Sir John Houghtons' critque of Nigel Lawsons' book - Summarised with diagrams from IPCC reports

Sir John Houghton (in Nature and a longer critique) says that Nigel Lawsons' book 'An Appeal to Reason' is largely one of misleading messages. In this post I've discussed his shorter critique in Nature magazine.

The first of the misleading messages Houghton says is Lawsons' "questioning of the reality of human-caused global warming itself... Lawson takes the record of global average temperature in the first seven years of this century as evidence that the scientists must have it wrong. By themselves, these years show no significant increase in temperature, but they are warmer on average by almost 0.1 °C than the previous seven years.

Even a casual inspection of the global record from 1970 shows two things: first a clear trend of about a 0.5 °C increase over the past 30 years, and second a substantial year-to-year variability of the kind that is well known to climatologists and has been attributed to phases of the El Niño/La Niña phenomenon, a regular feature of the Pacific climate (see Figure SPM.1 (left) from IPCC 2007 Summary for Policymakers, pg 3)

Lawson challenges the carefully worded conclusion of the UN's Intergovernmental Panel on Climate Change that "most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations." He does this, not with any analysis of his own, but by listing some of the sources of uncertainty that are in any case are thoroughly addressed by the IPCC.



Lawson argues that even if global average temperature increased by about 3 °C, such warming would be trivial, and even largely beneficial. But given that the difference in temperature between the middle of an ice age and the warm periods in between ice ages is only 5 or 6 °C, (I could not find evidence for these ice age figures, when I looked here) an increase of 3 °C , occurring over much shorter time periods — on the scale of centuries rather than millennia — is far from inconsequential.

Although they receive extensive coverage in the IPCC reports, Lawson completely ignores some of the most serious impacts of global warming: namely the floods and droughts that are expected to become more frequent and more severe with even small rises in temperature. (see diagram - Examples of impacts associated with global average temperature change from Summary for Policymakers, pg 10)



Considering the potential for more climate extremes and sea level rise in the future, there are likely to be hundreds of millions of refugees from the world's most affected nations. Where could those people go in our increasingly crowded world? Lawson denies that there is any problem.

He repeats a number of times his summary of the damage as the difference between people in the developing world being 8.5 times better off than they are now and the 9.5 times improvement that they would see in the absence of global warming. Sleight of hand with gross numbers of possible economic growth must not be allowed to hide the magnitude of the very real problems.

The 2007 IPCC report makes it clear that the anticipated impacts of global warming will lead to tens or hundreds of millions of people suffering loss of resources, livelihoods and land. For example impact of climate change in Africa (see diagram from Working Group 2 Summary for Policymakers Report, pg 13)



But even if such impacts were likely, we cannot afford to address them, says Lawson. To stabilize atmospheric concentrations of greenhouse gases during this century, emissions would have to be substantially reduced from today's levels by mid-century. And because carbon dioxide emitted into the atmosphere remains there on average for around 100 years, there is an urgent need to begin reductions now. Lawson writes this off as being difficult, inconvenient and very costly. But both the International Energy Agency and Shell have recently presented scenarios of changes in energy generation and use by 2050 that show it would be feasible to move substantially towards achieving the emissions reductions required. How great, then, is the cost?

The Stern Review on the Economics of Climate Change indicates that if we act quickly, this could be as little as a few per cent of GDP by 2050. Executive summary of Stern Report - my key points are here.

Crucially, delayed action will increase the price tag, with the cost of doing nothing and paying to adapt to change much greater than that of early mitigation.

Lawson begs to differ, arguing that the financial burden of reducing emissions sharply would simply be unjustified in the face of scientific uncertainty.