Is the climate changing?

The last few weeks have seen substantial questioning of the quality of the analysis of the global climate record. This presentation, made to the top year at a local secondary school, looks at the Oxford climate series and shows how the way the data is presented may significantly affect judgments on how fast warming is occurring at one particular point on the earth's surface. Apparently innocuous changes, such as varying the number of years in a moving average, can make substantial changes to the appearance of a temperature series. The notes to this presentation can be seen by downloading the PowerPoint file and clicking Notes Page in the View tab; or alternatively by downloading the PDF. Anybody wanting the raw data and the accompanying charts is very welcome to email Chris Goodall at

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Postscript on Kenya, climate change and malaria

The previous post on this web site analysed a recent DFID press release on malaria and climate change. I've been sent three recent papers by scientists in Kenya dealing with the epidemiology of malaria. Links to two of these articles are provided below. These documents show that the DFID assertion that malaria is increasing in highland regions of Kenya is highly questionable and that overall malaria rates are probably decreasing, although the geographic picture is complex. They also demonstrate that rates of infection respond to simple but well-targeted interventions. Eradicating malaria from Africa is a difficult target but not one without hope of success.

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Exaggerating the impact of climate change on the spread of malaria

A recent press release from the UK Department for International Development (DFID) suggested that millions more people in Kenya are susceptible to malaria as a result of mosquitoes colonising higher ground as global temperatures rise. ('New evidence of a link between climate change and malaria', 30.12.09.) The press release was extensively covered in UK newspapers and elsewhere. Simple analysis shows that the claims of the press release are almost entirely without foundation. The battle against the severe threat from climate change is impeded, not helped, by government departments issuing alarmist and exaggerated alerts based on poor science.

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CO2 proxies in the long-distant past

We don’t have direct CO2 records earlier than 800,000 years ago. So scientists use what are called 'proxies' – indicators that give us indirect estimates of the amount of carbon dioxide in the atmosphere. Advances in scientific techniques have given us increasingly good proxies, meaning we can be more confident that our estimates of CO2 levels hundreds of millions of years ago are about right. There are anomalies: the various different proxies don’t always provide similar results. A paper published this week goes a long way to removing one important anomaly. (1) It shows that the proxy that uses estimates of CO2 concentrations based on isotope levels in ancient soil carbonates may have over-recorded atmospheric carbon dioxide levels at some periods. This brings the figures into line with other measures. Why does this matter? In Mesozoic times, from about 250 to 80 million years ago, the soil carbonate proxy has previously suggested very high CO2 levels in the atmosphere. Some studies had concluded that the air had several thousand parts per million of carbon dioxide, peaking perhaps at fifteen times higher levels than today. But records suggest that the temperature was only a maximum of 10 degrees Celsius higher than today. If the standard 'carbon cycle' models are correct, the estimated CO2 concentrations ought to have produced warmer conditions. The importance of this new research is that it shows that adjusted soil carbon proxies indicate that Mesozoic CO2 concentrations probably never rose above 1,500 parts per million, a figure consistent with other proxies and with the probable temperature levels at time. This is one more important indication that ancient CO2 levels were strongly correlated with climate.

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Discipline envy

Richard Black, the BBC's online environment correspondent, attracted attention when he noticed that almost all climate sceptics are men. Instead, he might have chosen to comment that many of them were social scientists with leanings towards economics. Coincidentally, economics is populated by males. It is only this year that the first woman won the subject's Nobel prize, and her work would not be regarded as part of the subject by many academic purists. Sceptics Nigel Lawson, Steven Levitt, Bjørn Lomborg, and others all think about the world as economists. That's probably more important than that they are male.

