The Ontario Secondary School Teachers' Federation, one of Ontario's largest teachers' unions, wants to bolster its strike fund, apparently readying itself for possible labour action when its current contract expires in August 2017.For the sake of students, parents, and rank-and-file teachers who would rather focus on their classroom duties than labour action, let's hope the union leadership considers recent education spending increases in Ontario and the fiscal realities facing the province.Ontario is simply in no position to increase teacher salaries. The province will run its ninth consecutive budget deficit in 2016/17, and will see its net debt climb to more than $300 billion. Simply put, provincial finances do not permit further increases to teacher salaries.Furthermore, despite misguided rhetoric about “cuts” in funding and inadequate spending on education, the reality is that rapid spending increases in the public education sector—and specifically on teacher compensation—have been major drivers of overall provincial spending growth in recent years.For example, between 2003/04 and 2012/13 (the last year of available comprehensive data) spending on education in public schools in Ontario increased by 50 per cent. Almost $25 billion was spent on public school education in 2012/13, $8.3 billion more than was spent a decade earlier.It's important to put this spending in context by taking inflation and changes to enrollment into account. During the same 10-year period, the number of students enrolled declined by almost five per cent.Adjusting spending by inflation and the number of students reveals that expenditures per student increased to $12,299 (inflation-adjusted) from $9,193, a 34 per cent increase in per student spending in a single decade.These data demonstrate that the reality of education spending in Ontario has been a story of dramatic increase--not of cuts or spending restraint.And where did all of these extra dollars for education go?Unsurprisingly, a large chunk went to increased spending on compensation for public school employees (mostly teachers). Spending on wages and salaries for public school employees grew by 48.4 per cent during that decade. In fact, the single fastest growing component of education spending during this time was money directed to teacher pensions, which more than doubled—growing by more than 100 per cent.Of course, everybody agrees that teachers are an extremely important part of our community and need to be paid a fair wage. However, compensation decisions must also be made in the context of the fiscal realities facing the province, and the ability of the taxpayer to foot the bill for further wage increases.Given that Ontario has dedicated tremendous additional resources to education over the past decade, any demands for further increases by teacher unions should be met with skepticism by Ontario taxpayers.If teachers unions across Ontario consider the history of recent growth in education spending in Ontario and adjust their expectations to match the fiscal realities facing the province, perhaps new negotiations can result in deals that are fair to Ontario taxpayers and that don't result in labour disputes that hurt students, parents and teachers.Deani Van Pelt and Ben Eisen are analysts at the Fraser Institute.