Since starting to work for the Met Office I have been able to have a front row seat when some interesting new science is announced. Recently the Intergovernmental Panel on Climate Change (IPCC) released their fifth assessment report. This was reported pretty widely in the Guardian, the BBC and various other places and so I'm probably not bringing much to the table in talking about it now. However, the announcement and its content relates well to some of the wider themes I'm trying to explore in this blog and, as I'm experiencing some of the science first-hand I thought that I could write something worthwhile about it.
In case you want to go and read the original report, it is here. This is actually only one of four reports coming from each of three working groups and a synthesis report. The report I'm referring to is the WGI report which focusses on the physical science behind climate change and this is arguably the most important as it is this science which the other working groups build on. WGII concentrates on 'Impacts, Adaptation and Vulnerability' while WGIII takes on the problem of climate change mitigation.
The fact that the report exists at all (the IPCC AR5 WGI report to give it its full name) is amazing to me. The entire report is summarised in a trifling 14,000 word Summary for Policy Makers, in which every single sentence has been agreed upon by all 101 countries in attendance. Having spent literally months in meetings of five people simply trying to decide whether or not to buy a treadmill for the work gym I would be stunned if you told me that 101 countries had managed to agree on what time to have lunch.
One of the messages climate scientists are told to convey to the public is that there is an extremely strong consensus amongst scientists regarding the science behind climate change. I think that, if anyone truly still believes that human-driven climate change is a contentious subject, they should reflect on the fact that 101 countries could all agree on a report that unequivocally states that this is the case.
Not only does the report's existence refute the idea that intergovernmental bodies are unable to make any progress, it is also a remarkable testament to the power of peer review. In my last post I gave an example of peer review that shows how it can be a time-consuming, unsatisfactory process for all involved. That was for a paper involving only five authors and three referees. The WGI report involved 259 authors covering 14 main chapters utilising 1,089 reviewers who gave 54,677 comments.
The summary of the report, the Summary for Policy Makers, contains only robust science, agreed upon by all the attendees as well as the relevant scientists. I have it on good authority that there was less political motivation involved than might be expected. Certain oil-producing countries did apparently make every effort to stress the uncertainties inherent in the science of the report. However, while this is presumably politically/economically motivated, it can only lead to more robust findings. These findings have been boiled down to a single page (well, two sides) of the headlines which are kept here but, in case that still seems like a bit much, the climate scientist Professor Thomas Stocker has boiled these down to three main messages
What this shows is how much warming we might expect (y-axis) as a function of how much CO2 eventually ends up in the atmosphere (x-axis). This is presented for multiple potential scenarios referred to as 'RCP's. 'RCP' stands for Representative Concentration Pathway and relates the emission of greenhouse gases to the 'radiative forcing' that would result from that emission. There's a pretty good summary with all the detail you could probably ask for here but I'm going to leave 'radiative forcing' very loosely defined here as the difference between the heat energy received by the Earth (from the Sun) and the amount of energy radiated back into space. In a system in equilibrium this would be zero, with no overall warming or cooling resulting. We know that this value is not zero for the Earth at the present time and that is why it is warming. What the different trajectories followed by the different RCPs can tell us is what the eventual extent of the warming will be. The RCPs can also allow us to plan our emissions so as to take this into account. For example, the Copenhagen Accord (2009) stated that a temperature rise of 2°C or above would lead to 'dangerous climate change'. Of our four presented RCPs, the only one which would allow us to stay below a rise of 2°C (by the year 2100) is the RCP2.6. It is pretty much accepted that this is not going to happen. To follow RCP2.6 all man-made carbon emissions would have to cease today, a scenario I think we can all agree is unlikely (I apologise if this is hyperbole or a gross oversimplification, I am attempting to keep things non-technical and reasonably concise). Further, if you're sharp-eyed you may notice that the RCP2.6 pathway on the inlaid plot in the above figure goes into negative numbers meaning that, not only would carbon emissions have to decrease substantially, we would have to actually start removing carbon from the atmosphere via carbon capture or geoengineering. Scenarios which are now reportedly accepted by those within the UK government.
At the other extreme is RCP8.5 pathway, generally known as the 'business as usual' pathway. This is the scenario under which we continue to burn fossil fuels with absolutely no mitigation whatsoever. As you can see from the plot, this would lead to the Earth exceeding the 2°C milestone in something like 25 years. Whether we even have the resources to continue burning fossil fuels at our current rate for that long is a separate question but, as oil and gas become more scarce, they become more expensive leading to the techniques used to acquire them becoming more cost-effective, fracking being a case in point.
While it is somewhat unsettling to accept that climate change is now unavoidable, even at dangerous levels, I have found that scientists in the field are, if not upbeat, then at least somewhat positive. This positivity appears to be more of a recent development and it appears to be due to the fact that governments are actually listening these days. The fact that the IPCC AR5 reports even exist are a testament to that. At the Met Office I have been pointed towards five key components of our communications regarding climate change
The framing of climate change mitigation as 'affordable' and, more importantly, possible, may not place enough emphasis on the dangers of global warming and exaggerate our ability to deal with them. However, it does allow those in power to do something, which is always preferable to nothing.