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The Committee on Climate Change shouldn't have answered the question it was asked

The UK government asked the wrong question. It demanded that the Committee on Climate Change calculated how much air travel can rise without causing an increase in aviation emissions. Not unsurprisingly, the CCC answered by saying that the number of trips could rise at the same rate as efficiency improvements in air travel. The Committee said that emissions per passenger will fall by about 1% a year, and so travel could rise by about this amount. No shocks there. By 2050, the CCC opined, the number of passengers taking trips from UK airports can rise to 370 million a year, up from 230 million today. The maximum possible number of new passengers at Heathrow from the addition of new runway and sixth terminal is about 60 million. Hoorah, said the industry, there's space for the expansion. Unsurprisingly, the press misinterpreted the Committee's report and said that it had 'approved' the government's plans for the airport. By answering the government's disiningenous question, the CCC has lost some of its impartiality.

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Sceptic Ian Plimer on global warming: 'my theories are more evocative and sensual'

Professor Ian Plimer is one of the most influential global warming sceptics. A university academic in Australia, his trenchant views on climate change have helped persuade opposition politicians in his home country to back away from supporting schemes to reduce emissions. His book Heaven and Earth: Global Warming: The Missing Science remains a best-seller in the UK.

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Is energy efficiency really cheaper than switching to renewable energy sources as a way of cutting carbon emissions?

Let’s face it: energy efficiency is boring when compared to the (relative) excitement of developing new sources of low-carbon electricity or heat. The popular science magazines are full of articles on new forms of solar panel and the latest designs for wind turbines. Improving the insulation of ordinary homes, shifting to LED lighting or increasing the take-up of heat pumps rarely command the attention of editors.

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What are we really arguing about when we argue about climate change?

The phrase ‘the science is settled’ is regularly used by politicians arguing for meaningful action on climate change. To the majority of the world’s scientists, global warming is a clear and present danger and those who deny it, or argue that its effects will limited or benign, are dangerous lunatics. Nevertheless, an increasing numbers of voters, particularly in the US and the UK, have drifted into the sceptic camp in recent months and years. A Pew Research October survey in the US showed the percentage of people seriously concerned by the climate change issue down from 77% to 65% in two years. An international survey by HSBC showed a fall from 32% to 25% over the past year in the percentage of people saying that climate change was the biggest issue that respondents worried about. A batch of highly successful books from journalists and maverick scientists has provided the intellectual covering fire for this decline. The result of the growing scepticism will be a weakening of national resolutions to take the difficult steps required to shift rich countries away from dependence on fossil fuels.

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No difference in the nutritional value of organic and conventionally produced food

A study commissioned by the UK Food Standards Agency concluded that: 'there is little, if any, nutritional difference between organic and conventionally produced food and that there is no evidence of additional health benefits from eating organic food.'

Yes and no. What the study actually shows is that organic food typically does have higher levels of important nutrients but the high degree of variability in the measured levels means that we cannot be 95% sure that these higher levels are not the outcome of chance. The Food Standards Agency and the report’s authors have misled people interested in this topic and should revise the summaries of their work.

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The human brain is made for environmental complacency

Most governments in the developed world were elected on platforms that promised aggressive policies on greenhouse gas emissions. The reality has not matched the commitments made. The reasons for this are multitudinous and no one should ever underestimate the difficulties of weaning advanced societies off the use of cheap and convenient access to fossil fuels. But in addition to the standard reasons for slow progress we can see a large number of obstacles that spring from human psychology. In particular, some of the resistance to aggressive action on climate seems to spring from mental attitudes that may have helped us survive as a species in the past. Perhaps politicians intuitively recognise the existence of these barriers. So they continue to say that climate change is the most important problem facing humanity at the same time as adding new runways to the local airport or sanctioning the development of new coal-fired power stations.

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Trees die quicker in drought when temperatures are hotter

Perhaps this isn’t surprising, but a new piece of research shows that the ability of trees to survive drought is reduced when temperatures are higher. A species of pine that grows in dry conditions was exposed to temperatures 4.3 degrees higher than a control group. Both sets of trees were kept without water. The trees in the hotter atmosphere typically died in 18 weeks compared to the 25 weeks of the control.

