Category Archives: projections

Projected changes of precipitation and temperature extremes

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.

Posted in extremes, precipitation, projections, temperature, uncertainty, variability | Leave a comment

Wet get drier (eventually)?

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

Posted in GCMs, precipitation, projections, uncertainty | 3 Comments

Visualising UK summer temperatures – what are the odds?

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.

Posted in observations, projections, temperature, uncertainty, variability, visualisation | 8 Comments

More Mora emergence issues

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

Posted in emergence, GCMs, projections, uncertainty, variability | 2 Comments

Uncertainties in the timing of unprecedented climates

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

Posted in emergence, GCMs, IPCC AR5, projections, temperature, uncertainty, variability | 11 Comments

Comments on the GWPF climate sensitivity report

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

Posted in climate sensitivity, GCMs, IPCC AR5, observations, projections, temperature, uncertainty | 223 Comments

The cascade of uncertainty in climate projections

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

Posted in projections, temperature, uncertainty, variability, visualisation | 11 Comments

The future of the slowdown

Imagine it is 2031, and the IPCC is preparing to release its 8th Assessment Report. How does the recent slowdown in global mean surface temperature rise look? As this largely depends on how fast the climate warms from 2014 onwards, … Continue reading

Posted in observations, projections, temperature, visualisation | 25 Comments

The future of white Christmases

It’s December, which means the usual discussion as to whether or not it will be a white Christmas. You can even bet on it. But, how might these odds change in future? Are children going to know what snow is?

Posted in projections, variability, weather | 2 Comments

Updates to comparison of CMIP5 models & observations

As 2013 is nearly over, it is time for a short update to the comparisons of CMIP5 models and observations for global mean surface air temperatures. Part of the motivation for an update is the Cowtan & Way paper on … Continue reading

Posted in IPCC AR5, projections, temperature | 7 Comments

Effects of recent observed vs RCP forcings

The recent global temperature hiatus has been explained by the IPCC AR5 as partly due to natural radiative forcings (solar & volcanic effects) and internal variability. Recently, other effects such as CFCs and biases in the observational coverage have also … Continue reading

Posted in GCMs, projections, temperature | 4 Comments

Sources of uncertainty in CMIP5 projections

The recent IPCC AR5 includes a discussion on the sources of uncertainty in climate projections (Fig. 11.8, section 11.3.1.1), which updates previous analyses using CMIP3 (temperature, precipitation) to the latest CMIP5 simulations. The dominant source of uncertainty depends on lead … Continue reading

Posted in GCMs, IPCC AR5, projections, temperature, uncertainty, variability, visualisation | 13 Comments

Time of emergence of a warming signal

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

Posted in emergence, GCMs, IPCC AR5, projections, temperature, uncertainty | 11 Comments

Near-term global surface temperature projections in IPCC AR5

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

Posted in IPCC AR5, projections, temperature, uncertainty, variability | 25 Comments

Near-term regional climate: the range of possibilities

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

Posted in GCMs, projections, temperature, uncertainty, variability, visualisation | 12 Comments

Rates of change in global temperatures

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?

Posted in GCMs, observations, projections, temperature, uncertainty, variability | 6 Comments

Comparing global temperature observations and simulations, again

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

Posted in observations, projections, temperature, uncertainty, variability | 45 Comments

Reliability of regional climate trends

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

Posted in GCMs, observations, projections, temperature, uncertainty, variability | 4 Comments

Constraining projections with observations

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.

Posted in GCMs, observations, projections, temperature, uncertainty | 17 Comments

Updated comparison of simulations and observations

Now that 2012 is over, it is time to update a comparison of simulations and observations of global mean temperatures.

Posted in GCMs, observations, projections, temperature, uncertainty | 54 Comments

Visualising the role of natural variability

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.

Posted in GCMs, projections, temperature, uncertainty, variability, visualisation | 20 Comments

Global temperatures over the past decade

It is well known that the past decade or so has seen less global warming than might have been expected – but what is the cause? This is more of a discussion post, rather than any new analysis.

Posted in GCMs, projections, temperature, variability | 31 Comments

Projections of maize yields in France

A rather specific question today – what will happen to maize yields in France in 2016-2035?

Posted in crops, precipitation, projections, temperature, uncertainty, variability | 5 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 GCMs, projections, uncertainty, variability | 98 Comments

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 | 8 Comments