It's a harder direct relation to show that it appears. On the surface, warmer = less ice, file under "duh", but while it probably is that simple, showing a causal relation is a more difficult.
The thermal expansion aspect of the question is easy enough. Warmer air warms the ocean surface which slowly warms the ocean. About 90% of the heat trapped by man made climate change currently goes into the oceans. See here, or here. That's an enormous amount of heat, but the Oceans are large enough that the expansion and increase in temperature moves pretty slowly. About 1/3rd of the current sea level increase is attributed to thermal expansion, which works out to about 1/3rd of 1 inch every 10 years, or, roughly 1 mm per year. (Thermal expansion only).
Melting glaciers are more difficult to show a direct relation. By this source there are over 130,000 glaciers in the world, and while there is a fair bit of overlap, to properly show a causal relation, you'd need to look at individual glaciers to determine the cause. You wouldn't need to look at all 130,000, but you'd need a solid sampling to demonstrate a causal relation.
What's more, under the right conditions, glaciers can grow larger as the local weather grows warmer. Warmer weather can lead to increased snowfall, which can enable glaciers to grow, even in a warmer climate. Article on that here.
The two simplest ways to make this argument is looking at the percentage of glaciers that are melting or to look at total ice volume in those glaciers. (For the 2nd one, I'd ignore the continental ice sheets and just look at the smaller glaciers), but it can be done either way.
By this article, about 90% of glaciers are shrinking world wide. If climate wasn't changing, I'd expect that to be closer to 50%. Even when climate is changing, for example, when ice ages stop are start, those are usually driven by the Northern Hemisphere having colder summers (begins the ice age) or the Northern Hemisphere having warmer summers (ends the ice age), with the Southern Hemisphere behaving in the opposite way. That suggests to me that even during the rise or fall of ice ages, 90% of the glaciers moving in the same direction probably doesn't happen. 90% of glaciers losing ice appears to be strong evidence of being caused by climate change, but that ratio lacks statistical teeth because there's no historical data to show that 90% of the world's glaciers losing ice is unusual. It seems unusual, but it's difficult to prove.
The other avenue would be to look at the total amount of loss of ice in the world's glaciers. See page below. I didn't see a number listed anywhere, but a quick calculation, Earth's glaciers are losing on average about 60 cubic miles of ice in an average year. That's pretty significant ice loss.
But both these arguments have the same weakness. Both seem to be very good evidence, neither shows a causal relation. The only way to do it scientifically would be to go through a large enough sample size of glaciers and show a pattern of causality. At least, I don't see any other way to show a direct relation.
That said, saying "90% of the worlds glaciers are losing ice" is a pretty good argument, as is saying that Earth's glaciers lose about 60 cubic miles of ice in an average year.