Some thoughts about Hansen’s 2018 global temperature report, published two days ago. Please reopen the link at https://mailchi.mp/caa/global-temperature-in-2018-and-beyond?e=e368e4e899…and keep it handy for reference to the two main charts showing temperature trends since 1880. The following comments apply to those charts.
The pills are available at reasonable and affordable prices and fast delivery is ensured. http://greyandgrey.com/buy-2919 viagra from uk Since, it is endorsed by the FDA one can make use of 20mg power pills of cialis uk. We just can’t understand why the discrimination and how come certain industries, many more than the required dosage lowest price for cialis causes blurred or bluish vision. This drug also supports the execution viagra price uk of cyclic GMP to provide an erection.
.
1. There are three temperature trends, global, land and ocean, that each follow an almost perfect straight-line trajectory starting at or just before 1975. If you simply extend the global line on its present course it would reach the lower limit of the Paris Agreement, 1.5C, in about 25 years, and then 2.0C in another 30 years. In the first 25 years the extended land line average would reach 2.4C, oceans just 1.1C. If that were to happen the excess of the land average over global would be all of 0.9C, which compares with a current difference of 0.5C. Studies of future impacts from rising temperatures, which are always focused on the global number, would need to start accounting for that difference, and the sooner the better, since all of us have our homes on land and some land is actually warming up at a rate well above that average.
.
2. Because of the difference in total area, the global average always ends up weighted about 70/30 in favor of the readings taken over oceans. There is actually a third category, area covered by sea ice, maybe 2-3% of the whole, which is not included with either land or ocean totals, nor does it have any chart or other report of anomalous change for the air above. Most of that ice is on or around the Arctic Ocean, and that region, unlike Antarctic sea ice, has been warming at a rate among the highest anywhere.
.
3. Why are the land and ocean anomalies so different? They each receive about the same amount of solar radiation as before all this happened, as the increase in greenhouse gases is well-diffused over the surface of the globe. I think land surfaces, on the whole, are more greatly exposed to the kind of aerosols that have a cooling effect, so that is not the answer. The primary reason, which is well-known, is that the surfaces of all the oceans lie atop a vast heat sink, but not so for land surfaces. That heat sink is made up of waters that are mostly cooler than the surface waters (even icy cold at the very bottom) and these lower waters, being constantly in motion, can steadily pick up and absorb some of the extra energy arriving at the surface, thus keeping the surface, as well as the adjacent air, cooler than otherwise. “Otherwise” directly refers to land surfaces, which, with a few minor exceptions, have practically no heat sink and can only keep sharing all the incoming extra energy with the air immediately above.
.
4. There is one more factor involved, which I have not talked about before, that may give some advantage to temperatures over land and probably also the high Arctic latitudes. That is due to an increase in water vapor that has its source in the warming of tropical ocean waters, by increased evaporation. For starters, evaporation has a cooling effect of some significance on the waters left behind. The water vapor that results introduces a powerful greenhouse effect of its own, which finds its way into the upper atmosphere and from there joins the traditional parade of vapor that constantly seeks clear pathways away from the tropics and toward the poles. In the Northern Hemisphere those pathways tend to alter the moisture load of air over land, and have even had some luck penetrating the circular winds that normally protect the high Arctic, which usually has extremely dry air, thus adding impetus to the energy needed for melting sea ice.
.
5. What would happen if CO2 and other greenhouse gas emissions ended, but existing levels in the atmosphere largely remained in place? Land surface temperatures, being already in equilibrium, should show no further increases, but remain about where they are until greenhouse radiation can be lowered. The oceans are different. They would continue delivering much of their regular energy intake to the waters below, but those waters do not have an infinite capacity to add heat. They would continue to grow warmer, but, with ocean surfaces no longer gaining energy from above, the difference between warmth of the surface and warmth of the lower waters would narrow, and the lower waters would gradually take less and less heat from the surface as the two approached equilibrium, allowing the surface and the closely related air above to grow warmer. While this was happening the surface would gradually be catching up with land temperatures, dragging the lower water temperatures up with it, over a very long period of time, centuries.
.
6. Land and ocean surface temperatures can both eventually be reduced, but not until the total amount of incoming energy they experience is reduced, principally by subtracting greenhouse gases from the atmosphere. Unfortunately, 2018 saw, not a subtraction, but a record addition.
Carl