I'm on strike at the moment because of the pension changes, I'm an early career researcher. I'll give it a go explaining whats happened, but it may be a bit garbled as I'm a bit exhausted after spending all morning on the picket lines, it's bloody freezing out there!
I'm guessing you're working at a university, so probably your best bet is to just chat to a few people on your nearest picket line. Going on strike is always a personal decision, so some people may have slightly different reasons than others. I'll try and stick to generally to the ucu (university and college union) message.
The USS (university pension scheme) has stated they will be changing pensions from a career averaged defined benefit (known amount paid out, based on average salary over your employment) to a defined contribution scheme (known amount paid in). This pension scheme covers older universities (pre 1992), the newer universities can join the teachers pension scheme (a government backed defined benefit scheme) . This change follows the ending of a pension based on your final salary (in 2011ish) and changes in the last year or so capping the salary that is used to calculate the pension to £55k. This change has shown the average lecturer is likely to be around £10,000 a year worse off in retirement. It also will pass the risk of whether the investments are up/down at retirement onto the staff whereas currently the scheme is backed by all pre 92 universities, if on university folds the pension is shared amongst the rest with Cambridge at the top as the richest.
This change is due to recent valuation of the USS which showed it had a £7.5 billion deficit. There's a lot of debate amongst academics about how this pension valuation was calculated and whether it was done correctly. Currently they will not release the figures the pension valuation was based on or what assumptions were made (which you can imagine really pisses off academics).
The pension scheme was valued 3 times in the last 6 months or so giving different values of deficit, and this last valuation was accepted by the UUK (Universities UK, a body that represents all UK universities.) During the period of these valuations the UUK has sent all vice chancellors a survey (which was leaked
https://www.theguardian.com/uk-news/2018/feb/21/universities-strike-blamed-on-vote-by-oxbridge-colleges). In this survey they asked whether the universities were happy with the level of risk in the pension scheme and also asked if they were thinking of setting up their own pension schemes. 42% of the survey responses wanted to lower the risk so the USS started de-risking the pension by buying gilts and bonds, which obviously effects future growth and the pension valuation. It has since been leaked that a large number of the votes to de-risk were from Oxford and Cambridge colleges who were allowed to vote individually, giving a large weighting to only 2 of the 80ish universities in the scheme.
The universities and UUK have said they will continue to pay the same amount into the staff pensions (18%) however 4.75% of this will be used to reduce the deficit of the defined benefit pension and 13.25% directly into the staff members pension pot. This is pretty good by private business standards, however, I think it should be pointed out that pay is significantly lower than the private sector and that the staff have started pensions later due to studying for 7+ years, and that a lot of people are on fixed term and insecure contracts.
In addition to the pension there is also a feeling of 'the last straw' about this strike because of the general marketisation of universities within the UK, through massive tuition fees and universities investing more in infrastructure than staff.
Tomorrow the vice chancellors of the universities will be meeting in London to resume discussion, however the UUK have already stated that they will not discuss closure of the defined benefit pension or the valuation of the pension.
Personally I'm undecided about the closure of the move to a defined contribution scheme, I like the flexibilty to allow early retirement but feel that too little will be paid in by my employer. I work at one of the Oxbridge universities so I feel particularly motivated to strike, I've never gone on strike before and only joined the union 2 weeks ago!