Section 4.1 Making Future Projections - video
I enjoyed this video of Prof. Peter Cox wandering around the Met Office buildings - where I work!
Key points:
- Similar models are used for forecasting weather and climate - but climate models run over longer time-periods, so different effects (which last over longer time-periods) will play a greater part in modeling the climate rather than predicting the weather.
- These effects include changes to ocean current flows and the change in rates at which the oceans and plants absorb carbon.
- Fingerprinting - is the term for attributing effects to contributions to observations.
- We can have confidence in the validity of the models by seeing how well they coincide with the observation record.
- When forecasting though, this is more difficult because there are still lots of unknown effects that are difficult to model - such as how the carbon sinks effectiveness may change.
- Scenarios are defined to show how human activity may change in the future, such as different rates of population growth and how much CO2 we release - models are then run against these scenarios and the amount of global warming is predicted based on these scenarios.
- I think the use of scenarios is a key point for me, until recently I'd assumed climate models were producing actual forecasts over long time-scales (possibly with different components being includes). When in fact things like the amount of CO2 being put into the atmosphere is not predictable either - it's down to things like the economic cycle, and how we behave as a species going forward. So climate models aren't producing forecasts, they're looking at the effect of different scenarios.
Section 4.2 How much more will the Earth warm - article
A good article on different types of feedbacks and scenarios.
Key points for me:
- I always though more warming would lead to more low level clouds due to more water vapour being present, and this would further contribute to warming as low level cloud would have a blanket effect (compare night-time temperatures when low level cloud isn't present). However this article says low level cloud is close in temperature to the surface temperature, and hence doesn't really effect the overall balance whether they are present or not, due to them re-emitting a similar amount of energy to the surface (similar temperature). But in some parts of the globe, they re-emit energy into abundant water vapour above them, so the energy is absorbed here.
- I always thought high-level clouds contributed to global cooling because they help increase the albedo and reflect radiation back into space. This article says they absorb heat from lower in the atmosphere (that would otherwise escape from the atmosphere), but re-emit less due to their lower temperature, hence contributing to global warming.
- Clouds are confusing and their net effect is difficult to model! I need to think about them a bit more.
Section 4.3 (Optional Step) Run your own climate model - article
- Climate prediction website here
- Alternative Java Climate Model here
- Prof. Peter Cox provided some problems, excel model, and answers.
This all looks really good, but quite time-consuming, and I feel I'm behind schedule again, so I'll move swiftly on to...
Section 4.4 IPCC Fifth Assessment Report - discussion
Read this press release from the 30th January 2014 (topical or what?) from the IPCC Fifth Assessment Report.
Wow, this strikes me as a strongly worded statement about the increasing confidence in the attribution of global warming to human activity and greenhouse gases - phrases such as extremely likely and very high confidence are used at various points.
The discussion point though is "Does the recent change in global temperatures reflect the predictions of climate models?" - the relevent section of the release says that:
"Climate models have improved since the AR4. Models reproduce observed continental-scale surface temperature patterns and trends over many decades, including the more rapid warming since the mid-20th century and the cooling immediately following large volcanic eruptions (very high confidence).
Observational and model studies of temperature change, climate feedbacks and changes in the Earth’s energy budget together provide confidence in the magnitude of global warming in response to past and future forcing."
This article from the Skeptical Science website is rather good for answering the question How reliable are climate models? http://www.skepticalscience.com/climate-models-intermediate.htm
And someone else on the course has done a lot more homework than me http://takvera.blogspot.co.uk/2014/02/exclimate-are-recent-global.html
Section 4.5 The Geoengineering Dilemma - video
Prof. Jim Heywood introduces us to "Geoengineering".
Main points:
There are also links provided to two more articles:
Section 4.6 Are ideas to cool the planet realistic? - article
Nice little article, I like the quadrant chart showing potential effectiveness versus costs of different solutions.
Section 4.7 Should we geoengineer our climate? - discussion
A link to another article on the BBC website: Geoengineering: Risks and benefits
Q. What is your view on geoengineering? Should it be used to prevent our planet warming?
A. Having read the articles above, my initial reaction is that these methods are in the realms of fanciful science fiction and wouldn't actually solve the problem anyway. I think limited local carbon capture might work as part of an overall carbon emission reduction strategy but there is no "geoengineering silver bullet". There seems to be an interesting debate around the ethics of research into geoengineering - some people find the idea of deployment morally repugnant, and conclude that therefore research shouldn't take place. This strikes me as a rather dogmatic approach, and no area of potentially useful knowledge should, in my opinion, be considered "off limits". However, there is the valid point that the existence of research into geoengineering distracts the eye from the main issue, which is the rising rate of CO2 emission, and we should be focussing our main efforts on collectively reducing these emissions. I think the research should take place, but in a limited way appropriate to the anticipated benefits. I'm wary of widespread deployment of these techniques, as it seems that they introduce lots of risk and the consequences of which may not be entirely predictable - the idea that engineering our climate would have some direct "winners and losers" makes it a very contentious approach to attempt.
