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Category Archives: uncertainty
Model projections of heavy precipitation and temperature extremes include large uncertainties. However, disagreement between individual simulations primarily arises from internal variability, whereas models agree remarkably well on the forced signal. Post based on Fischer et al., 2014, Geophys. Res. Lett.
Investigations into the recent observed slower rate of global warming have largely been focussed on variability in the Pacific basin. Climate models also show similar slowdowns focussed in the Pacific (e.g. Meehl et al. 2011). But, is this the only … Continue reading
Global surface air temperatures have risen less rapidly over the past 15 years than the previous few decades. The causes of this ‘hiatus’ have been much debated. However, just considering surface temperatures does not tell the whole story – a … Continue reading
A prevailing paradigm of how rainfall patterns will change on a warming Earth is that the hydrological cycle strengthens causing wet regions to get wetter and dry regions to get drier. However, this is not always the case: Hawkins, Joshi … Continue reading
How will UK summer temperatures change in future? And, how might we best communicate the possibilities? This is a short post describing one effort in visualising the possible outcomes.
As the attention received by the ‘global warming hiatus’ demonstrates, global mean surface temperature (T) variability on decadal timescales is of great interest to both the general public and to scientists. Here, I will discuss a recently published paper (Brown … Continue reading
A previous post discussed the recent Comment on Mora et al., which considered mainly methodological & statistical errors. However, the erroneous assumptions regarding uncertainty in the Mora et al. study have further implications for their results on population and income. … Continue reading
Yesterday saw the publication of our Comment on Mora et al., along with Mora et al.’s Reply and an associated ‘News & Views’ piece. Although the Editors deserve credit for commissioning a News & Views piece on this exchange – … Continue reading
Back in October 2013, Nature published an analysis by Camilo Mora et al. which discussed when ‘unprecedented climates’ would emerge, with a focus on regions of high biodiversity. The paper was highlighted by Nature with an associated News & Views … Continue reading
Ideally, we would have observations of past weather everywhere for several centuries to reconstruct the state of the atmosphere and learn about its variability. But, we don’t. Instead, all the observations ever taken would, ideally, be available digitally for everyone … Continue reading
Guest post by Piers Forster, with comments from Jonathan Gregory & Ed Hawkins Lewis & Crok have circulated a report, published by the Global Warming Policy Foundation (GWPF), criticising the assessment of equilibrium climate sensitivity (ECS) and transient climate response … Continue reading
Climate projections have demonstrated the need to adapt to a changing climate, but have been less helpful (so far) in guiding how to effectively adapt. Part of the reason is the ‘cascade of uncertainty’ going from assumptions about future global … Continue reading
The recent IPCC AR5 includes a discussion on the sources of uncertainty in climate projections (Fig. 11.8, section 184.108.40.206), 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 version of the IPCC AR5 WG1 assessment on the physical basis for climate change has now been published. The AR5 includes, for the first time, a specific chapter and assessment on ‘near-term’ climate change, which covers the period … 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.