Climate science from climate scientists...
I was disappointed by the recent summary for policymakers (SPM) of the intergovernmental panel on climate change (IPCC) assessment report 5, now that I finally got around to read it. Not so much because of the science, but because the way it presented the science.
The report was written by top scientists, so what went wrong?
[Read more…] about A failure in communicating the impact of new findings
Do different climate models give different results? And if so, why? The answer to these questions will increase our understanding of the climate models, and potentially the physical phenomena and processes present in the climate system.
We now have many different climate models, many different methods, and get a range of different results. They provide what we call ‘multi-model‘ and ‘multi-method‘ ensembles. But how do we make sense out of all this information?
Some will be luckier than others when it comes to climate change. The effects of a climate change on me will depend on where I live. In some regions, changes may not be as noticeable as in others. So what are the impacts in my region?
[Read more…] about From global climate change to local consequences
A new report on extreme climate events in Europe is just published: ‘Extreme Weather Events in Europe: preparing for climate change adaptation‘. It was launched in Oslo on October 24th by the Norwegian Academy of Science and Letters, and the report is now available online.
What’s new? The new report provides information that is more specific to Europe than the SREX report from the Intergovernmental Panel on Climate Change (IPCC), and incorporate phenomena that have not been widely covered.
It provides some compelling information drawn from the insurance industry, and indeed, a representative from Munich Re participated in writing this report. There is also material on convective storms, hail, lightening, and cold snaps, and the report provides a background on extreme value statistics, risk analysis, impacts, and adaptation.
[Read more…] about A new European report on climate extremes is out
What is happening to sea levels? That was perhaps the most controversial issue in the 4th IPCC report of 2007. The new report of the Intergovernmental Panel on Climate Change is out now, and here I will discuss what IPCC has to say about sea-level rise (as I did here after the 4th report).
Let us jump straight in with the following graph which nicely sums up the key findings about past and future sea-level rise: (1) global sea level is rising, (2) this rise has accelerated since pre-industrial times and (3) it will accelerate further in this century. The projections for the future are much higher and more credible than those in the 4th report but possibly still a bit conservative, as we will discuss in more detail below. For high emissions IPCC now predicts a global rise by 52-98 cm by the year 2100, which would threaten the survival of coastal cities and entire island nations. But even with aggressive emissions reductions, a rise by 28-61 cm is predicted. Even under this highly optimistic scenario we might see over half a meter of sea-level rise, with serious impacts on many coastal areas, including coastal erosion and a greatly increased risk of flooding.
Fig. 1. Past and future sea-level rise. For the past, proxy data are shown in light purple and tide gauge data in blue. For the future, the IPCC projections for very high emissions (red, RCP8.5 scenario) and very low emissions (blue, RCP2.6 scenario) are shown. Source: IPCC AR5 Fig. 13.27.
[Read more…] about Sea level in the 5th IPCC report
Maybe you remember the rollout a few years ago of Open Climate 101, a massive open online class (MOOC) that was served sort of free-range from a computer at the University of Chicago. Now the class has been entirely redone as Global Warming: The Science of Climate Change within the far slicker Coursera platform. Beginning on October 21, the class is free and runs for 8 weeks. The videos have been reshot in a short and punchy (2-10 minute) format, for example here (8:13). These seem like they will be easier to watch than traditional 45-minute lectures from a classroom. It’s based on, and will show you how to play with, all-new on-line computer models, including extensive new browsing systems for global climate records and model results from the new AR5 climate model archive, an ice sheet model you can clobber with slugs of CO2 as it evolves, and more. Come and watch the train wreck join the fun! [Read more…] about Science of Climate Change online class starting next week on Coursera
The heat content of the oceans is growing and growing. That means that the greenhouse effect has not taken a pause and the cold sun is not noticeably slowing global warming.
NOAA posts regularly updated measurements of the amount of heat stored in the bulk of the oceans. For the upper 2000 m (deeper than that not much happens) it looks like this:
Change in the heat content in the upper 2000 m of the world’s oceans. Source: NOAA
[Read more…] about What ocean heating reveals about global warming
A couple of weeks ago, there was a small conference on Climate Science communication run by the AGU. Both Mike and I attended, but it was very notable that it wasn’t just scientists attending – there were also entertainers, psychologists, film-makers and historians. There were a lot of quite diverse perspectives and many discussions about the what’s, why’s and how’s of climate science communication.
There were a couple of notable features: the conference had a lively twitter hashtag (#climatechapman), and almost the entire proceedings were webcast live (schedule). The video from this has now been posted on YouTube in more bite-sized chunks.
While our own presentations (Mike here and Gavin here) are available, it is worth watching the presentations from people you might not have heard of, as well as a few from more established people. We’ll embed a few here, but please point out some of the other ones of interest in the comments.
[Read more…] about AGU Chapman Conference on Climate Science Communication
A while ago, I received a request to publish a paper on a post that I had written here on RealClimate, exposing the flaws in the analysis of Humlum et al., (2011).
Instead of writing a comment to one paper, however, I thought it might be useful to collect a sample of papers that I found unconvincing (usual suspects), and that have had a fairly high public profile.
[Read more…] about A new experiment with science publication
Guest commentary from Tim Osborn, Tom Melvin and Keith Briffa, Climatic Research Unit, UEA
Records of tree-ring characteristics such as their width (TRW) and density (usually the maximum density of the wood formed towards the end of the growing season – the “maximum latewood density” – MXD) are widely used to infer past variations in climate over recent centuries and even millennia. Chronologies developed from sites near to the elevational or latitudinal tree lines often show sensitivity to summer temperature and, because of their annual resolution, absolute dating and relatively widespread nature, they have contributed to many local, continental and hemispheric temperature reconstructions. However, tree growth is a complex biological process that is subject to a range of changing environmental influences, not just summer temperature, and so replication, coherence and consistency across records and other proxies are an important check on the results.
Tree-ring records have greater replication (both within a site and between nearby sites) than other types of climate proxy. Good replication helps to minimise the influence of random localised factors when extracting the common signal, and it also allows the comparison of information obtained from different independent sets or sub-sets of data. If independent sets of data – perhaps trees with different mean growth rates or from different sites – show similar variations, then we can have greater confidence that those variations are linked to real variations in climate.
In a new QSR paper (Briffa et al., 2013), (BEA13) we have used these approaches to re-assess the combined tree-ring evidence from the Yamal and Polar Urals region (Yamalia) of northern Siberia, considering the common signal in tree-growth changes at different sites and in subsets of data defined in other ways. Together with our Russian colleagues and co-authors, we have incorporated many new tree-ring data, to increase the replication and to update the chronology to 2005 and have reassessed the inferences about summer temperature change that can be drawn from these data. The paper is published as an open-access paper (no paywall) and supplementary information including the raw tree-ring and instrumental temperature data are available from our website.
[Read more…] about Yamal and Polar Urals: a research update