Section 4.8 Test
13 out of 15 this week - Gah! got the number of grid boxes in the Hadley Centre coupled model version 3 wrong - not really convinced that demonstrates a greater or lesser level of understanding of the subject. And I needed a second go at answering how far back in time does the validation of climate models run to check the modelled climate matches that of the past? I assumed the point of paleoclimate modelling is to validate our understanding of climate models and feedback mechanisms!
Section 4.9 Reflect
So the main themes this week were climate models are validated and checked, and account for most things we have been able to observe. The second half was about geoengineering, about which I had no previous knowledge. That was all new to me, and very interesting.
I've skipped the running your own model step, but have made a note of the resource URLs and would hope to revisit those pages at a later date.
I think I'm going to make a habit of visiting of the Skeptical Science and Real Climate websites to stay informed about the on-going debates.
Observational and model studies of temperature change, climate feedbacks and changes in the Earth’s energy budget together provide confidence in the magnitude of global warming in response to past and future forcing."
This article from the Skeptical Science website is rather good for answering the question How reliable are climate models? http://www.skepticalscience.com/climate-models-intermediate.htm
And someone else on the course has done a lot more homework than me http://takvera.blogspot.co.uk/2014/02/exclimate-are-recent-global.html
Section 4.5 The Geoengineering Dilemma - video
Prof. Jim Heywood introduces us to "Geoengineering".
Main points:
- There are two approaches to mitigating the effect of greenhouse gas emissions - CO2 removal mechanisms and solar radiation management. One seeks to remove CO2 from the atmosphere, the other to reflect more of the suns energy back out to space.
- With CO2 removal mechanisms you need to ensure you expend significantly less CO2 in the activity than you remove in order to make an impact. The best bet seems to be biofuel burning with carbon capture. I was interested to learn that half the turbines at the DRAX power station have been converted to burn bio-fuel. Bio-fuel creation also competes with food production on the same land.
- Solar radiation management introduces small particles into clouds to make them brighter and more reflective. This already happens on a small scale due to pollution from ships creating "ship tracks" above the ocean.
- Any approach taken to geoengineer the climate introduces risk - one, doing it in one hemisphere or the other may cause the tropical rain bands to move - creating droughts in some areas. Failure, or an inability to sustain the geoengineering methods may lead to a sudden jump in global temperature which would be harder to adapt to. The social consequences of these actions would be hard to predict.
- Any geoengineering done would only reduce the impact of global warming unless it could extract more CO2 from the atmosphere than all our activities across the planet add to it.
There are also links provided to two more articles:
- Why we'd be mad to rule out climate engineering
- Why has geoengineering been legitimised by the IPCC?
Section 4.6 Are ideas to cool the planet realistic? - article
Nice little article, I like the quadrant chart showing potential effectiveness versus costs of different solutions.
Section 4.7 Should we geoengineer our climate? - discussion
A link to another article on the BBC website: Geoengineering: Risks and benefits
Q. What is your view on geoengineering? Should it be used to prevent our planet warming?
A. Having read the articles above, my initial reaction is that these methods are in the realms of fanciful science fiction and wouldn't actually solve the problem anyway. I think limited local carbon capture might work as part of an overall carbon emission reduction strategy but there is no "geoengineering silver bullet". There seems to be an interesting debate around the ethics of research into geoengineering - some people find the idea of deployment morally repugnant, and conclude that therefore research shouldn't take place. This strikes me as a rather dogmatic approach, and no area of potentially useful knowledge should, in my opinion, be considered "off limits". However, there is the valid point that the existence of research into geoengineering distracts the eye from the main issue, which is the rising rate of CO2 emission, and we should be focussing our main efforts on collectively reducing these emissions. I think the research should take place, but in a limited way appropriate to the anticipated benefits. I'm wary of widespread deployment of these techniques, as it seems that they introduce lots of risk and the consequences of which may not be entirely predictable - the idea that engineering our climate would have some direct "winners and losers" makes it a very contentious approach to attempt.
Section 4.8 Test
13 out of 15 this week - Gah! got the number of grid boxes in the Hadley Centre coupled model version 3 wrong - not really convinced that demonstrates a greater or lesser level of understanding of the subject. And I needed a second go at answering how far back in time does the validation of climate models run to check the modelled climate matches that of the past? I assumed the point of paleoclimate modelling is to validate our understanding of climate models and feedback mechanisms!
Section 4.9 Reflect
So the main themes this week were climate models are validated and checked, and account for most things we have been able to observe. The second half was about geoengineering, about which I had no previous knowledge. That was all new to me, and very interesting.
I've skipped the running your own model step, but have made a note of the resource URLs and would hope to revisit those pages at a later date.
I think I'm going to make a habit of visiting of the Skeptical Science and Real Climate websites to stay informed about the on-going debates.
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