People march motivated either by despair or hope. In the case of the People's Climate March, it is appropriate to be motivated by both.

Despair because of damage already done by a changing climate: sea levels rising to threaten a billion people, global temperatures increasing, agricultural yields declining in Africa where the poor suffer most, species lost at a rate a thousand times higher than pre-industrial levels. And despair over missed opportunity, as some governments, such as the current U.S. administration, fail to adopt policies which we know would get us to a better place on climate change, economic growth and the well-being of people.

But much more important, people will march tomorrow in a spirit of hope -- based on experience and analysis that there is a path to a better future across almost every area of economic activity, and evidence that around the world opportunities for this better future are being seized. Because of our work at WRI and with our many partners and supporters around the world, we are confident in these reasons for hope:

  • We know cities can be more competitive, less polluted and more livable than they are now, at a lower cost. We know that cities don't need to lose 10 percent of their income to congestion and another 10 percent to pollution. We are encouraged that more than 7,000 cities have signed up to the Covenant of Mayors to do things differently.

  • We know we can nourish more people by wasting less of the food we produce. We know restoring degraded landscapes can support communities and livelihoods, and absorb massive amounts of carbon from the atmosphere. We are encouraged that 34 countries have recently committed to restore 365 million acres (148 million hectares) of degraded land.

  • We know that countries don't have to choose between a healthy environment and a healthy economy. The world needs to invest $90 trillion in infrastructure between now and 2030. We know that making those investments sustainable will actually cost less, improve competitiveness and help limit the most severe impacts of climate change. We are encouraged that more than 240 major global companies have committed to decarbonize their operations at a pace dictated by what the science demands, not by the short-term whim of stock markets.

  • We also know that the Paris Agreement on climate change can help vulnerable communities around the world, and advance countries' strategic interests at home. If the U.S. chooses to engage constructively, it can bolster its strategic and business interests, while creating modern U.S. jobs and supporting the international action that most Americans want. The U.S. administration unfortunately is acting to stifle the climate action needed to create a healthier economy and planet.

So for the moment we must straddle the emotions of hope and despair, a cognitive dissonance that juxtaposes inspiring evidence of hope and leadership in some spheres against inertia and untaken opportunities based on bad economics in others.

As a leading environmental and economic research institute, WRI has for 35 years taken a rigorous, evidence-based approach to explore policies and actions to address climate change. WRI has one of the longest histories of any organization working on this issue, helping to organize one of the first major international meetings on climate change way back in 1985. Over the years, we and many others have built up a deep stock of evidence that trade-offs between climate action and progress are false. With the right policies and modern leadership there is a much better way forward.

That's why on Saturday, our staff will march from our Washington office to the White House, joining hundreds of thousands of other people in the United States and around the world in a spirit of belief and determination. That's why we march.