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What has posterity done for us?

Most governments in the developed world were elected on platforms that included promises to pursue aggressive policies on greenhouse gas emissions. Broadly speaking, the reality has not matched the promises made. The reasons for this are multitudinous and no one should ever underestimate the difficulties of weaning advanced societies off the use of cheap and convenient access to fossil fuels. But in addition to the standard reasons for slow progress we can see a large number of obstacles that spring from human psychology. In particular, some of the resistance to aggressive action on climate seems to spring from mental attitudes that may have helped us survive as a species in the past. Politicians may intuitively recognise the existence of these barriers. So they continue to say that climate change is the most important problem facing humanity at the same time as adding new runways to the local airport or sanctioning the development of new coal-fired power stations.

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The global warming ‘standstill’

Nigel Lawson and others are suggesting that temperatures have ‘stabilised’ since the late nineties. 1998 saw the highest global average temperature and only 2005 has closely matched it. Since no year since 1998 has exceeded the record, some commentators are saying the global warming has stopped. The implication, sometimes stated, sometimes not, is that the increasing rate of growth of CO2 concentration is having no effect on temperature.

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Roy Spencer presentation to the Heartland Institute conference

The Heartland Institute, a US free-market think tank, held a conference on climate change in New York in early March. It was a forum for some of the climate change sceptics to discuss their research. The conference got very little coverage in the media and was ignored by the science pages of the newspapers. This seems a mistake. A large section of the population of the US and the UK, and smaller numbers elsewhere, believe that the apparent scientific consensus on global warming is a result of selective coverage by TV and press. The failure to cover presentations by some of the leading sceptics is support for the accusation that global media, and mainstream climate scientists, are refusing to engage with the dissenting views of reputable scientists who do not share the standard view.

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The promise of cellulosic biofuels

Switchgrass biofuel crop
Switchgrass biofuel crop

Will next-generation biofuels have a less destructive effect on agriculture? A study just published by US government scientists suggests that so-called ‘cellulosic’ ethanol has much better energy balance than today’s biofuels.[1] By energy balance, we mean the energy used to make the fuel compared to its energy value when burnt in a car’s engine. News summaries of the paper’s contents focused on one estimate that suggested that to make cellulosic biofuels might only need 6% of the energy value contained in the fuel. Depending on which crop is used, where it is grown, and how it is refined, most of today’s biofuels have only a weakly positive energy balance. So the paper gives hope that we might expect considerable progress towards carbon-neutral transport fuels when we can start refining all vegetable matter, not just foodstuffs, into fuels.

Cellulosic biofuels may well become important sources of motor fuels. There is certainly huge amounts of money flowing into the field. Unfortunately none of the news articles covering the US research pointed out the technology for turning cellulose into fuel is still a long way from commercial viability. Yes, we can turn grass into ethanol, but at prices which will double the price of petrol. And the greenhouse gas savings will almost certainly not be as attractive as the paper suggests, not least because the authors did not include the serious impact of nitrous oxide emissions from fertilised fields.

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Carbon uptake by plants and trees is vulnerable to autumn warming

Carbon dioxide levels in the atmosphere rise by about 2-3 parts per million every year and the rate is slowly increasing. As well as this upward trend, there is an annual cycle: carbon dioxide levels fall in the northern hemisphere summer and rise strongly in the winter. The reason is that most of the vegetated land area is in the northern hemisphere and during the northern summer plants and trees absorb CO2.One effect of increasing spring and autumn temperatures has been to increase the length of what is loosely called ‘the growing season’. Plant growth can start earlier in spring and can continue until later. It might be thought that this would help vegetation take up more CO2, acting as a counterweight to increased fossil fuel use.

