Getty ImagesAs well as checking the news for updates on events in the Middle East, many New Zealanders are also nervously checking their KiwiSaver balances.What they see is more than a snapshot of their own savings, it’s a window onto world events – in particular the rough ride stock markets are having as the price of oil spikes because of the US-Israeli attack on Iran.Oil, for better or worse, is the lifeblood of the global economy, a crucial ingredient in many products and the fuel that moves goods around the planet.A reduction in supply – or even the expectation of reduction – pushes oil prices up. Since the Iran crisis, it has risen from around US$60 per barrel to more than $100, with some analysts saying it could reach $150.When transport costs rise, prices rise with them and inflation and interest rates follow. Households spend less, businesses sell fewer goods and services, and potentially cut jobs.Lower economic activity means lower company profits. Higher interest rates reduce future growth. When geopolitical crises erupt, investors become nervous and demand a higher return for taking risk.Put those forces together and the result is usually the same: falling share prices. Because KiwiSaver funds are heavily invested in local and global share markets, many New Zealanders are likely seeing their balances fall as well.Take the long viewSo what should KiwiSaver investors do? Nothing – seriously. If watching your balance drop is causing anxiety, the best response might simply be to stop looking. But it’s also important to remember stock markets are resilient beasts. This is not the first time markets have faced an oil shock. The 1973–74 OPEC oil crisis led to fuel rationing, soaring inflation and economic disruption not seen since the 1920s. Stock markets around the world – including in New Zealand – felt that pain, with the Dow Jones and the NZ share market both falling by roughly 40%.But markets recovered. Returns remained weak for much of the 1970s, but over the following decades global share markets went from strength to strength.The first Gulf War in 1990 had a similar, though smaller, effect: rising oil prices, higher inflation and falling share prices. Once again, markets eventually recovered.For most of us, KiwiSaver is a long-term investment. Even if you are approaching retirement, most people will live several decades beyond it. Unless you need the money today, what happens in markets this month matters far less than what happens over the next ten or 20 years.On that timescale, the current crisis will likely be a blip that barely registers. Even the pain of the 1970s barely stands out when you look at a 100-year chart of the S&P 500 index against its long upward climb.Volatility – like we are seeing now – is the price investors pay for higher expected returns in the long run. It is felt most by investors in “growth” and “aggressive” KiwiSaver funds, which are heavily invested in shares.But those higher-risk funds have historically produced higher returns. Since KiwiSaver was introduced in 2007, investors have lived through the global financial crisis, COVID, trade wars and a period of very high inflation. Each caused markets to fall and created uncertainty for investors.Yet the cumulative return on a typical KiwiSaver growth fund since 2007 is around 240% – far higher than could have been earned in safer investments over the same period.The upside of volatilityVolatility is our friend when it comes to investing. It just doesn’t feel good while we are experiencing it. In fact, falling markets can sometimes help long-term investors.KiwiSaver contributions are invested regularly – usually every payday. Most funds invest those contributions immediately rather than trying to guess the “best” time to enter the market. That is probably a good thing, because there is little evidence that fund managers can reliably time the market.When prices are high, your contributions buy fewer shares. When prices fall, the same contribution buys more.Consider a KiwiSaver member contributing around $100 a month. If your fund was to invest in a single company with a share price of $10, you can would buy ten shares. If the next month the price falls to $5, that same $100 buys 20 shares. When prices eventually recover – as they usually do – you benefit from owning more shares than you otherwise would have.This process is known as “dollar-cost averaging”, and it underpins one of the most reliable sayings in finance: it is not timing the market that matters, but time in the market.Despite all the gloomy predictions and short-term pain right now, for KiwiSaver investors this is largely background noise.And let’s face it, if global share markets ever did collapse permanently, leaving KiwiSaver balances worthless, retirement savings would probably be the least of our concerns.Aaron Gilbert does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.