We’ve heard this before
Posted on May 12, 2011 by Anthony Watts
National Academy of Sciences :
Action needed to manage climate change risks — new report
WASHINGTON — Warning that the risk of dangerous climate change impacts is growing with every ton of greenhouse gases emitted into the atmosphere, a National Research Council committee today reiterated the pressing need for substantial action to limit the magnitude of climate change and to prepare to adapt to its impacts.
The nation’s options for responding to the risks posed by climate change are analyzed in a new report and the final volume in America’s Climate Choices, a series of studies requested by Congress. The committee that authored the report included not only renowned scientists and engineers but also economists, business leaders, an ex-governor, a former congressman, and other policy experts.
“The goal of the America’s Climate Choices studies is to ensure that climate decisions are informed by the best possible scientific knowledge, analysis, and advice, both now and in the future,” said committee chair Albert Carnesale, chancellor emeritus and professor, University of California, Los Angeles.
The new report reaffirms that the preponderance of scientific evidence points to human activities — especially the release of carbon dioxide and other greenhouse gases into the atmosphere — as the most likely cause for most of the global warming that has occurred over the last several decades. This trend cannot be explained by natural factors such as internal climate variability or changes in incoming energy from the sun. The report adds that the impacts of climate change on human and natural systems can generally be expected to intensify with warming.
“The new report reaffirms that the preponderance of scientific evidence points to human activities — especially the release of carbon dioxide and other greenhouse gases into the atmosphere — as the most likely cause for most of the global warming that has occurred over the last several decades.”
What evidence? What warming over the most recent decade?
This trend cannot be explained by natural factors such as internal climate variability or changes in incoming energy from the sun.
New solar reconstruction paper suggests 6x greater solar forcing change than cited by the IPCC
Posted on May 10, 2011 by Anthony WattsThis is interesting. This recent paper published in the journal Astronomy & Astrophysics here has done a reconstruction of TSI using Beryllium 10 isotope records combined with sunspot records. The paper suggests that the Total Solar Irradiance (TSI) has increased since the end of the Little Ice Age (around 1850) by up to 6 x more than cited by the IPCC.
Modulation potential (lower panel) and TSI reconstructions (upper panel) for the last 2500 years. Data prior to 1600 AD are based on the modulation potential derived from 10Be records from the Greenland Ice core Project (red curves). Data since 1600 AD are based on the two composites shown in Fig. 1 (red and cyan curves). The grey-shaded area indicates the intrinsic uncertainty.WUWT
6 X 0.12 = 0.72
What happens if we shift 0.6 wm-2 from anthropogenic forcing to natural forcing?
This makes the natural and anthropogenic forcing about equal… It also shows that the error bar of the anthropogenic forcing is larger than the forcing. Bear in mind that the IPCC also does not realize that most of the CO2 rise since 1700 is the result of oceanic outgassing associated with the warm-up from the Little Ice Age. So the potential anthropogenic forcing is more like 1/4 (or less) of the total forcing.
The Shapiro et al., 2011 TSI reconstruction correlates quite well with Ljungqvist’s 2010 Northern Hemisphere climate reconstruction…
Note that the sharp solar minima in ca. 700 AD and ca. 1400 AD were associated with the Dark Ages Cold Period and Little Ice Age. This fits in quite well with the overwhelming evidence of a Holocene millennial-scale climate cycle. It would also suggest that the mild climate conditions of the Modern Warming will begin to deteriorate by the end of the 21st century.