IPCC’s 4th Assessment Working Group I Report1.

We note that other statistical methodologies have been proposed and it is important that there is an open technical debate on their relevance to climate change analysis in the peer-reviewed literature.

In addition three-dimensional, physically-based climate models have been used to assess the climate’s natural internal variability and its responses to various external factors. Using standard scientific methods, the significance of observed global warming can be determined by testing detected temperature changes against the null hypothesis that they are entirely due to natural factors and have no anthropogenic contribution. The observed warming has been shown to be outside the bounds of natural climate system variability and is not consistent with model simulations that exclude anthropogenic factors, such as emissions of greenhouse gases. This inconsistency has been shown to be statistically significant1,2,3

I have offered the noble Lord a meeting with officials in three previous Written Answers (on: 13 February (Hansard, col. WA 158); 21 March (Hansard, col. WA 170) and 27 March (Hansard, col. WA 237-38) and I re-affirm this offer.

1 IPCC, 2007, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.) Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

2 Stott, P. A. and Gillett, N. P. and Hegerl, G. C. and Karoly, D. J. and Stone, D. A. and Zhang, X. and Zwiers, F. Detection and attribution of climate change: a regional perspective Wiley Interdisciplinary Reviews: Climate Change, 1,2,192-211,2010.

3 Hegerl, G. and Zwiers, F. Use of models in detection and attribution of climate change. Wiley Interdisciplinary Reviews: Climate Change, 2 (4), 570-591, 2011.