I'm a business major and a general amount of my studies has been studying economics and in turn a lot of recessions. However, it feels like recessions that stretch worldwide have become more common since at least the '80s. Personally, this is the second economic downturn I've lived through, and I was born shortly after the tech bubble but. Is there a historically relevant reason as of to why they feel like they happen more often, or is the concept of history so vast that economic downturns get buried in all of it?
This is a bit of a difficult issue to discuss on this sub due to the 20 year rule, so I can't discuss the 2008 global financial crisis nor the current pandemic, only the period from the 1980s to 2000.
The general opinion of macroeconomists is that, so far from there being more recessions, the 1980s-2000 period (and beyond) saw fewer, at least in developed countries with good statistics. This result is so well known that it has a name: The Great Moderation. This isn't just a US thing, but is generally the case amongst developed countries, though the date of the start of the fall in volatility varies, e.g. Germany saw a fall in volatility in 1971, Canada in 1988 (Summers, Table 1, page 7).
The commonly proposed explanations of The Great Moderation are better monetary policy, structural changes in inventory management, and good luck. These explanations could all be right, to some extent. In turn:
Average inflation fell during this period across the developed world, and in many countries the fall coincided with the fall in volatility, but in France, Germany and Italy volatility fell before inflation.
Inventories act as a buffer between goods production and goods sales, if more is produced than sold in a period then the difference can build up as inventories, if demand is higher than production then inventories can be run down (obviously this running down is limited by availability). Changes in inventories are measured as part of calculating GDP statistics and Peter Summers in a cross country study found that falls in the volatility of these were correlated with falls in the volatility of GDP.
Luck is hard to define, let alone measure. Peter Summers looked at oil price shocks and found a lack of connection.
You did ask about global recessions, not just volatility in each country. Again, global recessions aren't new, apart from the Great Depression of the 1930s, the IMF has labelled periods since 1960 in "in 1975, 1982, 1991, and 2009". They do note that the 2009 crisis was the most severe one, but that still was about 18 years after the 1991 crisis, compared to the 7 years from 1975 to 1982 and 9 years to 1991.
In summary, so far from there having been more widespread and severe recessions since the 1980s, there was a moderation. Therefore your second explanation seems more likely to be right.
Sources (not given in text)
Peter Summers, 2005, What Caused The Great Moderation, Federal Reserve Bank of Kansas City Economic Review, Q3 2005.