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Category Archives: uncertainty
The recent IPCC AR5 includes a discussion on the sources of uncertainty in climate projections (Fig. 11.8, section 126.96.36.199), which updates previous analyses using CMIP3 (temperature, precipitation) to the latest CMIP5 simulations. The dominant source of uncertainty depends on lead … Continue reading
The ‘signal’ of a warming climate is emerging against a background ‘noise’ of natural internal variability. Both the magnitude of the signal and the noise vary spatially and seasonally. As society and ecosystems tend to be somewhat adapted to natural … Continue reading
The final draft chapters of the IPCC AR5 WG1 assessment on the physical basis for climate change have now been published. The AR5 includes, for the first time, a specific chapter and assessment on ‘near-term’ climate change, which covers the … Continue reading
What are the possible regional temperature trends over the coming few decades? Globally, on average, there is expected to be a long-term warming, but this is not necessarily true for any particular location or period. What are the probabilities of … Continue reading
The Science Media Centre recently held a briefing for journalists on the recent slowdown in global surface temperature rise, and published an accompanying briefing note. The Met Office also released three reports on the topic. The key points were: (1) … Continue reading
The recent WMO press release on the climate of the 2001-2010 period highlighted that global temperature change was accelerating. Although this could be a misleading statement, should we even be expecting global temperature changes to be accelerating at present?
A recent comparison of global temperature observations and model simulations on this blog prompted a rush of media and wider interest, notably in the Daily Mail, The Economist & in evidence to the US House of Representatives. Given the widespread … Continue reading
Climate information for the future is usually presented in the form of scenarios: plausible and consistent descriptions of future climate without probability information. This suffices for many purposes, but for the near term, say up to 2050, scenarios of emissions … Continue reading
Can past observations be used to help constrain future temperature projections? This question is particularly relevant given the last decade which has shown relatively less warming than expected.
Now that 2012 is over, it is time to update a comparison of simulations and observations of global mean temperatures.
A new analysis by Clara Deser and colleagues (accepted for Nature Climate Change), provides some fantastic visualisations of the crucial role of natural variability in how we will experience climate.
A rather specific question today – what will happen to maize yields in France in 2016-2035?
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.
Reliable estimates of uncertainty are arguably more important than the actual value being quoted. I recently came across a classic example in astronomy.
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.
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.
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
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?
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
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
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.