Research published in Nature in early January very strongly suggests that this is not happening. Warmer autumns are associated with a bringing forward of the date at which plants start losing CO2, not the reverse. Higher spring and autumn temperatures are tending to decrease the length of the period each year in which northern hemisphere plants are taking up carbon. If this research is confirmed, this is yet another potential positive feedback because higher temperatures might diminish the ability of biomass to take up carbon.

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Rising trends in atmospheric CO2

CO2 output is accelerating, the ocean and land sinks are getting less effective at absorbing it. So the rate of growth of carbon dioxide in the atmosphere is increasing. (Canadell, Le Quéré, and others, 'Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks', Proceedings of the National Academy of Sciences, 25 October 2007; URL: [accessed 27 October 2007].)

The pre-industrial CO2 concentration in the atmosphere was about 280 parts per million. It was 381ppm in 2006. The growth rate between 2000 and 2006 was 1.93ppm, a significant increase on growth rates in earlier periods. Many policy-makers see it as vital to keep below concentrations of about 400ppm of CO2. The increase in the rate of rise of CO2 makes the achievement of this target more difficult.

Increases in the amount of CO2 in the atmosphere reflect the volume of global emissions and the effectiveness of the oceans and land mass in absorbing greenhouse gases. This paper contains evidence both that emissions growth is speeding up and that the greenhouse gas sinks are capturing less CO2.

The growth rate in emissions between 2000 and 2006 was 3.3% a year compared to 1.3% in the 1990s (please see the article on Chinese exports in this issue of Carbon Commentary for corroboration of this finding). This increase reflects fast economic growth, particularly in China and India and a worrying increase in the amount of CO2 produced per unit of global output. It cannot be stressed enough that this second cause of emissions growth is unexpected. We thought we were going to see energy use fall in relation to economic output.

By contrast, models have predicted a decline in the effectiveness of ocean CO2 ‘sinks’. This paper shows that we can have a strong suspicion (but not near certainty) that this process has started. The authors point to increasing wind speeds in the Southern Ocean as a primary cause. This turbulence ‘ventilates’ the carbon dioxide contained in the surface of the sea. Droughts in mid-latitude regions have contributed to the decreased efficiency of land absorption.

The paper concludes that – with large margins of error – economic growth generated 65% of the increase in atmospheric CO2; the decrease in the efficiency of the sinks generated another 18% and caused a rise in the carbon output required to generate a dollar of world GDP.

The authors summarise by saying that their results ‘characterize a carbon cycle that is generating stronger-than-expected and sooner-than-expected climate forcing’.

Bjørn Lomborg's new book Cool It

Bjørn Lomborg, a professor at Copenhagen Business School, is the most formidable critic of those who think that cutting climate-changing gases is the most important problem the world faces. He made his name with 'The Skeptical Environmentalist' and his new book continues his drive to get the world to see global warming as just one of the world's important problems. Lomborg believes climate change is happening, and that mankind’s activities are responsible. But he tells that we shouldn’t do much about global warming because the costs are very high and the benefits low and far-off. Like most books written by partisans in this impassioned debate, much of what he says can be questioned.

Nevertheless, this is an extremely valuable polemic: it stresses repeatedly that taking action to stop climate change may have very high short-term costs. If by clumsy attempts to hold down emissions we stunt the prospects for global economic growth, we may do more harm to the world’s poor than would be inflicted by climate change. It needs to be said time and time again that disease and malnutrition are killing far more people today than climate change. We are making progress diminishing the impact of these scourges. Despite what you sometimes read in the newspapers, world food supply and life expectancy are improving. Panic-stricken action on climate change must not be allowed to halt this progress. We need a rational assessment of whether it is best to spend money on slowing climate change or to whether we would achieve better effects from focusing resources elsewhere.

Bjørn Lomborg is an able debater with a passionate interest in his subject. But he overstates his case, focuses on only parts of the issue and avoids any discussion of a possible future acceleration of global warming. Even with these weaknesses Cool It needs to be part of the continuing debate on how to respond to the climate threat without crippling the poorest economies of the world.

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