From the University of Edinburgh , another one-paper syndrome in the making funded by an
NGO research council with a political mission to grab a headline. And, another poorly written press release where they don’t even cite the name of paper. Sigh.
Climate change has not been strongly influenced by variations in heat from the sun, a new scientific study shows
Climate change has not been strongly influenced by variations in heat from the sun, a new scientific study shows.
The findings overturn a widely held scientific view that lengthy periods of warm and cold weather in the past might have been caused by periodic fluctuations in solar activity.
Research examining the causes of climate change in the northern hemisphere over the past 1000 years has shown that until the year 1800, the key driver of periodic changes in climate was volcanic eruptions. These tend to prevent sunlight reaching the Earth, causing cool, drier weather. Since 1900, greenhouse gases have been the primary cause of climate change.
The findings show that periods of low sun activity should not be expected to have a large impact on temperatures on Earth, and are expected to improve scientists’ understanding and help climate forecasting.
Scientists at the University of Edinburgh carried out the study using records of past temperatures constructed with data from tree rings and other historical sources. They compared this data record with computer-based models of past climate, featuring both significant and minor changes in the sun.
They found that their model of weak changes in the sun gave the best correlation with temperature records, indicating that solar activity has had a minimal impact on temperature in the past millennium.
The study, published in Nature GeoScience, was supported by the Natural Environment Research Council.
Dr Andrew Schurer, of the University of Edinburgh’s School of GeoSciences, said: “Until now, the influence of the sun on past climate has been poorly understood. We hope that our new discoveries will help improve our understanding of how temperatures have changed over the past few centuries, and improve predictions for how they might develop in future. Links between the sun and anomalously cold winters in the UK are still being explored.”
I’m not so sure this fellow is fully versed on climatology. His papers up to 2011 were all about cosmology, then all of the sudden he starts publishing on climatology issues. One wonders if his previous funding dried up to make such a dramatic shift in study. Then there is: “…climatic fingerprints of high and low solar forcing derived from model simulations…”. IPCC Models haven’t been able to reproduce the last ten years; what makes them think they are worth anything 100-200 years ago?
Here is the abstract: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2040.html
Small influence of solar variability on climate over the past millennium
- Nature Geoscience (2013) doi:10.1038/ngeo2040
- Received 02 August 2013 Accepted 14 November 2013 Published online 22 December 2013
The climate of the past millennium was marked by substantial decadal and centennial scale variability in the Northern Hemisphere1. Low solar activity has been linked to cooling during the Little Ice Age (AD 1450–1850; ref. 1) and there may have been solar forcing of regional warmth during the Medieval Climate Anomaly2, 3, 4, 5 (AD 950–1250; ref. 1). The amplitude of the associated changes is, however, poorly constrained5, 6, with estimates of solar forcing spanning almost an order of magnitude7, 8, 9. Numerical simulations tentatively indicate that a small amplitude best agrees with available temperature reconstructions10, 11, 12, 13. Here we compare the climatic fingerprints of high and low solar forcing derived from model simulations with an ensemble of surface air temperature reconstructions14 for the past millennium. Our methodology15 also accounts for internal climate variability and other external drivers such as volcanic eruptions, as well as uncertainties in the proxy reconstructions and model output. We find that neither a high magnitude of solar forcing nor a strong climate effect of that forcing agree with the temperature reconstructions. We instead conclude that solar forcing probably had a minor effect on Northern Hemisphere climate over the past 1,000 years, while, volcanic eruptions and changes in greenhouse gas concentrations seem to be the most important influence over this period.
Figure 1: Simulations and temperature reconstructions.
a, Simulations with all forcings (red and green) compared with a reconstruction ensemble14 (blue), and instrumental HadCRUT4 (ref. 24) time series (centred on the average reconstruction over time of overlap, black).
The SI is here: http://www.nature.com/ngeo/journal/vaop/ncurrent/extref/ngeo2040-s1.pdf
h/t to Dr. Leif Svalgaard