Summary of Nir Shaviv: Cosmic rays and climate | Tom Nelson Pod #138

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00:00:00 - 01:00:00

Professor Nir Shaviv discusses his research on the link between cosmic rays and climate. He explains that variations in cosmic ray flux, due to our galactic environment, have been found to affect Earth's climate. By studying geological evidence and comparing it to cosmic ray flux variations, he concludes that higher cosmic ray flux has been associated with periods of climate change on Earth. Shaviv also notes that solar activity plays a role in modulating the flux of cosmic rays reaching Earth, and this link between solar activity and climate variations can be quantified. He argues that the sun's significant effect on climate is being overlooked by mainstream climate science.

00:00:00 In this section, Professor Nir Shaviv discusses his research on the link between cosmic rays and climate. He explains that long-term variations in cosmic ray flux, due to our galactic environment, have been found to affect Earth's climate. By studying geological evidence and comparing it to cosmic ray flux variations, he concludes that higher cosmic ray flux has been associated with periods of climate change on Earth. Shaviv also notes that solar activity plays a role in modulating the flux of cosmic rays reaching Earth, and this link between solar activity and climate variations can be quantified. He mentions that there is an amplification mechanism at work that cannot be solely explained by changes in radiance, and the microphysical processes responsible for this mechanism have been identified through lab experiments. Shaviv confidently asserts that the sun's significant effect on climate is being overlooked by mainstream climate science.
00:05:00 In this section, we learn that cosmic rays can be measured directly since the 1930s, but for longer time scales and to reconstruct variations, proxies are used. Proxies include measuring isotopes like carbon-14 or beryllium-10 in things such as tree rings, ice cores, and meteorites. By measuring the radioactive or stable isotopes, scientists can deduce the cosmic ray flux at different points in time. Additionally, by analyzing multiple meteorites statistically, scientists can determine the constant rate at which they break apart, allowing for the reconstruction of cosmic ray flux.
00:10:00 In this section, Dr. Nir Shaviv discusses the correlation between cosmic ray data and observed temperature data. He explains that understanding 20th-century temperature variations requires taking into account various factors, such as anthropogenic greenhouse gases and solar variability. Simply correlating temperature with these drivers does not capture the complexity of the climate system, which has a large heat capacity and involves processes like heat absorption and re-emission by the oceans. Dr. Shaviv suggests that between half and two-thirds of the warming over the 20th century can be explained by variations in solar activity, including cosmic ray variations. He also mentions that solar selectivity has decreased since the 1990s, yet temperatures have continued to rise, indicating that the sun's influence cannot be disregarded. Furthermore, he emphasizes that the climate system is not a simplistic cause-and-effect relationship and should not be reduced to a linear correlation.
00:15:00 In this section, the speaker discusses the relationship between sunshine, temperature, and the role of the sun in climate change. They point out that despite receiving less sunshine from June to August, it often feels hotter during this time. This suggests that factors other than sunlight may be responsible for the warming. They emphasize that predicting the behavior of the sun is challenging due to its chaotic nature, making it difficult to project future temperatures. However, they note that the sun has been exceptionally active in recent years, and if anything, its contribution to climate change may decrease in the future. They also mention that doubling the amount of CO2 should lead to a warming of around one to one and a half degrees, which aligns with empirical evidence when considering the sun's impact. Overall, they argue that climate sensitivity, or the degree of temperature increase due to CO2 doubling, is likely between one and one and a half degrees.
00:20:00 In this section, Nir Shaviv discusses the impact of solar activity on climate change and how it affects the mainstream climate community's perspective. He argues that ignoring the effects of the sun would require a larger climate sensitivity hypothesis, but if the sun's increased activity is considered, a smaller climate sensitivity would be needed to explain the same level of warming. Shaviv predicts that as clean and cost-effective nuclear power becomes more prevalent, there will be a switch away from CO2 emissions, limiting future temperature increases to around half a degree. He also explains how cosmic rays, modulated by solar activity, can explain historical temperature variations like the Minoan and Roman warm periods. Furthermore, he mentions that on longer timescales, changes in cosmic rays can occur due to our solar system's movement through the spiral arms, as well as a 32 million-year oscillation associated with the solar system's vertical motion perpendicular to the galactic plane.
00:25:00 In this section, Nir Shaviv discusses statistical significance and the variation in temperature data. He explains that the oscillation in temperature aligns with the proximity to the galactic plane and the period modulation expected from the solar system's orbit. This galactic motion is evident in the cosmic ray flux and climate patterns over long timescales. Shaviv acknowledges that other factors, such as atmospheric composition, also impact climate, but the galactic motion accounts for more than half of the variance. However, he is unsure about the specific cycles mentioned by Carl Otto Weiss in his podcast, noting that the milankovic cycles are the commonly accepted explanation for variations on tens of thousands to 100,000-year timescales.
