Dr. Andrew Dessler has been one of my most valuable and consistent advisors on the finer points of climate science, which makes sense, because he literally wrote the book, “Introduction to Modern Climate Change”, that is used in many college classrooms.
I spoke to Dr Dessler a couple weeks ago, and wanted to hear more simple explanations of climate science, since the recent year of weather extremes has a lot of people who might not have thought much before about climate, whether this is indeed a problem….
Worth a look if you have someone like that in your circle.
See also my previous post from this interview here – and stay tuned for more nuggets.
I sure wish he would have pointed out that water vapour is the most impactful variable on global energy imbalance and therefore greenhouse gases. Walter Jehne outed this in his early Harvard lecture, as being the conclusion of the Carter appointed taskforce. But they also said atmospheric water vapour was impossible to measure accurately so they settled for carbon dioxide which is must easier to track and measure. Jehne and others go on to explain that landscape degradation is largest factor in destabilizing hydrological (water vapour) cycles and causing severe weather events which accentuate effects of global heat imbalance. Fixating on the reductionistic logic of fossil fuel combustion and carbon pollution ignores the symbiotic interactions of civilization with landuse: degrading forest cover, urban heat islands, floods/drought cycle of destruction of top soil’s water retaining effects, and the biotic pump effect of vegetation.
Hi Ian,
Uncertain what you mean by “water vapour is the most impactful variable on global energy imbalance and therefore greenhouse gases.” – particularly the “and therefore” bit. On Earth with current development of the sun’s evolution, it’s the other way around. Persistent greenhouse gases + current solar flux is why we have any meaningful quantity of water vapor or liquid surface water. The sun can’t do the heating alone and a given parcel of water vapor is condensed out in weeks without extra heat to replenish by evaporation. (that’s why ice ages are dry). Fourier deduced that and wrote it up in the 1820s. The sun’s still too dim to sustain free water in the air without something else trapping some of the IR that’s headed to space.
Jehne appears to have fixated on his specialty as the cure for warming, but he fails to deal with the fact that the increase in available energy in the climate, caused directly by the increases in CO2, methane, nitrous oxide and flourinated refrigerants, is deeply affecting the hydrological cycles worldwide, even in unfarmed areas.
Intensification of hydrological cycles has been a predicted direct result of the increased downwelling IR from increased persistent greenhouse gases – since first predicted in the 1960s is is now observed in line with the physics.
The IPCC and other large reviews of the causes also clearly indicate that land uses affects temperatures, too – some changes have a cooling effect, some a warming effect. And the Dust Bowl here clarified the feedback loops when the wrong farming approach is applied in arid regions. But the -primary- driver of the rapid acceleration in temperatures now is the fossil carbon we dig up and set fire to. The IPCC (and other groups) also include shifts in land use and methods of sequestration including the methods Jehne promotes. It’s more than a simple focus on fossil fuels, but that is the largest issue to address.
Fixing our farming methods will help. It is not a cure-all for the other factors. I searched around a bit and three different references to Jehne suggested he doesn’t think we can get off of fossil fuels. That’s his opinion, but it’s the opinion of a soil biology specialist – not experts in energy systems or engineering.