Posts Tagged ‘global warming’

Ahead of the upcoming IPCC report into global climate, and climate change, the news agenda seems to been largely dominated by stories asking why global warming has paused for the last 15 years (see the BBC, the BBC again, the torygraph and the NZ herald among countless other examples).

A substantial part of this seems to be the repeat of familiar claims that 1998 was the hottest year on global record, and if global warming scientists were right there is no way that we should not have a seen a hotter year during the past 15 years. Hence, climate change has paused, the models and data suggesting that human fossil fuel emissions were to blame for late 20th century warming were wrong, and that consequently any argument for restricting emissions in future are null and void.

Which of course ought to lead to the question, who says that 1998 was the hottest year on record? Well the answer to this is somewhat complicated, but also somewhat revealing. It aint NASA, who run GISStemp (the Goddard Institute for Space Studies Surface Temperature Analysis) who have 2010 as the hottest year on record followed by 2005, with 9 of the 10 hottest years occurring after the year 2000 (with 1998 as the only pre-2000 year in that list).  It also isn’t NOAA (the US National Oceanic and Atmospheric Administration) who compile a global temperature record at the National Climactic Data Centre (NCDC), whose data again places 2010 as the hottest year on record, followed by 2005, with 1998 in third, and 9 of the hottest 10 years on record occurring after the year 2000 (ie after global warming has allegedly paused). Which leaves the UK Met Office’s Hadley Centre and and University of East Anglia’s Climactic Research Unit record HadCRU. The CRU is of course the unit who were the subject of the Climategate faux controversy where sceptics hacked emails, published some excepts from private correspondence out of context claiming fraud and data manipulation generating global headlines, and which were subsequently found by numerous independent investigations to have found no evidence of wrongdoing. The latest version of this temperature series is HadCRUT4v which again shows that 2010 was the hottest year on record, followed by 2005, followed by 1998.

So where does the 1998 was the hottest year claim come from? Well, HadCRUT4v is the latest, and most accurate temperature record maintained by the Met Office and CRU (for a detailed explanation of what’s changed look here). If we ignore that and instead use their previous version, HadCRU3v, then, and only then does 1998 appear to be the warmest year on record. So why did this old record suggest a different year to the NASA and NCDC records (and indeed the latest version of the CRU record)? Well the main reason for this was the different methods used to generate global temperatures. Of course none of these institutions are able to measure the temperature in every place in the world, they use stations in various locations, and the places where there tend to be the fewest stations tend to be the polar regions (where there also tend to be the fewest people). And one of the things we know quite well, is that the Arctic has been the fastest warming region on the planet. Whereas GISStemp interpolates values between measured locations in the Arctic, HadCRU3v left them blank as unknown, which introduced a cold bias into their dataset compared with the others, and explaining why it has been replaced by a dataset which features a greater number of stations and which correlates much more strongly with the other datasets.

So the ‘pause’ in climate change is something that only exists if you exclusively look at a now obsolete and known to be biased dataset generated by a group who those using this data have previously claimed to be frauds. And decide to ignore that 1998 was in any case a super El-nino which had a dramatic short term effect on global weather – hence the other 9 of the 10 hottest years on record all occurring since the year 2000. If you used 1997 or 1999 as start dates there wouldn’t appear to be any pause in any dataset (outdated or otherwise), but cherry-picking the year when specific short-term conditions made things abnormally hot added to cherry-picking a now obsolete dataset allows sceptics to make the global warming has paused argument (see this excellent skeptical science post for details on cherry-picking)

So why are so many mainstream media outlets focussing upon this as the main story in the lead up to the IPCC report? Probably because it’s a more sensationalist and conflict-driven story than one which reads science has been slowing progressing, turning a 90% confidence in predictions in 2007 into a 95% confidence by 2013, allied with a big PR drive from a number of the main players in the climate denial industry.


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Six degrees – Our Future on a Hotter Planet, is the title of Mark Lynas’s 2007 book (this review is from the updated 2008 version) which seeks to give a broad overview of what mainstream scientific opinion (ie those which have appeared in reputable peer reviewed journals) suggests the world might look like over the next century with variable amounts of warming from pre0industrial temperatures. As title of the book suggests, Lynas looks as what is likely to happen with 1 degree of warming, 2 degrees and so on.

Overall, the book is well researched and written, condensing a vast amount of scientific literature into 275 pages with clear references to the original material Lynas has cited. The prose is generally very straightforward, and consequently this is a book which anyone can pick up and read, which I’m sure was Lynas’s intention: seeking to present a simple but generally accurate picture of what science says a warming world will probably be like, and some of the reasons why this is likely to be enormously detrimental to most forms of human and non-human life on Earth.

