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Sea level in the 5th IPCC report

Filed under: — stefan @ 15 October 2013

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.

IPCC_AR5_13.27
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.
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Science of Climate Change online class starting next week on Coursera

Filed under: — david @ 14 October 2013

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! More »

The IPCC AR5 attribution statement

Filed under: — gavin @ 10 October 2013

Last year I discussed the basis of the AR4 attribution statement:

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.

In the new AR5 SPM (pdf), there is an analogous statement:

It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period.

This includes differences in the likelihood statement, drivers and a new statement on the most likely amount of anthropogenic warming.

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Climate Change on Film

Filed under: — stefan @ 8 October 2013

Making a film about climate change is difficult, especially if you want it to reach a wide audience. One problem is the long time scale of climate change, which fits badly with the time scale of a typical film narrative. That was the reason why in the Hollywood blockbuster The Day After Tomorrow some laws of physics were treated with a certain artistic freedom, in order to present a dramatic climate change within a few weeks instead of decades.

Mike and I have spent the last few days at a very interesting workshop in Iceland, where climate scientists, social scientists and filmmakers were  brought together in conjunction with the Reykjavik International Film Festival. I will make no attempt to reproduce the many exciting discussions which we had, that often continued into the night. Instead, I’d like to present two short films by workshop participants. I chose a contrast of hot and cold.

First, the cold. The following film is a trailer by Phil Coates, a British filmmaker and expedition leader, who has filmed in extreme conditions on all seven continents. It is a “work in progress” under the working title “North Pole Living on Thin Ice”. Coates was dropped off with three scientists on the sea ice near the North Pole. On foot out on the Arctic Ocean they made oceanographic and ice thickness measurements. Soon you will be able to experience this research expedition on film. The scientific findings of the team will of course come out in the scientific literature.

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The evolution of radiative forcing bar-charts

Filed under: — gavin @ 7 October 2013

As part of the IPCC WG1 SPM(pdf) released last Friday, there was a subtle, but important, change in one of the key figures – the radiative forcing bar-chart (Fig. SPM.4). The concept for this figure has been a mainstay of summaries of climate change science for decades, and the evolution over time is a good example of how thinking and understanding has progressed over the years while the big picture has not shifted much.


The Radiative-Forcing bar chart: AR5 version

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