The best thing about studying history comes from the lessons we can learn to better inform the actions we take today. During my freshman year at Yale, my class in “Global Environmental History” discussed a drought that struck a settlement in part of the Levant. The villagers faced a choice: Adapt to the transformed conditions, move or die. They failed to adapt, they chose to stay put and they suffered the consequences.

President Vladimir Putin’s recent annexation of Crimea and the uncertainties surrounding his potential next moves demand that the United States and her allies re-evaluate their strategy toward Russia. Adapt to these new realities, or suffer the consequences of inaction and perpetuating the status quo.

There are several moves that can be made to counter Russia and hopefully motivate it to reassess the costs of continuing its hostilities. But among the most impactful is energy. If Europe wants to be the master of its own destiny, it needs to get off of Russian fuel and transition to a clean energy society.

Significant action by Europeans is largely handicapped by their dependency on Russian fossil fuels. Nearly one-third of Europe’s crude oil and nearly 40 percent of its natural gas is supplied by Russia. Europe can be grateful for its mild winter (unlike us here in New Haven), which has left gas storage at around 45 percent of capacity when it’s usually depleted at this time of year. While this may give Europe a small deal of maneuverability in the short term, it cannot bank on such luck again. They’ll likely need Russian fuel for the next several years (although the United Kingdom’s shortsighted deal to buy Russian gas coming into place this year seems to limit the country’s options to diversify). But if Europe can chart a new long-term course for energy security, then they may deprive Mr. Putin both of one of his best bargaining chips and sources of national revenue. Even if a future Russia is capable of sustaining itself without European markets, Europe will have removed a powerful choke hold Mr. Putin currently possesses.

Fossil fuels provide the financial power for Mr. Putin to execute his hostile and illegal actions. Let’s cut him off.

Two legitimate options exist for the U.S. and Europe moving forward: Shift Europe’s primary natural gas source to the U.S. and significantly boost development of renewable energy projects. Now full disclosure: I’m an environmentalist. And that’s exactly why I’m considering this situation from a geostrategic perspective. There are several important calculations to consider with this strategy, and they all deal with cost. Can Europe afford the bump in prices when switching from Russian to American gas? When would such a shift be able to realistically occur? How many renewable projects can be implemented that substantially reduce Europe’s fossil fuel portfolio, and at what price? When will sufficient safeguards be put in place for natural gas drilling so that development doesn’t come at ruinous costs to human and environmental health (like fracking)? These questions can’t be answered quickly. But the most important take-away from them is that the cost of inaction is a too steep of a price to pay, and less oil, safer natural gas extraction and transportation and better integration of renewable energy offer a legitimate way forward that avoids incurring the bill.

Just as with dithering and business-as-usual for addressing global warming, surrendering our resolve to act intelligently puts human welfare and safety at risk. Energy, the environment and security are inextricably linked. Vladimir Putin has just given us an impetus and an opportunity to both weaken his position and address the threat multiplier of climate change by asserting that our energy future will be cleaner. If there was ever a time to recognize the strategic argument about the power of renewable energy to reduce the influence of fossil fuels and break one of Russia’s main financial spigots and leverage points, it is now. As if all the other reasons weren’t good enough.

Mr. Putin is taking the long view, and our leaders must as well.

Sam Teicher is a first-year student in the School of Forestry & Environmental Studies. Contact him at samuel.teicher@yale.edu.