While Lynas does mention the potential positives of a mildly warming world such as increased growing seasons and crop production in Russia, the Ukraine and Canada, these are heavily outweighed by rising probabilities of drought, water shortages (largely from glaciers melting away), floods, mass crop failures, loss of biodiversity and potential social and ecological collapses. Lynas does a good job in this respect of respecting regional differences, but connecting these regions into a broader global picture.

Particularly frightening are the predicted prospects of a world more than two degrees warmer than the pre-industrial global mean, as not only are the effects of such climactic change going to be more severe, but there exists a reasonable chance that once warming reaches this oft-discussed tipping point that natural positive feedback loops kick in which alter the global climate so as to reach the kind of steady-state seen in other global extinction events, a six degree rise in temperature. Lynas does a very good job in explicating how some of these effects may arise, and in spelling out the kind of drastic changes they would entail for the planet’s climate.

While generally I think the book has been well though out and written, there were a few bits of linguistic sloppiness which frustrated me. Describing a world which is six degrees warmer than 150 years ago as ‘the ultimate apocalypse’ merely gives ammunition to those who seek to decry Lynas as a false prophet of global doom. If the apocalypse is the end of the world what exactly the ultimate apocalypse? The sun going supernova? The Galaxy collapsing into a black hole? No… a similar amount of warming to other mass extinction events such as the Permian. Six degrees of warming may well see the extinction of the human species (as Lynas states) but this is very different from it being the ultimate apocalypse, and this kind of exaggerated statement is the only thing that really stops me from saying that this is a book that everyone should read. Which is a shame, because most of it isn’t alarmist nonsense, but a very clear and well written summary of the scientific evidence surrounding our probable future climate.

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The synthesis report from this year’s Copenhagen conference on climate change gives dire warning of the consequences of inaction about global warming. The report contains the most comprehensive update to climate science since the IPCC AR4 report. The report emphasizes six key messages, each of which is given its own chapter. Find the pdf of the report here

Recent observations show that greenhouse gas emissions and many aspects of the climate are changing near the upper boundary of the IPCC range of projections. Many key climate indicators are already moving beyond the patterns of natural variability within which contemporary society and economy have developed and thrived. These indicators include global mean surface temperature, sea level rise, global ocean temperature, Arctic sea ice extent, ocean acidification, and extreme climatic events. With unabated emissions, many trends in climate will likely accelerate, leading to an increasing risk of abrupt or irreversible climatic shifts.

The research community provides much information to support discussions on “dangerous climate change”. Recent observations show that societies and ecosystems are highly vulnerable to even modest levels of climate change, with poor nations and communities, ecosystem services and biodiversity particularly at risk. Temperature rises above 2C will be difficult for contemporary societies to cope with, and are likely to cause major societal and environmental disruptions through the rest of the century and beyond.

Rapid, sustained, and effective mitigation based on coordinated global and regional action is required to avoid “dangerous climate change” regardless of how it is defined. Weaker targets for 2020 increase the risk of serious impacts, including the crossing of tipping points, and make the task of meeting 2050 targets more difficult and costly. Setting a credible long-term price for carbon and the adoption of policies that promote energy efficiency and low-carbon technologies are central to effective mitigation.

Climate change is having, and will have, strongly differential effects on people within and between countries and regions, on this generation and future generations, and on human societies and the natural world. An effective, well-funded adaptation safety net is required for those people least capable of coping with climate change impacts, and equitable mitigation strategies are needed to protect the poor and most vulnerable. Tackling climate change should be seen as integral to the broader goals of enhancing socioeconomic development and equity throughout the world.

Society already has many tools and approaches – economic, technological, behavioural, and managerial – to deal effectively with the climate change challenge. If these tools are not vigorously and widely implemented, adaptation to the unavoidable climate change and the societal transformation required to decarbonise economies will not be achieved. A wide range of benefits will flow from a concerted effort to achieve effective and rapid adaptation and mitigation. These include job growth in the sustainable energy sector; reductions in the health, social, economic and environmental costs of climate change; and the repair of ecosystems and revitalisation of ecosystem services.

If the societal transformation required to meet the climate change challenge is to be achieved, a number of significant constraints must be overcome and critical opportunities seized. These include reducing inertia in social and economic systems; building on a growing public desire for governments to act on climate change; reducing activities that increase greenhouse gas emissions and reduce resilience (e.g., subsidies); and enabling the shifts from ineffective governance and weak institutions to innovative leadership in government, the private sector and civil society. Linking climate change with broader sustainable consumption and production concerns, human rights issues and democratic values is crucial for shifting societies towards more sustainable development pathways.

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