From the University of Edinburgh:
Warming slow-down not the end of climate change, study shows
A slow-down in global warming is not a sign that climate change is ending, but a natural blip in an otherwise long-term upwards trend, research shows.
In a detailed study of more than 200 years’ worth of temperature data, results backed previous findings that short-term pauses in climate change are simply the result of natural variation.
The findings support the likelihood that a current hiatus in the world’s year-on-year temperature increases – which have stalled since 1998 – is temporary.
Scientists from the University of Edinburgh analysed real-world historic climate records from 1782 to 2000, comparing them with computerised climate models for the same timescale.
They were able to separate the influence on climate trends of man-made warming – such as from greenhouse gas emissions – and of natural influences in temperature – such as periods of intense sunlight or volcanic activity.
This showed that random variations can cause short term interruptions to climate patterns in the form of a pause or surge in warming, in both the real data and in the models, typically lasting up to a decade. Extreme natural forces, such as strong volcanic eruptions, were shown to disrupt climate trends for decades.
The research highlights the impact of volcanic eruptions on climate, when particles produced can reflect sunlight from Earth, causing long-lasting cooling. The eruption of Mount Tambora in Indonesia in 1815 was among the biggest in recent times, causing a so-called year without summer. Scientists estimate that, if it occurred today, it would cause a 20-year climate hiatus.
Their study, published in Geophysical Research Letters, was supported by the European Commission.
Dr Andrew Schurer, of the University of Edinburgh’s School of GeoSciences, who led the research, said: “Human activity is causing the word to warm, and natural variability can cause this trend to slow down or speed up. Our study backs scientific understanding that climate change can experience periods of hiatus, but the overall trend is towards a warmer planet.”
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This has to qualify as one of the worst press releases we’ve ever seen via Eurekalert. The don’t give the name of the paper, the DOI, or any links to it. We are required to look it up, because, you know, these people are just too busy saving the world to stoop to such serf-like tasks.
Determining the likelihood of pauses and surges in global warming
Andrew P. Schurer, Gabriele C. Hegerl and Stephen P. Obrochta
http://onlinelibrary.wiley.com/doi/10.1002/2015GL064458/full
Abstract
The recent warming “hiatus” is subject to intense interest, with proposed causes including natural forcing and internal variability. Here we derive samples of all natural and internal variability from observations and a recent proxy reconstruction to investigate the likelihood that these two sources of variability could produce a hiatus or rapid warming in surface temperature. The likelihood is found to be consistent with that calculated previously for models and exhibits a similar spatial pattern, with an Interdecadal Pacific Oscillation-like structure, although with more signal in the Atlantic than in model patterns. The number and length of events increases if natural forcing is also considered, particularly in the models. From the reconstruction it can be seen that large eruptions, such as Mount Tambora in 1815, or clusters of eruptions, may result in a hiatus of over 20 years, a finding supported by model results.
Key Points
- The recent hiatus is not unusual in the context of the last 230 years
- Models agree with observations regarding likelihood and pattern of events
- Likelihood increases if natural forcings (e.g., volcanic) are also considered
Figures as they were provided in the preview, no captions given.
I’d tend to believe them more if they could actually show a Tambora style eruption that has occurred in the last 15-20 years, and also explain why the effect of Pinatubo was so short lived if in fact volcanoes are affecting global climate as they say.
I think Willis does a far better job of explaining it here: http://wattsupwiththat.com/2013/05/25/stacked-volcanoes-falsify-models/