In case you want to go and read the original report, it is here. This is actually only one of four reports coming from each of three working groups and a synthesis report. The report I'm referring to is the WGI report which focusses on the physical science behind climate change and this is arguably the most important as it is this science which the other working groups build on. WGII concentrates on 'Impacts, Adaptation and Vulnerability' while WGIII takes on the problem of climate change mitigation.
The fact that the report exists at all (the IPCC AR5 WGI report to give it its full name) is amazing to me. The entire report is summarised in a trifling 14,000 word Summary for Policy Makers, in which every single sentence has been agreed upon by all 101 countries in attendance. Having spent literally months in meetings of five people simply trying to decide whether or not to buy a treadmill for the work gym I would be stunned if you told me that 101 countries had managed to agree on what time to have lunch.
One of the messages climate scientists are told to convey to the public is that there is an extremely strong consensus amongst scientists regarding the science behind climate change. I think that, if anyone truly still believes that human-driven climate change is a contentious subject, they should reflect on the fact that 101 countries could all agree on a report that unequivocally states that this is the case.
Not only does the report's existence refute the idea that intergovernmental bodies are unable to make any progress, it is also a remarkable testament to the power of peer review. In my last post I gave an example of peer review that shows how it can be a time-consuming, unsatisfactory process for all involved. That was for a paper involving only five authors and three referees. The WGI report involved 259 authors covering 14 main chapters utilising 1,089 reviewers who gave 54,677 comments.
The summary of the report, the Summary for Policy Makers, contains only robust science, agreed upon by all the attendees as well as the relevant scientists. I have it on good authority that there was less political motivation involved than might be expected. Certain oil-producing countries did apparently make every effort to stress the uncertainties inherent in the science of the report. However, while this is presumably politically/economically motivated, it can only lead to more robust findings. These findings have been boiled down to a single page (well, two sides) of the headlines which are kept here but, in case that still seems like a bit much, the climate scientist Professor Thomas Stocker has boiled these down to three main messages
- The evidence for climate change is unequivocal
- The role of human influence in climate change is clear
- The limiting of climate change will require substantial carbon reductions
What this shows is how much warming we might expect (y-axis) as a function of how much CO2 eventually ends up in the atmosphere (x-axis). This is presented for multiple potential scenarios referred to as 'RCP's. 'RCP' stands for Representative Concentration Pathway and relates the emission of greenhouse gases to the 'radiative forcing' that would result from that emission. There's a pretty good summary with all the detail you could probably ask for here but I'm going to leave 'radiative forcing' very loosely defined here as the difference between the heat energy received by the Earth (from the Sun) and the amount of energy radiated back into space. In a system in equilibrium this would be zero, with no overall warming or cooling resulting. We know that this value is not zero for the Earth at the present time and that is why it is warming. What the different trajectories followed by the different RCPs can tell us is what the eventual extent of the warming will be. The RCPs can also allow us to plan our emissions so as to take this into account. For example, the Copenhagen Accord (2009) stated that a temperature rise of 2°C or above would lead to 'dangerous climate change'. Of our four presented RCPs, the only one which would allow us to stay below a rise of 2°C (by the year 2100) is the RCP2.6. It is pretty much accepted that this is not going to happen. To follow RCP2.6 all man-made carbon emissions would have to cease today, a scenario I think we can all agree is unlikely (I apologise if this is hyperbole or a gross oversimplification, I am attempting to keep things non-technical and reasonably concise). Further, if you're sharp-eyed you may notice that the RCP2.6 pathway on the inlaid plot in the above figure goes into negative numbers meaning that, not only would carbon emissions have to decrease substantially, we would have to actually start removing carbon from the atmosphere via carbon capture or geoengineering. Scenarios which are now reportedly accepted by those within the UK government.
At the other extreme is RCP8.5 pathway, generally known as the 'business as usual' pathway. This is the scenario under which we continue to burn fossil fuels with absolutely no mitigation whatsoever. As you can see from the plot, this would lead to the Earth exceeding the 2°C milestone in something like 25 years. Whether we even have the resources to continue burning fossil fuels at our current rate for that long is a separate question but, as oil and gas become more scarce, they become more expensive leading to the techniques used to acquire them becoming more cost-effective, fracking being a case in point.
While it is somewhat unsettling to accept that climate change is now unavoidable, even at dangerous levels, I have found that scientists in the field are, if not upbeat, then at least somewhat positive. This positivity appears to be more of a recent development and it appears to be due to the fact that governments are actually listening these days. The fact that the IPCC AR5 reports even exist are a testament to that. At the Met Office I have been pointed towards five key components of our communications regarding climate change
- Climate change is happening
- This is largely due to us
- Overall it will be bad
- Scientists overwhelmingly agree on above
- There are many things we can do about above and we're free to argue about what
The framing of climate change mitigation as 'affordable' and, more importantly, possible, may not place enough emphasis on the dangers of global warming and exaggerate our ability to deal with them. However, it does allow those in power to do something, which is always preferable to nothing.
