There has been essentially no global warming since 1998. Some would choose 1997, others would more conservatively use 2002 as the proper starting date, based on satellite data. Of course, this is quite unexpected, since CO2 — a leading GHG, which climate models presume to cause anthropogenic global warming (AGW) — has been increasing rapidly in the 21st century.
Even if we cannot readily find the cause for the “pause” — as it is sometimes called — we can be absolutely sure that it was not predicted by any of the dozens of the UN-IPCC’s General Circulation Models (GCMs). Therefore, logically, such non-validated GCMs cannot, and should not, be used to predict the future climate — or as a basis for policy decisions.
Here I would like to discuss some of the possible causes for the GW “hiatus.” Its existence is creating a scientific challenge for climate skeptics — and a real crisis for alarmists; it can no longer be ignored by any who consider themselves to be scientists — nor, indeed, by responsible politicians.
One possibility, of course, may be that the pause is simply a statistical fluctuation, like tossing a coin, with 15 to 18 heads in a row. Such an explanation cannot be dismissed out of hand, even though it has a very low probability — which becomes even smaller with each passing year of no GW. Obviously, climate alarmists like this possibility — although the number of such ‘true believers’ is shrinking. Most have started to look for a physical cause for the pause — an explanation of why current GCMs are failing to match observations.