00:30:00 In this section, the speaker discusses the dominant cycles in climate change over hundreds of thousands of years, noting that the change in eccentricity plays a significant role. There is no observed relationship between solar activity and volcanic or geological activity on Earth. The speaker explains that the distance between the Earth and the Sun does not change significantly enough to cause any climate variations. They also mention their collaboration with Henrik Svensmark and hint at a potential upcoming movie. When asked about the biggest errors made by other skeptics in the climate debate, the speaker points out that some people falsely claim that CO2 has no effect on the energy budget, which is incorrect given evidence of the greenhouse effect. However, there are reasons to believe that the radiative forcing of CO2 could be somewhat less than what is currently estimated. They highlight the lack of correlation between CO2 and temperature, noting that variations in CO2 levels throughout history have not directly influenced climate.
00:35:00 In this section, Dr. Nir Shaviv discusses the increase in solar flux over the past four billion years, which cancels out the variations that CO2 has on temperature. He also highlights some common mistakes made by both skeptics and mainstream climate researchers, such as not taking into account heat capacity and using simplistic models to correlate temperature with different drivers. He mentions that there are very few researchers working on cosmic rays due to the difficulty of obtaining funding and publishing in the field. Additionally, he explains that short-term variations in cosmic ray activity are not his focus, but he discusses how changes in solar activity can impact temperature variations over longer time scales. Finally, he mentions the link between cosmic rays and atmospheric aerosols, which affect the formation of cloud condensation nuclei.
00:40:00 In this section, the speaker explains that variations in the cosmic ray flux can influence cloud characteristics and ultimately affect climate. They discuss how changes in cloud cover and reflectivity can lead to cooling or warming effects. The speaker also mentions different time scales, such as short-term fluctuations and long-term variations, where solar activity and climate show correlations. The connection between the solar cycle and cloud cover is highlighted, with the observation that the polarity of the sun's magnetic field switches every 11 years.
00:45:00 In this section, the speaker explains how cosmic rays and their interaction with the sun can influence climate. They mention that the odd and even cycles of the sun's activity do not look the same, and the flux of cosmic rays during solar minimum is sharp in one polarity and smooth in another. This behavior is also observed in cloud cover, indicating a correlation between cosmic rays and cloud formation. Additionally, the speaker discusses the microphysical effects of cosmic rays on aerosol nucleation and growth. Theoretical understanding, empirical evidence, and laboratory experiments support the role of cosmic rays in climate change. However, the speaker points out that people are reluctant to accept this connection because it challenges the prevailing idea of global warming and the sensitivity of climate to greenhouse gases. The possibility of electrical charge affecting weather phenomena and rain falling faster than terminal velocity is briefly mentioned, but the speaker notes that they have not studied this specifically.
00:50:00 In this section, Nir Shaviv discusses the correlation between solar activity and the rate of change of sea level. He presents a graph showing that the rate of change of sea level follows solar activity, indicating that when the sun is active, the oceans expand. Shaviv emphasizes that this relationship is statistically significant and proves that the sun has a significant effect on climate. However, he criticizes the IPCC for ignoring this evidence and reaching their own conclusions. Shaviv argues that even if the mechanism behind this effect is not fully understood, it should still be considered in climate models. He also mentions that the mechanism is now understood to be related to cosmic rays. Ultimately, Shaviv asserts that the sun's influence on climate cannot be overlooked.
00:55:00 In this section, Nir Shaviv discusses the difficulties in obtaining funding for his research on cosmic rays and climate. He explains that grant proposals are often reviewed by external reviewers who are usually biased against his work, making it extremely hard to secure funding in a standard way. However, he has been able to receive some funding directly from the Israeli government due to the more open-minded nature of the scientific community in Israel. Shaviv mentions that the most important funding would be to run the experiments in Denmark, which would require hundreds of thousands of dollars over several years. He also suggests needing around $50,000 a year for other operational costs.

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After a lengthy conversation, the host wraps up the discussion by asking if the guest has any additional points to make, but the guest suggests discussing the weather instead for a lighter topic. Ultimately, they decide to conclude the conversation, with the host expressing their enjoyment and gratitude for the guest's valuable insights and proposing the possibility of having them back on the show in the future.