Surface measurements have various major sources of error, which have to be guestimated away in an ad hoc manner. The only data that is arguably good enough to estimate the rather small changes in climate is Australia, Britain, and the US – which on the whole have not been warming as measured by surface instruments. And even for them, the warming estimated from surface instruments is rather similar to various sources of error, that have to be “corrected”. The main contribution to global warming as measured by surface instruments comes from sources where you can get any result you want by rather arbitrarily deciding some data is good enough to include, and some data is not, by cherry picking particular events – for example warm nights indicate America is warming, but hottest days indicates America is cooling. You can always find one indicator to be alarmist about, but on the whole, where our data is good, surface instruments indicate little or no global warming. Because our surface instrument database is noisy, inaccurate, and incomplete, there is plenty of room to spin it any way one pleases.

The most precise measurement of global warming comes from satellites, which indicate a warming of one degree centigrade per century.

Recent changes in the icecaps indicate slight warming over the last thirty years ago, though the antarctic icecap has increased by almost the same amount as the arctic icecap has decreased, but the icecaps still have substantially more ice than a hundred years ago. The landing sites of early antarctic explorers are now behind a vast barrier of thick, and very old, ice impenetrable to icebreakers. A century ago there was too much open water at the North Pole, even in midwinter, to access it by dog sled, yet today, you can access it by dog sled in winter. Early attempts to reach the North Pole by dog sled had huge problems with open, ice free areas of water. Recent efforts to recreate those trips using identical equipment just took a straight line over solid ice.

The worlds biggest glaciers, the ones in the Himalayas are growing. Greenland glaciers are arguably shrinking, but by a miniscule amount. Glaciers do not tell you today’s weather as compared to yesterday, but today’s weather as compared with a very long time ago. Which fits with the experiences of arctic and antarctic explorers a century or so ago. Different glaciers are giving different indications, which is consistent with the conjecture that some years, some decades, and some centuries are warmer, and others are cooler.

So, lukewarming is true, for the moment, natural variation is true, and catastrophic warming is not true.