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Author Archives: Ed Hawkins
Nice climate figures
“A picture is worth a thousand words”, says the popular adage. It is something that we, as climate scientists, should take seriously, especially given the vast quantities of literature we might read through.
Posted in Uncategorized
2 Comments
On comparing models and observations
There has been some recent blog discussion on comparing observations and climate models consistently. Here is my effort at such a comparison using the CMIP5 models which are already available.
Posted in Uncategorized
88 Comments
The value of old weather observations
Previous posts have described some initial analysis of the data from the Old Weather project, which is using public volunteers to digitise new historical weather observations from Royal Navy ships during World War 1. The good news is that these … Continue reading
Posted in Uncategorized
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Reconstructing Atlantic atmospheric variability
In a previous post I discussed the Old Weather project which is using volunteers to transcribe the hand-written weather data from Royal Navy ships logs in the World War 1 period. The good news is the first 243 ships have … Continue reading
Posted in Atlantic, history, variability, weather
4 Comments
The importance of reliable uncertainty estimates
Reliable estimates of uncertainty are arguably more important than the actual value being quoted. I recently came across a classic example in astronomy.
Posted in uncertainty
14 Comments
Time of emergence of climate signals
The time at which the signal of climate change emerges from the ‘noise’ of natural climate variability (Time of Emergence, ToE) is a key variable for climate predictions and risk assessments.
Posted in GCMs, temperature, uncertainty, variability
2 Comments
Uncertainty in temperature variability
It is well known that there is considerable uncertainty in the projected response of climate models to increases in radiative forcing. However, there is also considerable uncertainty in the model simulated internal variability.
Posted in GCMs, temperature, uncertainty, variability
1 Comment
Climate uncertainty: moving from ‘what’ to ‘when’
Update (23/10/11): The full article has now been published in Nature Climate Change Climate projections (such as from the IPCC) usually consider the question of “what will happen to our future climate”. But, this question may be more informative if … Continue reading
Posted in GCMs, projections, temperature, uncertainty
7 Comments
Uncertainty in uncertainty
There has been much discussion recently on whether GCMs participating in intercomparisons, such as CMIP3 and CMIP5, are ‘independent’. But if they are not, how does this make a difference to the uncertainty in our projections for future climate?
Posted in GCMs, projections, temperature, uncertainty
3 Comments
Trends in Central England Temperature
Previous posts have discussed climate variability in general, and modelled decadal trends in temperature specifically. However, I should have considered decadal trends in observations as well, especially as there is a long temperature record available for the UK.
Posted in GCMs, temperature, variability
4 Comments
Visualising climate with 2d colour bars
A recent paper by Teuling et al. suggested the use of 2d colour bars for visualising climate fields. I thought I would give this a try – and Ryan Teuling was kind enough to provide the code to construct the … Continue reading
Posted in precipitation, projections, uncertainty, visualisation
1 Comment
Learning about past climate from ships logs
Understanding the climate of the past is extremely valuable to help put modern weather observations into a long-term context. Although we have considerable records of past weather, especially over land, more data is always welcome. Given the British obsession with … Continue reading
Posted in Arctic, history, sea-ice, variability, weather
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When to use uncertain climate forecasts
Climate models produce projections of changes in climate from the present day, but these projections have a range, or spread. A simple measure of the confidence in a forecast would be the signal-to-noise ratio, r, of the size of the … Continue reading
Posted in GCMs, precipitation, projections, uncertainty
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What is a year?
A rather surprising question perhaps, but the answer is, ‘it depends’. There is no climatic reason to define a year from January to December, but that is what is generally done. But, is this the best definition?
Posted in SSTs, temperature, variability
3 Comments
Hysteresis of the Atlantic MOC in an AOGCM
UPDATE (16/06/11) – the paper describing this work has now been published and highlighted. The potential for a rapid collapse in the strength of the Atlantic overturning circulation (AMOC) has long been recognised. The pioneering work of Stommel first suggested … Continue reading
Posted in Atlantic, GCMs, hysteresis, MOC
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Arctic predictability
After attending a recent workshop on Arctic predictability, I thought a brief discussion on sea-ice variability and potential predictability might be of interest.
Posted in Arctic, GCMs, predictability, sea-ice, SSTs, variability
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A brief history of early climate science
Something a little bit different for this post…. After all the recent controversy over hacked emails, IPCC errors and the British public apparently growing more skeptical about climate science and scientists, it is perhaps interesting to take a step back … Continue reading
Posted in history
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Atlantic multi-decadal variability
Observations of Atlantic SSTs show significant multi-decadal variability since 1870 (see red line in figure 2 below), often termed the Atlantic Multi-Decadal Oscillation (AMO), though there is no clear evidence that it is really an ‘oscillation’.
Posted in Atlantic, GCMs, SSTs, variability
2 Comments
Communicating climate variability
Update 10/03/11 – Accepted article also online. Comments very welcome. Communicating the differences and links between climate variability and climate change is of growing importance, and I am currently writing an article for “Weather” on this.
Posted in GCMs, projections, temperature, uncertainty, variability
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Consensus in precipitation projections
In the AR4, the IPCC presented this figure showing the consensus in precipitation projections for the 21st century, designed to be of use to planning for adaptation and mitigation. The coloured regions show where changes are likely to occur. My … Continue reading
Posted in GCMs, precipitation, projections, variability
2 Comments
Global mean temperature variability in observations and GCMs
I am often surprised at how different climate models can be. Shown below is the annual mean, global mean surface air temperature from control runs of 21 of the AR4 GCMs, along with the observations (HadCRUT3). The spread in the magnitude of variability is enormous, as seen by eye, but also the timeseries have very different ‘memory’ characteristics. Continue reading
Posted in GCMs, temperature, variability
1 Comment